Manufactured Foundation Drainage System Installation.

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Material is generally supplied in rolls that is simply applied to the waterproofed walls by using double-sided masking tape, sealant, or other adhesives recommended by the waterproofing membrane manufacturer; see installation photograph, Fig. 2.10. The material is installed like roofing shingles, overlapping in the direction of water flow, starting with the lower portion first, lapping higher elevation goods over the already installed piece to match the manufacturer-supplied flange edges (Fig. 2.11). Drainage systems can also be applied directly to lagging prior to concrete placement (Fig. 2.12).

FIGURE 2.10 Application of drainage system system using termination bar directly over terminating edge of waterproofing membrane.

FIGURE 2.11 Application of drainage system.

FIGURE 2.12 Drainage system being applied directly to founda- tion lagging.

The filter fabric material is always  applied facing out, and manufacturers provide additional fabric at ends to overlap all seams. The terminated ends of the material are covered with the fabric by tucking it behind the plastic core sheet. Side edges of the sheet are typically attached together by overlapping and applying an adhesive. Figure  2.13 shows a partially completed drainage system installed with appropriate drain field gravel backfill.

FIGURE 2.13 Installation of drainage field adjacent to foundation for completion of prefabricated drainage system.

Figure 2.14 details the use of drainage systems for under-slab drainage. Figure 2.15 details the use of these systems for horizontal transitioning to vertical drainage at a below-grade tunnel installation.

Backfilling should take place as soon as possible after installation; using the available site soil is acceptable. Backfill should be compacted as required by specifications using plate vibratory compactors. Caution should be taken during compaction not to damage the fabric material.

FIGURE 2.14 Manufactured drainage system used for below-slab drainage.

FIGURE 2.15 Below-grade tunnel waterproofing using both horizontal and vertical drainage application.

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WATERSTOPS - WATERPROOFING.

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Whenever a construction joint occurs in a below-grade concrete structure, a waterstop should be installed in the joint to prevent the transmission of water through the joint.

Construction joints, also referred to as “cold-joints,” occur when one section of concrete is placed and cured or partially cured before the adjacent concrete placement occurs. This occurs frequently in concrete structures at locations including

● Transitions between horizontal and vertical components
● When formwork is insufficient to finish the structure in one placement, such as long lengths of wall area
● Where design elements require a change in form design
● When concrete placement is stopped, for schedule reasons or end of workday

In most of these cases a joint is not actually formed; the cold or construction joint reference refers to the area of concrete structures where two different concrete placements have occurred (properties of concrete preventing it from forming an excellent bond to itself and the previously placed concrete). In addition, control joints are added to a poured-in-place concrete structure to control cracking that occurs from shrinkage in large placements. Control joints are typically recommended for installation at no more than 30 ft apart. The joints are typically the weakest points of the concrete structural components, but not subject to movement other than structural settlement.

Below-grade conditions present conditions that make it very likely that water, which is present under hydrostatic pressure, will infiltrate through these construction joints. To prevent this from occurring, waterstops are commonly specified for installation at every construction joint on concrete work below-grade. The capability of waterstops to prevent infiltration at these weak points in the structure is critical to successful waterproofing of below-grade structures, so their importance should never be underestimated.

Waterstops are used for waterproofing protection on a variety of below-grade concrete structures including

● Water treatment facilities
● Sewage treatment structures
● Water reservoirs
● Locks and dams
● Basement wall and floors
● Parking structures
● Tunnels
● Marine structures

Waterstops are premanufactured joint fillers of numerous types, sizes, and shapes.
Waterstops are available in a variety of compositions including

● Polyvinyl chloride (PVC)
● Neoprene rubber
● Thermoplastic rubber
● Hydrophilic (modified chlorophene)
● Bentonite clay
● Asphalt plastic

The first three, PVC and rubber types, are manufactured exclusively for use in poured-in-placed concrete structural elements. The remaining three, while mainly used for concrete installations, can be used with other building materials such as concrete block and are also excellent where installations involve metal protrusions in or adjacent to the construction joint. Manufacturers also make waterstops that are resistant to chemicals and adverse groundwater conditions. A summary of the properties of the various type water-stop is shown in Table 2.1. As with many products, manufacturers have begun making systems that approach “idiot-proof” installations.

 TABLE 2.1 Comparison of Various Waterstop Types

PVC waterstops have long been the standard within the construction industry. They are provided in a variety of shapes and sizes for every situation to be encountered, as shown in Fig. 2.16.

FIGURE 2.16 Typical PVC waterstops and their properties.

PVC waterstops with the dumbbell shape in the middle are used for installation where actual movement is expected in the substrate, typically not thermal movement but structural movement. Figure 2.17 shows an expansion joint installation with the bulb portion of the waterstop left exposed to permit movement. However, waterproofing applications require the joint to be filled with a properly designed sealant joint to permit a waterproofing below-grade membrane to run continuously over the joint.

FIGURE 2.17 Use of PVC waterstop in expansion joint.

The problem with PVC waterstops is their susceptibility to improper installation (99% principle) or damage during the concrete placement. The waterstop must be held in place properly during the first half of the concrete placement. This is accomplished by a variety of methods as shown in Figs. 2.18 and 2.19. This situation is not idiot-proof and must be carefully monitored for quality control to ensure that the waterstop remains positioned during both halves of the concrete placement activities. Far too often, the PVC waterstop ends up folded over, preventing it from functioning properly. In addition, workers installing the reinforcing bars will often burn, puncture, or cut the waterstop.

FIGURE 2.18 Placement and securing of waterstops at construction joints.

FIGURE 2.19 Placement of waterstop for first half of concrete placement.

In striving to make waterstops idiot-proof, manufacturers have created several alternatives to the PVC standard including many hydrophilic derivatives. These systems, along with the bentonite and asphalt plastic, are used mainly for control joints and not provided for expansion joints. These systems are simple to install, and do not have to be installed in both sections of concrete placements. The material is adhered directly to the edge of the first concrete placement in preparation for the second placement of concrete. Note this detailing in Fig. 2.20 and in the photograph of the installed product, Fig. 2.21.

FIGURE 2.20 Typical installations of hydrophilic or similar waterstop materials

FIGURE 2.21 Installed asphaltic waterstop.

The materials generally expand after being wetted by the water contained in the concrete mixture. This swelling action enables the materials to fill the voids within the joint to form a watertight construction joint. Since these products expand in the presence of water, they must not be wetted prematurely.

This requires that the second concrete placement take place almost immediately after the waterstop placement, otherwise the joint might expand if exposed to rain or dew. The asphalt plastic is not susceptible to moisture like bentonite or hydrophilic materials, but their limited elastomeric capabilities might prevent the complete sealing of the joint if some areas are not bonded properly.

The materials are easily installed in a variety of positions for properly detailing watertight joints below-grade as shown in Fig. 2.22. None is meant for exposure to the elements and must be completely covered by the concrete placement. As such, they present limited expansion capabilities for the substrate. When an expan-
sion waterstop material is required, the PVC or rubber types are required.

FIGURE 2.22 Several recommended uses of hydrophilic waterstop.

Waterstop size is determined by the expected head of water pressure to be encountered at the joint. Table 2.2 summaries the recommended waterstop and minimum depth of embedment into the concrete sub- strate for various head pressures. Actual site conditions vary, and these measurements should be used only as approximations.

 TABLE 2.2 Suggested Waterstop Sizing for General Conditions

Waterstop manufacturers will recommend actual joint design when actual job conditions are submitted for review.

WATERSTOP INSTALLATION - WATERPROOFING.

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PVC/Neoprene Rubber/Thermoplastic Rubber
Waterstops of this type are placed in the concrete formwork and tied or secured to firmly position the material during concrete placement. It is imperative that the waterstop is never allowed to fold over during concrete placement. Figure 2.23 shows some typical methods to secure the waterstop prior to the first concrete placement. Figure 2.24 details the method for installing waterstop using a keyed joint.

FIGURE 2.23 Securing of PVC waterstop for first concrete placement.

FIGURE 2.24 Formwork with keyway joint sys- tem. Note the bulb is centered directly in midpoint of the joint to ensure proper functioning as an expansion joint.

To secure the flange in place for both concrete placements, the waterstop is generally secured using wires tied to the reinforcing steel every 12 in. The wire should be tied through the first or second ribs of the waterstop flange, never going beyond the second flange as shown in Fig. 2.25.

FIGURE 2.25 Securing PVC waterstop for second con- crete placement.

Note that in each of these details the center bulb is directly in the midpoint of the joint. This is to ensure that the waterstop acts properly as an expansion joint during anystructural movement.

The bulb must never be placed completely in one side of the placement or it will lose all its capability to act as an expansion material. Nails or any other construction debris should not be allowed to puncture the waterstop bulb or any part of the flange near the bulb.

When using waterstops at construction joints, material with bulb ends makes securing to reinforcing steel easier by using wire rings that pass through the bulb but not the flange. Figure 2.26 details the steps using this system for both halves of the concrete placement.

FIGURE 2.26 Placement procedures for end bulb waterstop.

Placing PVC and rubber waterstops in the field usually requires some welding to joint ends of rolls or making necessary changes in plane. Waterstop should never be installed by merely lapping the ends together. The material must be heat-welded to fuse the ends together by using manufacturer-supplied splicing irons that melt the ends that are then held together until they cool, forming one continuous piece. Refer to Fig. 2.27 for a field weld application.

FIGURE 2.27 Field welding operation of PVC waterstop.

Testing of failed joints usually reveals that failures were either the cause of improperly positioned material, Fig. 2.28, (folded over during concrete placement) or where directional changes occurred in structure that the waterstop did not conform to. Whenever heat welding is used, the material is adversely affected at this point and its properties are not equal to the original material. Therefore it is recommended that whenever major directional changes are designed into a structure, the contractor should secure prefabricated fittings.

FIGURE 2.28 Improperly positioned, placed, and secured waterstop.

Waterstop manufacturers will usually provide a variety of premolded splice pieces for directional changes,
as shown in Fig. 2.29. Also, most manufacturers will offer to custom-make the required splices to ensure the successful applications with their material.

FIGURE 2.29 Typical manufactured PVC waterstop splices and transition pieces.

At all penetrations in below-grade slabs or walls, waterstop should also be installed continuously around the penetration to protect against water penetration. Figure 2.30 details the use of waterstop installed continuously around a structural steel column that penetrates the concrete slab over the foundation.

FIGURE 2.30 Waterstop application around structural steel column foundation supports.

Photographs in Figs. 2.31 and 2.32 show how complicated waterstop installations can become. Such detailing necessitates the use of premanufactured weld splices to ensure watertight applications. These photographs also emphasize how important proactive job-site quality-control procedures are, to verify that the PVC waterstop is installed and maintains proper positioning during concrete placement.

FIGURE 2.31 Placement of spliced PVC joint in form- work.

FIGURE 2.32 Field quality-control procedures ensure successful installation of waterstop.

HYDROPHILIC/BENTONITE/ASPHALT RUBBER - WATERPROOFING.

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These systems are all installed after the first concrete placement has occurred, with the materials attached directly to the first half by a variety of methods. The waterstop is supplied in rolls in lengths of several hundred feet and the material is adhered to the substrates by a variety of methods as recommended by the manufacturer.

Typically, the concrete does not need to be cured completely, as this would interfere with the placement schedule of the concrete. Substrate preparation is usually minimal, ensuring that there are no form release agents, fins, or other protrusions that can damage or puncture the waterstop during installation. Attachment is completed by a variety of methods, some as simple as nailing the strip to the concrete to hold it in place temporarily until the second half of concrete placement occurs.

It is imperative that the hydrophilic and bentonite materials are not left exposed to rain-fall before concrete is placed. If this occurs, the material will swell and lose all its capability to seal the joint after concrete placement. The photographs in Fig. 2.33 show a typical waterstop installation using a swelling material that is adhered to the substrate with sealant.

FIGURE 2.33 Installation of swell-type waterstop.

PREVENT CAPILLARY ACTION - CONSTRUCTION DETAILS.

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Construction details must be included to prevent natural capillary action of soils beneath foundations or below-grade floors. Capillary action is upward movement of water and vapor through voids in soil from wet lower areas to drier high areas. Capillary action is dependent upon the soil type present. Clay soils promote the most capillary action, allowing more than 10 ft of vertical capillary action. Loose coarse gravel prevents capillary action, with this type of soil promoting virtually no upward movement.

Capillary action begins by liquid water saturating lower areas adjacent to the water source. This transgresses to a mixture of liquid and vapor above the saturation layer.

Finally, only vapor exists in upper soil areas. This vapor is as damaging as water to interior building areas. Soil capillary action can add as much as 12 gal of water per day per 1000 sf of slab-on-grade area if insufficient waterproofing protection is not provided.

Microscopic capillaries and pores that naturally occur in concrete substrates create the ability for the concrete to allow water and moisture to move readily through below-grade walls and floors. This process is particularly sustainable when the interior space of the structure has lower humidity than the 100% humidity of the adjacent water-saturated soil and when the occupied space is warmer than the soil. These conditions present ideal circumstances for water to be actually drawn into the occupied space if not protected with waterproofing materials or at minimum vapor barriers where appropriate.

Water vapor penetrates pores of concrete floors, condensing into water once it reaches adjacent air-conditioned space. This condensation causes delamination of finished floor surfaces, mildew, and staining.

Therefore, it is necessary to prevent or limit capillary action, even when using waterproof membranes beneath slabs. Excavating sufficiently below finished floor elevation and installing a bed of capillary-resistant soil provides drainage of water beneath slabs on grade.

This combination of foundation drainage and soil composition directs water away from a structure and is necessary for any waterproofing and envelope installation. Refer again to Fig. 2.1 for recommended controls for proper surface and groundwater.

FIGURE 2.1 Below-grade drainage detailing.

WATERPROOFING: POSITIVE AND NEGATIVE SYSTEMS.

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In new and remedial installations, there are both negative side and positive side below-grade systems. Positive-side waterproofing applies to sides with direct exposure to water or a hydrostatic head of water. Negative-side waterproofing applies to the opposite or interior side from which water occurs. Examples are shown in Fig. 2.34.

FIGURE 2.34 Below-grade positive and negative waterproofing details.

Although both systems have distinct characteristics, as summarized in Table 2.3, the majority of available products are positive-type systems. Negative systems are limited to cementitious-based materials, which are frequently used for remedial applications. Some materials apply to negative sides of a structure for remedial applications but function as positive-side waterproofing. These materials include chemical grouts, epoxy grouts, and pressure grouts. Admixtures (material added or mixed into mortars, plaster, stucco, and concrete) have both positive and negative features but are not as effective as surface-applied systems.

TABLE 2.3 Comparison of Positive and Negative Waterproofing Systems*

The principal advantage of a negative system is also its principal disadvantage. It allows water to enter a concrete substrate, promoting both active curing and the corrosion and deterioration of reinforcing steel if chlorides are present. Positive-side waterproofing produces an opposite result—no curing of concrete, but protection of reinforcing steel and of the substrate itself.

Positive and negative below-grade systems include

● Cementitious systems
● Fluid-applied membranes
● Sheet-membrane systems
● Hydros clay
● Vapor barriers

CEMENTITIOUS WATERPROOFING SYSTEMS.

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Cementitious waterproofing systems contain a base of Portland cement, with or without sand, and an active waterproofing agent. There are four types of cementitious systems: metallic, capillary system, chemical additive systems, and acrylic modified systems.

Cementitious systems are effective in both positive and negative applications, as well as in remedial applications. These systems are brushed or troweled to concrete or masonry surfaces and become an integral part of a substrate.

Cementitious systems are excellent materials for use with civil and infrastructure projects, both above and below-grade, using both positive and negative applications. These projects generally consist of large concrete components that make the same generic composition cementitious systems relatively easy to specify and install without compatibility problems. Among the types of structures cementitious systems are used for:

● Tunnels
● Underground vaults
● Water reservoirs
● Water and sewage treatment facilities
● Elevator and escalator pits
● Below-grade concrete structures
● Swimming pools
● Cooling tower basins

In new construction, where costs and scheduling are critical, these systems are particularly effective. They do not require a completely dry substrate, and concrete does not need to be fully cured before application. This eliminates well pointing and the need for water control during construction. These systems apply to both walls and floors at one time, thereby eliminating staging of waterproofing operations. No subslabs are required for horizontal applications in new construction preventative waterproofing installations.

Finally, in cases such as elevator pits, the waterproofing is completed almost any time during construction as best fits scheduling.

All cementitious systems are similar in application and performance but repel water differently by the proprietary additives of a manufacturer’s formulations. Cementitious systems have several mutual advantages, including seamless application after which no protection board installation is necessary.

All cementitious materials lack crack bridging or elastomeric properties but are successfully applied to below-grade areas that do not experience thermal movement. However, below-grade areas are subject to freeze-thaw cycling and structural settlement. If these cause movement or cracking, a cementitious system will crack, allowing water infiltration.

⇒ Metallic systems   Metallic materials contain a mixture of sand and cement with finely graded iron aggregate or filings. When mixed with water to form a slurry for application, the water acts as an agent permitting the iron filings to oxidize. These materials expand...

⇒ Capillary/crystalline systems   Capillary/crystalline systems are mixtures of cement and sand in combination with proprietary chemical derivatives in dry or liquid form. The systems are applied in trowel, brush, or spray applications. Unlike other cementitious systems however...

⇒Chemical additive systems  Chemical cementitious systems are a mixture of sand, cement, and proprietary chemicals (inorganic or organic), which when applied to masonry or concrete substrates provide a watertight substrate by chemical action. Proprietary chemicals...

⇒ Acrylic modified systems   Acrylic modified cementitious systems add acrylic emulsions to a basic cement-and-sand mixture. These acrylics add waterproofing characteristics and properties to in-place materials. Acrylic systems are applied in two trowel applications, with a reinforcing...

Metallic Waterproofing Systems.

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Metallic materials contain a mixture of sand and cement with finely graded iron aggregate or filings. When mixed with water to form a slurry for application, the water acts as an agent permitting the iron filings to oxidize. These materials expand due to this oxidizing, which then effectively seals a substrate and prohibits further transmission of water through the material. This system is one of the oldest methods used for waterproofing (first patented in 1906) and remains today an effective waterproofing system. (See Fig. 2.35.) Metallic systems are applied in two or three coats, with the final coat a sand and cement mixture providing protection over base coat waterproofing where exposed. This final coat seals the metallic coats and prevents leaching or oxidization through paints or finishes applied over waterproofed areas. To prevent excessive wear, concrete toppings are installed over horizontal exposed surfaces subject to pedestrian or vehicular traffic.

FIGURE 2.35 Negative application of cementitious water- proofing.

If drywall or paneling is installed over the waterproofing, furring strips are first applied by gluing them directly to the cementitious system. This eliminates nailing the boards through the cementitious membrane. Carpet perimeter tracks should be applied in the same manner to prevent damage.

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Capillary/crystalline Waterproofing Systems.

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Capillary/crystalline systems are mixtures of cement and sand in combination with proprietary chemical derivatives in dry or liquid form. The systems are applied in trowel, brush, or spray applications. Unlike other cementitious systems however, capillary have the additional advantage of an application using only the dry mix product that is broadcast directly over concrete that has not yet reached final set and cure. This is referred to as the “dry-shake” method, commonly used on slab components as a vapor barrier, as additional protection with below-grade slab waterproofing systems, or as a stand-alone waterproofing system. A typical dry-shake application is shown in Fig. 2.36.

A capillary/crystalline system not only waterproofs, as a system itself; the chemical additives are able to penetrate into the concrete wall or slab and react with the calcium hydroxide and available capillary water present to form crystalline structures within the concrete itself. These crystalline structures block transmission of water through the sub- strate, adding additional water repellency to the envelope components.

FIGURE 2.36 Dry-shake application of crystalline cementitious waterproofing.

The chemical process begins immediately upon application of the waterproofing system but can take as many as 30 days to fully reach maximum repellency. Once fully cured, capillary/crystalline systems have been tested to withstand hydrostatic pressures as great as 400 ft of water head. These systems have other advantages compared to other cementitious systems, including the following:

● No need for a protection layer.
● Some products have stated capability to seal hairline cracks that occur after installation.
● Most are not harmed in the presence of chemicals and acids, making their application ideal for storage tanks, sewage treatment facilities, and similar structures.
● Penetrate and react with the concrete substrate to form additional “belt and suspenders” protection.

Curing installed systems is critical for adequate crystalline growth. The curing should continue 24–48 hours after installation. Concrete or masonry substrates must be wet to apply these systems, which may be installed over uncured concrete.

In exposed interior applications, coating installation should be protected by plastic, dry- wall, or paneling applied over furring strips. Floor surfaces are protected by concrete overlays, carpet, or tile finishes.

Chemical Additive Waterproofing Systems

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Chemical cementitious systems are a mixture of sand, cement, and proprietary chemicals (inorganic or organic), which when applied to masonry or concrete substrates provide a watertight substrate by chemical action. Proprietary chemicals are unique to each manufacturer, but typically include silicate and siloxane derivatives in combination with other chemicals. While the chemicals do not penetrate the substrate like the other cementitious systems, chemical systems also effectively become an integral part of the substrate after application.

Chemical cementitious systems, approximately 1 16-in thick, are thinner applications than other cementitious products. As with all cementitious systems, concrete or masonry substrates need not be dry for application. Chemical systems do not require curing, but capillary systems do.

Acrylic Modified Waterproofing Systems

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Acrylic modified cementitious systems add acrylic emulsions to a basic cement-and-sand mixture. These acrylics add waterproofing characteristics and properties to in-place materials. Acrylic systems are applied in two trowel applications, with a reinforcing mesh added into the first layer immediately upon application. This mesh adds some crack-bridging capabilities to acrylic installations. However, since the systems bond tenaciously to concrete or masonry substrates, movement capability is limited.

Acrylic cementitious systems are applicable with both positive and negative installations.
Concrete substrates can be damp, but must be cured for acrylic materials to bond properly. Alkaline substrates can deter performance of acrylic-modified cementitious systems. Acrylic-modified materials are applied in a total thickness of approximately  1 8 in.

Reinforcing mesh eliminates the need for protective covering of the systems on floor areas in minimal or light-traffic interior areas.

The properties of all types of cementitious systems are summarized in Table 2.4.

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Before applying cementitious systems, substrates must be free of dirt, laitance, form release agents, and other foreign materials. Manufacturers typically require concrete surfaces to be acid-etched, lightly sand-blasted, or bush-hammered to a depth of cut of approximately 1 16 in. This ensures adequate bonding to a substrate.

All tie holes, honeycomb, and cracks must be filled by packing them with an initial application of the cementitious system. Refer to Fig. 2.37. Construction joints, wall-to-floor joints, wall-to-wall intersections, and other changes in plane should be formed or grooved with a 1-in by 1-in cutout to form a cove. This cove is then packed with cementitious material before initial application. This is a critical detail for cementitious systems, as they do not allow for structural or thermal movement. This cove prevents water infiltration at weak points in a structure where cracks typically develop. At minimum, if a cove is not formed, place a cant of material at the intersections, using a dry mix of cementitious material.

FIGURE 2.37 Patching of concrete substrate prior to waterproof- ing application.

Cementitious systems do not require priming of a substrate before application. However, wetting of the concrete with water is necessary.
Cementitious systems are available in a wide range of packaging. They may be premixed with sand and cement in pails, or chemicals and iron may be provided in separate containers and added to the sand-and-cement mixture. Products are mixed in accordance with manufacturers’ recommendations, adding only clean water.

Typically, cementitious systems are applied in two coats after the initial preparatory work is complete. First coats may be proprietary materials only. Second coats are usually the chemical or metallic materials within a cement-and-sand mixture. Third coats are applied if additional protection is necessary. They consist only of sand and cement for protecting exposed portions or adding texture. Acrylic systems often require a reinforcing mesh to be embedded into the first-coat application.

Thickness of a system depends upon the sand and cement content of the coatings. The systems are applied by trowel, brush, or spray. Refer to Fig. 2.38. Certain systems are dry-broadcast over just-placed concrete floors to form a waterproofing surface integral with the concrete.

FIGURE 2.38 Spray, trowel, and brush applications of cementitious waterproofing.

This method is referred to as the dry-shake application method. Broadcasting powder onto green concrete is followed by power troweling to finish the concrete and distribute the chemicals that are activated by the concrete slurry. This method should not be used for critical areas of a structure subject to water head, as it is difficult to monitor and control. Refer again to Fig. 2.36.

FIGURE 2.36 Dry-shake application of crystalline cementitious waterproofing.

To protect exposed floor applications, a 2-in concrete topping, carpet, tile, or other finish is applied over the membrane. Walls can be finished with a plaster coating or furred out with adhesively applied drywall or other finish systems.

These systems require proper curing of the cementitious waterproof coating, usually a wet cure of 24–48 hours. Some systems may have a chemical additive to promote proper curing.

These systems do not withstand thermal or structural substrate movement. Therefore they require special detailing at areas that are experiencing movement, such as wall-floor intersections.

It is advantageous to install negative cementitious systems after a structure is completely built.
This allows structural movement such as settling to occur before application.
A typical installation for all cementitious systems is elevator and escalator pits similar to Fig. 2.39, which details the installation for this type application. Note that the system calls for two coats with no protection course and the typical cove detailing at the wall-floor intersection. This detailing would be improved by the installation of waterstop at these intersections. Some cementitious manufacturers will permit the use of their product to supplement protection of these intersections when waterstop is not used, as shown in Fig. 2.40.

FIGURE 2.39 Typical cementitious cetailing for elevator pit waterproofing.

FIGURE 2.40 Application details for critical wall-to-floor juncture, with product run continuously under the wall structure.

In this detail, the cementitious product is installed continuously on the floor-foundation slab under the wall area intersection. Further protection could be added by installing premanufactured drainage systems on the walls and below-slab locations.


While not often recommended for below-grade applications subject to hydrostatic pressure, concrete block walls are sometimes used as the wall component. The mortar joints are the weak points in this design, and cementitious systems often are not able to protect against the settlement cracking that occurs. Typically, fluid-applied membranes or sheet-good systems would be preferred; however, some cementitious manufacturers do provide detailing for this type of installation, as shown in Fig. 2.41. Note that the cementitious system is applied as a positive system in this situation, with two heavy slurry coats applied to afford  the necessary protection required. Also note that a cove cant is added to the exterior side also at the wall-floor intersection in addition to the cove installation on the floor-wall negative application. Since waterstop is not applicable for the concrete block, the manufacturer prescribes a detail coat of the material on the foundation before block is laid. A drainage system is installed for additional protection, as should a vertical drainage system. Again, such a detail should be used with caution because of the mortar joint weakness. Figure 2.42 details a manufacturer’s alternative installation suggestion using the cementitious system in both interior and exterior waterproofing applications to ensure watertightness under a “belt and suspenders” system.

FIGURE 2.41 Application of detail for cementitious waterproofing over concrete block.

FIGURE 2.42 Installation detail suggesting both negative and positive application of cementitious waterproofing.

Cementitious systems are ideal for many below-grade civil structures that are typically concrete structures. Figure 2.43 provides a manufacturer’s cementitious system for an underground vault. Note in this detail how  the cementitious system is used as a negative system on the slab-on-grade portion, then transitions to a positive system on the walls and ceiling structure.

FIGURE 2.43 Civil structure cementitious waterproofing detailing.

This transfer from negative to positive is accomplished by applying the cementitious system continuously along the slab including the area beneath the exterior walls. Cove details packed with the manufacturer’s materials occur at the floor-wall juncture. A cove is also used for additional protection at the construction joint in the wall. It would be recommended that waterstop be used at the wall floor juncture and the construction joint for the most complete envelope protection.

Figures 2.44 and 2.45 present typical detailing for cementitious systems on two other civil projects, a sewage treatment digester and a swimming pool structure. Similar detailing of cementitious systems can be easily transferred to other concrete structures below-grade. Again, combining the proper use of waterstop, cove installations at structure weak points (note the cove installation recommendations at pipe and other similar penetrations in Fig. 2.46), and cementitious applications in accordance with manufacturer’s instructions will result in watertight below-grade concrete structures.

FIGURE 2.44 Civil structure cementitious waterproofing detailing.

FIGURE 2.45 Civil structure cementitious waterproofing detailing.

FIGURE 2.46 Penetration detailing using cementitious waterproofing.

FLUID-APPLIED SYSTEMS - WATERPROOFING

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Fluid-applied waterproof materials are solvent-based mixtures containing a base of urethanes, rubbers, plastics, vinyls, polymeric asphalts, or combinations thereof. Fluid membranes are applied as a liquid and cure to form a seamless sheet. Since they are fluid applied, controlling thickness is critical during field application (see Fig. 2.47).

Therefore, field measurements must be made (wet or dry film) for millage control. The percentages of solids in uncured material vary. Those with 75 percent solids or less can shrink, causing splits, pinholes, or insufficient millage to waterproof adequately.

Fluid systems are positive waterproofing side applications and require a protection layer before backfilling. Fluid-applied systems are frequently used because of their ease of application, seamless curing, and adaptability to difficult detailing, such as penetrations and changes in plane. These systems allow both above- and below-grade applications, including planters and split-slab construction. Fluid systems are not resistant to ultraviolet weathering and cannot withstand foot traffic and, therefore, are not applied at exposed areas.

FIGURE 2.47 Spray application of fluid-applied membrane.

Several important installation procedures must be followed to ensure performance of these materials. These include proper concrete curing (minimum 7 days, 21–28 days preferred), dry and clean substrate, and proper millage. Should concrete substrates be wet, damp, or uncured, fluid membranes will not adhere and blisters will occur. Proper thickness and uniform application are important for a system to function as a waterproofing material.

Materials can be applied to both vertical and horizontal surfaces, but with horizontal applications, a subslab must be in place so that the membrane can be applied to it. A topping, including tile, concrete slabs, or other hard finishes, is then applied over the mem- brane. Fluid materials are applicable over concrete, masonry, metal, and wood substrates.

Note the application to below-grade concrete block wall in Fig. 2.48.
Fluid-applied systems have elastomeric properties with tested elongation over 500 percent, with recognized testing such as ASTM C-836. This enables fluid-applied systems to bridge substrate cracking up to  1 16-in wide.

FIGURE 2.48 Fluid-applied membrane application to below-grade block wall.

An advantage with fluid systems is their self-flashing installation capability. This application enables material to be applied seamless at substrate protrusions, changes in planes, and floor-wall junctions. Figure 2.49 details a typical below-grade application using fluid membranes. Fluid materials are self-flashing, with no other accessories required for transitions into other building envelope components. However, a uniform 50–60 mil is difficult to control in field applications, and presents a distinct disadvantage with fluid systems.

FIGURE 2.49 Typical below-grade application detailing for fluid-applied membranes.

These systems contain toxic and hazardous chemicals that require safety protection during installation and disposal of materials. Refer to Chap. 14 and the discussion on V.O.C. materials.

Fluid-applied systems are available in the following derivatives: urethane (single or two-component systems), rubber derivatives (butyl, neoprene, or hypalons), polymeric asphalt, coal tar, or asphalt modified urethane, PVC, and hot applied systems (asphalt).

Urethane
Urethane systems are available in one- or two-component materials. Black coloring is added only to make those people who believe waterproofing is still “black mastic” comfortable with the product. Urethanes are solvent-based, requiring substrates to be completely dry to avoid membrane blistering.

These systems have the highest elastomeric capabilities of fluid-applied membranes, averaging 500–750 percent by standardized testing. Urethanes have good resistance to all chemicals likely to be encountered in below-grade conditions, as well as resistance against alkaline conditions of masonry substrates.

Rubber derivatives
Rubber derivative systems are compounds of butyls, neoprenes, or hypalons in a solvent base. Solvents make these materials flammable and toxic. They have excellent elastomeric capability, but less than that of urethane membranes.

Rubber systems are resistant to environmental chemicals likely to be encountered below grade. As with most fluid membranes, toxicity requires safety training of mechanics in their use and disposal.

Polymeric asphalt
A chemical polymerization of asphalts improves the generic asphalt material qualities sufficiently to allow their use as a below-grade waterproofing material. Asphalt compounds do not require drying and curing of a masonry substrate, and some manufacturers allowinstallation of their asphalt membranes over uncured concrete.

However, asphalt materials are not resistant to chemical attack as are other fluid systems. These membranes have limited life-cycling and are used less frequently than other available systems.

Coal tar or asphalt-modified urethane
Coal tar and asphalt-modified urethane systems lessen the cost of the material while still performing effectively. Extenders of asphalt or coal tar limit the elastomeric capabilities and chemical resistance of these membranes.

Coal tar derivatives are especially toxic, and present difficulties in installing in confined spaces such as small planters. Coal tar can cause burns and irritations to exposed skin areas. Field mechanics should take necessary precautions to protect themselves from the material’s hazards.

Polyvinyl chloride
Solvent-based PVC or plastics are not extensively used in liquid-applied waterproofing applications. These derivatives are more often used as sheet membranes for roofing. Their elastomeric capabilities are less than other fluid systems and have higher material costs.
They do offer high resistance to chemical attack for below-grade applications.

Hot-applied fluid systems
Hot-applied systems are improvements over their predecessors of coal tar pitch and felt materials. These systems add rubber derivatives to an asphalt base for improved performance, including crack-bridging capabilities and chemical resistance.

Hot systems are heated to approximately 400°F in specialized equipment and applied in thickness up to 180 mil, versus urethane millage of 60 mil (see Fig. 2.50). Asphalt extenders keep costs competitive even at this higher millage. These materials have a considerably extended shelf life compared to solvent-based products, which lose their usefulness in 6 months to 1 year.

FIGURE 2.50 Application process for hot-applied membrane.

Since these materials are hot-applied, they can be applied in colder temperatures than solvent-based systems, which cannot be applied in weather under 40°F. Manufacturers often market their products as self-healing membranes, but in below-grade conditions this is a questionable characteristic. Properties of typical fluid-applied systems are summarized in Table 2.5.

FLUID SYSTEM APPLICATION - WATERPROOFING

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Substrate preparation is critical for proper installation of fluid-applied systems. See Fig.2.51 for typical fluid system application detail. Horizontal concrete surfaces should have a light broom finish for proper bonding. Excessively smooth concrete requires acid etching or sandblasting to roughen the surface for adhesion.

Vertical concrete surfaces with plywood form finish are satisfactory, but honeycomb, tie holes, and voids must be patched, with fins and protrusions removed (Fig. 2.52).

Wood surfaces must be free of knotholes, or patched before fluid application. Butt joints in plywood decks should be sealed with a compatible sealant followed by a detail coat of membrane. On steel or metal surfaces, including plumbing penetrations metal mustbe cleaned and free of corrosion. PVC piping surfaces are roughened by sanding before membrane application.

FIGURE 2.51 Typical application detailing of below-grade fluid-applied membrane.

FIGURE 2.52 Preparation of block wall prior to membrane application.

Curing of concrete surfaces requires a minimum of 7 days, preferably 28 days. On subslabs, shorter cure times are acceptable if concrete passes a mat dryness test. Mat testing is accomplished by tapping visquene to a substrate area. If condensation occurs within 4 hours, concrete is not sufficiently cured or is too wet for applying material.

Blistering will occur if materials are applied to wet substrates, since they are non- breathable coatings. Water curing is the recommended method of curing, but some manu- facturers allow sodium silicate curing compounds. Most manufacturers do not require primers over concrete or masonry surfaces; however, metal substrates should be primed and concrete if required (Fig. 2.53).

FIGURE 2.53 Roller application of fluid-applied membrane.

All cold joints, cracks, and changes in plane should be sealed with sealant followed by a 50–60-mil membrane application, 4-in wide. Figure 2.54 details typical locations where additional layers of membrane application are required for reinforcement.

FIGURE 2.54 Reinforcement detail of membrane at changes-in-plane and areas of high stress. (Note sealant cant added at floor-wall juncture, and membrane layers at changes-in-plane.)

Cracks over 1/ 16-in should be sawn out, sealed, then coated. Refer to Fig. 2.55 for typical detailing examples.

FIGURE 2.55 Substitute crack detailing and preparation for membrane appliation.

At wall-floor intersections, a sealant cant approximately 1 2–1 in high at 45° should be applied, followed with a 50-mil detail coat. All projections through a substrate should be similarly detailed. Refer again to Fig. 2.56 for typical installation detailing. At expansion joints and other high-movement details, a fiberglass mesh or sheet flashing is embedded in the coating material. This allows greater movement capability.

FIGURE 2.56 Transition detailing for membrane applications.

Figure 2.57 provides a perspective view of a typical below-grade fluid-applied membrane application using a sheet material to reinforce the horizontal-to-vertical transition.

FIGURE 2.57 Perspective detail emphasizing the reinforcing of the wall-to-floor transition.

The detail coat applied at this point provides additional protection at the same transition.
This detail emphasizes the 90%/1% principle, assuming that the weak point in this structure (wall to floor juncture) is a likely candidate for water infiltration. Recognizing this, the manufacturer has tried to idiot-proof the detail by adding several layers of protection, including the waterstop and drainage board that properly completes the waterproof installation.

The detailing provided in Fig. 2.58 shows a fluid membrane application that runs continuously on the horizontal surface, including beneath the wall structure. Many engineers will not permit such an application due to the membrane acting as a bond break between the wall and floor components that might present structural engineering problems.

FIGURE 2.58 Application detailing using drainage board in lieu of protection board for additional waterproofing protection.

In Fig. 2.59, the manufacturer has detailed the use of a liquid membrane over foundation lagging using a fluid-applied membrane before the concrete is placed. In this detail, the membrane is applied to a sheet-good fabric that acts as the substrate. This is applied over a premanufactured drainage mat to facilitate water drainage and hydrostatic pressure.

FIGURE 2.59 Fluid-applied membrane detail for application directly to foundation lagging.

This would be a difficult application, and not as idiot-proof as using a clay system in a similar installation as outlined later in this chapter.

All penetrations occurring through a membrane application must be carefully detailed to prevent facilitating water infiltration at this “90%/1% principle” envelope area. Figure 2.60 shows a recommend installation at a pipe penetration. Note that the concrete has been notched to install sealant along the perimeter of the pipe. The waterproof membrane is then detail-coated around the pipe, followed by the regular application.

FIGURE 2.60 Penetration detailing for membrane waterproofing applications

Fluid-applied membrane applications all require that the termination of the membrane be carefully completed to prevent disbonding at the edge and resulting water infiltration. Figure 2.61 shows the membrane terminating with a sealant of manufacturer-supplied mastic. Figure 2.62 details the use of a reglet to terminate and seal the membrane, which could also simultaneously be used to terminate above-grade waterproofing.

FIGURE 2.61 Termination detailing for membrane waterproofing.

FIGURE 2.62 Reglet termination detailing for membrane waterproofing.

Control coating thickness by using notched squeegees or trowels. If spray equipment is used, take wet millage tests at regular intervals during installation. Application by roller is not recommended. Pinholes in materials occur if a substrate is excessively chalky or dusty, material cures too fast, or material shrinks owing to improper millage application.

Fluid membranes are supplied in 5- or 55-gal containers. Their toxicity requires proper disposal methods of containers after use. Since these materials rapidly cure when exposed to atmospheric conditions, unopened sealed containers are a necessity.

These materials are not designed for exposed finishes. They will not withstand traffic or ultraviolet weathering. Apply protection surfaces to both horizontal and vertical applications. On vertical surfaces, a
1 2-in polystyrene material or other lightweight protection system is used. For horizontal installations a
1 8-in, asphalt-impregnated board is necessary. On curved surfaces, such as tunnel work, 90-lb. roll roofing is usually acceptable protection. For better protection and detailing, use premanufactured drainage board in lieu of these protection systems (Fig. 2.63).

FIGURE 2.63 Application of premanufactured drainage board in lieu of protection board to protect mem- brane.

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Thermoplastics, vulcanized rubbers, and rubberized asphalts used in waterproofing applications are also used in single-ply roofing applications. Although all systems are similar as a generic grouping of waterproofing systems, consider their individual characteristics whenever you choose systems for particular installations.

Sheet membranes have thickness controlled by facto manufacturing. This ensures uniform application thickness throughout an installation. Sheet manufactured systems range in thickness from 20 to 120 mil. Roll goods of materials vary in width from 3 to 10 ft.

Larger widths are limited to horizontal applications, because they are too heavy and difficult to control for vertical applications.

Unlike liquid systems, sheet system installations involve multiple seams and laps and are not self-flashing at protrusions and changes in plane. This is also true for terminations or transitions into other members of the building envelope.

Applications below grade require protection board during backfill operations and concrete and steel placements. Fins and sharp protrusions in substrates should be removed before application, or they will puncture during installation. Materials used in vertical applications should not be left exposed for any length of time before backfilling.

Weathering will cause blistering and disbonding if backfill operations must begin immediately after membrane application.

Vertical single-ply applications are more difficult than fluid applications, due to the difficulty of handling and seaming materials. Seams are lapped and sealed for complete

waterproofing. In small, confined areas such as planter work, vertical installation and transitions to horizontal areas become difficult and extra care must be taken.

Thermoplastics
Thermoplastic sheet-good systems are available in three compositions: PVC, chlorinated polyurethane (CPE), and chlorosulfonated polyethylene (CSPE), which is referred to as hypalon. Materials are manufactured in rolls of varying widths, but difficulty with vertical applications makes smaller widths more manageable.

On horizontal applications, wider roll widths require fewer seams; therefore, it is advantageous to use the widest workable widths. All three systems adhere by solvent- based adhesives or heat welding at seams.

PVC membranes are available in thicknesses of 30–60 mil. CPE systems vary by as much as 20–120 mil, and hypalon materials (CSPE) are 30–35 mil. All derivatives have excellent hydrostatic and chemical resistance to below-grade application conditions. PVCmembranes are generically brittle materials requiring plasticizers for better elastomeric properties, but elongation of all systems is acceptable for below-grade conditions.

Vulcanized rubbers
Vulcanized rubbers are available in butyl, ethylene propylene diene monomer (EPDM), and neoprene rubber. These materials are vulcanized by the addition of sulfur and heat to achieve better elasticity and durability properties. Membrane thickness for all rubber systems ranges from 30–60 mil. These materials are nonbreathable, and will disbond or blister if negative vapor drive is present.

As with thermoplastic materials, vulcanized rubbers are available in rolls of varying widths. Seam sealing is by a solvent-based adhesive, as heat welding is not applicable. A separate adhesive application to vertical areas is necessary before applying membranes.

Vulcanized rubber systems incorporate loosely laid applications for horizontal installations.

Although other derivatives of these materials, such as visquene, are used beneath slabs as dampproofing membranes or vapor barriers, they are not effective if hydrostatic pressure exists. Material installations under slabs on grade, by loose laying over compacted fill and sealing joints with adhesive or heat welding, are useful in limited waterproofing applications.

This is a difficult installation procedure and usually not specified or recommended.

Loosely laid applications do, however, increase the elastomeric capability of the mem- brane, versus fully adhered systems that restrict membrane movement.

Rubberized asphalts
Rubberized asphalt sheet systems originally evolved for use in pipeline protection applications. Sheet goods of rubberized asphalt are available in self-adhering rolls with a  polyethylene film attached. Self-adhering membranes adhere to themselves, eliminating the need for a seam adhesive. Sheets are manufactured in varying widths of 3–4 ft and typically 50-ft lengths.

Also available are rubberized asphalt sheets reinforced with glass cloth weave that require compatible asphalt adhesives for adhering to a substrate. Rubber asphalt products require a protection layer, to prevent damage during backfill or concrete placement operations.

Self-adhering asphalt membranes include a polyethylene film that acts as an additional layer of protection against water infiltration and weathering. The self-adhering portion is protected with a release paper, which is removed to expose the adhesive for placement.

Being virtually self-contained, except for primers, this system is the simplest of all sheet materials to install. Figure 2.64 details a typical below-grade installation.

FIGURE 2.64 Below-grade sheet waterproofing system detailing.

Self-adhering membranes are supplied in 60-mil thick rolls, and accessories include compatible liquid membranes for detailing around protrusions or terminations. Rubberized asphalt systems have excellent elastomeric properties but are not used in above-grade exposed conditions. However, membrane use in sandwich or split-slab construction for above-grade installations is acceptable.

Glass cloth–reinforced rubber asphalt sheets, unlike self-adhering systems, require no concrete curing time. Separate adhesive and seam sealers are available. Glass cloth rubber sheets are typically 50 mil thick and require a protection layer for both vertical and horizontal applications. Typical properties of sheet materials are summarized in Table 2.6.

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SHEET WATERPROOFING SYSTEM APPLICATION

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Unlike liquid-applied systems, broom-finished concrete is not acceptable, as coarse finishes will puncture sheet membranes during application. Concrete must be smoothly finished with no voids, honeycombs, fins, or protrusions. Concrete curing compounds should not contain wax, oils, or pigments. Concrete surfaces must be dried sufficiently to pass a mat test before application.

Wood surfaces must be free of knotholes, gouges, and other irregularities. Butt joints in wood should be sealed with a 4-in-wide membrane detail strip, then installed. Masonry substrates should have all mortar joints struck flush. If masonry is rough, a large coat of cement and sand is required to smooth surfaces.

Metal penetrations should be cleaned, free of corrosion, and primed. Most systems require priming to improve adhesion effectiveness and prevent concrete dust from interfering with adhesion (Fig. 2.65).

FIGURE 2.65 Applying primer to concrete substrate in preparation for sheet system.

All sheet materials should be applied so that seams shed water. This is accomplished by starting at low points and working upward toward higher elevations (Fig. 2.66). With adhesive systems, adhesives should not be allowed to dry before membrane application. Self-adhering systems are applied by removing a starter piece of release paper or polyethylene backing, adhering membrane to substrate (Fig. 2.67).

FIGURE 2.66 Application of sheet membrane.

FIGURE 2.67 Removing release paper backing from self-adhering sheet membrane.

With all systems, chalk lines should be laid for seam alignment. Seam lap requirements vary from 2 to 4 in (Fig. 2.68). Misaligned strips should be removed and reapplied, with material cut and restarted if alignments are off after initial application. Attempts to correct alignment by pulling on the membrane to compensate may cause “fish mouths” or blisters.

FIGURE 2.68 Seam lap detailing for sheet membranes.

A typical sheet membrane application is shown in Fig. 2.69.

FIGURE 2.69 Typical sheet membrane application detailing.

At changes in plane or direction, manufacturers call for a seam sealant to be applied over seam end laps and membrane terminations (Fig. 2.70). Materials are back-rolled at all seams for additional bonding at laps (Fig. 2.71). Any patched areas in the membrane should be rolled to ensure adhesion.

FIGURE 2.70 Applying mastic termination detailing.

FIGURE 2.71 Back-rolling membrane at seams to ensure bonding.

Each manufacturer has specific details for use at protrusions, joints, and change in plane (Fig. 2.72). Typically, one or two additional membrane layers are applied in these areas and sealed with seam sealant or adhesive (Fig. 2.73). Small detailing is sealed with liquid mem- branes that are compatible and adhere to the sheet material. Figure 2.74 details a typical col- umn foundation waterproofing application. Figure 2.75 shows the proper treatment of a control or expansion joint using sheet systems.

FIGURE 2.72 Transition detailing for sheet membranes.

FIGURE 2.73 Applying reinforcement strips at transition details.

FIGURE 2.74 A column foundation waterproofing detail.

FIGURE 2.75 Expansion joint treatment using sheet system

Protection systems are installed over membranes before backfilling, placement of rein- forcing steel, and concrete placement. Hardboard, 1 8–1 4-in thick, made of asphalt-impregnated material is used for horizontal applications. Vertical surfaces use polystyrene board, 1 2-in thick, which is lightweight and applied with adhesives to keep it in place during back-fill. Sheet systems cannot be left exposed, and backfill should occur immediately after installation.


Protrusions through the membrane must be carefully detailed as shown in Fig. 2.76.

FIGURE 2.76 Protrusion detailing for sheet systems.

 Manufacturers require an additional layer of the sheet membrane around the penetration that is turned on or into the protrusion as appropriate. A bead of sealant or mastic is applied along the edges of the protrusion. For expansion joints in below-grade walls or floors, the installation should include appropriate waterstop and the required additional layers of membrane (Fig. 2.77). Sheet systems must be terminated appropriately as recommended by the manufacturer. Termination details prohibit water from infiltrating behind the sheet and into the structure. Termination bars are often used as shown in Fig. 2.78. Reglets can be used (Fig. 2.79); these also permit the termination of above-grade waterproofing in the same reglet that then becomes a transition detail.

FIGURE 2.77 Expansion joint treatment incorporating waterstop.

FIGURE 2.78 Termination of sheet membrane using termination bar.

FIGURE 2.79 Termination of sheet membrane using reglet.

HOT-APPLIED SHEET SYSTEMS - WATERPROOFING

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Hot-applied systems are effectively below-grade roofing systems. They use either coal tar pitch or asphalts, with 30-lb roofing felts applied in three to five plies. Waterproofing technology has provided betterperformance materials and simpler applications, limiting ho systems usage to waterproofing applications.

Hot-applied sheet systems have installation and performance characteristics similar to those of roofing applications. These systems are brittle and maintain very poor elastic properties. Extensive equipment and labor costs offset inexpensive material costs. Below- grade areas must be accessible to equipment used for heating materials. If materials are carried over a distance, they begin to cool and cure, providing unacceptable installations.

Properties of typical hot-applied sheet systems are summarized in Table 2.7.

CLAY SYSTEMS - WATERPROOFING AND CONSTRUCTION

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Natural clay systems, commonly referred to as  bentonite, are composed primarily of montmorillonite clay. This natural material is used commercially in a wide range of products including toothpaste. Typically, bentonite waterproofing systems contain 85–90 percent of montmorillonite clay and a maximum of 15 percent natural sediments such as volcanic ash.

After being installed in a dry state, clay, when subjected to water, swells and becomes impervious to water. This natural swelling is caused by its molecular structural form of expansive sheets that can expand massively. The amount of swelling and the ability to resist water is directly dependent on grading and clay composition. Clay swells 10–15 percent of its dry volume under maximum wetting. Therefore, it is important to select a system high in montmorillonites and low in other natural sediments.

Bentonite clay is an excellent waterproofing material, but it must be hydrated properly for successful applications. Clay hydration must occur just after installation and backfilling, since the material must be fully hydrated and swelled to become watertight. This hydration and swelling must occur within a confined area after backfill for the waterproofing properties to be effective. Precaution must be taken to ensure the confined space is adequate for clay to swell. If insufficient, materials can raise floor slabs or cause concrete cracking due to the swelling action.


Clay systems have the major advantage of being installed in various stages during con- struction to facilitate the shortening of the overall building schedule or reducing any impact the waterproofing system installation might have. Clay systems can be installed before concrete placement by adhering the waterproofing product to the excavation lagging system as shown in Fig. 2.80, or against slurry walls or similar excavation and foundation support systems as detailed in Figs. 2.81 and 2.82.

FIGURE 2.80 Clay system applied directly to foundation lagging.

FIGURE 2.81 Clay system applied directly to shotconcrete foundation wall.

FIGURE 2.82 Application of clay panels directly to foundation sheet piling.

Clay systems can also be applied to the inside face of concrete formwork that is intended to be left in place due to site access constrictions; a similar installation photo- graph in shown in Fig. 2.83. These application methods permit the contractor to provide an effective waterproofing installation without having to delay the schedule awaiting the concrete placement and curing time necessary for other types of below-grade products.

FIGURE 2.83 Clay membrane applied to inside of concrete formwork.

 This also holds true for the typical waterproofing of elevator pits shown in Fig. 2.84.

Here the clay panels are laid directly on the compacted soils before concrete placement, without a working or mud slab required for the waterproofing installation. Again, this can save not only construction time but associated costs as well.

FIGURE 2.84 Typical clay system detailing for elevator pit with no mud slab required.

There is no concrete cure time necessary, and minimal substrate preparation is necessary. Of all waterproofing systems, these are the least toxic and harmful to the environment. Clay systems are self-healing, unless materials have worked away from a substrate. Installations are relatively simple, but clay is extremely sensitive to weather during installation. If rain occurs or groundwater levels rise and material is wetted before backfilling, hydration will occur prematurely and waterproofing capability will be lost, since hydration occurred in an unconfined space.

Immediate protection of applications is required, including uses of polyethylene covering to keep materials from water sources before backfill. If installed in below-grade conditions where constant wetting and drying occurs, clay will eventually deteriorate and lose its waterproofing capabilities. These systems should not be installed where free-flowing groundwater occurs, as clay will be washed away from the substrate.

Bentonite clays are not particularly resistant to chemicals present in groundwater such as brines, acids, or alkalines.

Bentonite material derivatives are now being added to other waterproofing systems such as thermoplastic sheets and rubberized asphalts. These systems were developed because bulk bentonite spray applications cause problems, including thickness control and substrate adhesion. Bentonite systems are currently available in the following forms:

● Bulk
● Fabricated paper panels
● Sheet goods
● Bentonite and rubber combination sheets
● Textile mats

Bulk bentonite
Bulk bentonite is supplied in bulk form and spray-applied with an integral adhesive to seal it to a substrate. Applications include direct installations to formwork or lagging before foundation completion in lieu of applications directly to substrates. Materials are applied at quantities of 1–2 lb/ft^2.

Bulk bentonite spray applications provide seamless installations. Controls must be pro- vided during application to check that sufficient material is being applied uniformly.

Materials should be protected by covering them with polyethylene after installation. Due to possibilities of insufficient thickness during application, manufacturers have developed several clay systems controlling thickness by factory manufacturing, including boards, sheets, and mat systems.

Panel systems
Bentonite clays are packaged in cardboard panels usually 4 ft^2, containing 1 lb/ft^2 of bentonite material. Panels are fastened to substrates by nails or adhesives. Upon backfilling, panels deteriorate by anaerobic action, allowing groundwater to cause clay swelling for water- proofing properties. On horizontal applications the panels are simply laid on the prepared substrates and lapped (Fig. 2.85).

FIGURE 2.85 Clay sheets installed under horizontal concrete slab; note the waterstop installed in the cold joint.

These systems require time for degradation of cardboard panels before swelling and watertightness occurs. This can allow water to penetrate a structure before swelling occurs.

As such, manufacturers have developed systems with polyethylene or butyl backing to provide temporary waterproofing until hydration occurs.

Panel clay systems require the most extensive surface penetration of clay systems.
Honeycomb and voids should be filled with clay gels before panel application. Special prepackaged clay is provided for application to changes in plane, and gel material is used at protrusions for detailing.  Several grades of panels are available for specific project installation needs. These include special panels for brine groundwater conditions (Fig. 2.86), and reinforced panels for horizontal applications where steel reinforcement work is placed over panels.

FIGURE 2.86 Saltwater panel application.

Panels are lapped onto all sides of adjacent panels using premarked panels that show necessary laps.

Bentonite sheets
Bentonite sheet systems are manufactured by applying bentonite clay at 1 lb/ft^2 to a layer of chlorinated polyethylene. They are packaged in rolls 4 ft wide. The addition of poly-ethylene adds temporary waterproofing protection during clay hydration. This polyethylene also protects clay material from prematurely hydrating if rain occurs before backfilling and adds chemical-resistant properties to these systems.

Some manufacturers have developed sheet systems for use in above-grade split or sandwich slab construction. However, constant wetting and drying of this system can alter the clay’s natural properties, and waterproofing then depends entirely upon the polyethylene sheet.

Bentonite and rubber sheet membranes
Bentonite and rubber sheet membrane systems add clay to a layer of polyethylene, but also compound the bentonite in a butyl rubber com position. Materials are packaged in rolls 3 ft wide that are self-adhering using a release paper backing. They are similar to rubberized asphalt membranes in application and performance characteristics.

These combination sheet systems are used for horizontal applications, typically split- slab construction in parking or plaza deck construction. As with rubberized asphalt sys- tems, accessories must be used around protrusions, terminations, and changes in plane.

The polyethylene, butyl rubber, and bentonite each act in combination with the others, providing substantial waterproofing properties.

Unlike other clay systems, concrete substrates must be dry and cured before application.

Care must be taken in design and construction to allow for adequate space for clay swelling.

Bentonite mats
Bentonite mat systems apply clays at 1 lb/ft^2 to a textile fabric similar to a carpet backing.

This combination creates a carpet of bentonite material. The coarseness of the fabric allows immediate hydration of clay after backfilling, versus a delayed reaction with card-board panels.

The textile material is not self-adhering, and adhesives or nailing to vertical substrates is necessary. Protection with a polyethylene sheet after installation is used to prevent pre- mature hydration. This system is particularly effective in horizontal applications where the large rolls eliminate unnecessary seams. This lowers installation costs as well as prevents errors in seaming operations.

Properties of typical clay systems are summarized in Table 2.8.

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Natural clay waterproofing materials require the least preparatory work of all below-grade systems. Concrete substrates are not required to be cured except for rubberized asphalt combination systems. Concrete can be damp during installation, but not wet enough to begin clay hydration.

Large voids and honeycombs should be patched before application. Minor irregularities are sealed with clay gels. Most concrete curing agents are acceptable with clay systems.
Masonry surfaces should have joints stricken flush. Note the standard application detailsin Figs. 2.87, 2.88, and 2.89.

FIGURE 2.87 Clay system detail for foundation water- proofing using mub slab.

FIGURE 2.88 Clay system detail for foundation water- proofing without, with horizontal membrane applied directly to grade.

FIGURE 2.89 Grade beam detailing for clay system.

Bentonite materials combined with butyl rubber require further preparation than other clay systems, including a dry surface, no oil or wax curing compounds, and no contaminants, fins, or other protrusions that will puncture materials.

The variety of bentonite systems available means that applications will vary considerably and have procedures similar to the waterproofing systems they resemble in packaging type (e.g., sheet goods). Bulk clay is applied like fluid membranes. Panels and sheetsas sheet-good systems, and butyl compound-polyethylene systems are applied virtuallyidentically to rubberized asphalt systems.

With bulk systems, proper material thickness application is critical as it is with fluid-applied systems. Bulk systems are sprayed or troweled, applied at 1–2 lb/ft^2of substrate.

Panel and mat systems are applied to vertical substrates by nailing. Horizontal applications require lapping only. These systems require material to be lapped 2 in on all sides.

Cants of bentonite material are installed at changes in plane, much the same way as cementitious or sheet-applied systems. Bentonite sheet materials are applied with seams shedding water by starting applications at low points.

Outside corners or turns receive an additional strip of material usually 1 ft wide for additional reinforcement (Fig. 2.90). Chalk lines should be used to keep vertical applications straight and to prevent fish mouthing of materials. All end laps, protrusions, and terminations should be sealed with the clay mastic, as shown in Figs. 2.91 and 2.92. Proper termination methods are shown in detail in Figs. 2.93 and 2.94.

FIGURE 2.90 Clay system applied to lagging detailing. Note reinforcement at corner.

FIGURE 2.91 Typical penetration detailing for clay system.

FIGURE 2.92 Pile cap detailing for clay system.

FIGURE 2.93 Termination detailing for clay system.

FIGURE 2.94 Termination detailing for clay system using reglet.

VAPOR BARRIERS - USE IN CONSTRUCTION WORK

April 29, 2013, 8:53 am

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Vapor barriers are not suitable for waterproofing applications. As their name implies, they prevent transmission of water vapor through a substrate in contact with the soil. Typically used at slabs-on-grade conditions, they also are used in limited vertical applications.

Vapor barriers are sometimes used in conjunction with other waterproofing systems, where select areas of the building envelope are not subject to actual water penetration.

Vapor barriers are discussed only to present their differences and unsuitability for envelope waterproofing.

As previously discussed, soils have characteristic capillary action that allows the upward movement or migration of water vapor through the soil. Beginning as water and saturating the soil immediately adjacent to the water source, the capillary action ends as water vapor in the upper capillary capability limits of the soil.

Vapor barriers prevent upward capillary migration of vapor through soils from penetrating pores of concrete slabs. Without such protection, delamination of flooring materials, damage to structural components, paint peeling, mildew formation, and increased humidity in finished areas will occur. Vapor barriers can also prevent infiltration by alkaline salts into the concrete slab and flooring finish.

Vapor barriers are produced in PVC, combinations of reinforced waterproof paper with a polyvinyl coating, or polyethylene sheets (commonly referred to as  visquene).

Polyethylene sheets are available in both clear and black colors in thicknesses ranging from 5 to 10 mil. PVC materials are available in thickness ranging from 10 to 60 mil.

Typical properties of vapor barriers are summarized in Table 2.9.

Vapor barriers are rolled or spread out over prepared and compacted soil, with joints lapped 6 in. Vapor barriers can be carried under, up, and over foundations to tie horizontal floor applications into vertical applications over walls. This is necessary to maintain the integrity of a building envelope.

Mastics are typically available from manufacturers for adhering materials to vertical substrates. In clay soil, where capillary action is excessive, laps should be sealed with a mastic for additional protection. Proper foundation drainage systems should be installed, as with all waterproofing systems.

Vapor barriers are installed directly over soil, which is not possible with most waterproofing systems. Protection layers or boards are not used to protect the barrier during reinforcement application or concrete placement.