Various Waterproofing Technologies From STP


Waterproofing is one of the most important parameters considered in the construction of building and structures to prevent leakages, dampness, etc., and making the structures durable and long lasting.

Waterproofing is defined as a treatment of a surface or structure to prevent the passage of water under hydrostatic pressure, whereas damp proofing is defined as a treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure. The damp proofing is rather to retard but not to stop the absorption of water or water vapour through concrete or masonry, which results into the dampness on structure. To retard dampness or prevent dampness barrier system is to be used.

For waterproofing modern advanced technologies are being used worldwide.

Types of Modern Waterproofing Systems

The old traditional systems of waterproofing have certain limitations and being replaced by modern waterproofing systems. These are different types of waterproofing such as admixtures, impregnation, film forming liquid membrane, surfacing, joint seal, Injection grouting etc.

Among all these will discuss about two types, Admixture and film forming liquid membranes.

Admixtures

Admixtures are used in concrete during construction for different purposes. The various types of mineral admixtures such as lime, silica, fly-ash and chemical admixtures like plasticizers, super plasticizers, water reducers and high range water reducers, accelerators, retarders, viscosity modifying admixtures, air entraining admixtures and shrinkage reducing admixtures are widely used for specific purposes. But all these help to reduce the water content of the mix and make the concrete dense, compact crack free and durable and thus able to make leakage free structure.

STP Limited has introduced in recent time ShaliPlast LW++, Admixture-cum-Corrosion Inhibitor for Reinforced Cement Concrete.

ShaliPlast® LW++ is an integral liquid waterproofing compound, which protects concrete internally from water ingress as well as saves the re-bars of reinforced concrete and mortar against chloride induced corrosion. The unique bi-polar compound migrates through concrete during curing process and puts a passive layer over re-bars to stop chloride corrosion. It is an additive for concrete, mortar and plasters. It contains additives and polymers, which makes the concrete cohesive and reduces capillaries. ShaliPlast LW++, being an Admixture-cum-Corrosion Inhibitor, is designed for use in concrete as such. For any mix design where other water reducing admixture is already present, a compatibility study is suggested for such applications before going for bulk batch production of concrete. It conforms the requirements of IS 2645, IS 9103 and ASTM C 1582M.

Liquid Membrane

The concept of liquid water proofing has existed from 1800s, when natural bitumen was combined with jute, straw, rag felt and other manmade materials to provide a waterproofing solution for roofs. In the early twentieth century the manufacture of liquid roof coatings became a commercial activity, with the earliest coatings being based on liquefied rubber. The 1960s and 1970s saw the introduction of acrylics, acrylic emulsions, styrene butadiene’s and unsaturated polyesters, which led to improved quality and durability of the coatings. In 1970s, the first water based elastomeric roof coatings were introduced. In the late 1980s, single component moisture-cured polyurethane based liquid membranes were developed and remain the basis of most of today’s cold applied liquid roof coating technologies. Liquid roofing involves the application of a monolithic, fully bonded, liquid based coating to a roof. The coating cures to form a rubber-like elastomeric waterproof membrane, capable of stretching and returning to its original shape without damage. Such coating systems are usually reinforced with secondary materials such as glass-reinforced plastic to provide additional tensile strength. The coatings can be applied over concrete.

Polymer Modified Liquid Waterproofing Membrane

In the recent past, acrylic polymer based waterproofing membranes experienced fast development and formed several product lines such as flexible polymer modified membranes, polymer modified cement-based coatings etc. Among these, flexible acrylic membrane is the main product. The rigid waterproofing materials are modified by adding an organic polymer, a waterproofing admixture, a water reducer, and an expansion admixture to reduce and compensate for cement shrinkage, to prevent cracking, to reduce and refine the capillary pores of the materials, and to make the concrete denser and improve the impermeability remarkably. Although these materials have good aging resistance, they cannot accommodate extensive deformation of the base because of their rigidity. If dry shrinkage or expansion and contraction due to temperature changes lead to cracking of the base layer, the waterproofing layer may also crack or delaminate, which will affect the waterproofing performance. Their application will be limited greatly, and they cannot be applied to large-area waterproofing engineering of floors and roofs.

Advantages

Because of the better durability and less environmental pollution during their production and application, cement-based waterproofing materials can be widely used on different base materials and are very convenient in application. A great deal of effort has been put into the studying and comparing of these materials. By improving the formulation and the production process, a polymer modified cement material with a lower ratio of polymer/cement and water/cement evenly mixed and dispersed under the impact of temperatures and high shear force can be made. It combines the advantages of a rigid cement waterproofing material with those of a flexible waterproofing material (such as rubber and plastic). Using a calendaring process, a flexible cement-based waterproofing material with a denser structure, better waterproofing performance, excellent durability, and capable of accommodating deformation of the base can be obtained.

Salient features are:

Suitable for any climate - remains flexible in arctic cold; will not crack or dry out in desert heat; unaffected by ultraviolet radiation resulting from long-term sun exposure; resistant to ozone, acid rain, and most other air pollution.

Environment-friendly - water-based coatings contain no toxic dispersants or tints; ideal for roofs used for rainwater collection; safety precautions for applicators are same as for water-based house paints.

Bonds to almost anything - suitable substrates include asphalt, wood, metal, concrete, and rigid foam insulation boards.

Durable colours - architectural colours such as reds, greens, and greys match traditional metal roofs; white keeps buildings significantly cooler in the summer, saves energy, and minimizes urban heat-island effect.

STP has almost all types of liquid membrane waterproofing systems available as mentioned above. Considering the Indian climate, the economical solution will be STP’s ShaliCrylLM :1K UV Resistant Acrylic Liquid Membrane.

ShaliCryl® LM is a single component UV resistant, highly unique, elastomeric, heavy duty monolithic / seamless terrace waterproofing liquid membrane system. ShaliCryl® LM is specially developed with high mechanical strength, elastic and resilient acrylic polymers, selected fillers, light fast and weather durable pigments, microfibres, additives and best quality fungicidal in water medium. Membrane is formed in-situ on the applied surface. ShaliCryl® LM is three-layer system with coats in 3 different colours ensuring proper build-up of the thickness. It has UV cross linking technology, which makes it a reliable waterproofing system. Due to unique cross-linking mechanism, ShaliCryl® LM becomes more durable with age and is widely used in all advanced countries for waterproofing.

Polymer Modified Bitumen Emulsions and Solutions

In these systems, bitumen is modified with suitable polymers or co-polymers to enhance durability, flexibility and elasticity to the dried coating. These products can be supplied as water-based emulsions or solvent based solutions. Water-based products are normally applied in appropriate weather conditions as recommended by the manufacturer. In addition to bitumen and polymer modifiers, both the emulsion and solutions may also contain inert fibres and fillers. The products are designed for application by brushing or spraying or may be suitable for spreading.

STP’sShaliUrethane® BTD is UV resistant, high performance, water based, cold applied, single component elastomeric in-situ liquid membrane for waterproofing. ShaliUrethane® BTD forms a seamless monolithic membrane, which can be applied on moist surface not exceeding 5%. It conforms to ASTM C 836 and ASTM D 6083. Use Horizontal / Vertical grade of ShaliUrethane® BTD for horizontal / vertical application respectively having following advantages.
Can be applied on moist surface also, Excellent water vapour barrier, High Crack Bridging, Monolithic / seamless in-situ Membrane, Excellent adhesion to concrete, Excellent elongation and very good low temperature flexibility.

ShaliUrethane® LHM is single component, high tensile, high solid, moisture cured, modified Polyurethane elastomeric liquid membrane for waterproofing with an elongation of 700% ± 50. ShaliUrethane® LHM forms a seamless monolithic membrane by reaction with atmospheric moisture. It conforms to ASTM C-836 and ASTM C-898. Use horizontal / vertical grade of ShaliUrethane® LHM for horizontal / vertical applications respectively.

ShaliUrethane LHM can be protected with 50 mm PCC admixed with integral waterproofing or with a coat of ShaliCryl 215/ShaliCryl LM HI: Heavy Duty Reinforced, Heat Insulation Acrylic Liquid Membrane, ShaliCryl® LM HI is a single component, highly elastomeric, UV resistant, heavy duty, monolithic, water based waterproofing acrylic liquid membrane system. ShaliCryl® LM HI has high mechanical strength, elastic and resilient acrylic polymers, selected fillers, light fast durable pigments, microfibers and additives which imparts excellent weather resistance. The latest ceramic micro technology provides solar energy reflecting property enhancing cooling effect inside rooms. The microspheres in the coating reflect most of the solar energy back to the atmosphere and allow very little radiation energy to penetrate through roof. Low thermo-conductivity of the fillers and microsphere provides very effective thermal insulation.

Its Benefits are:

Cost-effectiveness. The process of liquid roofing provides a cost-effective method of making a new or existing roof waterproof. It can deliver up to 25 years performance depending on the coating system employed. It is estimated that liquid roofing is 70% less expensive than overall roof replacement in refurbishment situations.

High performance. Liquid roofing can be undertaken with high performance materials. Many of the products used in the liquid roofing process have been independently tested and their performance verified.

Safety. Unlike the installation processes of pre-formed membranes, liquid roofing does not involve hot works. Hot work on roofs is an extremely high-risk process, that poses a significant fire risk to contractors as well as the building and its occupants. The coating material used in the liquid roofing process is applied cold, thus negating any fire risk.

Encapsulation. When applied, liquid roofing systems encapsulate the surface they are applied to, preserving whatever is underneath and protecting it from weathering. This is especially desirable when dealing with asbestos roofs, as attempted removal of asbestos roofing can damage it, releasing material that can trigger asbestosis. Using a liquid coating system instead seals the asbestos, therefore making disturbance of the material more difficult.

Conclusion

Importance of waterproofing treatment using various innovative methods or systems are gaining momentum, till recently the treatment was treated by the architects/consultants as secondary issues. In most of the cases, this aspect of building construction lies with the client, who is ignorant and goes for the material readily available in the market that too without having basic information about the products or systems. With globalization, these new generation products are now accessible in our country.