FOUNDATION WATERPROOFING

Waterproofing of your foundation plays a key role in contributing to overall building strength. Due to the capillary movement of water, the water rises from the soil to the foundation. As it passes through the foundation, it rises higher and reaches the walls. It is common for foundation/basement to become damp/wet as it is one of the areas that is subjected to high moisture levels as it is directly in contact with the earth surface. Hence it is also challenging to diagnose the waterproofing fault in this area as even a visible leak could be a result of underlying high moisture. One should consider a professional opinion when the following occur: –

• Floor/ walls: – leakages/ water stains
• Floor- water puddles
• Mold/foul smell

So, to prevent the water from reaching the retaining walls, a waterproofing system needs to be laid at the plinth level.

Waterproofing should always be provided from the positive side but in case if there is no access from that side then negative side treatment can also be opted for. Difference between the two types of treatment is that –

Recommended solution by Aquaseal

1) Crystalline based Cementitious system (can be used from both positive and negative side) – These systems are an active system and can be used on either side of the structure i.e., positive, and negative side. The crystalline system includes normal Portland cement, specially treated quartz, and a compound of active chemicals.

When applied to a concrete surface, the active chemicals react with moisture and the un hydrated cement particles to cause a catalytic reaction which generates an insoluble, crystalline structure. These crystals fill the pores and minor shrinkage cracks in the concrete to prevent any further water ingress (even under pressure).

However, the system will still allow the passage of vapour through the structure (i.e. the concrete will be able to “breathe”). Even after the concrete has cured, the system remains dormant in the concrete and will reactivate in the presence of moisture to seal capillary tracts and hairline cracks. In addition to waterproofing the structure, it also protects concrete against seawater, wastewater, aggressive ground water and many other aggressive chemical solutions.

The system is approved for use in contact with potable water, and is therefore suitable for use in water storage tanks, reservoirs, water treatment plants, etc.

Prior to application of these systems, the surface must be clean and sound as per checklist i.e., all joints, honeycombs and hollowness must be packed with crystalline/ repair mortar. Pressure grouting using PRAH (Permeability Reducing Admix for Hydrostatic Conditions) at all weak spots/zones. Angle fillet min 50*50mm must be made at the starter joint using PMM. The surface must always be in SSD.

Post-treatment: The treated areas should be kept damp for a period of 10 days and must be protected against direct sun, wind, and frost, by covering with polyethylene sheeting, damp burlap or similar.

2) Polymer based Elastomeric Cementitious coating system (only positive side)- Polymer based Elastomeric Cementitious coating systems are high performance elastomeric cementitious coating used for waterproofing and to protect atmospherically exposed reinforced concrete structures from attack by acid gases, chloride ions, oxygen & water.

These systems can be used on concrete, brick and block work substrates and is equally suitable for new and existing structures. The product is designed to reface and even out variations in concrete and masonry surfaces and bridge shrinkage cracks. It provides a seamless, flexible waterproof coating suitable for water tanks, reservoirs, drainage culverts basements and roofs. The product provides a tough durable water-resistant coating. These systems are preferred as an undercoat system as they are not UV stable.

Prior to application of these systems, the surface must be clean and sound as per checklist i.e., all joints, honeycombs and hollowness must be packed with PMM (Polymer Modified Mortar) /Non-Shrink repair mortar. Pressure grouting using PRAN (Permeability Reducing Admix for Non-Hydrostatic Conditions) at all weak spots/zones. Angle fillet min 50*50mm must be made at the starter joint using PMM. Surface must be in SSD state.

Also depending on the porosity of the concrete, a silicon-based sealer- Zycosil or an acrylic based sealer-La Brush seal can be provided as an additional coating before application of the cementitious waterproofing system.

An additional glass fiber mesh reinforcement of 45 GSM can be sandwiched between the first and the second coat in case of areas exceeding 5000 sq ft.