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October, 1998 NOT a single drop of water will enter your house even in torrential rains. That is the new commitment made by water-proofing compounds that have recently been developed by the construction chemicals industry. Be it a basement or a swimming pool, a terrace garden or the sunken roof of a bathroom, all can be given a foolproof treatment against any kind of dampness. Not only this, even efflorescence and saltpetre action cab be taken care of. Chemical injection grouting for rapid grouting of foundation bolts of heavy machinery with high vibratory loads and chemical DPC treatment against rising dampness in a building that has already been erected may ensure that the building that was likely to be abandoned, lasts a life time now. A rapid development in construction chemicals and admixtures has opened new possibilities of saving old buildings as well as making new buildings damp proof, impervious and efflorescence free. Water-proofing is not the only area covered by the construction chemicals developed now but providing protective coatings to floors against abrasion and chemical action, creating water repelling barriers and sealing all types of cracks in sanitary ware, plumbing joints, tiles, stone ware joints, walls and roofs can also be achieved by use of these admixtures. Wall and floor tiles are more and more in demand than ever. The tile adhesives available now can provide best adhesion & mortar workability, making the job of tile fixing much easier, spot free, full of strength and durability. A notable achievement of these admixtures is that their use can bring an enhancement in quality of construction itself. Two most important aspects of an admixture to be added to concrete or mortar are that the admixture must be chloride free and compatible with the cement under use. There should not be any adverse chemical reaction among the cement and the admixture. The admixtures developed now to act as accelerators, retarders, plasticisers, super plasticisers and air entraining agents fully meet with these two requirements. There are other aspects such as non shrinking quality of admixtures and higher workability and these too are well served by the array of concrete admixtures developed by Indian chemical industry. To avoid confusion or incorrect use of construction chemicals and admixtures, these can be classified into five categories as concrete admixtures, water-proofing compounds, protective coatings, adhesives and sealants. Under each category, these compounds can further be classified on the basis of their base material and best possible use. A manufacturer may suggest his item as a ‘master-product’ suitable for use under all conditions and circumstances but one product may certainly have a better specific use than the other and this classification of chemicals and admixtures may serve as a ready-reckoner to have a better choice. Concrete admixtures can be best classified as plasticisers, super plasticisers, accelerators, retarders and air-entrainers. These admixtures are added to concrete during its preparation and before its placement in position. These admixtures may bring durability, strength enhancement, workability, corrosion protection and flexural strength to concrete. The choice depends upon the objective to be achieved. These ad- mixtures facilitate construction and save cement besides enhancing physical properties of concrete. The air entrainers provide remarkable frost resistance property to concrete. Dampness in buildings, Efflorescence on walls or saltpetre problem are of common occurrence in buildings. The basis cause of all these is a rising dampness from foundations, presence of humidity in walls or a leak or water passage in the roof. The nitrates, chlorides and sulphates present in the walls come out along with moisture and appear on the wall surface as efflorescence making it look ugly & full of stains. The source of moisture has to be located, plugged and at the same time the porosity of walls is to be treated by application of suitable water-proofing coating. Colourless, odourless and water repelling coatings that penetrate deep into the wall should be selected for use. A leakage may not only become a nuisance but damage to the structure may also happen. Right use and application of water proofing admixtures save structural failure also. A number of protective coatings have now been invented. These surface treatments may save a structure if there had been poor workmanship during construction. Cracks may appear in a structure due to temperature fluctuations. Instead of waiting for the cracks to appear and then applying sealants to them, it will be better to apply protective coatings and to overcome the hidden defects. The protective coatings developed these days are also capable of resisting mild acids, abrasion, algae and ultraviolet rays in addition to providing water-proofing, heat resistance and withstanding thermal expansion and contraction. Marble, granite, stone slabs and various types of tiles have now become of common use. The adhesives developed recently provide excellent adhesion properties and also render spotfee service. Some of the adhesives are fully effective even if used in damp conditions. Among sealants, the polysulphide sealants carry remarkable sealing characteristics. These have come under wide use in airports, dams, reservoirs, atomic power stations, bridges, sub-ways and buildings. Their tensile adhesion, peel adhesion, ultraviolet resistance and water resistance have touched excellent levels. Silicon sealants have proved highly useful in structural glazing, curtain walls, automobile and coach building. Any joint or crack can be sealed for a 10 year service or more by use of these sealants.
The construction chemical industry has developed very fast in the last few years aiming at a synthesis of chemistry and construction. Ask any house owner, hotel manager, maintenance engineer or building care-taker, the major problems faced by him are leakages, dampness, cracks and efflorescence. Right use of admixtures can help in saying goodbye to these problems for ever.
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