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CHEMICAL SEALERS COMPARISON

In order to understand why conventional sealer materials could not offer guaranteed long term waterproofing solutions to concrete under high thermal stress we must look at their chemical limitations. This sub-section will also facilitate to give a chemical explanation to why. Radcon Formula #7 is a suitable alternative to membranes. There are many different brands of chemical sealers on the market and all fall under one of three categories.

Silanes or Siloxane type materials utilize a solvent to gain penetration into concrete, they then form a hydrocarbon link within the concrete which repels water. The product will continue to block these pores and capillaries and cracks up to 0 , 3mm which are present at the time of application provided hydrostatic pressure is not applied. Any further cracking as a result of shrinkage or thermal stress will be future paths for the ingress of water and chloride ions.

Permanent pounding or hydrostatic pressure will overcome the ability of a silane to repel water and pollutants, this also casts doubts of the material's performance under wind driven rain.

In summary, the main performance advantages that Radcon #7 has over Silane type materials are, the ability of Radcon #7 to seal cracks up to 2mm, withstand any amount of hydrostatic pressure, a re-sealing capability, and an increase of consolidation or hardness of the penetrated zone.

Radcon Formula #7 has the further advantage of being environmentally friendly as it contains no solvents such as those found in silanes or siloxanes.

There are a number of different brands of sealers that rely on the growth of crystals to fill the pores and hairline cracks in the concrete. They claim to seal up to 0.3mm cracks and can be - applied against hydrostatic pressure. These materials are designed and primarily used for the waterproofing of low thermal stress areas such as basements.

They cannot be guaranteed to seal cracks in concrete under high thermal stress. The reason behind this is due to the fact that the crystals formed are a homogeneous material with a consistent rate of expansion and contraction. Concrete, on the other hand, is not a homogeneous material and will have different rates of expansion and contraction according to the variables in the mix. Thus the crystals in the cracks cannot accommodate the movement as a result of high thermal stress and will fail.

Radcon #7 on the other hand remains, as a slightly amorphous material thus is able to accommodate the movement in shrinkage cracks under high thermal stress.

Silicates have been used generally as case hardeners and sealers. Sodium Silicate will react with a Calcium solution (i.e. lime water) to form a calcium silicate hydrate gel. This is a relatively fast reaction when sodium silicate is sprayed onto a concrete surface such that absorption is limited to the first few millimeters. The calcium silicate hydrate will provide a temporary waterproof seal for a period of time and the treatment will also harden the concrete. This calcium silicate hydrate gel will dehydrate over time and no longer prevent the ingress of water and contaminants.

Radcon Formula #7 utilizes a biochemical function that alters its base, Sodium Silicate, in such a way to produce the unique performance characteristics best outlined through our product test information.

Radcon Formula #7 reacts with the free calcium in concrete and water to form a gel in all the voids, capillaries and cracks in the treated matrix. This gel will not dehydrate and will remain reactive upon contact with further water. Thus when future hairline cracking appears the product will reactivate and create a watertight seal.

Radcon Formula #7 will penetrate up to 20mm in 25mpa concrete and will waterproof a concrete slab undergoing high thermal stress with cracks up to 2mm that go right through the slab.

As Radcon Formula #7 occludes the free calcium and water in the treated matrix the carbonation process is greatly inhibited. The pore blocking action of a Radcon Formula #7 treatment prevents the ingress of air borne pollutants such as the chloride ions. (Warnock Hersey Report ~ 50244-C7-416600, January 20, 1989)

Further benefits of a Radcon Formula #7 treatment are that the alkalinity is maintained or reinstated on carbonated concrete and there is an increase in hardness of the penetrated zone.