The effect of acute environmental conditions on water penetration rate and surface strength of concretes containing fibrous microsilica gel and super gel using in situ tests

The mechanical and chemical characteristics of concrete undergo changes in extreme environmental conditions, which often reduce the strength and durability. Therefore, the use of additives that increase the reliability of concrete in acute conditions is required. It is also important to use tests that are able to measure the permeability and resistance of concrete both in situ and in the laboratory without damaging the concrete. Therefore, it was decided to investigate the effect of some additives on the durability of concrete, which are recently widely used in Iran. There is not much research on the effect of these materials on the durability and reliability of concrete in extreme environmental conditions. In this research, by using in-situ cylindrical chamber and twist-off tests, the effect of different cycles of freezing and thawing on the permeability and surface resistance of ordinary concretes and concretes was evaluated. Contains additives. Contrary to DIN 1048 and BS EN 12390-8 standards, which require breaking concrete to measure permeability, the volume and depth of water penetration can be measured in the cylindrical chamber test without damaging the concrete. The obtained results show that by using the cylindrical chamber . Also, about 78% decrease in the strength of the surface layer of concrete occurred in the first 50 cycles and the remaining 22% occurred in the next 100 cycles. The permeability of concrete containing microsilica gel and supergel was calculated to be about 50% and 30% lower than the permeability of normal concrete, respectively.