Effects of polycarboxylic acid superplasticizer on hardened concrete
(1) effect on concrete strength
In the case of concrete cement content and slump constant, because of the addition of air-entraining agent or air-entraining water-reducing agent, on the one hand, you can increase the concrete air content, on the other hand, can reduce unit water use in concrete, namely lower water/cement ratio, and thus its impact strength.
Results from water, concrete strength increases, however, from the perspective of air, concrete strength is down (in most cases). Therefore, the addition of air-entraining agent or air-entraining water-reducing agent on concrete's strength is the combined result of the two functions.
Generally, in the case of cement content and slump constant, each additional gas 1%, 28-day strength and 2%-3%; If you keep the water/cement ratio unchanged, 1% each additional content, 28 day strength and 5%-6%. Mixing air entraining water-reducing agent, due to the large water reduction, concrete strength can be reduced or slightly increased.
(2) the effect of elastic modulus
Mixing or air-entraining water-reducing agent of concrete with air entraining agent, its generally lower modulus of elasticity than without, and lower the level of variation greater than strength. The reason for this is due to the existence of a large number of tiny bubbles in cement paste, paste elastic modulus decreased.
(3) impact on drying shrinkage
Addition of air-entraining agent or air-entraining water-reducing agent on shrinkage effect is this: air drying shrinkage increases, and slush makes dry cut small, so the end result is actually a combination of two functions.
In General, after mixing air entraining agent, the shrinkage of the concrete will increase, but not much. And the addition of air-entraining water-reducing agent of concrete due to the large water reduction, the drying shrinkage of concrete without equal.
(4) against the effect of seepage
Due to mixed added introduction gas agent or introduction gas reduction agent, makes concrete water reduced, bleeding settlement rate reduced, also that hardening pulp body in the big fine hole reduced, set material pulp body interface structure improved, bleeding channel, and settlement crack reduced, addition, introduced of bubble occupy has concrete in the of free space, damage has hair fine tube of connected sex, these role are will will improve concrete of anti-penetration sex.