Effect of Active Powder and Highly Dispersed Fiber Composite on Crack Resistance and Impermeability of Concrete

A variety of functional active powder and highly dispersed fibers were mixed into concrete as the anti-cracking agent in a certain proportion. The effects of the anti-cracking agent on concrete’ s mixing properties, mechanical properties, early crack resistance, impermeability and shrinkage were studied, and the mechanism of the influence of anti-crack agent on the anti-crack and anti-seepage performance of concrete was analyzed. The results show that the anti-cracking agent can improve the comprehensive properties of concrete, especially the crack resistance and impermeability. Adding 1 kg anti-cracking agent to each cubic meter of concrete mixture can reduce the early crack by 85%, the seepage height by 65%, and the shrinkage of 28 d and 90 d by 34% and 30% respectively. When the content of anti-cracking agent increases to 1.5 kg, the improvement effect decreases. The anti-cracking agent improves the concrete performance through the filling effect of powder and the bridging effect of fiber. It does not participate in the hydration reaction of the cement, but can accelerate the hydration rate, and excessive amount of anti-cracking agent causes stress concentration, which weakens the improvement effect of concrete performance.