Analysis on the Strength of Cement Mortar Mixed with Construction Waste Brick Powder

The pile-up of massive construction waste causes serious challenges to environment and engineering practice. In order to promote the reuse rate of construction waste bricks, the effects of the content and fineness of construction waste brick powder and of brick powder-silica flour mixture on the strengths of cement mortar were experimentally investigated. Based on the test results, the significance of the particle characteristics of brick powder on mortar strength was analyzed by grey entropy method. The experimental results show that the early strength of cement mortar decreases due to the addition of brick powder; the reduction is, however, not significant when the content of brick powder is less than 10%; the 28 d strength of cement mortar increases with a proper content of brick powder. The grey entropy analysis indicates that the particle characteristics have strong influence on the activity of brick powder and mortar strength; the strength is significantly dependent on specific surface area and the fraction of particles smaller than 20 μm. Fine brick powder and silica flour can improve the macroscopic strengths of cement mortar by affecting the type and quantity of hydration products and the structure of interfacial transition zone between cement paste and sand.