Abstract: Recycled coarse aggregate prepared from brick and concrete construction waste usually contains part of the brick aggregate. In order to study the failure mode and the influence of brick content on the properties of mixed recycled coarse aggregate concrete, the recycled concrete aggregate and brick aggregate were mixed in various proportions (volume fraction) to prepare mixed recycled aggregate, and the natural aggregate was replaced by mixed recycled aggregate in 30% to produce concrete specimens for test. The experimental results indicate that the natural aggregate in mixed recycled aggregate concrete fails along the interface transition zone between the aggregate and the mortar, while the recycled brick coarse aggregate is fractured through the aggregate. When the brick content is less than 18%, there is no obvious effect on compressive strength and resistance of chloride penetration, and once the brick content is more than 18%, compressive strength and resistance of chloride penetration decrease obviously. The higher the content of brick is, the worse the salt frost resistance of concrete is. When the brick content is constant, the higher the water cement ratio is, the smaller the adverse effect of recycled brick coarse aggregate on the compressive strength of concrete.

Key words: mixed recycled coarse aggregate, concrete, chloride penetration resistance, cube compressive strength, salt frost resistance