Influence Of Recycled Aggregate Strengthen And Adding Fiber On The Properties Of Recycled Aggregate Concrete

In this thesis, an experimental investigation was conducted to study the influence of aggregate strengthen and adding fiber on the properties of recycled aggregate concrete.The performance of three types of coarse aggregate (natural aggregate NA and recycled aggregate RA and recycled aggregate treated by capillary crystalline solution RA-1) were tested, and there was an tentative characterization to the angularity of the coarse aggregate. Three types of method to enhance the performance of the recycled aggregate concrete were conducted:1, treat the recycled coarse aggregate by the DPS solution;2, adding polypropylene fiber to the recycled aggregate concrete;3, adding steel fiber to the recycled aggregate concrete. Then the function of the three methods were tested by mechanical property and durability experiment.This thesis consists of two parts:1, Study of the coarse aggregate. Grading analysis, apparent density, water absorption, crushing value and soundness were conducted on the NA, RA and treated recycled aggregate (RA-1); angularity of the coarse aggregate were described, and the differences were studied.2, Study of the recycled aggregate concrete. ten types of concrete (water-binder ratios were0.26and0.60) were made to test the effect of the three methods mentioned above on the recycled aggregate concrete.The results showed that the RA had lower apparent density, worse particle size distribution, higher water absorption, worse crushing value and worse soundness. Compared with NA, RA also had more irregular surface and worse texture. The three methods to enhance the recycled aggregate concrete were proved to be effective: process the recycled coarse aggregate with the DPS solution can obviously improve the compressive strength and splitting tensile strength of the recycled aggregate concrete when the water-binder ratios was0.26; adding steel fiber can improve the splitting tensile strength and the fracture energy without influencing the compressive strength when the water-binder ratios was0.26; adding polypropylene fiber can only improve the fracture energy, and it has better effect when the water-binder ratios was0.60than when the water-binder ratios was0.26, adding polypropylene fiber may decrease the chloride ion penetration resistance.