Experimental Study on Recycling of Waste Concrete Based on Geopolymer Technology

Based on the basic principle of geopolymer technology, the geopolymer cementitious materials were prepared by waste concrete powder and fly ash. Geopolymer recycled concrete is the preparation of geopolymer cementitious material and the waste concrete recycled aggregate. The optimum mix ratio of the geopolymer cementitious material, physical and mechanical properties of recycled aggregates, and mechanical properties of recycled concrete is determined by experiment. The results show that the optimum ratio of geopolymer cementitious material is 30:70 for the ratio of waste concrete powder to fly ash (CP: FA), NaOH solution concentration is 18 mol/L and water glass modulus is 1.5. When content of geopolymer cementitious material is 5% to 7%, the unconfined compressive strength of recycled concrete is greater than 3.0 MPa, splitting strength is greater than 0.4 MPa, and the uniaxial compression resilient modulus is between 2750 MPa and 4000 MPa. Geopolymer recycled concrete can not only solve the treatment of waste concrete, but also reduce the exploitation of natural stone, the use of cement and the emission of air pollutants, which has obvious environmental, economic benefits.