Study On Heat Treatment To Recover The Activity Of Hydrated Cementing Material Basics

The national construction waste output rosed sharply, along with the speed of our country's urbanization, the construction of urban construction and development of larg e-scale urban renewal, the scale of residential district and road expansion project is carr ied out. According to statistics, 2013 China's construction waste emissions had reached14 tons, compared with 09 years of production increased by 3 times. Most of these con struction waste are untreated, they were be open dumped or simple landfilled. It lead se riousit environmental pollution and waste of resources. It is extremely urgent to dispos e of more and more construction wastes. The following conclusions had been drown.(1) The influence of low temperature preheating treatment on the microstructure damage of the waste concrete and its mechanism were explored. The results show that the optimum cryogenic temperature of waste concrete is 300 degrees, in this degrees broken is easy. when the waste concrete is heated, With the increase of temperature, the sand stone and cement gelation components apparented thermal expansion coefficient difference. At the interface, a new crack is extended and extended, The bonding stress between cement and sand is reduced. Waste concrete after low temperature preheating treatment, The cement paste that is wrapped in the aggregate is completely stripped off, it is fractured by grinding and extrusion. The sand stone and cement gelation components could be separated by cyclone separation.(2) The effect of low temperature preheating treatment on the energy consumption of the waste concrete is studied. The results show that: Compared with the cement clinker, the grinding energy of the waste concrete is less than the cement clinker 1/2. The grinding energy of the waste concrete after low temperature preheating at 300 is only 1/5 of cement clinker. The preheating treatment of higher than 300 degrees did not continue to reduce the grinding energy of the waste concrete, and its grinding energy increased.(3) Use the waste concrete as mineral admixture have a good operation. When 30% waste concrete is be added, the compressive strength of 7 waste concrete was 16 MPa, and the strength of 28 days was 23 MPa. And when 60% waste concrete is be added, the compressive strength of 7 waste concrete was 12.5MPa, and the strength of 28 days was 14 MPa. The compressive strength depends on the amount of the waste concrete unhydrated cement clinker composition of how much.(4) Study on the basic mechanism research of the recovery of hydration cementitious materials by heat treatment The factors that affect the activity recovery of the hydration cementitious components include: Calcination time, calcination temperature,cooling system and so on. Has hydrated portland cement in 750 degree conditions for 120 minutes, The compressive strength could reach 46.70 Mpa. After heat treatment, hydration cementitious component had a good cementitious property.