Experimental study on the replacement of roadside filling concrete fine aggregate with coal liquefaction slag

Coal liquefaction slag is a new type of solid waste in coal chemical industry.The existing stacking treatment has great environmental pollution and brought great environmental pressure to coal enterprises.It is urgent to explore the comprehensive utilization method of coal to coal liquefaction slag.Based on the experience of preparing concrete with industrial waste slag, the experiment of replacing concrete fine aggregate with coal liquefaction slag was carried out.Under different water cement ratio conditions, the proportion of coal liquefaction slag is 20%, 40%, 60%, 80% and 100%, respectively.The slump, initial setting time and uniaxial compressive strength of concrete were tested.Due to the characteristics of rough surface, short fiber and slightly high water absorption rate of coal liquefaction slag, the replacement of fine aggregate by coal liquefaction slag has a negative impact on the working performance of concrete.After replacing river sand with coal tar furnace slag in different proportions, the slump of concrete decreases, the initial setting time is shortened, but the uniaxial compressive strength increases in different degrees.The concrete with water cement ratio of 0.40, 0.43 and 0.46 can meet the strength requirements of C30 grade, and the concrete with water cement ratio of 0.49 can meet the strength requirement of C25 grade.The test results show that it is feasible to develop the concrete material from coal liquefaction slag, which provides a new way for the utilization of solid waste from coal liquefaction slag.