Abstract:In order to dispose the slag produced by tunnel excavation, and to solve the problems of insufficient supply of and demand for the natural sand and high cot in the construction of mountain road, the tunnel slag from a tunnel excavation in Chi-qi Expressway is taken as the raw material to prepare the machine-made sand used into concrete. The influences of the stone powder content, grading, grain shape feature, MB value and other characters of the machine-made sand on the concrete slump are studied. The test results show that the slump of machine-made sand concrete increases first with the increase of stone powder content, and then decreases gradually when the content exceeds 5.4%. Among the three gradations listed, JP2 with the particle contents greater than 1.18 mm and less than 0.075 mm contribute greatly to the slump of machine-made sand concrete. The particle characteristics of machine-made sand have good linear correlation with slump. The larger the Mb value of machine-made sand is, the smaller the slump of concrete will be. The Mb value of machine-made sand should be controlled during production.