隧道洞渣机制砂特性对混凝土坍落度的影响研究

为处置开挖隧道所产生的洞渣，解决山区公路建设天然砂供需不足，以及成本高昂的问题，以池祁高速某隧道开挖的洞渣为原材制备机制砂用于混凝土中，研究了机制砂石粉含量、级配、砂粒形状特征、MB值等特性对混凝土坍落度的影响。试验结果表明：随着石粉含量的增加，机制砂混凝土的坍落度先增大，当含量超过5.4%后逐渐减小；所列3种级配中，大于1.18 mm和小于0.075 mm颗粒含量较少的JP2对机制砂混凝土的坍落度贡献较大；机制砂颗粒特征与坍落度具有良好的线型相关性；机制砂MB值越大导致混凝土的坍落度减小，在生产时应控制机制砂的MB值。

Study on Influence of Machine-made Sand Characteristics of Tunnel Slag on Concrete Slump

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.