Study on preparation and modification of synchronous grouting material with waste fine sand slag by shield method

In order to solve the problem of difficult treatment and non-reuse of waste residue soil in subway tunnel shield construction. Based on the Fuzhou subway project, the synchronous grouting material was prepared by replacing river sand with an equal mass ratio of shield fine sand slag, and the influence of shield fine sand on its performance was studied. On this basis, the influence of the water-binder ratio, cement-sand ratio, expansion water ratio, and powder-cement ratio on the performance of grouting material was analyzed. The test results show that the working performance and mechanical properties of synchronous grouting material gradually deteriorate with the increase of fine sand content. The order of influencing factors on the consistency of fine sand synchronous grouting material is as follows: water-cement ratio > mortar ratio > powder-cement ratio > expansion water ratio. The order of influencing factors on compressive strength is as below: water-cement ratio > mortar ratio > expansion water ratio > powder-cement ratio. It is recommended that the optimal mix proportion of synchronous grouting material with fine sand is 6.3% cement, 19.0% fly ash, 3.9% bentonite, 48.8% fine sand, and 22.0% water.