Investigating the feasibility of using basalt powder instead of cement in two-component backfilling grout in mechanized tunneling

چکیده مقاله

Nowadays, tunnel excavation projects in urban environments have witnessed significant growth. Given the shallow depth of tunnels in such environments, they are mostly excavated inside the soft ground using the earth pressure balance machine (EPBM). Considering the high volume of grout injection in this type of excavation, using cement replacement materials can lower the cost and the environmental risks of two-component grout. One of these replacement materials is basalt powder (BP) obtained from basalt quarry stone cutting. The present study assesses the feasibility of using BP obtained from quarry stone cutting as a substitute for cement in the two-component backfilling grout. The results showed that BP can be used as a very suitable substitute for cement in the composition of the two-component grout. Based on the obtained results, the strength of the basalt-containing two-component grout is almost equal to that of the grout that contains cement without basalt. Also, the results obtained for the mix design with 30% BP are in good agreement with those of the mix design containing only cement in terms of bleeding, gelling time, and Marsh funnel tests. As a result, using industrial waste significantly reduces grouting costs and grout’s environmental risks.