Performance and engineering application of effective microfine cement-based grout(EMCG) for water-rich sand strata

The Portland cement clinker and industrial wastes were selected to prepare the effective microfine cement-based grout(EMCG) adopting optimization methods of particle size distribution and hydration activity excitation. Through laboratory tests, the main features of EMCG such as flowability, viscosity, stability, initial/final setting time, strength and volume stability were studied, and the main properties of ordinary Portland cement 42.5(OPC), microfine Portland cement(MC), microfine sulphoaluminate cement(MSAC) and self- developed EMCG were compared. Based on mineral test methods of XRD and SEM, the hydration mechanism of EMCG was studied. Through grouting simulation experiments, the grouting strengthening property of EMCG on sand specimens was investigated, and different microcosmic reinforcement modes of slurry-rock for various grouts were compared. Field tests were performed to evaluate the plugging and reinforcement effects of EMCG on water-rich sand strata. The results show that the flowability of EMCG suspension is optimal when the water solid ratio(W/S), and the amounts of fly ash and superplasticizer(SP) are 1.5:1-2:1, 40%-50% and 1.5%-2.0% respectively and that the controlling factors of pumping stability are fineness and W/S. The strength and reinforcement effect of EMCG are the best, followed by MSAC and MC, and then OPC. The 7-day strengths of EMCG reinforced specimens are over 70% of the 28-day strengths. It is also shown that the EMCG suspensions have advantages of excellent groutability, pumping stability, setting controllability, volume stability, high strength, favorable hydration mineral, compact microstructure and so on, and hence, can effectively improve the integrity and stability of water-rich sand strata. Due to its high performance and excellent engineering applicability, EMCG is an efficient and excellent grout especially for anti-seepage and reinforcement of water-rich sand strata. © 2019, Science Press. All right reserved.