Study of Rapid Filtration of Cement Based Grouts by a Steel Model in the Field

This paper aims to evaluate the role of rise in the grouting pressure rate on the filtration of cement-base grouting. In order to simulate the actual conditions, a steel model has been used which can be injected with a grouting piston pump similar to the construction conditions. Two pressure routes have been used in this study one of which, the pressure is suddenly increased so that in 1 min, the pressure reaches the test reference pressure value (10 bar). In the second route, it took about 10 min to reach the desired pressure. The test results show that in the case of rapid increase in the grouting pressure of the cement-base grouts, the flow reduces immediately and eventually the joint is plugged completely (called rapid filtration). However, when the grouting pressure increases gradually, the flow rate increases proportionally leading to an appropriate grout penetration. These tests were repeated for grouts with different water to cement ratios (W/C). Results show that thinner grouts penetration was less affected by increasing the pressure rate. Besides, the filtration process of the grout was monitored by measuring the output grout.