Design of eco-efficient grouts intended for soil nailing

The work reported is a feasibility study to evaluate the pertinence of using metakaolin (MK) in grout intended for soil nailing. MK allows a strong decrease of CO2 emission compared to grouts containing cement only. The experimental program was divided into two steps: a first step to study the formulation parameters of the grouts by means of a mixture design plan, followed by an in situ program of pull-out tests to evaluate the performance of the grouts designed. The results show that metakaolin is compatible with this kind of application, since it improved the environmental balance of grouts by reducing the cement content. Moreover, its pozzolanic effect counteracted some of the cement dilution. The in situ pull-out tests highlighted the minimum performance levels necessary for the grout to fulfill its role of transferring stresses between soil and nail.