Lithostab as Technique for Improving the Geotechnical Performance of a Lateritic Soil in Road Construction

This article focuses on a technique for shallow mechanical improvement of soil which deals with the utilization of crushed granite mixed in a certain percentage with lateritic soils during road construction in Burkina Faso.Lithostab is the simplified name for litho-stabilization,a technique for improving laterite by adding crushed granite that increases the CBR(California bearing ratio)of that material for being used in road construction.Class 0/25 of crushed granite added to a laterite in our case gives good performance in terms of CBR.Indeed,the CBR index which was initially 48 at 98%of the OMP(optimum modified Proctor)goes to 88.And from 84 at 98%of the OMP,it goes to 128 for 30%of class 0/25 of crushed granite added.This means that class 0/25 of crushed granite provides better CBR index to that material when it is incorporated at 30%.So,lithostab is an easy to implement eco-friendly material for road construction because of the utilization of local materials.Then,it contributes to the protection of the environment in the sense that its production does not require a lot of energy and does not release large quantities of carbon dioxide into the atmosphere.

Effect of environment change on the strength of cement/lime treated clays

The field strengths of cement/lime treated clays were investigated in the Ariake Sea costal lowlands.The deposition environment of the investigation location is reconstructed and compared to the present ground environment.The mechanism of the ground environment change and its effect on the strength of cement/lime treated soil are discussed.The strength development of improved soil using cement and lime in different curing environments was investigated in the laboratory for studying the effect of environment change on the strength also.It has been found that the strength deterioration of improved soil in deep mixing method is due to 1)the ground environment change due to the secondary oxidation which results in low pH value and high organic content,and 2)the formations of the porous structures result from the elution of the calcium ions.Also,it has been found that the initial strength increase of the improved soil is related to the dissolved silica and that the dissolution of the silica in clay minerals needs long time.When examining the longterm strength for preventing strength degradation,the effect of environmental change has to be considered.The importance of measuring pH and oxidation-reduction potential(ORP)of the ground for cement/lime solidification method is explained.