Marginal lateritic soil/crushed slag blends as an engineering fill material

Lateritic soil (LS) with suitable mechanical properties is commonly used as the subbase and as engineering fill material in roads. However, LS is becoming increasingly scarce as a source for road projects. The usage of marginal LS as a pavement subbase and engineering fill material leads to some challenging issues that this research seeks to address. This paper evaluates the possibility of using crushed slag (CS), a waste by-product, as a replacement material to stabilize marginal LS for engineering fill applications. An investigation was undertaken on the physical and mechanical properties of the LS/CS blends at various CS replacement contents. The laboratory evaluation program included particle size distribution, specific gravity, water absorption, Los Angeles (LA) abrasion, Atterberg limit, California Bearing Ratio (CBR) and swelling tests. CS replacement was found to reduce the fine content and increase the abrasion resistance of the marginal LS, resulting in a reduction in liquid limit, plasticity index, LA abrasion and particle breakage. With increases in the CS replacement content, a marked improvement in the physical properties of the blends was found, including increased soaked CBR and reduced swelling. Normalized CBRCS /CBR0 and SCS /S0 and CS replacement relationships were developed in this research. CBRCS and SCS are the CBR and swelling values at various CS replacement contents, respectively and CBR0 and S0 are the CBR0 and swelling values at a 0% CS replacement content, respectively. The results are expected to be of interest to both geotechnical and pavement practitioners. The physical and mechanical properties of the blends with a minimum of 10% CS replacement content were found to meet the national local road authority requirements for engineering fill material

Laboratory investigation of cement-stabilized marginal lateritic soil by crushed slag–fly ash replacement for pavement applications

Road construction consumes vast quantities of high-quality quarry materials. Lateritic soil (LS) is commonly used as a natural resource for subbase and base materials in Thailand. This research aims to study the feasibility of using crushed slag (CS) and fly ash (FA) to improve the physical properties of marginal LS prior to cement (C) stabilization for pavement applications. The pozzolanic materials in CS and FA were found to react with Ca(OH)2 produced by hydration, which results in the formation of cementitious products over time. Geotechnical engineering laboratory tests were conducted to evaluate the possibility of using cement stabilized LS/CS/FA blends as pavement subbase/base materials. The durability of the blends against wetting and drying cycles were also studied. The unconfined compressive strength (UCS) development of the mixtures was examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. CS was found to have a high potential for minimizing swelling, which controls the durability of the stabilized material. Based on the specification of the Department of Highways, Thailand, the 3% C samples were found to be suitable as a subbase material when blended with 30% CS replacement and as a base material when blended with CS and FA at LS:CS:FA=70:0:30 and 70:15:15. The CS replacement was found to prolong the service life of stabilized subbases/bases with up to 12 wetting-drying cycles. This research confirms the possibility of incorporating LS/CS/FA in road work applications, with significant environmental benefits