Environmental assessment of cement-stabilised lateritic soil/melamine debris for Thailand’s pavement

Mirzababaei, M ORCiD: 0000-0002-4801-8811Increased utilisation of melamine products has resulted in large quantities of melamine debris (MD) being stockpiled annually in landfills. In this research, MD was partially replaced with marginal lateritic soil (LS) to develop non-hazardous cement (C)-stabilised pavement sub-base and sub-grade materials. The 7 d unconfined compressive strength values of 3% C-stabilised 80% LS/20% MD blend and 5% C-stabilised 80% LS/20% MD blend met the strength requirement for sub-grade and sub-base materials, as specified by the Department of Highways, Thailand. The leachability of the heavy metals of the C-stabilised LS/MD blends was measured and compared with international standards. The leachate results indicated that the C-stabilised LS/MD blends can be safely used in sustainable pavement applications, as the leachate heavy metal concentrations were within acceptable ranges. The outcome of this study will promote the usage of waste MD in an environmentally friendly manner in pavement construction applications

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