Performance of unpaved laterite road treated with chemical additives and waste tire

摘要

Lateritic unpaved roads are widely spread in Malaysian territory. These red-yellow lateritic layers normally have poor engineering properties such as large settlements, low shear strength and bearing capacity. Major difficulties may arise during the construction of a lateritic layer which are deterioration and diffusion of dust on the road surface, and also durability problems associated with cyclic loading repetition. Waste tires are encountered all over the world in increasing numbers. Shredded scrap tires and crumbssoil mixtures are currently used in a wide range of civil engineering structures like lightweight fills for slopes, retaining walls, embankments etc. This thesis presents and discusses the condition of lateritic soil stabilized by using the shredded tires, tire crumbs and traditional active additive materials such as cement and lime for unpaved road application. Experimental tests such as X-ray diffraction (XRD), scanning electron microscope (SEM), california bearing ratio (CBR), consolidated undrained (CU) triaxial, permeability, and highway accelerated loading instrument (HALI) tests were carried out to evaluate the microstructures, elements, durability and geotechnical strength properties of tropical laterite soils. These tests were conducted to determine the influence of stabilizers on the surface of the lateritic soil layers in terms of loading cycles, and short term behaviour. The quick undrained triaxial and CBR tests were carried out on samples at different curing times to establish the optimum mix design. The strength parameters were determined from CU triaxial tests on unsoaked samples. The HALI test was used to study the strength, durability and deformation after determination of the best formulation for each stabilizer in combination with laterite soils under accelerated trafficking load, simultaneously. The close range Photogrammetry technique was also used to capture images of deformed untreated and treated surface. The camera data were analysed using software known as Australis, and Surfer 10 were used to evaluate the performance of unpaved road stabilization with traditional active additives and waste tires. After eliciting of results and data and use of the comparison curves, the behaviour of stabilized soil with different combination were determined. The highest and lowest permeability were STc (soil and tire crumbs) and SC (soil and cement) at 14 days, respectively. The highest CBR values occurred for SC on unsoaked condition in 14 days. The HALI test shows that the highest reduction in settlement was exhibited by SL (soil-6%lime) after 14 days curing. Also, the experimental results show that 6% of lime/cement and 6% of shredded tires/tires crumbs changed the soil strength, durability, and permeability properties of the lateritic soil for unpaved road applications. The results indicate that the shredded scrap tire and crumbs mixed with active additive had reduced the settlement significantly and also had increased the strength. The analysis of data by close range Photogrammetry technique shows a close approximation to the data obtained from LVDT’s equipment (less than 4.5% variance). The numerical simulation results carried out using ABAQUS 6.11 show a noticeable similarity to the results obtained by full scale HALI model and it is recommended using ABAQUS to simulate the unpaved road behaviour under cyclic loading to save time and cost.