Sustainable design performance of cementitious binder for construction stabilised soil/subgrades

The enhancement of both existing and virgin pavement materials has been successfully executed in Malaysia since the 1980s using the procedure of In-situ Stabilisation. Most designated projects have utilised cement or lime as the binding agent for subgrades, granular bases and sub-base materials. The utilisation of cementitious binders is increasingly favoured in Malaysia as asset owners acknowledge the need of establishing robust foundations for pavement projects. In pavement design, the two most pivotal inputs that affect the overall thickness of a pavement structure are the traffic loadings and the design subgrade California Bearing Ratio (CBR). The stiffness of soil/subgrade is the critical variable that can be optimised for enhancement and should be improved wherever feasible. Cement and lime are very effective in significantly enhancing bearing capacity, mitigating volumetric instability and specifically incorporating lime to diminish the moisture susceptibility of clayey, expansive and plastic materials frequently found in pavement subgrades. Some of the soil characteristics may contain organic i.e. peat soil that may require the additional imported suitable earth or additional material such as crusher run, fly ash or slag shall be taken into consideration. The examination of the soil characteristics, this research is focusing the design process and validating the performance of the admixture from laboratory and field evaluation based on the design charts and specifications addressed for cement and lime including of pavement layers to be treated and process of the soil treatment. The methods of the stabilisation’s research analysis which referred to laboratory testing from few projects undertaken to compare the results findings are met or achieved accordingly. Therefore, for design criteria choosing binder agents for type soils can be relate to plasticity index (PI) range between 10% to 20% by using cement and 20% and above which is high plasticity and moisture which may produce to acidic reaction to be used quicklime as a binder agent. Identifying the proportion of the binders is crucial to ensure the flexibility of the pavement layers. The average results of the proportion of the binders shown at 4% which same as industrial design. Overall result from the design and process of this research can be concluded as significantly help the stakeholder i.e. designer, site supervisory and end user for cost and time saving. This study presents a novelty contribution through the completion and integration of laboratory based on Field Density Test (FDT) California Bearing Ratio and Unconfined Compressive Strength (UCS) test to validate the mechanical performance of stabilised soil or subgrades). A key innovation of this research is the development of a simplified calculation method whereby compaction density and plasticity index data which derived from field measurements, can be used to manually estimate soil performance parameters without the need for extensive laboratory testing. Furthermore, the proposed formulation provides a practical and reliable approach for determining the optimum percentage of cement or lime required for soil stabilisation, thereby offering a cost effectiveness, time efficient and field applicable solution for pavement and ground improvement design.