Soil-cement is a highly compacted mixture of soil/aggregate, portland cement, and water. Soil-cement differs from Portland cement concrete pavements in several respects. One significant difference is the manner in which the aggregates or soil particles are held together. A Portland cement concrete pavements mix contains sufficient paste (cement and water mixture) to coat the surface area of all aggregates and fill the void between aggregates. In soilcement mixtures, the paste is insufficient to fill the aggregate voids and coat all particles, resulting in a cement matrix that binds nodules of uncemented material. It is widely used as a low-cost pavement base for roads, residential streets, parking areas, airports, shoulders, and materials-handling and storage areas. Its advantages of great strength and durability combine with low first cost to make it the outstanding value in its field. A thin bituminous surface is usually placed on the soil-cement to complete the pavement.
The cost of soil-cement compares favorably with that of granular-base pavement. When built for equal load-carrying capacity, soil-cement is almost always less expensive than other low-cost pavements. Economy is achieved through the use or reuse of in-place or nearby borrow materials. No costly hauling of expensive, granular- base materials is required; thus both energy and materials are conserved. The major engineering benefits of cement stabilization are increased strength, stiffness, better volume stability and increased durability.
The improvement of the unconfined compressive strength (UCS) of LSC composite was also evaluated. As regards the application aspect, the results shows that cement mixed lateritic soils are suitable for base course construction. The investigation also shows that increase in UCS was attributed to the cement hydration within soil mass, resulting in the formation of reaction products as analyzed by XRD. It was also found that UCS was proportionally increased with the amount of the major reaction products such as calcium silicate hydrate (CSH). They used the Portland cement is a popular additive for stabilization.
They carried out unconfined compression test and UCS of composite soil cement was determined at various curing ages. From this they observed that UCS increased with increasing cement content as well as with increasing time of curing.A quantitative assessment of soil mineral composition was performed using X-RAY diffractometer, XRD, PHILIPS X’Pert MPD, Netherlands.
Soil-cement thicknesses are less than those required for granular bases carrying the same traffic over the same subgrade. This is because soil-cement is a cemented, rigid material that distributes loads over broad areas. Its slab-like characteristics and beam strength are unmatched by granular bases. Hard, rigid soil-cement resists cyclic cold, rain, and spring-thaw damage. Cement stabilizes soil in two ways. First, it reduces soil plasticity, especially for the soil in which there is high amount of clay particles. The second is cementation which is very important because clay is not its main composition. In fine grained silty and clayey soils, the hydration of cement develops strong linkages between the soil aggregates to form a matrix that effectively encases the soil aggregates. Old soil-cement pavements in all parts of the continent are still giving good service at low maintenance costs. Soil-cement has been used in every state in the United States and in all Canadian provinces. Specimens taken from roads show that the strength of soil-cement actually increases with age; some specimens were four times as strong as test specimens made when the roads were first opened to traffic. This reserve strength accounts in part for soil-cement’s good long-term performance.