Problematic soil stabilization processes involve the application of binders to improve the engineering properties of the soil. This is done to change the undesirable properties of these soils to meet basic design standards. However, very little attention has been given to the reactive phase of soil stabilization. This phase is the most important in every stabilization protocol because it embodies the reactions that lead to the bonding of the dispersed particles of clayey soil. Hence, this reactive phase is reviewed. When clayey soils which make up the greatest fraction of expansive soil come in contact with moisture, they experience volume changes due to adsorbed moisture that forms films of double diffused layer on the particles. When this happens, the clayey particles disperse and float, increasing the pore spaces or voids that exist in the soil mass. Stabilizations of these soils are conducted to close the gaps between the dispersed clayey soil particles. This is achieved by mixing additives that will release calcium, aluminum, silicon, etc., in the presence of adsorbed moisture, and a hydration reaction occurs. This is followed by the displacement reaction based on the metallic order in the electrochemical series. This causes a calcination reaction, a process whereby calcium displaces the hydrogen ions of the dipole adsorbed moisture and displaces the sodium ion responsible for the swelling potential of clayey soils. These whole processes lead to a pozzolanic reaction, which finally forms calcium alumina‐silica hydrate. This formation is responsible for soil stabilization.

The effect of NBA on the durability of the hydraulically bound cemented lateritic soil was investigated and results were observed. Preliminary tests conducted showed that the natural soil was an A-2-7 soil according to AASHTO classification system, poorly graded, highly plastic and had high swell potential. The treatment exercise showed that the gradation and strength properties improved with the addition of the NBA materials at the rate of 5, 10 and 15% by weight of the solid. The erodibility and loss of strength on immersion tests conducted showed that the cemented soil improved on these properties from a highly erodible and non-durable stabilized matrix to a very less erodible and very durable stabilized matrix with a consistent durability index above 80%. With the foregoing, the nanostructured material additives have proved to be good materials for use in the stabilisation of a more durable, and less erodible subgrade, backfill or foundation material.

The swelling potential, shrinkage limits, strength development and durability of crushed waste ceramic base geopolymer cement (CWCbGPC) treated test soils A, B and C have been studied under the laboratory conditions. The test soil samples were preliminarily investigated and characterized under the laboratory conditions. Soils A, B and C were classified as A-2-7, A-2-6 and A-7, respectively, according to the AASHTO classification method. They were also classified according to USCS as poorly graded. Additionally, soils A and C were observed as having higher clay content than soil B. They were also classified as highly plastic with plasticity index above 17% and expansive. The free swell index and shrinkage tests showed that they had high potential for swelling and shrinkage. The treated soils show significant improvement in swelling, shrinkage, strength development and durability with CWCbGPC while the cemented soils failed in terms of shrinkage and durability, which proved that Portland cements have high potential for shrinkage with soil blends. The results of the laboratory study have shown that CWCbGPC and other geopolymer cements can totally replace Portland cements in civil engineering works more especially in the construction of hydraulically bound structures.

Volume change in expansive soils is a problem encountered in earth work around the world. This is prominent with hydraulically bound structures or foundations subjected to prolonged moisture exposure. This behavior of clayey used as subgrade, foundation, landfill, or backfill materials causes undesirable structural functionality and failures. To prevent this happening, clayey soils are studied for possible volume change potential and degree of expansion. Consequently, the problematic soils are stabilized. In this work, the stabilization of clayey highly expansive soil classified as A‐7‐6 soil and highly plastic with high clay content was conducted under laboratory conditions. The treatment exercise was experimented using quicklime‐activated rice husk ash (QARHA), hydrated lime‐activated rice husk ash (HARHA), and calcite‐activated rice husk ash (CARHA) at the rates of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%. Upon treatment with the three calcium compounds to produce three sets of treated experimental specimens, the plasticity index was observed and recorded and swelling potentials were evaluated using the plasticity index method (PIM). The results showed a consistent improvement on the properties of the treated soil with the addition of the different activated admixtures. While the utilization of CARHA and HARHA improved the clayey soil to medium expansive soil, the treated clayey soil substantially improved from highly expansive soil with a potential of 23.35% to less expansive with a final potential of 0.59% upon the addition of 10% QARHA. Finally, QARHA was adjudged as the best binding composite due to the highest rate of reduction recorded with its utilization.