The alkaline viscous substances used as reinforcement have engendered long term erosion of laterite groundwork. Scene sampling and archetype testing were executed in a geotechnical engineering project. Chemical erosion of laterite by alkaline material were investigated, and accelerated life tests were designed for laterite eroded by alkaline materials. Engineering factors were compared and concentrations of seeping support ions were tested for studying laterite eroded by alkaline viscous substances. Mechanism of laterite groundwork eroded by alkaline viscous substances was established. The chemical reactions are important cause for reduction of laterite groundwork life and long term economic benefit, and even can cause catastrophic accident.