Corrosion of Surface of Set Cement by Different Acids

Acids have strong corrosion to cement; different acids corrode cement in different mechanisms. The solution and dispersion of set cement in hydrochloric acid and hydrofluoric acid were studied by static soaking of set cement in these acids. Using SEM, polarized light microscope and X-ray energy spectrometer, the surface composition and textures of set cement being corroded by acids can be measured. These studies helped understand the cleansing of cement scales with acids. When dissolved in hydrochloric acid, the residue of cement was mainly SiO₂, and when dissolved in hydrofluoric acid, the residue became CaF₂. Hydrofluoric acid dispersed ball-shaped cement remarkably, and can damage the adhesion of cement, producing crystal defect in cement which accelerated the disintegration of set cement. This study will play important roles in the preparation of cleansing fluid and in fast cleansing of set cement remained in containers and pipes.