Fire Resistance of Sewage Sludge Ash Blended Cement Pastes

The aim of the present study is to investigate the hydration characteristics and the fire resistance of sewage sludge ash blended cement pastes by the determination of compressive strength, bulk density, and total porosity in addition to XRD and SEM techniques. Sewage sludge ash modifies the hydration of cement because of its pozzolanic reaction with portlandite favoring the formation of crosslinked fibrous calcium silicate of low Ca/Si ratio. Hence, it was concluded that thermal damage of cement pastes after the exposure to high treatment temperatures (i.e., crack formation and loss of mechanical properties) was effectively reduced with sewage sludge as content up to 20 wt% because of that the presence of crosslinked fibrous calcium silicate strengthens the cement matrix.