Sulfuric Acid Attack on Concrete Sewer Pipe

Research was performed to determine if selected surface treatments would react chemically with the portland cement and increase the resistance of a mortar to sulfuric acid attack. Four parameters were investigated: (1) Portland cement type; (2) water/cement ratio; (3) sulfuric acid concentration; and (4) chemical surface treatment. The laboratory tests did not produce a desired solution for the problem of sulfuric acid attack on portland cement mortar. However, the experience in the laboratory did lead to the following conclusions: (1) Magnesium silicofluoride, sodium silicate, potassium silicate, and sodium alginate do not benefit the resistance of portland cement mortar to sulfuric acid attack; (2) even weak sulfuric acid solutions caused deterioration of both treated and untreated mortars; (3) varying the constituents of mortar produced from either Type I or Type II cement do not prevent failure due to sulfuric acid attack; and (4) sulfuric acid attack on portland cement mortar is a surface phenomenon and does not affect the structural integrity of the interior of the mortar specimens.