Resistance of high alumina and portland cement to H2SO4

Recently, there has been an insurgence of new technologies used in rehabilitating existing sanitary sewer systems, which have experienced hydrogen sulfide corrosion, and reducing the cost of maintaining these systems. "No dig" technologies are on the rise in the United States and include such innovations as synthetic liners, PVC inserts and grouting systems. The mortars, used in the grouting systems, are the main focus of this paper. A series of tests designed to assess the resistance of different mortars in dilute sulfuric acid solution, simulating the harsh environmental conditions found in sanitary sewer systems, were performed. The mortars used for this study were High Alumina Cement (HAC), Portland Cement and sand (PC), and Portland Cement, sand and silica fume (MSPC) mortars. The specimens made from these mortar mixes were submerged in water and cured for 28 days. After curing, the specimens were immersed in three different dilute sulfuric acid solutions, 1.0%, 5.0% and 10.0% by volume. Comparisons were made by observing the loss in mass of the specimens. Specimen masses were recorded at 7, 28 and 56 days. At 56 days the tests were discontinued. A 25% decease in mass was considered as an indication of failure for the test specimens. After a review of the data gathered, it was found that the HAC mortar appeared to perform better than the PC or MSPC mortars. The HAC mortar maintained an average of approximately 75% of its mass throughout the test period, in all three of the acid solutions. Alternatively, the PC and MSPC mortars placed in the 5.0% and 10.0% solutions lost more than 25% of their mass, within the first 20 day of the test. The PC and MSPC mortars maintained greater than 75% of their mass, in the 1.0% solution.