Improvement of durability of cement pipe with high calcium fly ash geopolymer covering

Abstract

Cement pipes have been used to transfer the domestic sewage and industrial wastewater due to its cost effectiveness. However, they faced the acid attack problem owing mainly to the high content of calcium compounds in the composite. Coating of cement pipes is one of the methods to protect the cement pipe surface from acid attack. An alumino-silicate geopolymer provides excellent mechanical properties and resistance to severe environments. Therefore, this research proposed the covering of cement-based materials with geopolymer. The covered specimens were immersed in deionized water (pH = 6.1), 0.005% H2SO4 (pH = 3), 5% MgSO4 (pH = 7.7) and 3% H2SO4 (pH = 0.3, representing the worst condition in the wastewater system). The pH and Ca2+ content of immersion solutions were measured. In addition, mechanical and chemical properties of geopolymeric-covering material were tested after the immersion in solutions for 30 and 90 days.