Identification of controlling factors for the initiation of corrosion of fresh concrete sewers.

摘要: The development of concrete corrosion in new sewer pipes undergoes an initiation process before reaching active stage. This period is assumed to last several months years but the key factors affecting process, and its duration, are not well understood. study therefore focused on this initial stage effect environmental factors. Such knowledge important for effective management sewers, as every year life extension such systems has a very high financial benefit. long-term (4.5 year) been conducted purpose-built chambers that closely simulated environment, with control three being hydrogen sulfide (H2S) gas phase concentration, relative humidity air temperature. Fresh coupons, cut from industry-standard pipe, were exposed corrosive conditions chambers, both partially submerged wastewater. A total 36 exposure investigated determine controlling by regular retrieval coupons detailed analysis surface pH, sulfur compounds (elemental sulfate) mass loss. Corrosion times thus determined different conditions. It was found time gas-phase partially-submerged positively correlated H2S only at levels 10 ppm or below, indicating oxidation rate rather than concentration limiting factor during Relative also played role coupons. However, affected these direct contact sewage hence did have sufficient moisture enable microbial processes proceed. shortened higher temperature due positive impact reaction kinetics. These findings provide real opportunities pro-active asset aim delay on-set processes, extend service through improved prediction optimization capacity.