آب و فاضلاب (Oct 2015)
Estimation of Concrete Strength in Sewer Systems
Abstract
Environmental conditions in sewer systems are such that the concrete in the sewer structures are attacked and heavy losses are inflicted. In this paper, the results of an in-situ study of the effects of environmental and service conditions on the surface strength of concrete are presented. In these investigations, different concrete mixes with different strengths were examined in the sewer system in the city of Malayer where the ambient pH (inside the sewage pipe and above the passing sewage line) ranged from 4 to 6. The in-situ, twist-off method was used for measuring the surface strength of concrete samples. Results indicate that concrete strength decreased with reducing pH level. Under neutral conditions, however, the strength of almost all the concrete specimens increased after 135 days. Finally, the concrete specimens with no additives exhibited reduced strength while those containing 10 percent micro-silica showed an increase in strength.
