Underground sewer network is a part

Underground sewer network is a part of urban lifeline project. At present, the whole world is facing the aging and deterioration of sewage pipelines, and the maintaining and renewing of concrete sewers cost lots of money [1], so it is urgent to find concrete materials with better durability. In the service process of concrete sewer pipes, microbial effect [2] is considered to be the main cause of concrete degradation in sewage environment apart from physical and chemical effects [3,4]. This is because in sewage there are a large number of organic and inorganic substances containing carbon, hydrogen, oxygen, nitrogen, sulfur and other elements, which will eventually be decomposed into carbon dioxide, sulfate, nitrate, hydrogen sulfide, etc. under the metabolic action of microorganisms, and further transformed into sulfuric acid, nitric acid and various organic acids [5-7]. Among them, the biological sulfuric acid produced by sulfur oxidizing bacteria (SOB) under the aerobic conditions is the main cause of concrete degradation in the unfilled space of gravity sewage pipe [8], which often originates from the sewage level and gradually develops to the crown of the pipe [9].