2.1 Raw materials
The 42.5 sulfoaluminate cement used for the test is offered by Tangshan Polar Bear Building Materials Co., Ltd. Its chemical composition is given in Table 1. Its physical properties are given in Table 2. The foamer is HTW-1 composite protein foamer. The carbon fiber is offered by Taili Carbon Fiber Co., Ltd., with a length of 3 mm and a fiber diameter of 7 µm. The graphite is provided by Baichuan Environmental Engineering Co., Ltd., with a grain size of 23 µm. The water reducing agent is a powdered polycarboxylic acid water reducing agent. The hydroxypropyl methylcellulose used for the test is offered by Jinzhou Fuqiang Fine Chemical Co., Ltd. The tap water is adopted.