Influence of CG With High Content of Metallic Particles as a Cement Admixture on Cement Strength

摘要

Copper gangue (CG), containing a large amount of water with grain sizes of 0.037 to 0.10 mm, is an inactive industrial waste generated from copper refineries. When it is dried and used as a cement admixture, the influence of the presence of finely dispersed metallic particles in CG on the microstructure and compressive strength of cement paste has been studied. The results show that the higher the replacement of CG is, the lower the compressive strength of cement mortar is. However, the long-term strength of the specimens with 10 percent CC, especially after being cured for 3 months, approached to that of the plain mortar. Its mechanism was studied by an electron probe X-ray microanalyzer (EPXMA). The results indicate that a small quantity of Fe (OH)_3 centre dot nH_2O slowly formed from Fe_2O_3 in the presence of Ca (OH)_2, free CaO and MgO of the clinker also slowly hydrated and formed Ca (OH)_2 and Mg (OH)_2 respectively, so the hardened cement paste became more compact.