Strength, durability and microstructure study of cow dung ash based cement for sustainable development

摘要

Cow dung ash (CDA) is a waste material that is hazardous to health but often dumped in villages. However, CDA has pozzolanic properties that make it possible to be used in cement as a sustainable development practice, replacing some of the huge amount of CO2 generated worldwide in the production of Portland Cement (PC). In the present study mortars were prepared in which we substituted CDA for OPC by various proportions, and measured their strengths after 7 and 28 days of curing. After 7 days, the strongest mortar among the formulations tested was that with 10% CDA substitution (11.12 MPa, vs. 10.98 MPa control); after 28 days, that with 20% CDA substitution was strongest (27.58 MPa, vs. 22.85 control). EDX analysis and SEM imaging showed that adding CDA increased the amount of crystalline calcium silicate hydrate (Ca-Si-H) formed. Further, for 0%, 10%, 20%, 25% and 30% replacement of OPC by CDA, water absorption values are 5.67%, 5.22%, 5.11%, 4.6%, 4.53% respectively and sorptivity values are 4 x 10(-5), 3 x 10(-5), 3 x 10(-5), 3 x 10(-5), 2 x 10(-5) respectively. Additionally, increased replacement of OPC by CDA yields products with better resistance to chemical attack by HCl, NaCl and H2SO4. The water absorption, sorptivity, and chemical resistance tests thus demonstrate that OPC replacement improves the durability of the resulting concretes. Thus, the replacement of OPC by CDA shows improvements in both strength and durability. Moreover, the use of CDA lessens the cost of concrete and lowers its carbon dioxide emissions.