The effect of pozzolanic waste of different nature on the hydration products, structure and properties of hardened cement paste

Abstract

The paper analyses the effect of different pozzolanic waste – ground waste glass, metakaolin and addition made of ground waste glass and metakaolin, on cement hydration and physical-mechanical properties of hardened cement paste. Four batches of specimens were made for the tests. Cement (C) in the cement matrix was replaced with 5% of ground waste glass (5S), 15 % of metakaolin and mixed pozzolanic was addition (MIX 20) made of 5% of ground waste glass and 15 % of metakaolin. The best improvement of mechanical properties after 90 days of curing was observed in the specimens modified with the mixed pozzolanic addition. X-ray, TGA tests and microstructure analysis revealed that the improvement of mechanical properties is caused by the higher content of hydration products and a strong contact zone between glass particles and foam glass splinters present in metakaolin waste addition. The formation of C-S-H hydrates on the surface of glass foam splinters and in the pores was also observed. This kind of microstructure formation has a positive effect on cement matrix microstructure and physical-mechanical properties of hardened cement paste.