Strength gain mechanism for green mortar substituted marble powder and brick powder for Portland cement

Abstract

This experimental research aims to carry out chemical characterisation and microstructure observation of cement paste as well as strength development monitoring of cement mortar up to 90 days of curing. Cement paste and cement mortar is prepared by using marble powder (MP) and/or brick powder (BP) up to 35 and 65% by weight of pure Portland cement, sand and tap water. Green cement paste and green cement mortar is used to prepare several specimens, which are cured into water at 21 ± 2 °C and 98% relative humidity until testing. Results indicate that substitutions up to 6% by weight of ground marble powder (MP) and 35% by weight of ground brick powder (BP), separately replacing pure Portland cement, positively influence compressive strength and flexural strength development with respect to the reference mortar prepared with pure Portland cement. However, MP enables a densification for microstructure of cement paste by increasing the strength gain as well as BP substitution exhibits opposite trend. Moreover, the substitution effect of MP on the strength gain of MP-based green mortar especially deals with fluctuation of calcium oxide (CaO), iron oxide (Fe2O3), sodium oxide (Na2O) and alkali in the MP-based green binder paste while the substitution effect of BP on the strength gain of BP-based green mortar relates to the continuously increase of calcium oxide (CaO) and iron oxide (Fe2O3) in the BP-based green binder paste.