Physico-thermal and microstructural properties of thermal-efficient mortars made with low cement content

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This paper utilized supplementary cementitious materials (SCMs) as partial substitution of the cement (PC) as the binder when expanded glass (EG) was used as the only aggregate in the production of thermal efficient mortars. The SCMs utilized are silica fume, slag, fly ash and glass powder. The corresponding influence of these SCM types and content on the properties of thermal efficient mortars were evaluated. The SCMs were used up to 75% replacement of PC by weight, and PC to EG ratio was fixed at 1:3. The outcome of this study revealed that the inclusion of SCMs as partial substitution of PC caused a decrease in the mortars’ density and thermal conductivity by up to 25.4% and 10.1%, respectively. However, the use of these high-volume SCMs has a negative impact on permeability and compressive strength. With the exception of mortars made with fly ash as 50% and 75% replacement of the PC, all mortars developed satisfied the compressive strength requirement (i.e. a minimum of 10 MPa at 28 days) proposed for the construction of thermal wall panels. Nonetheless, the use of SCMs resulted in a reduction in the drying shrinkage with higher reduction evident with higher content of fly ash used to replace PC.