Effects of Mica and Feldspar as partial cement replacement on the rheological, mechanical and thermal durability of self-compacting mortars

Abstract In this experimental study, the impacts of replacing cement by Mica and Feldspar on rheological, mechanical and thermal durability of self-compacting mortars (SCMs) are investigated. The cement was partially replaced by Mica and Feldspar at the substitution rates of 10%, 20% and 30%. In general, 14 mix designs of SCMs were considered in two series with w/b ratios of 0.4 and 0.3. For assessment of rheological properties, mini-cone slump flow test and mini V-funnel tests were performed. The compressive strengths after 3, 7, 28 and 90 days of curing, and the 28-day flexural strength were obtained. All mixes were subjected to water absorption and sorptivity tests. For investigating the thermal durability, residual compressive strength after high-temperature exposure at 600 °C were investigated. Also, the microstructure of specimens was assessed by using Scanning Electron Microscope (SEM) images. The results indicated that all the SCM mixes containing Mica and feldspar with different w/b ratios had acceptable rheological properties considering EFNARC criteria. Mechanical properties were slightly decreased by Mica and Feldspar replacement, and the mixes containing Feldspar showed higher mechanical properties in comparison with mixes containing Mica. Replacing the cement by Mica and Feldspar decreased the sorptivity coefficient of SCMs and remarkably improved the thermal durability. Mix designs contained 20% of Mica showed the maximum residual compressive strengths after high temperature exposure in both w/b ratios.