Abbas J. Mohammed; Maan S. Hassan; Hussein Al-Quraishi
Abstract
Quartz powder is used in ultra-high-performance concrete to improve granular packing, but repeated inhalation during manufacture can cause health issues. The mechanical properties of ...
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Quartz powder is used in ultra-high-performance concrete to improve granular packing, but repeated inhalation during manufacture can cause health issues. The mechanical properties of UHPC are influenced by the post-setting curing method. A hypothesis suggests limestone powder could be a viable filler to mitigate these issues under three different curing regimes, replacing quartz powder of similar size. The study assessed 18 mixtures with different w/b ratios for flow characteristics and compressive strength after 7 and 28 days of curing under various conditions. Limestone powder positively impacted compressive strength and had fresh properties. A two-factor interaction model accurately correlated variables and responses. Numerical optimization was performed to find the optimal mixture with proper flow and the highest compressive strength. The use of 150 kg/m3 of locally sourced limestone powder in the mixture with a w/b ratio equal to 0.198 and a 48hr-90°C curing regime can be considered the optimal amount to secure the greatest modeling compressive strength (169.10 MPa at 7 days and 181.71 MPa at 28 days), fulfilling the limit values of spread flow (220 mm) with the increasing percentage ratio of 67% and 49% at 7-days and 28-days ages under 90°C heat curing when the w/b equals 0.198.
