Plastic viscosity of cement mortar with manufactured sand as influenced by geometric features and particle size. (September 2021)

• Record Type: Journal Article
• Authors: Ren, Qiang; Tao, Yaxin; Jiao, Dengwu; Jiang, Zhengwu; Ye, Guang; De Schutter, Geert
• Is Part Of: Cement & concrete composites. Volume 122(2021)
• Publication Date: 2021-09
• Subjects: Plastic viscosity -- Geometric features -- Manufactured sand -- Packing fraction -- Relative paste film thickness; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2021.104163
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: This paper investigates the plastic viscosity of cement mortar with manufactured sand (MS) concerning the influences of geometric features and particle size of MS. The geometric features, including overall shape, angularity and roughness, of MS with various particle sizes were evaluated by aspect ratio, convexity area ratio, convexity perimeter ratio and circularity. The plastic viscosity of cement mortar was calculated based on the Bingham model. Results show that the combined effects of overall shape, angularity and roughness provide coarser MS particles with lower circularity. In terms of relative plastic viscosity, Robinson model shows optimal fittings for all mixtures and is thus used to determine the packing fraction of MS under shearing. From the particle packing viewpoint, shear-induced orientation increases the packing fraction of non-spherical MS particles from the random loose packing fraction and the influence is increasingly prominent with the decrease of circularity. The relative volume fraction is an important parameter influencing the relative plastic viscosity of mixtures with MS while the relative paste film thickness (R_PFT), calculated from the real packing fraction and specific surface area (SSA), is found as the dominating factor. The dependence of plastic viscosity of cement mortar on geometric features and particle size of MS can be attributed to their influences on the packing fraction and SSA of particles. Highlights: ➢Increment of packing fraction due to shearing increases with decreased circularity. ➢Relative volume fraction is an important factor of plastic viscosity. ➢Relative paste film thickness is the dominating factor of plastic viscosity.