A qualitative approach to describe the viscosity of flowable concrete made with manufactured sand containing different microfines

• Published in: Construction & building materials Vol. 451; p. 138858
• Main Authors: Zhu, Jiang, Zhou, Yichuan, Li, Chao, Jia, Jian, Li, Hongtu, Cai, Qingjun, Hou, Pengkun, Zhao, Piqi, Shu, Xin, Li, Zhen, Huang, Yongbo, Cheng, Xin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.11.2024
• Subjects: Excess fluid; Manufactured sand; Particle packing; Qualitative approach; Viscosity; Particle packing; Viscosity; Manufactured sand; Excess fluid; Qualitative approach
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138858

The concrete made with different manufactured sands can exhibit complex rheological properties. The prediction of viscosity is crucial in concrete placement, but remains challenging given the varied content and characteristics of microfines in the sands. This paper studies the influence of tuff (TF) and limestone (LS) microfines with disparate particle size distributions on the pseudo-Newtonian viscosity of concrete prepared with crushed sand. The concrete had a fixed water-to-binder mass ratio of 0.32 and polycarboxylate ether superplasticizer (PCE) dosage of 0.14 % by mass of biner. Test results showed that the microfines in manufactured sand can reduce the aggregate-to-excess cement paste ratio, leading to lower contact interactions between the aggregate grains. But the ratio of total powder particles and entrained air to excess interstitial solutions increased for the fluid paste matrix of the concrete, which caused greater flow resistance related to the powder contacts and air bubble deformations. A qualitative approach correlating the volume ratio of aggregate grains to excess cement pastes and that of total powder particles and entrained air to excess interstitial solutions was proposed to describe the pseudo-Newtonian viscosity of concrete, regardless of the different microfine additions in manufactured sand. •Microfines in manufactured sand can reduce the ratio of aggregate grains to excess cement paste of concrete.•The decreased aggregate-to-excess paste ratio does not necessarily cause lower viscosity of concrete.•The additional microfines from manufactured sand and entrained air jointly elevate the viscosity of cement paste.