The influence of long-distance pumping on the workability, mechanical strength, and frost resistance of SCC

Concrete pumping technology is widely used in reservoirs, dams, harbours and other hydraulic structures. To investigate the effects of pumping on the flowability, mechanical strength and frost resistance of hydraulic concrete, long-distance pumping tests were carried out on self-compacting concrete (SCC). This paper investigated the influence of high-pressure pumping on the workability, mechanical strength and frost resistance of SCC by analysing the changes in various properties of SCC before and after long distance pumping. The flowability of the fresh concrete decreased after long-distance pumping. Compared to before pumping, the slump of the four groups of SCC decreased by an average of 3.93% and the slump-flow decreased by an average of 23.09%. The homogeneity and stability of the fresh SCC improved significantly after pumping. After pumping, the V-funnel time of SCC was reduced by an average of 82.32% and the segregation rate was reduced by an average of 125.76%. Additionally, there was a slight increase in mechanical strength indicated by an average increase of 5.87% in cubic compressive strength, 8.99% in axial compressive strength, 7.78% in tensile splitting strength, and 5.22% in modulus of elasticity. Notably, the frost resistance of the SCC showed significant improvement after pumping. Under non freeze-thaw conditions, the compressive strength of SCC after pumping increased by an average of 5.87%. After 200 freeze-thaw cycles, the compressive strength (after pumping) increased by an average of 12.46%. An air void analyser was then used to test the air-void parameters to analyse the effect of long-distance pumping action on the air voids parameters. The study further established the correlation between air-void structure characteristics and freeze-thaw resistance. Under freeze-thaw conditions, the compressive strength showed a linear correlation with air content and spacing factor. The process of pumping can enhance the air-void structure of SCC, leading to improved frost resistance. Therefore, in the design of concrete frost resistance, pumping can be considered as an influencing factor to improve the frost resistance of concrete.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025).