Kaleta-Jurowska Alina, Jurowski Krystian
Faculty of Civil Engineering and Architecture, Opole University of Technology, Katowicka 48, 45-061 Opole, Poland.
Materials (Basel). 2020 Oct 18;13(20):4646. doi: 10.3390/ma13204646.
This paper presents the results of tests on high performance concrete (HPC) prepared and cured at various ambient temperatures, ranging from 12 ∘C to 30 ∘C (the compressive strength and concrete mix density were also tested at 40 ∘C). Special attention was paid to maintaining the assumed temperature of the mixture components during its preparation and maintaining the assumed curing temperature. The properties of a fresh concrete mixture (consistency, air content, density) and properties of hardened concrete (density, water absorption, depth of water penetration under pressure, compressive strength, and freeze-thaw durability of hardened concrete) were studied. It has been shown that increased temperature (30 ∘C) has a significant effect on loss of workability. The studies used the concrete slump test, the flow table test, and the Vebe test. A decrease in the slump and flow diameter and an increase in the Vebe time were observed. It has been shown that an increase in concrete curing temperature causes an increase in early compressive strength. After 3 days of curing, compared with concrete curing at 20 ∘C, an 18% increase in compressive strength was observed at 40 ∘C, while concrete curing at 12 ∘C had a compressive strength which was 11% lower. An increase in temperature lowers the compressive strength after a period longer than 28 days. After two years of curing, concrete curing at 12 ∘C achieved a compressive strength 13% higher than that of concrete curing at 40 ∘C. Freeze-thaw performance tests of HPC in the presence of NaCl demonstrated that this concrete showed high freeze-thaw resistance and de-icing materials (surface scaling of this concrete is minimal) regardless of the temperature of the curing process, from 12 ∘C to 30 ∘C.
本文介绍了在12℃至30℃的不同环境温度下制备和养护的高性能混凝土（HPC）的试验结果（还在40℃下测试了抗压强度和混凝土混合料密度）。在制备过程中特别注意保持混合料各组分的假定温度，并保持假定的养护温度。研究了新拌混凝土混合料的性能（稠度、含气量、密度）和硬化混凝土的性能（密度、吸水率、压力下的水渗透深度、抗压强度以及硬化混凝土的冻融耐久性）。结果表明，温度升高（30℃）对工作性损失有显著影响。研究采用了混凝土坍落度试验、跳桌试验和维勃试验。观察到坍落度和流动直径减小，维勃时间增加。结果表明，混凝土养护温度升高会导致早期抗压强度增加。养护3天后，与在20℃养护的混凝土相比，在40℃养护的混凝土抗压强度提高了18%，而在12℃养护的混凝土抗压强度低11%。温度升高会使养护超过28天后的抗压强度降低。养护两年后，在12℃养护的混凝土抗压强度比在40℃养护的混凝土高13%。在有NaCl存在的情况下对HPC进行的冻融性能试验表明，这种混凝土无论养护温度在12℃至30℃之间，都表现出高抗冻融性和除冰材料（这种混凝土的表面剥落最小）。
