LNG储罐低温混凝土配合比及抗压强度试验研究

Mix proportion and compressive strength test of concrete for LNG tank under low temperature

通过收集整理液化天然气(LNG)储罐混凝土实际配合比信息,并按规范要求进行了不同低温环境下的抗压强度测试,考察LNG储罐混凝土在低温环境下抗压强度的变化规律。结果表明:各储罐项目配合比用料基本一致,粉煤灰与矿粉用量略有差异,粉煤灰选用F类I级时,其混凝土抗压强度在常温及低温下都处于较高水平;矿粉选用S105级时,其混凝土抗压强度在低温下提升幅度最大。LNG储罐混凝土低温抗压强度随温度的降低明显增强,且温度越低,混凝土破坏越突然。在3个低温(-40℃、-120℃和-190℃)环境下,实测混凝土抗压强度分别是常温环境抗压强度的1.41、1.84和1.97倍,均满足规范要求。含水率是混凝土抗压强度低温增强的重要指标,但规范要求的低温环境混凝土抗压强度含水率影响系数与实际抗压强度的提升效果之间,规律并不明显。试验结果可为LNG储罐低温混凝土的配合比设计及安全性评估提供参考。

According to the actual mix proportion of LNG tank concrete and the requirements of the GB 51081—2015 Technical Code for the Application of Under Cryogenic Circumstance,the compressive strength tests under different low temperature conditions were conducted to investigate the compressive strength of LNG tank concrete under low temperature circumstances.The results indicate that the composition of concrete used in all LNG tank projects are basically the same,while the dosage of fly ash and mineral powder is slightly different.The compressive strength of concrete is at a high level under normal and low temperatures when fly ash is selected as Class F grade I.When it comes to mineral powder,Grade S105 performs best at low temperatures.The compressive strength at a low temperature of LNG tank concrete increases with the decrease in temperature,and the lower the temperature,the more abrupt the concrete damage.Under the three low temperature environments of-40℃,-120℃and-190℃,the measured compressive strength of concrete is 1.41 times,1.84 times and 1.97 times that of normal temperature environment respectively,which all meet the specification requirements.Water content is an important indicator of low temperature enhancement of concrete compressive strength,but the effect of influence coefficient of water content on the concrete compressive strength under low-temperature environment recommended by the specification,are not evident on the actual compressive strength enhancement.The test results can provide a reference for the design and safety assessment of low temperature concrete for LNG tank.