C40大体积筏板混凝土制备的关键技术与性能研究

Research on Key Preparation Technology and Performance of C40 Large Volume Raft Concrete

大体积筏板混凝土对施工连续性、混凝土配合比及耐久性能等要求较高,因此必须做好温控措施,避免结构出现有害裂缝。本文研究了不同胶凝材料体系、不同砂率对C40大体积筏板混凝土工作性能、力学性能、热学性能、耐久性能的影响规律,结果表明:基于不同性能测试结果,编号C4006组混凝土的综合性能较优,其损失可控、流动性能良好,28、60 d抗压强度分别为52.1、60.4 MPa,抗渗等级达到P12,抗氯离子渗透性能良好,抗碱-集料反应性能及抗钢筋锈蚀性能良好;28 d干燥收缩率为自收缩率的5倍左右,覆膜养护良好;水化速率合理,降温曲线平稳;28个测试点位中只有3个点高于同龄期混凝土的劈裂抗拉强度,抗裂性能较优。

Large volume raft concrete requires high requirements for construction continuity,concrete mix ratio,durability,etc.Therefore,temperature control measures must be taken to avoid the occurrence of harmful cracks in the structure.This article investigates the influence of different cementitious material systems and sand ratios on the workability,mechanical properties,thermal properties,and durability of C40 large volume raft concrete.The results show that bases on different performance test results,the comprehensive performance of concrete with the code C4006 is superior,with controllable losses and good flowability.The compressive strength at 28 and 60 days is 52.1 and 60.4 MPa respectively,and the anti-seepage grade reaches P12.It has good resistance to chloride ion penetration,alkali-aggregate reaction,and steel corrosion;the drying shrinkage rate after 28 days is about 5 times the self-shrinkage rate,indicating good curing of the film covering;reasonable hydration rate and stable cooling curve;among the 28 test points,only 3 points have higher splitting tensile strength than the same age concrete,indicating better crack resistance performance.