温和地区实际服役水工混凝土的抗冻性检验标准研究

EXAMINATION STANDARD OF HARDENED CONCRETE ON FREEZING RESISTANCE PERFORMANCE UNDER ACTUAL WORKING CONDITIONS IN MILD REGIONS

为提高温和地区已建工程水工混凝土的抗冻性检验水平,结合该类地区广泛应用的设计抗冻等级(F50和F100),以及泵站、闸坝等典型水工建筑物普遍使用的强度等级(C25、C30和C35),设计了硬化含气量梯度变化的多种二级配混凝土。通过硬化气孔参数测试、冻融循环试验和回归分析,探讨了各参数之间的关联性和硬化含气量的控制标准;并在扬州市某泵站工程取芯试验对该标准进行可行性论证。室内试验表明,混凝土相对动弹模量与硬化含气量有着较好的对数相关关系;对于C25、C30和C35水工混凝土,F50抗冻等级的硬化含气量应分别不低于1.4%、1.1%和1.1%;F100抗冻等级的硬化含气量应分别不低于2.4%、2.4%和2.0%。工程现场取芯试验结果表明,该标准具有较强的实用性。

To improve the inspection capacity of freezing resistance of hydraulic concrete structures built in mild regions,a variety of two graded concrete with hardening air content gradient are designed,considering the characteristics of freezing resistance grades(F50,F100)and strength grades(C25,C30 and C35)of concrete in hydraulic project such as pumping station and gate dams.Through the test of hardening pore parameters,freeze-thaw cycle test,and regression analysis,the correlation between the parameters and the control standard of hardening gas content are discussed.The feasibility of the standard is demonstrated in the coring test of a pump station project in Yangzhou.Laboratory tests show that the relative dynamic elastic modulus of concrete and the hardened air content fit the logarithmic correlation.For C25,C30,and C35 hydraulic concrete,the hardened air content of F50 frost resistance grade should not be less than 1.4%,1.1%and 1.1%respectively.The hardening air content of F100 frost resistance grade should not be less than 2.4%,2.4%and 2.0%respectively.The field test results show that the standard has the practicability.