混凝土冻融环境区划与抗冻性寿命预测

Environmental zonation and life prediction of concrete in frost environments

针对现场冻融环境和室内冻融环境间的巨大差异,建立室内冻融试验与现场冻融之间的关系和衡量混凝土现场冻融环境作用效应强弱的量化方法.结合我国部分地区的实测或统计年均冻融循环次数,以年均负温天数为指标建立现场冻融循环次数的统计方法,进一步给出计算现场冻融循环次数的实用公式.以环境的平均降温速率为指标,基于静水压理论,针对饱水状态下的混凝土得到不同冻融环境下混凝土损伤之间的比例关系,给出室内等效冻融循环次数的计算方法,利用室内等效冻融循环次数对混凝土抗冻耐久寿命进行预测.以等效室内冻融循环次数为量化指标完成了全国冻融环境的耐久性影响程度区域等级的划分,提出利用区划图进行耐久性设计的方法.

Focusing on the huge differences between field and laboratory freeze-thaw environments,a quantitive method to measure the effect of field freeze-thaw environments on concrete durability was provided as well as the relationship between on-site test in natural environments and indoor experiment.After considering available data of natural annual average freeze-thaw cycles,a statistical method was proposed to get the on-site freeze-thaw cycles by using the average annual number of negative-temperature days as an index.A practical formula was obtained to predict the natural freeze-thaw cycles accordingly.Then the proportion of concrete damage between different freeze-thaw environments was obtained based on the hydrostatic pressure theory according to the average freezing rate in the freezing and thawing.A method for predicting the equivalent laboratory freeze-thaw cycles from on-site freeze-thaw cycles was given.Furthermore,the durable life of concrete in natural frost environments can be easily predicted by the equivalent laboratory cycle number.Finally,the environmental zonation under freeze-thaw condition in China was established by taking the equivalent laboratory freeze-thaw cycles as a quantitive index,and a durability design method was presented accordingly by using the zonation map.