基于实测表面活化能的高原地区混凝土受冻临界强度预测  

Prediction of frost-resisting critical strength of plateau concrete based on measured apparent activation energy

作　　者：李雪峰[1,2] 王华牢 刁波[2] Li Xuefeng;Wang Hualao;Diao Bo(Research Institute of Highway Ministry of Transportation,Beijing 100088,China;School of Transportation Science and Engineering,Beihang University,Beijing 100191,China)

机构地区：[1]交通运输部公路科学研究院,北京100088 [2]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《农业工程学报》2018年第8期117-123,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(51308846)

摘　　要：准确预估混凝土强度发展,避免其因未达到受冻临界强度而遭受负温是青藏高原地区混凝土施工时需面临的重要问题。针对现有成熟度法在对混凝土强度预测时,存在始终将表面活化能视为定值从而导致其预测精度下降的不足。该文通过设定目标预测强度以缩小强度预测范围,同时改进表面活化能的取值方法,提出了一种针对目标强度范围内混凝土强度进行准确预测的改进成熟度方法,并通过室内恒温及变温养护试验对该方法的预测准确性进行验证。试验结果表明,使用传统方法对目标强度范围内混凝土抗压强度进行的24组预测值中,20组预测值与实测值间误差大于10%,而利用改进成熟度法进行预测时,36组中有33组预测强度值与实测值间误差不超过10%,预测精度明显高于传统方法。因此,在高原地区该法可被用于对混凝土抗压强度发展进行准确预估,从而保证其在遭受负温时已达到受冻临界强度值。Accurately estimating the development of concrete compressive strength and avoiding suffering from negative temperature before concrete compressive strength reaches the frost-resisting critical strength is an important issue for concrete construction in the Qinghai-Tibet Plateau.When predicting the strength of concrete based on the traditional maturity method,there exists low prediction accuracy because the apparent activation energy is treated as constant value in the entire process of forecasting strength.In fact,the apparent activation energy value is influenced by many factors,such as curing temperature,degree of hydration and type of cementitious material.There is not any unique value that can precisely predict the concrete strength throughout the curing period.In view of the above shortcomings,an improved maturity method is proposed through modifying the determined value of apparent activation energy.And the specific methods are as follows:Firstly,according to the typical service environments of concrete structures,the durability requirements of the environment for the concrete are determined,and then the predicted target strength and the corresponding prediction range can be determined.Secondly,3 temperatures are selected to maintain the concrete at a constant temperature,one of which is the standard curing temperature(usually 20℃).The compressive strength of concrete at different ages under different curing temperatures is tested.By assuming apparent activation energy values,the test ages at the other 2 temperatures except the standard curing temperature are converted to the ages under the standard curing temperature.Then the apparent activation energy and the corresponding parameters in the strength-age curve are obtained when the error between the actual strength and the predicted strength of the concrete within the range of target strength is minimized.At last the calculated parameters are utilized to predict the concrete strength at different ages.In order to verify the accuracy of the modified meth

关 键 词：混凝土 温度 抗压强度 高原 表面活化能 受冻临界强度 

分 类 号：TU528[建筑科学—建筑技术科学]