反映温度历程的掺粉煤灰水工混凝土抗压强度模型探讨

Discussion on Compressive Strength Model of Fly Ash Hydraulic Concrete Reflecting Temperature History

由于综合考虑温度历程、养护龄期以及粉煤灰掺量对混凝土抗压强度影响的模型研究相对偏少,因此本文基于正交设计法开展了不同养护温度(5℃、20℃、35℃)、养护龄期(7d、14d、28d)和粉煤灰掺量(0%、15%、35%)下的水工混凝土抗压强度试验,并分析3种影响因素对混凝土抗压强度发展的规律,进而基于等效龄期理论建立了反映温度历程的掺粉煤灰水工混凝土抗压强度模型.试验结果分析表明,混凝土早龄期抗压强度随养护龄期的增加而增加,养护温度越高、粉煤灰掺量越小,强度发展越快;粉煤灰掺量是影响强度的主要因素,养护温度次之,养护龄期影响最小;所建的组合指数式模型能够较准确预测不同温度历程下粉煤灰混凝土的早期抗压强度,为粉煤灰混凝土的优化设计提供依据.

The model research on the compressive strength of concrete under the influence of temperature history,curing age and fly ash content is relatively rare.Based on the orthogonal design method,hydraulic concrete compressive strength test are developed under different curing temperatures(5℃,20℃,35℃),curing ages(7d,14d,28d)and fly ash contents(0%,15%,35%)in this paper.And then the law of the development of concrete compressive strength is analyzed under the three influencing factors.Finally,compressive strength model of fly ash hydraulic concrete reflecting temperature history is established based on the theory of equivalent age.The test results show that,the compressive strength of concrete in early age increases with the increase of curing age;the higher the curing temperature is controlled and the less the amount of fly ash is added,the faster the strength develops;fly ash content has the greatest influence on the compressive strength of concrete,followed by curing temperature;and the influence of curing age is the smallest;the combined exponential model proposed can accurately predict the early compressive strength of fly ash concrete under different temperature histories and provide a basis for the optimal design of fly ash concrete.