高速铁路自密实混凝土合理养护温度研究

Study on Reasonable Curing Temperature of Self-compacting Concrete for High-speed Railway

CRTSⅢ型无砟轨道自密实混凝土由于其结构的密闭性,养护过程中混凝土水化热不易散发,热量积聚容易产生较大的温度梯度和较高的整体温度,会导致其产生较大的温度应力而出现早期裂缝。对此,本文开展现场试验,对养护过程中自密实混凝土的温度进行实时动态监测,明确自密实混凝土在养护过程中所承受的温度荷载,并建立有限元模型,分析自密实混凝土养护过程中在温度梯度、整体温降等荷载作用下的应力应变,研究冬季施工合理温度控制条件。得出以下结论:(1)养护前期自密实混凝土中部与边缘区域会达到5℃的温差,养护结束时混凝土的整体温降约为5℃;(2)冬季施工时,需确保自密实混凝土在养护1 d时间内中间与边缘区域的温度差值不超过8℃,养护过程中自密实混凝土的整体温降不超过10℃。

Due to the structure tightness of the self-compacting concrete for CRTSⅢballastless track,the hydration heat in the concrete is not easy to be dissipated during the curing.The accumulation of heat is likely to produces larger temperature gradient and a higher overall temperature,which will lead to a larger temperature stress and early cracks.Therefore,this paper carries out field tests to monitor dynamically the temperature of self-compacting concrete in real time during curing,clarifies the temperature load of self-compacting concrete during curing,establishes a finite element model to analyze the stress and strain of self-compacting concrete during curing under the action of temperature gradient and overall temperature loads and studies the reasonable temperature control conditions for winter construction.Study results show that the temperature difference between the middle and the edge of the self-compacting concrete in the early stage of curing will reach 5℃and the overall temperature of concrete will drop about 5℃at the end of curing.During construction in winter,it is necessary to ensure that the temperature difference between the edge region and the middle region of self-compacting concrete cannot exceed 8℃during curing for 1d and the overall temperature of the self-compacting concrete during curing cannot drop over 10℃.