| Popis: |
Based on massive concrete block in practical engineering, the effect of new pouring precooling concrete on lower layer concrete in different seasons was simulated by using three-dimensional finite element simulation program of non-steady temperature field, and the temperature changes near the surface of lower layer concrete have been analyzed detailedly. It is indicated that, there is obvious “cold strike” effect of new pouring precooling concrete on lower layer concrete in summer, the effect in autumn followed by, and there is also the effect in spring but not obvious. In winter, as ambient air temperature is very low, there is not “cold strike” effect and the lower layer concrete temperature gradually recovery after pouring new concrete. Because actual concrete pouring deck surface maintenance is often not in place, the surface temperature of the pouring deck, which is greatly influenced by ambient air temperature and solar radiation, is very high in high temperature seasons. At the moment, the “cold strike” effect of new pouring precooling concrete on lower layer concrete is very obvious and likely to lead to the crack of the concrete. Hence, it is suggested that, after finish pouring of concrete and final set of concrete, sprinkling water or flowing water maintenance should be carried out in high temperature seasons, such as summer and autumn; before pouring the concrete, it is better to take measures, like spray and sprinkling water, to reduce the surface temperature of lower layer concrete, and try to avoid starting pouring concrete at midday. |
