| The mass concrete has big hydration heat and is easy to crack. The temperaturevariation between inside and outside of the concrete is the key to the construction control.Winter construction increases the degree of construction control difficulty of massconcrete. Based on the practical engineering of the foundation slab of14#building inXichenghuayu district, combining with the characteristics, such as mass concrete, winterconstruction, no post-poured strip etc, researches on raw material selection, mixproportion optimization and construction curing process are studied deeply.Considering the demand of mass concrete and winter construction for cement,Portland cement which has moderate hydration heat is chosen. Adding part of fly ash andgranulated slag powder instead of cement can decrease the hydration heat and addingsuitable amount of expansion agent can solve the problem that there are no post-cast stripsin long raft. By contrast of multiple mix proportion testes, the mixture ratio of C30massconcrete is optimized on the premise that the strength of concrete and appropriatehydration heat are guaranteed.Besides the selection of raw materials and the optimization of mixture ratio, themeasures, such as layered casting and reinforce of the surface heat preservation, areadopted in this project to control the temperature variations between inside and outside ofthe concrete and to avoid the temperature cracking inside the concrete. The temperature ismeasured in time by setting the embedded pipe. The measurement method of temperatureinside the concrete is improved and the construction quality of mass concrete is ensured.Results show that the measured temperature variations between inside and outside arenot more than the specification requirements of25℃. And there are no obviousconstruction joint and fracture phenomenon. The strength of reserved block of each groupalso meets the design requirements and the physical quality of overall concrete is good. |
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