| This thesis discusses the influence of early high-temperature water curing onmineral admixture concrete and microstructure.Since the early post-performancehigh-temperature curing on concrete will cause some problems,In this paper, thepre-cure time is extended and mineral admixtures are added to improve thesituation,at the same time,the influence of the temperature of water curing、intensity ofpre-curing、the mix type and leaving time are studied to provide reference for thecuring system especially the steam-curing of precast member, meanwhile the variationof mineral concrete with the variation of properties of curing conditions is got.First of all in this thesis,via exploring experiments,both the time needed inpre-curing and the duriation of water-curing in different temperatures are obtained todetermin the Benchmark curing system.then after the concret of different mix is curedaccording to the basical curing system, both compressive strength and splitting tensilestrength of different duriation are tested.According to the mechanical experimentresults, micro-structure tests and Degree of hydration test are conducted,to study therelationship between macroscopic mechanical properties and micro-structure、degreeof hydration of fly ash.The following are the main study results:1. The early compressive strength and tensile strength of both ordinary concretand mineral admixture concrete increases as the curing-temperature increases.Thelaw of long-term compressive strength and curing-temperature is opposite to the lawof early compressive strength and curing-temperature.2. Along period of time to cure is suitable for both ordinary concret and mineraladmixture concrete. before curing at high temperature, Increase pre-curing strengthhelp to decrease internal microfracture, improve the microstructure and refine porestructure.3. No matter which method of curing is adopted,long-term compressive strengthof ordinary concret is larger than the strength of mineral concret.The long-term tensilestrength of concrete mixed with minerals is the largest,with the temperature of watercuring20℃and the duriation28days.It is suitable to adopt high-temperature curingfor concrect mixed with one and two kinds of mineral,while concrect mixed withthree kinds of mineral and ordinary portland cement concrete should be cured innormal situation. 4. High temperature curing does not bring about retraction of long-termcompressive strength. tensile strength do not always increse along with the growthtrends of exposure times.when the curing temperature range from20℃to80℃,itincrease and then started to pour shrinkage at100d,the higher curing temperature is,the greater degree of shrinkage is.5．Microstructure (pore structure and the morphology of hydration product)ofmineral mixture-cement system has a good correlation between the compressivestrength. Increasing pre-curing strength can effectively refine pore distribution ofmortar and improve the morphology of hydration products, the higher curingtemperature is,the wosre the microstructure shows,but after high pre-curing and40℃water curing,the effect can come up to Standard curing.6.From the degree of hydration of fly ash test: the enlargement of initial curingtemperature and pre-cuiring strength can significantly increase the hydration degree offly ash;Along with the prolongation of exposure times, hydration degree of all kindsof mineral mixture-cement systems showed a trend of growth, but growth ratedecreases; At the same time, the lower the curing temperature, the greater the increaseof the degree of hydration of fly ash along with age.compared with fly ash-cementsystem, the add of other mineral admixture reduce the hydration degree of fly ash flyash. |
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