Study On Thermal Properties Of Concrete With High Volume Of Fly-ash

With the increasing usage of concrete in engineering construction, the durability ofconcrete structure draws more and more attention of the people.The hydration heat ofconcrete is an important factor which affects the durability of concrete structure most. As aresult, nowadays, people pay more attention to the hydration heat of concrete. Due to the longstudy of the hydration heat of concrete, people found that the concrete mixed with fly ash, cannot only reduce the hydration heat which can improve the durability of the concretestructure,but also reduce the pollution of fly ash on the environment effectively. Besides, theusage of large dosage of fly ash on the reduction of hydration heat is more obvious. Therefore,the research on the thermal properties of concrete mixed with high volume fly ash have greatinfluence both on project construction and the harmony between human and nature.In this paper, with the help of experiment respectively studied the water-binder ratio,dosage of fly ash and water reducing agent dosage,the usage of which cause the properties offly ash concrete adiabatic temperature’s rise. It also points out that the change of the dosage offly ash, water-binder ratio, sand ratio, water reducing agent dosage, the aggregate of dry andwet state have great effect on the properties of fly ash concrete temperature conductivity.These findings can provide great reference for the application of concrete with high volume offly-ash in the practical engineering.Due to the limitation of objective conditions, comprehensive test cannot be finished inthe limited time. In order to solve this problem, the adiabatic temperature rise test and the testtemperature conductivity are arranged respectively as followings.First, with the help of the uniform experiment, the changes of the large quantity of fly ashconcrete performance of adiabatic temperature rise influenced by the amount of fly ash,water-binder ratio and water reducing agent were found. Then, it analyzed the change rule offly ash concrete adiabatic temperature rise influenced by the factors of certain age,water-binder ratio, dosage of fly ash and dosage of water reducing agent.Second, with the help of orthogonal test, the effects of the large quantity of fly ash concretetemperature conductivity influenced by the dosage of fly ash, water-binder ratio, sand ratio,water reducing agent dosage and the aggregate of dry and wet state were measured. Then, itanalyzed the factors of fly ash concrete influence of the temperature conductivity primary andsecondary order and the significance level. Finally, combined with the regression analysis,variation of fly ash concrete temperature conductivity with the dosage of fly ash, water-binderratio, sand ratio, water reducing agent dosage and the aggregate of dry and wet state wasfitted.The results of the test showed that, as for the large quantity of fly ash concrete adiabatictemperature rise, the greater the mixing amount of the fly ash, the smaller of the fly ashconcrete adiabatic temperature rise. Water reducing agent dosage has more significant effecton fly ash concrete adiabatic temperature rise of7days. The smaller the dosage of water reducing agent, the smaller of the fly ash concrete adiabatic temperature rise. But it has noeffect on fly ash concrete adiabatic temperature rise of28days. As for the large quantity of flyash concrete temperature conductivity, sand ratio has more significant effect on fly ashconcrete temperature conductivity than other factors, such as the replacement amount of flyash, water cement ratio, dosage of water reducing agent and the aggregate of dry and wet state.Besides, the fly ash concrete temperature conductivity would increase with the increase of thesand ratio, decrease with the decrease of the sand ratio. The dosage of fly ash also hassignificant influence on concrete temperature conductivity. If the fly ash content increased,the fly ash concrete temperature conductivity would reduce, otherwise it would increase.Water cement ratio, dosage of water reducing agent and the aggregate of dry and wet statehave a measure of influence on fly ash concrete temperature conductivity. Among thosefactors, fly ash concrete temperature conductivity would decrease with the increase of watercement ratio and increase with the decrease of the water cement ratio. Fly ash concretetemperature conductivity would increase with the increase of the dosage of water reducingagent and would decrease with the decrease of the dosage of water reducing agent. Using thedry state aggregate to pour the fly ash concrete, the temperature conductivity is smaller; whileusing the aggregate of saturated surface dry state, the fly ash concrete temperatureconductivity is larger.