Preparation And Performance Of Fast-seting And Rapid-high-strength Concrete

Because of these characteristics for example short setting time, high early strengthand good durability, early strength concrete and super early strength concrete werewidely used in quickly repair engineering such as concrete pavement and airport runway,and the same to fast repair scrambling engineering like harbor wharf, bidge and tunel.The traditional craftsmanship based on special cement or special process, it’s notsuitable for engineering application because of the shrinking late strength of concrete,expensive raw materials or complex technological process. So this subject is designed tocompound the fast-seting and rapid-high-strength concrete for using the conventionalraw materials and ordinary technological process.Based on super early strength concrete and high strength concrete preparationtechnology, the study focused on putting forward a new method to compound fast-setingand rapid-high-strength concrete, that is using42.5R ordinary portland cement mixingappropriate amount of silica fume, at the same time, the super early strength agentwhich was made up of the quick setting early strength component and water reducingcomponent was joined to compound fast-seting and rapid-high-strength concrete. Usingtraditional raw materials and general technological process to develop the concretewhich owns these features, for example no less than30min initial setting time and notmore than50min final setting time, the10MPa compressive strength and1.5MPaflexural strength at6h, the40MPa compressive strength and5MPa flexural strength at1d, the80MPa compressive strength and10MPa flexural strength at28d, and so on. Atthe same time, the quick setting early strength component having inflence on cementpaste setting time was studied. And that the total dosage of gelled material, dosage ofsilica fume, types of water reducing component, dosage of the quick setting earlystrength component and ratio of its internal components, water/binder ratio etc. hadeffect on the setting time and early compressive strength was studied too.The frost resistance performance and sulfate attack resistance performance of thefast-seting and rapid-high-strength concrete was studied by using fast freeze-thawcycling test and sulfate dry-wet cycling text. The results prove that the concrete massloss did not exceed2%and the compressive strength loss of concrete was no more than15%after500times fast freezing and thawing cycles. And there was no loss butincreased of the concrete mass and the corrosion coeffcient of concrete had no less than 75%after120times sulfate dry-wet circulation. That is to say, the test preprationconcrete has good performance of frost resistance and sulfate attack resistance.The homemade super early strength agent haing effect on the cement hydration andhardening process was studied based on analysis of XRD and DTA-TG test. Then wecan explain the rapid harding and early strength mechanism of the homemade superearly strength agent in this test on the microcosmic side.