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Research on High-performance Lightweight Aggregate Used in the Pumping Lightweight Aggregate Concrete

Author: PengWei
Tutor: HuangZhengYu；LiuMingLiang
School: Hunan University
Course: Materials Engineering
Keywords: High - performance lightweight aggregate Lightweight aggregate concrete Performance Pumping technology
CLC: TU528.2
Type: Master's thesis
Year: 2009
Downloads: 212
Quote: 0
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Abstract


Lightweight aggregate concrete A man-made or natural lightweight aggregate concrete alternative to ordinary aggregate. Lightweight, high strength, good thermal insulation properties, fire resistance, seismic performance, and comprehensive economic and technical effects and other significant advantages, it has great technology in long-span bridges, high-rise buildings, marine engineering and other engineering applications economic advantages, has become an important development direction of modern concrete. The high-performance lightweight aggregate is a recent years a new type of artificial concrete aggregate, compared with the traditional ordinary lightweight aggregate, due to the choice of raw materials, the distinction of the production process, which has a low water absorption, water-saturated short time, water absorption small changes with the pumping pressure, and high intensity. This allows it to better adapt to the high-level, long span structures for lightweight aggregate concrete material requirements, is a new high-performance lightweight construction materials. Compared with ordinary light aggregate, high-performance lightweight aggregate has a lower water absorption. Saturated water absorption at atmospheric pressure and normal lightweight aggregate about than the high-performance lightweight aggregate times. Negative or positive pressure conditions, the water absorption of both greater. Full of high-performance lightweight aggregate water speed is relatively fast. High-performance lightweight aggregate is generally not taken pre-wet processing; ordinary lightweight aggregate pre-pre-wet 24 hours or under vacuum conditions at atmospheric pressure water-saturated wet for 15 minutes or so to make lightweight aggregate. Normal lightweight aggregate, not only under normal pressure water absorption and under pressure conditions, the water absorption varies with the pressure size significantly greater impact not only on the slump loss, pumping performance, but also the strength of the concrete will produce adversely affected. High-performance lightweight aggregate even in a negative or positive pressure conditions, the water absorption of only 7 to 8%, only 2 to 3% higher than the atmospheric water absorption. High-performance lightweight aggregate concrete mixture maintained within 1.5 hours pumping slump slump no significant change in the pumping process, can be more responsive to the commonly used structural concrete ready-mix, construction of the pumping process. Lightweight aggregate concrete segregation of lightweight aggregate particle size, the viscosity of the cement mortar, cement mortar and lightweight aggregate density control, reduced by fly ash and slag, and to adjust the percentage of sand and lightweight aggregate particle size technical measures can effectively control the segregation of lightweight aggregate concrete. Control of lightweight aggregate concrete segregation is a systems engineering must be integrated into the various factors affecting the segregation and integrated control in order to achieve the best results. The evaluation of the performance of high-strength lightweight aggregate concrete work: When the slump sl extended degree sf ratio in the range of 0.4 to 0.5, the best performance of the concrete mixture; of concrete mixture sl / sf is greater than 0.5, too viscous, should not be pumped; easy segregation of concrete mixture when sl / sf less than 0.4. When the preparation phase for the lower strength of lightweight aggregate, lightweight aggregate concrete, lightweight aggregate strength than mortar strength, failure characteristics similar performance with the failure characteristics of ordinary concrete, the concrete strength is determined primarily by the strength of mortar, concrete preparation belongs to composite soft materials; Conversely, when the preparation of high strength lightweight concrete, coagulation strength lightweight aggregate to determine the performance failure characteristics of lightweight aggregate concrete, lightweight aggregate and damages, preparation of concrete are composite hard material. Lightweight aggregate concrete strength by many factors, including the cylinder compressive strength of lightweight aggregate, lightweight aggregate particle size, particle shape; certain strength lightweight aggregate is only suitable for the preparation of a certain strength of concrete, and the preparation of high-strength lightweight aggregate Concrete must be using high strength lightweight aggregate. Appropriate rate of sand types and mixing amount of mineral admixtures for concrete strength significantly affected. Curing conditions on the strength of lightweight aggregate concrete. The water absorption of lightweight aggregate concrete pumping, concrete pump. Low water absorption, high-performance lightweight aggregate can reduce the pump pressure of the concrete mixture slump loss, the incorporation of superplasticizer, high-quality mineral admixture to improve the flow properties of the concrete mixture, the incorporation of organic fiber improve resistance to segregation of the concrete mixture performance is an important technical means good performance lightweight aggregate concrete pumping. This test uses a high-performance lightweight aggregate was mixed with superplasticizer quality mineral admixture and organic fiber \successfully applied to obtain significant economic benefits. This article in the widely read information at home and abroad on the basis of scientific arrangements test, the performance difference between the analysis of the high-performance lightweight aggregate and ordinary lightweight aggregate to identify the high-performance lightweight aggregate in structural lightweight aggregate concrete application program and the appropriate construction technology of pumping construction. Lightweight aggregate concrete composition, structure and properties of relations, proved the law of development of lightweight aggregate concrete strength, a clear relationship between the characteristics of lightweight aggregate concrete strength preparation knot Tao light bone aggregate concrete technology roadmap, given the optimal fit lightweight aggregate concrete work performance evaluation to find the resolve lightweight aggregate concrete, low intensity, crack poor pumping performance and poor method. Improve our level of lightweight aggregate concrete and save resources, energy, sustainable development strategy, which will be of great significance.

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CLC: > Industrial Technology > Building Science > Building Materials > Non-metallic materials > Concrete and concrete products > Lightweight concrete
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