Research On High-performance Lightweight Aggregate Used In The Pumping Lightweight Aggregate Concrete

Lightweight aggregate concrete is the concrete that use of a natural or man-made light-weight aggregate alternative to ordinary aggregate. With its high-strength lightweight, good insulation, fire-resistant properties, and a good comprehensive aseismic performance of effective economic and technological advantages, it has tremendous technical and economic advantages in the long-span bridges, high-rise building, marine engineering projects, has become a modern concrete's important direction of development.High-performance lightweight aggregate is a new type of man-made concrete aggregate in recent years.Compared with the traditional lightweight aggregate, since the choice of raw materials, production technology distinction, it has low water absorption, saturated short time, water absorption with small changes in pressure pumping, and other characteristics, this make it better adapt to the high-level, long-span structures for concrete material requirements, is a new type of high-performance light-weight materials.Compared with ordinary lightweight aggregate, high-performance lightweight aggregate has low water absorption. Under normal pressure, lightweight aggregate ordinary about the saturation water absorption of high-performance lightweight aggregate than 2 times as large. In the vacuum or pressure conditions, the greater difference between the two water absorption. High-performance lightweight aggregate of saturated speed is faster. High-performance lightweight aggregate therefore generally do not take pre-wet processing; and ordinary lightweight aggregate will need to pre-wet under normal pressure for 24 hours or under vacuum conditions 15 minutes to make lightweight aggregate saturated.Lightweight aggregate ordinary atmospheric pressure and water absorption is not only big, but also in the pressure conditions, the water absorption with the pressure changes in the size significantly, not only by the loss of slump, pumping performance of a greater impact, but the strength of concrete will have adversely affected. High-performance lightweight aggregate even in the negative or positive pressure conditions, its water absorption is only 7 to 8 percent, only the high-pressure water absorption 2～3%. Therefore high-performance lightweight aggregate concrete mixture at 1.5 hours of pumping required to maintain the slump in the process of pumping slump has not significantly change the current structure can be better adapted to general use of ready-mixed concrete, Pumping construction technology.The degree of segregation of Llightweight Aggregate Concrete has controled by lightweight aggregate particle size, viscosity of cement mortar, the density difference of cement mortar and lightweight aggregate. Through the mixing of fly ash and slag, adjust sand rate and reduce the size of lightweight aggregate technical measures can effectively control the segregation of lightweight aggregate concrete. But control of the segregation of lightweight aggregate concrete is a systematic project, we must consider the impact of isolation of a variety of factors, integrated control to achieve the best results.High-strength lightweight aggregate concrete evaluation of performance indicators: When the slump degrees and expansion ratio of 0.4 to 0.5 range, concrete mixing performance were the best; when sl / sf larger than 0.5, the concrete mixture is too thick, not pumping; when sl / sf less than 0.4, the concrete mixing easily layered structures disintegrate.When compared with the preparation of a lower intensity of light aggregate lightweight aggregate concrete, that is lightweight aggregate strength than high strength mortar, the destruction of the characteristics of the performance of ordinary concrete with the destruction of a similar strength of concrete by mortar intensity decisions, preparation of concrete are composite soft materials; the other hand, when the preparation of high-strength lightweight aggregate concrete, the coagulation primarily by the strength of lightweight aggregate to make a decision on the performance of lightweight aggregate concrete for the destruction of the characteristics, that is lightweight aggregate damage first, preparation of concrete are composite hard materials.Lightweight aggregate concrete strength is subject to many factors, including the lightweight aggregate strength of the cylinder pressure, lightweight aggregate particle size, particle shape, etc.; a certain strength of lightweight aggregate is only suitable for the preparation of a certain strength of concrete, the preparation of high-strength lightweight aggregate Concrete must be selected high-strength lightweight aggregate. Suitable sand ratio, the type of mineral admixture and mixing also for a clear impact on the strength of concrete. Conservation conditions on the strength of lightweight aggregate concrete did not affect the basic.The water absorption of lightweight aggregate have significant impacts on concrete pumping ,it is an important condition for the pump. Use the low water absorption, high-performance lightweight aggregate can reduces the concrete mixture's pump pressure slump loss. Incorporation superplasticizer, high-quality mineral admixture concrete mixture to improve the flow of performance, mixing organic fiber concrete mixture to improve the performance of anti-segregation is to enable the performance of lightweight aggregate concrete pumping well for the technical means .In this study, high-performance lightweight aggregate and the use of incorporation superplasticizer, high-quality mineral admixture and organic fibers in the "three-doped" and other technical means, the preparation of a fiber-reinforced high-strength lightweight aggregate concrete pumping, and in engineering The successful application, to make significant economic benefits.This article is based on the extensive reading at home and abroad information, to be tested scientifically, to analyze the performance difference between the high-performance lightweight aggregate common with the traditional lightweight aggregate, to identify high-performance lightweight aggregate in the structure of the lightweight aggregate concrete application program and appropriate construction technology in the construction of pumping.Through research the lightweight aggregate concrete's composition, structure and properties of the relationship, has proven high-strength lightweight aggregate concrete strength of the law of development, defined the relationship between the characteristics of the lightweight aggregate with the concrete strength, made the technical line of prepared the structure lightweight aggregate concrete, given with the best programs, established a lightweight aggregate concrete workability evaluation, to find a solution to lightweight aggregate concrete working poor, low-intensity, anti-cracking poor, poor pumping and so on. This will be of great significance to raising the technical level of lightweight aggregate concrete ,save resources and energy, to achieve sustainable development strategy.