預(yù)應(yīng)力混凝土的廣泛應(yīng)用外文翻譯-文庫(kù)吧
2025-04-16 14:23 本頁(yè)面
【正文】 lt holes around a vertical and horizontal cracks. physical factors Physical factors means the sleeper manufacture and laying, in the course of operating the hot and cold, wet and dry, such as the role of freezing and thawing. When the conservation process of warming up steam soon, when the high temperature thermostat, the concrete gas, water, cement, gravel, and so different coefficient of thermal expansion of different materials, and concrete structure of the early intensity and low, so that hightemperature gas, water greatly expanded, resulting in Concrete internal structural deficiencies, easily lead to the surface in particular sleeper End of the concrete surface cracks, loose. For some time, many factories in the production of steam conservation sleeper no precustody time, warming up quickly, thermostat temperature is higher than 95 ℃ , Stripping at the end of the concrete sleeper swelling, loose situation often occurred. Chemical factors Chemical factors that steel corrosion, concrete corrosion, carbonated, alkali aggregate reaction, and so on. China on the concrete sleeper, which alkali aggregate reaction (AAR) caused the damage can not be ignored. Alkali aggregate reaction of the three conditions are: aggregate activity, highalkali cement and water, the destruction of more than three is a chemical reaction, in the aggregate in the concrete and cement interface on the formation 西南交通 大學(xué)本科 畢業(yè)設(shè)計(jì) 第 3 頁(yè) of silicate gel, Volume expansion caused concrete cracking. One of the most mon base silica reaction. As China39。s cement production for a long time not to limit alkali content. Using highalkali cement increased cement production and reduce costs. China has some areas of concrete coarse aggregate (stone) has obvious base activity, a bination of both together, easy to form alkali aggregate reaction (AAR) damage. This issue is from the late 1960s, a factory production of priestess’s concrete sleeper (and bridges) and the fracture occurred repeatedly cracking, and the structure, process, laying the conservation conditions to improve still further fracture, cracking there until the late 1980s, began to be recognized and confirmed by the pilot. Inspection process is: first concrete sleeper in the coresample, the test items, including: ① the naked eye or using threedimensional microscope, and then sidethin reflective microscope, the damage caused by the general AAR regular injury aggregate particles, the more cracks from the aggregate Extending to the slurry, and sometimes also obvious observation aggregate stars expected to split or torn edges. This feature is very important, because of salt corrosion, chemical corrosion, steel corrosion, carbonate, such as mechanical load will not make aggregate particles by injury, so this is AAR and other factors undermining the main features。 ② coupled with the ability to rely on the electron microscope Spectrum analysis can be measured alkali silicate gel39。s chemical position, this is a direct proof of AAR. In addition, concrete aggregate for mechanical and chemical methods (generally deal with hydrochloric acid) separation, reuse and rapid method of identification its phasealkali activity. To sum up, vertical cracks in the main by internal factors (materials, structure, technology factors) due to external factors (loading and freezethaw, wet and dry cycle) is only promote their dev
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