Study On The Alkali-Aggregate Reaction In Concretes And The Measure For Decreasing Harm In Urumqi

The durability is the important property. The requirement for the durability is supplemented in the revised code < Standard for engage and acceptation of concrete construction > GB 50204-2002, GB 50010 –2002, including limitation of alkali content for the concrete which isn't indoor. This limitation is the measure for preventing the construction from the harm by the alkali-aggregate reaction (AAR). AAR is one of the important factors. Because the harm by AAR is entirely and can't be prevented, it is called as "cancer". There are a lot of cases harmed by AAR around the world. More attention is paid for AAR in many large-scale domestic constructions, and measures are taken. In Xinjiang, on the contrary, attention isn't paid for AAR; further measures aren't taken from design, construction to supervision. The result of looking into the archives shows the study doesn't be done about AAR in architecture region. So the study should be done about if there is potential danger by AAR in Xinjiang, and if the limitation for alkali content need be executed. By three steps the study is done. At first step the alkali-activity of the aggregate used in the construction is studied in Urumqi. From Wulabo, Xishan, Kaziwan and Toutunhe, 120 specimens are picked and the spectrographic analysis is done to the specimens. The result shows the specimens are potential alkali-activity aggregates. Further the expansion of mortar-stick is tested, the expansion at 14th day reach over 0.1%, the result shows the aggregates have high alkali-activity. According to the code the limitation for alkali content in per cubic meter concrete. At second step alkali content in ordinary concrete designed in normal proportion is studied. The content of 32.5 P.C,32.5P.O, 42.5P.O, 52.5P.O,52.5P.Ⅱhave been tested and the result is from 0.7% to 1.1%.