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近几年来,在一些建筑物或构筑物中,由于钢筋混凝土质量低劣留下了不少隐患,甚至发生倒塌事故。剖析其原因,当前部分钢筋混凝土工程质量低劣,除了取决于各种原材料及其配合比的选择外,还与施工过程中不能进行严格的质量控制有关。 一、当前钢筋混凝土工程材料存在的质量问题 1.砂、石子:(1)含泥量控制不严,骨料表面附着的粘土、淤泥、有机质、硫化及硫酸盐等,会影响和水泥的粘结,使混凝土强度降低,同时还会增加混凝土用水量,从而增大混凝土的收缩。(2)石子表面特征及颗粒形状不符合要求,含有过多的针状颗粒(颗粒长度大于该颗粒所属粒级的平均粒径的2.44倍)及片装颗粒(厚度小于平均粒径的0.4倍)。针、片状颗粒不仅本身容易折断,影响混凝土的强度,而且会增加骨料的空隙率,并影响混凝土拌合物的工作性。
In recent years, due to the poor quality of reinforced concrete in some buildings or structures, many hidden dangers and even collapse accidents have occurred. Analysis of the reasons for the current poor quality of some reinforced concrete projects, in addition to the choice of various raw materials and their mix ratio, but also with the construction process can not be strictly controlled. I. Current Quality Problems in Reinforced Concrete Engineering Materials 1. Sand and gravel: (1) Slurry content is not strictly controlled. Clay, silt, organic matter, vulcanization, and sulphate adhering to the aggregate surface will affect cement adhesion. As a result, the strength of the concrete is reduced, and at the same time, the concrete water consumption is increased, thereby increasing the shrinkage of the concrete. (2) The surface characteristics of the stone and the shape of the particles do not meet the requirements. It contains too many acicular particles (particle length is greater than 2.44 times the average particle size of the particle belongs to) and tablet-mounted particles (thickness is less than 0.4 times the average particle size) ). Needle and flake particles not only break easily, affect the strength of the concrete, but also increase the porosity of the aggregate and affect the workability of the concrete mix.