高强轻骨料混凝土拌合物性能及影响因素试验研究

Experimental Study on Influencing Factor of Workability of High-strength Lightweight Aggregate Concrete

采用粉煤灰等量取代水泥以及轻质砂代替普通砂,制备了高强轻骨料混凝土。通过试验研究了轻骨料吸水特性,颗粒类型和粒径,砂的细度模数,粉煤灰等级等因素对混凝土拌合物性能的影响,并且利用工业CT分析了骨料内部孔隙。结果表明,页岩陶粒充分预湿以后,轻骨料混凝土具有良好的流动性且经时损失小;圆球型陶粒混凝土相比于碎石型陶粒混凝土的拌合物性能更好,同时,粒径偏大的陶粒容易出现上浮现象。掺入超细粉煤灰的轻骨料混凝土拌合物性能有较大改善,掺入Ⅰ级粉煤灰试样的工作性相差不大,掺入Ⅱ级粉煤灰的试样的工作性有所降低;从拌合物性能优化的角度考虑,细度模数为2.4～2.8的砂较适合作为轻骨料混凝土用砂,且用轻质砂代替普通砂可使轻骨料混凝土容重大幅度降低。

High-strength lightweight aggregate concrete （HSLWC） was prepared by using fly ash to substitute with equivalent cement and lightweight sand to substitute with normal sand. Factors that may influence workability, such as water absorption of lightweight aggregate, grain size, diameter of particle and fly ash, were studied through experiments. The internal pore structure of lightweight aggregate was detected by industrial computed tomography. The test results show that concrete with pre-wetted ceramisite as coarse aggregate has good workability. Compared to crashed ceramisite, spherical ceramisite is better for the improvement of concrete workability but the phenomenon that the ceramisite aggregate separate from the cement paste was easy to appear even using spherical ceramisite when the grain size of ceramisite was too large. The workability of lightweight concrete was improved significantly when ultra-fly ash is added. Meanwhile, when I -grade fly ash was added, the workability of lightweight concrete was without apparent change, but the workability of lightweight concrete reduced when 11 -grade fly ash was added. Sand with fineness modulus between 2.4 and 2.8 is suitable for lightweight aggregate eonerete. The density of light weight aggregate concrete decreased obviously when normal sand was replaced by lightweight sand.