LC60级高强自密实轻骨料混凝土配制技术

Preparation Technology of LC60 High Strength Self-Compacting Lightweight Aggregate Concrete

分别选用堆积密度为500,600,700,800 kg/m3的页岩陶粒作为轻骨料,通过调整水胶比控制浆体强度,预湿骨料确保混凝土工作性能,添加高分子增稠剂增加轻骨料的稳定性,配制出湿表观密度为1900 kg/m3的自密实轻骨料混凝土,并测试了其中陶粒与浆体界面过渡区的显微硬度。结果表明:自密实轻骨料混凝土抗压强度随页岩陶粒堆积密度增加而增加,随水胶比增大而降低,且受页岩陶粒预湿时间影响;配制LC60级高强自密实轻骨料混凝土宜选用800 kg/m3的页岩陶粒,水胶比不宜高于0.29,预湿时间宜在1 h左右;高分子增稠剂可在不改变轻骨料混凝土流动性能的情况下提高浆体的屈服应力,抑制轻骨料的上浮,提升轻骨料的分布均匀性;与相同强度等级的普通混凝土相比,LC60级高强自密实轻骨料混凝土中陶粒与浆体界面过渡区显微硬度更高,耐久性能更好。

Shale ceramsite with bulk density of 500,600,700,800 kg/m3 was selected as light aggregate and the water binder ratio was adjusted to control the paste strength.The pre-wetted aggregate was used to ensure the working performance of concrete and the stability of lightweight aggregate was increased by adding polymer thickener.The selfcompacting lightweight aggregate concrete with apparent density of fresh concrete of 1900 kg/m3 was prepared,and the microhardness of the transition zone between ceramsite and paste was tested.The results show that the compressive strength of self-compacting lightweight aggregate concrete increases with the increase of shale ceramsite bulk density and decreases with the increase of water binder ratio,and is affected by the pre-wetted time of shale ceramsite.For LC60 high strength self-compacting lightweight aggregate concrete,shale ceramsite with bulk density of 800 kg/m3 should be selected,the water binder ratio should not be higher than 0.29,and the pre-wetted time should be about 1 h.The polymer thickener can increase the yield stress of the paste,inhibit the floating of the lightweight aggregate,and improve the uniformity of the lightweight aggregate distribution without changing the fluidity of the lightweight aggregate concrete.Compared with ordinary concrete with the same strength grade,microhardness of the interface transition zone between ceramsite and paste of LC60 high strength self-compacting lightweight aggregate concrete is higher and the durability is better.