纳米材料改性再生骨料混凝土断裂性能

Fracture Performance of Recycled Aggregate Concrete Modified by Nanomaterials

关键词:  再生骨料混凝土  双K断裂参数  纳米SiO₂  纳米CaCO₃  纳米压痕

Key words:  recycled aggregate concrete（RAC）  double-K fracture parameter  nano-SiO₂  nano-CaCO₃  nanoindentation

摘要:

将纳米SiO₂（纳米硅溶胶和纳米SiO₂粉末）与纳米CaCO₃粉末加入再生骨料混凝土（RAC）中，制备得到纳米材料改性RAC.通过三点弯曲梁试验与传统电测法测试其断裂性能.结果表明：适当掺量的纳米SiO₂和纳米CaCO₃粉末能够有效提高RAC的28 d抗压强度与劈裂抗拉强度；分别掺入1.0%纳米硅溶胶、0.5%纳米SiO₂粉末和2.0%纳米CaCO₃粉末对RAC双K断裂参数和断裂能的提升效果最佳；相较普通混凝土，纳米材料改性RAC的断裂面出现更多贯通再生骨料的裂缝；纳米材料能够促进生成致密程度高的水化产物，减少混凝土界面过渡区内部的孔隙数量.

Abstract:

Recycled aggregate concrete （RAC） was modified by adding nano-SiO₂ （nano-silica sol and nano-SiO₂ powder）and nano-CaCO₃ powder to study the fracture performance. The fracture property of RAC modified by nano-materials was tested by three-point bending beam method and traditional electrical measurement. The results show that the 28 d compressive strength and splitting tensile strength of RAC can be effectively improved by adding proper amount of nano-SiO₂ and nano-CaCO₃. Adding 1.0% nano-silica sol，0.5% nano-SiO₂ powder and 2.0% nano-CaCO₃ powder respectively has the most effective on the improvement of double-K fracture parameters and fracture energy. After the addition of nanomaterials， more cracks pass through the recycled aggregate than that for ordinary concrete； nanomaterials promote production of higher density hydrate and reduction of the number of internal pore in interface transition zone.