纳米颗粒对道路粉煤灰混凝土耐磨性能的影响及作用机理

Effect and Mechanism of Nano-particles on Wear Resistance of Road Fly Ash Concrete

为探讨纳米颗粒对道路粉煤灰混凝土耐磨性能的影响,采用纳米材料和超细粉煤灰等量取代水泥制备了纳米改性粉煤灰水泥砂浆,在此基础上制备出三种纳米改性道路粉煤灰混凝土:纳米Si O_2(NS)混凝土、纳米SiC(NC)混凝土和纳米复掺混凝土,并研究了两种纳米材料对粉煤灰水泥砂浆力学性能和道路粉煤灰混凝土耐磨性能的影响及作用机理。结果表明:混凝土中掺入纳米材料能显著提高其耐磨性能。单掺NS混凝土中NS最优掺量为2%,单掺NC混凝土中NC最优掺量为3%;而复掺2%NS、2%NC时,纳米复掺混凝土耐磨性最佳,与基准混凝土相比,磨损量降低了75%。分析认为:纳米材料的表面效应、活性效应和微集料填充效应使其具有较大的表面能,在水泥浆体中与Ca(OH)2晶体发生二次水化反应,改善了Ca(OH)2的取向程度,强化了水泥石微细观结构,优化了水泥基体内孔径分布与孔结构,使其更加密实,从而提高了道路粉煤灰混凝土的耐磨性能。

In order to investigate the effect of nano-particles on the wer resistance of road concrete containing fly ash, nano-modified fly ash cement mortar specimens were prepared by replacing equivalent cement with nano-materials and ultra-fine fly ash, and on this basis, three types of nano-modified fly ash concrete were prepared, which was nano-Si02 concrete, nano-SiC concrete and nano double-doped concrete, respectively, afterwords the effects and mechanisms of two types of nano-materials on the mechanical properties of fly ash cement mortar and the wear resistance of road fly ash concrete were studied. The results indicate that the wear resistance of road fly ash concrete is improved significantly when nano-materials are added. The optimum content of nano-SiO2 for single doping NS concrete is 2% , and the optimum content of nano-SiC for single doping NC concrete is 3 % ; the wear resistance of nano double-doped concrete is the best when the mixing content of NS and NC is 2% and 2% , respectively, compared with the reference concrete, the wear loss has decreased by 75%. Analysis shows that nanomaterials have larger surface energy due to its surface effect, active effect and microscopic aggregate filling effect, the nano-particles react with Ca （OH）2 crystal when the secondary reaction of hydration happen in the cement paste, which has changed the orientation degree of Ca（ OH）2 and strengthened the microstructure in cement paste, has optimized the pore diameter distribution and pore structure of cement matrix, making the slurry more dense, thereby improving the wear resistance of road fly ash concrete.