使用粉煤灰和矿渣作为碱活化材料代替水泥的复合材料可以克服使用碱活化材料制备的碱活化胶凝材料的缺陷和负面影响。在这项研究中,以粉煤灰和矿渣为原料制备碱活性复合胶凝材料。对炉渣含量的影响进行了实验研究,活化剂浓度和养护龄期对复合胶凝材料抗压强度的影响。用水化热表征了微观结构,X射线衍射(XRD)傅里叶变换红外光谱(FT-IR),压汞孔隙率法(MIP)和扫描电镜(SEM),揭示了其内在的影响机制。结果表明,提高固化龄期可提高聚合反应程度,3天后复合材料的7天抗压强度达到77~86%。除10%和30%矿渣含量的复合材料外,分别达到33%和64%,分别,他们在7天的28天抗压强度,其余复合材料达到95%以上。该结果表明,碱活化粉煤灰-矿渣复合胶凝材料在早期阶段具有快速的水化反应,在后期阶段具有缓慢的水化反应。矿渣量是碱活化胶凝材料抗压强度的主要影响因素。当炉渣含量从10%增加到90%时,抗压强度呈现持续增加的趋势,最大抗压强度达到80.26MPa。炉渣含量的增加将更多的Ca2+引入系统,这增加了水合反应速率,促进更多水化产物的形成,细化结构的孔径分布,减少孔隙率,并形成更致密的微观结构。因此,提高了胶凝材料的力学性能。当活化剂浓度从0.20增加到0.40时,抗压强度呈现先增加后降低的趋势,最大抗压强度为61.68MPa(在0.30获得)。活化剂浓度的增加改善了溶液的碱性环境,优化水合反应的水平,促进更多水化产物的形成,并使微观结构更致密。然而,活化剂浓度过大或过小阻碍了水化反应并影响胶凝材料的强度发展。
Composites that use fly ash and slag as alkali-activated materials instead of cement can overcome the defects and negative effects of alkali-activated cementitious materials prepared with the use of an alkali-activated material. In this study, fly ash and slag were used as raw materials to prepare alkali-activated composite cementitious materials. Experimental studies were carried out on the effects of the slag content, activator concentration and curing age on the compressive strength of the composite cementitious materials. The microstructure was characterized using hydration heat, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM), and its intrinsic influence mechanism was revealed. The results show that increasing the curing age improves the degree of polymerization reaction and the composite reaches 77~86% of its 7-day compressive strength after 3 days. Except for the composites with 10% and 30% slag content, which reach 33% and 64%, respectively, of their 28-day compressive strength at 7 days, the remaining composites reach more than 95%. This result indicates that the alkali-activated fly ash-slag composite cementitious material has a rapid hydration reaction in the early stage and a slow hydration reaction in the later stage. The amount of slag is the main influencing factor of the compressive strength of alkali-activated cementitious materials. The compressive strength shows a trend of continuous increase when increasing slag content from 10% to 90%, and the maximum compressive strength reaches 80.26 MPa. The increase in the slag content introduces more Ca2+ into the system, which increases the hydration reaction rate, promotes the formation of more hydration products, refines the pore size distribution of the structure, reduces the porosity, and forms a denser microstructure. Therefore, it improves the mechanical properties of the cementitious material. The compressive strength shows a trend of first increasing and then decreasing when the activator concentration increases from 0.20 to 0.40, and the maximum compressive strength is 61.68 MPa (obtained at 0.30). The increase in the activator concentration improves the alkaline environment of the solution, optimizes the level of the hydration reaction, promotes the formation of more hydration products, and makes the microstructure denser. However, an activator concentration that is too large or too small hinders the hydration reaction and affects the strength development of the cementitious material.