硼砂-硅酸钠碱激发矿渣砂浆干缩和微观特性试验研究  

Experimental study on drying shrinkage and microscopic characteristics of borax-sodium silicate alkali-activated slag mortar

作　　者：陈海明[1,2] 秦子光 陈杰 张亚东 吴鹏 CHEN Haiming;QIN Ziguang;CHEN Jie;ZHANG Yadong;WU Peng(School of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan 232001,China;Engineering Research Center of Underground Mine Construction,Ministry of Education,Anhui University of Science and Technology,Huainan 232001,China)

机构地区：[1]安徽理工大学土木建筑学院,安徽淮南232001 [2]安徽理工大学地下矿山建设教育部工程研究中心,安徽淮南232001

出　　处：《实验技术与管理》2024年第4期25-31,共7页Experimental Technology and Management

摘　　要：碱激发材料(AAMs)具有高强、低碳等优点,但是其相较于水泥基材料较大的干燥收缩率限制了其应用和推广。该文设计了一种复合激发剂,开展了硼砂-硅酸钠碱激发矿渣(AAS)砂浆的干缩和微观特性试验研究。采用压汞法(MIP)、X射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)对样品进行测试和表征,分析了复合激发剂减缩机理。试验结果表明,硼砂-硅酸钠复合激发剂有效降低了AAS砂浆的干缩;XRD结果显示AAS砂浆中存在钠硼解石相(NaCaB_(5)O_(6)(OH)_(6)(H_(2)O)_(5));FTIR分析表明,最优硼砂比例下(20%),AAS砂浆的Si—O—T(T代表Si、Al或B)谱带明显增强,通过MIP分析得到AAS砂浆的中孔(<50nm)数量减少,这有助于缓解收缩应力,降低砂浆的干缩率。该研究结果可以为AAMs的减缩和应用提供参考依据,激发学生在建筑领域的碳减排思维,提升解决关键问题的能力。[Objective]Alkali-activated materials(AAMs)present numerous advantages,such as high strength and a low carbon footprint.However,their wide application is hindered by significant shrinkage.This study addresses this key challenge by developing a composite activator to examine the drying shrinkage and microscopic characteristics of borax–silicate sodium alkali-activated slag(AAS)mortar.[Methods]The samples were tested and characterized using mercury intrusion porosimetry(MIP),X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier-transform infrared spectroscopy(FTIR).These methods helped to analyze the reduction mechanism of the composite activator on drying shrinkage.MIP is a significant technique for investigating the structure properties of porous materials.Numerous studies have established a connection between the drying shrinkage of cement-based materials and their porous structures.Given that both AAMs and cementitious materials are classified as porous materials,MIP could also be applied to AAMs.SEM enabled the observation of the mortar microstructure,while XRD was instrumental in characterizing the hydration products of the mortar.FTIR analysis provided insights into the strength of chemical bonds in the gel of the AAS mortar,particularly after the introduction of new B—O bonds resulting from borax hydrolysis.[Results]The experimental results showed that:1)B10-N6.3 exhibited the highest fluidity(183 mm),which was 5%higher than that of C-N7.0.2)The drying shrinkage of B20-N5.6 at 7 days was 34% and 25% lower than that of C-N7.0 and C-N5.6,respectively.This reduction further increased to 12% and 8%at 28 days,respectively.3)MIP indicated fewer pores of less than 50 nm in B20-N5.6(3.38%)compared to the control group C-N7.0(5.78%).4)SEM images showed that borax addition lessened the microcracks in the AAS mortar.XRD detected the presence of the ulexite phase(NaCaB_(5)O_(6)(OH)_(6)(H_(2)O)_(5))in the AAS mortar.5)FTIR analysis showed a significant enhancement in the Si—O—T(T represents Si,Al,

关 键 词：碱激发材料 硼砂 干缩 压汞法 傅里叶变换红外光谱 

分 类 号：TU526[建筑科学—建筑技术科学] TU528