H2O2 and NaClO were used for surface oxidation treatment of chopped carbon fiber.Chopped carbon fiber rein-forced gypsum-based composite materials were prepared by three dispersion methods of PCE,HPMC and ultrasonic dispersion,and then the mechanical properties were studied.The results show that the surface roughness of the oxidized chopped carbon fiber in-creased with the increase of the content of hydrophilic oxygen-containing functional groups hydroxyl and carbonyl,and the oxidized chopped carbon fiber had the best dispersion effect in PCE solution.The mechanical strength of gypsum hardened were effectively improved by adding chopped carbon fiber.The strength of gypsum hardened increased maximum by 72.4％with the chopped car-bon fiber treated by PCE dispersion,which content was 1％and the length was 6 mm.The dispersion of chopped carbon fiber in gypsum paste was improved by the dual action of adsorption of PCE on the surface of chopped carbon fiber and the steric hin-drance effect formed by the reaction of PCE with gypsum particles,and then the mechanical strength of gypsum-based composites materials was improved.
为解决传统固化剂硅酸盐水泥(P)能耗高、CO2 排放高等问题,研究了以普通硅酸盐水泥(OPC)-矿渣微粉(GBFS)-钢渣微粉(SS)-脱硫石膏(DG)体系制备的土体固化剂(固化剂G)对不同含水率淤泥无侧限抗压强度的影响,并分析其固化机理.结果表明,在淤泥含水率 17%时,G固化体强度略高于P固化体,而淤泥含水率 45%和 70%时,G固化体 7d强度略高于P固化体,28 d强度则低于P固化体.原因是固化剂G在淤泥土中能快速生成大量针棒状的钙矾石(AFt),将淤泥土颗粒连接在一起,形成三维空间网络,并且后期水化硅酸钙凝胶持续增多,逐步填充孔隙,形成致密的整体,强度提高.
溶液型液体无碱速凝剂AF-LR-FSA因其促凝效果好、绿色环保等优势,已成为当前喷射混凝土技术的研究热点.然而AF-LR-FSA中重要促凝成分硫酸铝极易从水相体系中析出,严重影响其稳定性.选择多种酸作为稳定剂,研究了单一酸和多种酸对AF-LR-FSA稳定时间、水泥砂浆凝结时间和强度的影响.结果发现,体系中含2 种及以上有机酸可提高产品稳定性,其中 1 种有机酸为抗坏血酸(VC)时稳定性更好,稳定时间最长可达到180 d.
通过研究建筑石膏种类、轻骨料种类、纤维素醚种类的选择,纤维素醚的黏度和用量,普硅水泥用量及缓凝剂用量等对轻质抹灰石膏的涂布率、抗压强度、拉伸粘结强度等性能的影响,确定了高涂布率轻质高强抹灰石膏的配比组成为:石膏粉 88%～90%,普硅水泥2.0%～4.0%,轻骨料8.0%,掺黏度为50000 mPa·s的EH纤维素醚0.25%～0.35%,蛋白质类缓凝剂用量为 0.015%～0.020%.制备的高涂布率轻质抹灰石膏施工顺滑,物理性能符合GB/T 28627-2023的技术要求.
采用化学试剂模拟含铬固废,掺入水泥生料煅烧成熟料,研究铬掺量、铬价态及生料成分对熟料浸出毒性、抗压强度、水化活性、矿物组成的影响.结果表明:随CrO3 掺量增加,熟料水化物的Cr(Ⅵ)浸出浓度增大,而随养护龄期延长,各试样的浸出浓度又有所减小.CrO3 掺量低于2%时基本不影响水泥硬化体的抗压强度,掺量超过2%时试件强度骤降.若含铬固废中同时存在碱金属离子,熟料的Cr(Ⅵ)浸出浓度会略有增大,但矿物组成、水化活性等基本不受影响;不论工业固废中含有Cr(Ⅵ)或Cr(Ⅲ),水泥窑协同处置的效果基本相当.
