高强钢绞线网加固混凝土粘结性能试验研究

通过高强钢绞线网聚合物砂浆加固层与混凝土结构的剥离破坏试验,对加固层与混凝土界面的剥离破坏特征进行了研究。探讨了单侧加固、植筋加固及U型加固等不同的加固方式对加固层抗剪承载力及抗剪强度的影响。试验结果表明,采用U型加固等增加粘结面积的方式能有效提高加固层粘结面抗剪承载力,但同时会削弱加固层的抗剪强度,而在界面上植入抗剪钢筋后,能同时提高聚合物砂浆加固层的抗剪承载力及抗剪强度。根据试验结果,提出了最小植筋率的建议值。     

Preparation and properties of a long-life cementbased mortar used on metal oilcans

Organic-based materials are often used as the coating of metal oilcans. But they need to be sprayed several times in the whole life of oilcans because of the short-life of organic components. To overcome this problem, a type of long-life flexible cement-based anti-corrosion material used on the surface of metal oilcans was developed according to the principle that the steel reinforced concrete can remain the same life with buildings. The materials with different formulas composed of acrylic ~nulsion, cement and other additives were prepared. Because the ratios of polymer to cement played the decisive role in the adhesion and anti-corrosion characteristics, their effects on the physical performances were investigated by comparing the mechanical properties, anti-corrosion and anti-aging properties. The relationship between microstructure and macroscopic properties was also discussed.     

Impact of sand and filler materials on the hydration behavior of calcium aluminate cement

In earlier work, we have observed discrepancies relating to the early hydration of calcium aluminate cement (CAC) when comparing data from heat flow calorimetry of CAC paste with results from mortar strength tests using the crushing method. Here, we investigated on this phenomenon and found that the sand which is used as a filler exerts a major influence on CAC hydration resulting in acceleration. Furthermore, in particular fine filler materials such as, for example, microsilica, fine limestone powder, and especially α- and γ-Al₂O₃ also produced a strong hydration accelerating effect which is dependent on their specific surface area. The mechanism underlying the acceleration is that under alkaline conditions their negative surface charge attracts calcium ions as was confirmed via inductively coupled plasma atomic emission measurements. Such a layer generates favourable conditions for the nucleation of CAC hydration products (C-A-H phases). The resulting crystalline hydrates which form on the surface of the filler particles submerged in CAC cement pore solution were visualized via SEM imaging. This way, specifically selected fillers can significantly accelerate CAC hydration and save precious lithium salts which are commonly used to boost the early strength of CAC.     

特细砂自流密实砂浆

探讨了特细砂砂浆流动度和含砂率对特细砂砂浆自流密实能力的影响,提出用强度比表示特细砂砂浆的自流密实能力,目的在于充分发挥特细砂砂浆的自流密实能力,节约水泥．     

粘土对聚羧酸减水剂性能的影响及机理研究

粘土作为杂质存在于混凝土的组分如砂石中,粘土对聚羧酸减水剂有较强的吸附性,从而影响混凝土的工作性。研究了不同粘土对掺聚羧酸减水剂的水泥浆体及砂浆流动性的影响规律,探讨了聚羧酸减水剂与粘土的相互作用机理。研究结果表明,不同粘土对水泥浆体的流动性有不同程度的影响,蒙脱土和膨润土相对于高岭土及筛分土对砂浆的流动性影响更为显著;同时,相对于不掺聚羧酸的砂浆,粘土对掺聚羧酸减水剂砂浆的流动性影响更为显著。粘土自身的吸附性与疏水基的定向吸附共同作用及粘土中的金属离子与聚羧酸的螯合作用可能是粘土吸附聚羧酸减水剂的机理。     

高压喷射选用灌浆材料的探讨

高喷灌浆在使用水泥砂浆作为主材进行灌注后,板墙的稳定性和连续性得到了很大的提高,防渗效果明显,并节省了大量的水泥,有效降低了工程成本.     

超效缓粘结预应力材料试验研究

缓粘结预应力的关键技术之一是缓凝砂浆的研究．基于此试制出了缓凝期为30d以上的超效缓凝剂;并针对其凝结时间、强度、体积稳定性等进行了研究．研究得出了缓凝砂浆的强度和凝期与配比的关系,强度和凝期与温度的关系等．可见超效缓凝砂浆配置技术可广泛应用于预应力工程,应用前景广阔．     

点荷法砂浆强度的简化换算公式

在GRC网格布加固空心砖砌体的受剪性能试验中，使用点荷法对144个砂浆试样进行了强度测试，通过与砂浆标准试件的抗压强度值相比较，表明点荷法是一种：隹确可靠的砂浆强度测试方法；文章对大量试验数据进行回归分析，提出了点荷法计算砂浆强度的换算修正公式，通过工程实践证明了该公式结论可靠，应用简便。     

邯郸地区再生骨料在混凝土和砂浆中应用研究

摘要：全面研究了邯郸地区用砖混结构建筑垃圾生成的再生骨料的粒径、堆积密度、吸水率、筒压强度等基本性能。通过试验,分别测试了以建筑垃圾为骨料的再生混凝土的干表观密度、抗压强度、抗渗性、抗冻性等相关的物理力学性能、以混凝土废渣为粗骨料的再生混凝土的抗压强度和以建筑垃圾作为细骨料等体积替代砂浆中的砂的再生砂浆的抗压强度,并分别与普通混凝土和砂浆对比分析。试验结果表明：以建筑垃圾为骨料的再生混凝土具有良好的基本力学性能,强度最高可达C30;用混凝土废渣作为粗骨料配制的再生混凝土的强度等级可达C50;再生砂浆的强度不降低。研究结果可供工程应用和科学研究参考,为再生混凝土和砂浆的进一步研究提供了一定的理论依据。