等强条件下橡胶微粒混凝土抗压特性及弹性模量研究

掺加橡胶微粒可以明显改善混凝土的力学特性。采用橡胶微粒等体积取代细骨料的方法,通过不断调整配合比,反复试验配制出橡胶微粒体积掺量分别为0%、10%和15%的等强度(30 MPa)橡胶微粒混凝土,探讨橡胶微粒混凝土的抗压强度变化规律,以及在等强条件下不同橡胶微粒掺量对混凝土弹性模量的影响。结果表明:掺入橡胶后,混凝土的前期强度(3 d和7 d)发展较基准混凝土变缓,7 d以及14 d后强度出现较大幅度的增长,28 d后各个配比混凝土立方体抗压强度增幅不大;掺入一定量的橡胶后,混凝土的抗裂性能得到了一定程度的改善,橡胶微粒体积掺量越大,试件受压破坏后的完整性越好;掺入橡胶后,混凝土的弹性模量呈现出近乎线性的大幅下降趋势。     

再生骨料的基本物理力学性能试验研究

再生骨料的物理力学性质是影响其运用范围、再生混凝土性能的本质因素。通过对公路废弃混凝土所制成的再生骨料和天然骨料同时进行物理力学性能试验研究,获得了骨料的表观密度、吸水率、压碎值、磨耗损失和针片状颗粒含量值。通过对再生骨料和天然骨料的试验结果进行对比分析发现,再生骨料除了针片状颗粒含量值会略优于天然骨料,其他四种物理力学性质均比天然骨料差,但两者的差异性不大。     

阿尔塔什水利枢纽工程深厚砂砾石覆盖层混凝土防渗墙施工技术研究

阿尔塔什水利枢纽工程是我国在建面板堆石坝工程之一,其深厚的砂砾石覆盖层和庞大的坝体,在施工和运行过程中均会对防渗墙的应力应变产生较大的影响,处理不好直接会影响到大坝整体防渗效果和工程安全。如何在保证施工质量的前提下,优化施工方案,改善防渗墙应力状况,是施工技术研究重点。通过对防渗墙的受力特性、深厚覆盖层的工程特性分析和研究,从防渗墙成墙槽段划分、墙段连接技术、强漏失地层成槽技术和固壁泥浆配比等关键技术上进行优化和改进,有效的消减了防渗墙在坝体填筑和蓄水过程中的应力应变集中,保证防渗墙的成墙质量和运行效果。     

Influences of metallic polymeric materials on the properties of fresh polyester and acrylic polymer concrete

To investigate the influences of three metallic polymeric materials in polyester and acrylic fresh polymer concretes (PCs), PC‐incorporated different levels of these materials have been investigated for their properties of fresh PC. The mix design was made and optimized for workability, strength, and economy, depending on the resin viscosity, the intended use, and the additional quantities of these polymeric materials. The properties investigated include workability, working time, and curing time of fresh PC. It is concluded that these polymeric materials offer the possibility of improving properties of polyester and acrylic fresh polymer concretes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

含碳硫硅酸钙腐蚀产物的微观结构与生成机理

通过X射线衍射分析、扫描电镜、X射线光电子能谱分析、Fourier变换红外光谱分析及激光Raman光谱分析等现代测试技术,分析英国某桥墩基部腐蚀产物的微观结构,证实所取样品中含有大量的碳硫硅酸钙晶体,已发生了明显的碳硫硅酸钙型硫酸盐侵蚀.探讨了碳硫硅酸钙的腐蚀机理.     

一种聚羧酸型高效减水剂的试验研究

采用溶液共聚合成了一种聚羧酸型高效减水剂,对合成中影响减水剂性能的各种因素进行了分析;运用正交实验法,得出了合成该减水剂最佳配方和工艺条件;并研究了该减水剂对水泥净浆性能和混凝土性能的影响。结果表明,该产品掺量少(1.2%)、分散性能好(减水率25.4%)、混凝土性能高(抗压强度比178%)、不含甲醛等有害物,是一种良好的混凝土减水剂。     

试析钻孔灌注桩基础施工技术在桥梁工程中的应用

通过以某桥梁工程为例,探析了钻孔灌注桩基础施工技术在桥梁工程中的具体应用,并为类似桥梁工程的基础施工人员提供了一定的参考和依据。     

利用工业废石膏作水泥缓凝剂的技术研究

介绍了利用生产混凝土外加剂时排放的工业废石膏作为水泥缓凝剂的研究。研究结果表明,废石膏作为水泥缓凝剂单独使用时虽然可能会影响水泥的凝结时间和强度,但如果与天然石膏搭配使用,并控制适当的SO3掺量,就可以在原有生产工艺参数基本不变的条件下,生产出合格的水泥,而且可以配制出符合建筑工程要求的高性能混凝土。     

Defining anchor lengths of steel and CFRP plates bonded to concrete

At Luleå University of Technology, research is taking place in the area of plate bonding, i.e. when concrete members are strengthened by bonding steel or fibre-reinforced plastic (FRP) plates to their surface. The research work started in 1988. Both comprehensive experimental work and theoretical work have been performed. This paper presents the results of tests performed on concrete prisms onto which steel or carbon-fibre-reinforced plastic (CFRP) plates have been bonded. The criteria for the necessary anchor lengths for both the materials are presented as well as the critical strain level in the concrete at failure. Tests are compared with the Volkerson theory for lap joints. The results from the tests show that there is a specific anchor length for each material used. The tests also show that the strain limit in the concrete is the governing factor for failure. Furthermore, a compression between test and theory shows that the derived elastic theory can be used for moderate levels of load.     

Evaluation on steel bar corrosion embedded in antiwashout underwater concrete containing mineral admixtures

This study aims the evaluation of the corrosion of steel bar embedded in antiwashout underwater concrete, which has rather been neglected to date. To that goal, accelerated steel bar corrosion tests have been performed for three series of steel bar-reinforced antiwashout underwater concrete specimens manufactured with different admixtures and under different environments. The three series of antiwashout underwater concrete were: concrete constituted exclusively by ordinary portland cement (OPC), concrete composed by ordinary portland cement mixed with fly-ash in 20% ratio (FA20) and concrete with ground granulated blast furnace slag is mixed in 50% ratio (BFS50). And, the three different environments were: manufacture in the air, in tap water, and in artificial seawater.Measurement results using half-cell potential surveyor showed that, among all the specimens, steel bar in OPC manufactured in artificial seawater was the first one that exceeded the threshold value proposed by ASTM C 876 with a potential value below − 350 mV after 14 cycles. And, the corresponding corrosion current density and concentration of water soluble chloride were measured as 0.3 μA/cm² and 0.258%. On the other hand, for the other specimens that are FA20 and BFS50, potential values below − 350 mV were observed later at 18 and 20 cycles, respectively.Results confirmed the expectation that mineral admixtures may be more effective in delaying the development of steel bar corrosion in antiwashout underwater concrete.