铁尾矿砂自密实水泥基材料性能研究

采用铁尾矿砂取代部分天然砂配制自密实水泥基材料,研究了其流动性和基本力学性能。同时,引入相对扩展度值Γp和相对流动速率Rp两参数表述拌合物流体常数屈服应力和塑性粘度的宏观表现形式。试验结果表明,随着铁尾矿砂取代率增加,拌合物流动性降低;强度随龄期变化规律与基准配合比相似,但也随铁尾矿砂取代率增加而降低。工程应用中建议铁尾矿砂取代率不超过30%。

双护盾TBM自密实回填快速支护施工技术及应用

采用双护盾TBM开挖隧洞时,传统豆砾石回填技术回填质量差、工序繁多、回填滞后。本文提出了一种全新的施工技术,将回填材料换为自密实材料,配合使用充气止浆环进行止浆,极大提升了回填质量。文中详细阐述了该施工技术的施工工艺和质量控制方法,通过回填质量评价,证明了新型施工技术可显著提升施工质量,且具有明显的经济效益和社会效益,值得推广应用。

地铁易维修板式无砟轨道填充层材料工作性能研究

通过标准单元试验测试填充材料的基本物理及力学性能、室内疲劳试验测试该材料填充层的实际受载情况和长期耐久性能,分析研究材料的工作性能和长期耐久性能以及填充层之间的黏结性能。研究表明:选用的自密实聚合物水泥砂浆具有快硬、流动性好等特性,且分层填充后层间黏结性能较好,满足地铁有效天窗时间内填充层修复的施工性能;在最不利疲劳荷载作用下,填充层结构整体稳定性较好,多次填充时填充层黏结面及其与减振垫接触面的应力状态分析是检算该类轨道结构安全性的关键,填充层结合面的最大拉应力远小于其承载能力。

新型土木工程材料的类别、应用及发展趋势

文章阐述了应用新型土木工程材料的意义;介绍了新型土木工程材料的类别及其应用,包括新型混凝土材料、新型复合材料、智能土木工程材料;分析了新型土木工程材料的发展趋势,包括绿色化、复合化、高性能、智能化。

纤维水泥基自密实补强材料流动性能试验研究

首先通过调整组分在不加入纤维的情况下使水泥基自密实补强材料具有良好的流动性能和早强性能,然后再加入纤维并调整组分使其流动性能满足要求。结果表明,纤维掺量为0.30、0.50、0.70 kg/m^(3)时,PP纤维和PVA纤维初始流动度降低幅度分别为12.90%和6.90%、18.20%和24.80%、30.10%和33.10%。纤维掺量为0.70 kg/m^(3)时,材料可以获得良好的流动性。给出了纤维掺量与流动度的关系公示。适当延长搅拌时间,可以使纤维的分散效果更理想。

Properties of Fresh and Hardened Self-compacting Concrete Produced by Using Locally Available Materials

Self-compacting concrete （SCC） is defined so that no vibration is necessary for the compaction. The main criteria of producing SCC have to satisfy the following characteristics [1, 2, 3]： （1） Ability to flow into and completely fill complex forms under its own weight; （2） Ability to pass through and bond to congested reinforcements; （3） High resistance to aggregate segregation. Self-compacting concrete presents a significant sign in improving the product quality and efficiency of the building industry. It also enhances the working conditions and the quality and appearance of concrete. Japan has been used self-compacting concrete in bridge, building and tunnel construction since the early 1990s. In the last decade, SCC has been produced a high potential for greater acceptance and wider applications in highway bridge construction in the Europe and U.S.. However, till now, there is no application of SCC in the construction industry in Egypt. Therefore, the main objective of this research is to produce SCC by using the locally available materials in our region such as basalt, gravel, sand, limestone powder and silica fume. Experimental programme was designed to characterize the properties of fresh and hardened SCC. It comprises different concrete mixes thbricated with different types and percentages of constituent materials. Three full-scale reinforced concrete beams were fabricated from the SCC mixes and tested under flexure. For the purpose of comparison, an extra RC beam was made of conventional normal concrete to serve as a reference beam. This study, in general, demonstrated that the applications of SCC in construction industry oiler products with enhanced characteristics as well as could be economical.

排水用离心玻璃钢夹砂管最新规程关键技术解读

中国工程建设标准化协会发布的《离心浇铸玻璃纤维增强塑料夹砂管排水埋地管道工程技术规程》(T/CESS 1130—2022,以下简称《规程》)已于2023年1月1日起施行。《规程》从管材、设计、施工、功能性试验、验收等方面做出规定,对保证管材生产质量、规范工程设计、提升管道工程质量具有重要意义。对《规程》中的关键技术进行了详细解读,包括管道防腐及耐久的要求、管材环刚度、接口方式及适用条件、结构计算、检查井连接方式、顶管及内衬管施工要求和自密实回填材料七个部分。该技术解读有助于对《规程》的推广及应用。