高性能耐久混凝土质量控制探讨

在桥梁工程中,混凝土施工占有很大的比例。跨海大桥客运专线快速铁路的出现使高性能耐久混凝土的质量控制尤为重要。混凝土质量优劣直接影响到桥梁的质量、安全和经济使用寿命。高性能耐久混凝土质量控制的主要有:原材料质量,配合比设计,混凝土生产,混凝土成型及养护几个方面。切实控制混凝土施工质量,进而保证我国混凝土工程的质量,建设高质量的桥梁工程。本文就混凝土强度及耐久性主要影响因素有原材料质量,配合比设计进行了分析,重点就高性能耐久混凝土质量控制进行了详细的阐述。     

浅谈影响混凝土弹性模量因素的试验研究

本文以正在建设中的吉图珲铁路客运专线为工程背景,通过对客运专线预应力混凝土现浇梁和连续梁用高性能混凝土配合比的弹性模量进行分析,考虑了砂率、水胶比、粗骨料、矿物掺合料、养护时间等因素对弹性模量的影响,设计了多个配合比。     

基于32m预应力箱梁C50混凝土配制技术的研究

本文主要结合高耐久、高性能混凝土配合比的设计方法,以及客运专线所处施工环境原材料的实际现状,对客运专线32m预应力混凝土箱梁C50高性能混凝土的配合比设计方法进行了分析。     

高铁客运专线高性能混凝土配合比设计及施工常见问题的解决措施

随着我国高铁客运专线的不断建设,在混凝土配合比设计及施工方面也有了长足的进步,但是在进行设计与施工的过程中,仍然存在着许多问题,并且现有的高性能混凝土配合比设计水平及施工水平仍然不能够满足目前的高铁运营要求。本文将针对目前高铁客运专线高性能混凝土配合比设计及施工的发展现状进行分析,从而针对施工中的常见问题予以概述,以此提出相应的解决措施,提升目前高铁客运专线高性能混凝土配合比设计及施工的相应水平。     

高性能混凝土配合比的配制分析

本文介绍了高性能混凝土设计技术指标,分析了实现混凝土高能性化的技术途径,详细阐述了高性能混凝土配合比的设计过程,供大家参考。     

泵送高性能混凝土配合比设计和变形性能研究

该文以三角岩大桥为例,以100年使用年限为目标,分析了适用于该工程的高性能混凝土配合比设计及优化措施,确定可行的配合比,按照特定的用量要求拌制高性能混凝土。提出配合比设计思路与方法。组织收缩徐变试验,判断箱梁高性能混凝土的变形性能,并评价高性能混凝土在不同龄期的表现。结果显示,早龄期混凝土的自收缩因粉煤灰掺量的增加而得到改善,徐变性能有所优化。在用水量一致的前提下,当混凝土强度等级提高时,徐变系数增加,集料用量减少,其中粗骨料最显著,胶凝材料用量增加。     

探讨高性能混凝土配合比设计

高性能混凝土是一种新型高技术混凝土,是在大幅度提高普通混凝土性能的基础上采用现代混凝土技术制作的。本文从原材料品质、配合比参数确定的技术要点及配合比设计方法进行了分析。     

浅谈聚羧酸系减水剂在京沪高速铁路VI标段高性能混凝土的中应用

京沪高速铁路Ⅵ标段主要为桥梁工程,采用高性能混凝土结构,设计寿命100年。本文主要介绍了聚羧酸系减水剂在该工程中的应用,重点探讨了原材料选择、生产过程质量控制、高性能混凝土配合比设计及聚羧酸系减水剂在高性能混凝土施工中应注意问题,并指出高性能混凝土与普通混凝土的异同。     

贵广怀集制梁场C50梁体混凝土配合比优化设计总结

文章从粉煤灰掺量、水胶比、砂率及混凝土含气量等几方面入手,着重对C50梁体混凝土的弹模及lOd强度进行检测,配制出了满足设计和施工要求的高性能梁体混凝土配合比,对以后铁路工程梁体配合比设计有很好的借鉴意义。     

高速公路预制T梁用高性能混凝土性能研究

为揭示高速公路预制T梁中高性能混凝土耐久性机理性及早期工作性能,研究立足于福建宁德G104高速公路,依据高速公路T梁用高性能混凝土相关规程设计出4种配合比,通过对比4种高性能混凝土工作性、力学性、耐久性,结果如下:1)C1配合比2 h后坍落度、含气量损失率均高于其他3种配合比;2)28 d力学性能发展规律为C4>C3>...     

京沪高铁路电缆槽、人行道盖板活性粉末混凝土（RPC）试验研究

主要针对京沪高速铁路土建六标电缆槽盖板和人行道步板活性粉末混凝土（RPC）配合比设计，满足《客运专线活性粉末混凝土（RPC）材料人行道挡板盖板暂行技术条件》前提下选择原材料，通过多种配合比比较，选定最优配合比，并应用于电缆槽盖板和人行道步板生产。     

Mix design of concrete for prestressed concrete sleepers using blast furnace slag and steel fibers

The application of ground granulated blast furnace slag (GGBFS) and steel fibers in prestressed concrete railway sleepers was investigated in this study. The use of GGBFS was considered as an eco-friendly material aimed at reducing CO₂ emissions and energy consumption as well as to enhance the durability performance of railway sleepers. Steel fibers improves the durability and structural performance in terms of crack control and reduction of spalling and can replace shear reinforcement. The mix proportions of the concrete incorporating GGBFS (56% GGBFS) and GGBFS with steel fibers (56% GGBFS and 0.75% steel fibers) were determined through a series laboratory tests and a life cycle assessment. These mixes satisfied the requirements of the Korean Railway Standard and resulted in improved flexural capacity as well as less CO₂ emissions compared with current railway sleepers. Using these mixes, a total of ninety prestressed concrete sleepers were produced in a factory under the same manufacturing process as current railway sleepers, and their mechanical properties as well as durability performance were evaluated. The mix with partial replacement of Type III Portland cement by GGBFS showed an improved resistance to chloride ion penetration and freeze-thaw cycles compared with the concrete used for current railway sleepers. However, these mixes were more vulnerable to carbonation. The mix with GGBFS and steel fibers (mix BSF) showed a slightly better durability performance than the mix with GGBFS only (mix BS), including better carbonation and freeze-thaw resistances. The mix BSF showed decreased chloride ion penetration depth than mix BS but showed a slightly higher chloride ion diffusion coefficient.     

Geopolymer concrete-filled pultruded composite beams – Concrete mix design and application

The limited research on the geopolymer concrete mix design for targeting a specific strength is identified an obstacle for their effective design and wide use. In this paper, a mix design procedure has been proposed for fly-ash based geopolymer concrete and its use as infill hybrid composite beam is investigated. Then, the structural performance of geopolymer concrete filled hybrid composite beam is investigated to determine their possible application in civil infrastructure. Firstly, a detailed procedure of mix design for fly-ash based geopolymer concrete is presented. Secondly, three hybrid beams filled with geopolymer concrete were prepared and tested in a four-point bending setup to evaluate their flexural modulus and modulus of rupture. Numerical and analytical evaluation of the behaviour of hybrid beam were performed and results showed a good agreement with the experimental investigation. Thirdly, the suitability of the beam for a composite railway sleeper is evaluated and compared with existing timber and composite sleepers. Finally, the beams’ performance in a ballast railway track is analysed using Strand7 finite element simulation software and the results showed that the new concept of using geopolymer concrete as infill to pultruded composite section satisfied the stiffness and strength requirements for a railway sleeper.     

石屑应用于混凝土中的探索性试验

本文将石屑和水洗河砂按比例配制组成混合砂应用于混凝土中,通过试验调整和试用,混凝土工作性和强度良好。     

自密实道面抢修混凝土试验研究

针对机场水泥混凝土道面破坏时如何能够在短时间内进行快速修复的迫切问题,采用快硬早强型特种水泥、高效外加剂和矿物掺合料,进行配合比优化设计和性能试验研究。试验表明,所配制的混凝土工作性能良好,加水拌合后4h即可达到某新型战机起飞最低强度要求,能够满足机场道面抢修技术要求,这种混凝土也可用于公路水泥混凝土路面抢修。     

SPS-8P-2型聚羧酸系泵送剂在中低强度等级预拌混凝土中的应用

SPS-8P-2聚羧酸系泵送剂经混凝土配合比研究和生产实践应用证实,可以在C20-C40预拌商品混凝土中应用,具有良好的工作性,混凝土配合比中的“浆骨比”是工作性的关键。     

Optimum content of copper slag as a fine aggregate in high strength concrete

This study investigated the mechanical properties of high strength concrete incorporating copper slag as a fine aggregate and concluded that less than 40% copper slag as sand substitution can achieve a high strength concrete that comparable or better to the control mix, beyond which however its behaviors decreased significantly. The workability and strength characteristics were assessed through a series of tests on six different mixing proportions at 20% incremental copper slag by weight replacement of sand from 0% to 100%. The results indicated that the strength of the concrete with less than 40% copper slag replacement was higher than or equal to that of the control specimen and the workability even had a dramatic growth. The microscopic view demonstrated that there were limited differences between the control concrete and the concrete with less than 40% copper slag content. It also suggested that the determination of the copper slag replacement level should consider with the desired compressive strength of concrete.     

Response of high performance concrete plates to impact of non-deforming projectiles

The relatively recent technology, which enables the production of high strength concrete (HSC), makes HSC a prospective material for the construction of impact-resisting barriers. However, current penetration formulae are based on test data of normal strength concrete (NSC) and their extrapolation to higher concrete strengths is unsafe. The response of 80×80 cm high performance concrete (HPC) plate specimens to an impact of non-deforming steel projectiles was examined in an experimental study. The tests were planned with an aim to observe the influence of the concrete mix ingredients and amount and type of reinforcement on the performance of HSC under this type of loading. The variants that were examined were the aggregates (different types and maximum size), addition of micro-silica (MS) and steel fibers, and reinforcement details. The main findings show that design of HPC barriers to withstand impact loads involves several aspects. These are aimed at achieving enhanced properties of the structural element, where only one of which is the concrete's compressive strength.