探讨减少40mm×40mm水泥抗压夹具误差的方法

本文分析了40mm×40mm水泥抗压夹具误差产生原因,结合日常校准工作实际积累的数据,探讨减少40mm×40mm水泥抗压夹具误差的方法,提出加强夹具生产过程控制和改进夹具设计方案的解决途径。

浅析影响水泥抗压试验对比误差的仪器因素

水泥强度是水泥质量指标中一个重要测试项目。国内外大量试验早已证明,加荷速度对试体的表观强度影响极大,加荷速度快测得的强度偏高,反之偏低。因此,为了准确测得水泥试体强度,在GB177中明确规定了抗压破型的加荷速度,规定控制在(5±0.5)kN/s的范围内,尤其是在试体接近破坏时更应严格掌握。

水泥抗压夹具示值相对误差的不确定度评定

本文介绍了水泥抗压夹具示值相对误差的不确定度的评定方法。

无机防水堵漏材料凝结时间与抗压抗折强度的影响因素研究

制备了无机防水堵漏材料,探讨了R.SAC 42.5水泥、P.O 42.5水泥、石英砂用量以及水温、加水量对其凝结时间和1 h抗压抗折强度的影响。结果表明:配方中主要原材料对凝结时间的影响程度依次为:R.SAC 42.5水泥用量>P.O 42.5水泥用量>石英砂用量;加水量越多、水温越低,无机防水堵漏材料的凝结时间越长。

水泥抗压夹具校准方法的研究

根据水泥抗压夹具工作原理和技术特性，参考国家相关标准，确定并验证了校准参数和校准方法，并对其进行不确定度分析，研究制定出水泥抗压夹具校准方法，为校准水泥抗压夹具提供技术依据。

计算机控制电液式水泥抗折抗压试验机设计研究

文章提出了一种计算机控制电液式水泥抗折抗压试验机 ,介绍了试验机的设计原理和性能特点 ;其液压系统利用一只数字式微小流量阀 ,通过二位三通换向阀 ,分别控制 0～ 10kN和 0～ 2 0 0kN两套系统以恒定速率均匀加载 ;试验结果表明该系统完全满足国际GB 2 2 8— 2 0 0 1和GB/T 176 71— 1999规定的要求 。

水泥抗压夹具校准方法的研究

目前对水泥抗压夹具的检测,实验室一般是采用购置国家水泥质量监督检验中心监制的抗压夹具与使用中的抗压夹具进行比对的方法来验证其是否符合要求,然而这种方法既不科学又不可靠。为确保水泥抗压强度测量结果的准确、可靠,提高水泥产品的质量,

水泥混凝土抗压试件的制作

现场制作混凝土抗压试块是评定交通土建行业中水泥混凝土质量的重要手段和最直接的方法。并就工作实践对水泥混凝土试压块制作过程中试模选择、试件制作、试件养护、强度评定提出注意事项。

恒加荷水泥压力试验机的计量检定

伴随着水泥行业的快速发展,由于其性能直接影响建筑的质量,因此相应的水泥强度测量设备(水泥恒加荷压力试验机)的应用也越来越广,研究如何确保水泥恒加荷压力试验机测量准确度具有重大意义。本文在阐述恒加荷水泥压力机基本原理的基础上,简单介绍了其检定条件和方法。

混凝土抗压试件的制作与抗压强度试验

水泥混凝土试件是评定水泥混凝土质量好坏的重要手段和最直接的方法，它也为工程技术人员控制水泥混凝土施工质量提供了最有效的办法。就工作实践，对水泥混凝土试件制作过程中试模选择、试件制作、试件养护、抗压强度试验、强度评定提出注意事项。

Determination and Evaluation of Strength Characteristics of Dry Jet Mixing

Dry jet mixing (DJM) for soft soil stabilization has been widely used since 1980s. The quality and strength of stabilized columns are fundamental parameters to evaluate the stabilization work. This paper presents the standard penetration test (SPT) method and its test results on cement columns. It is shown that SPT is an effective and simple method for inspecting and evaluating cement columns. The strength characteristics along the length of the column, a good correction between SPT blow count and the unconfined compressive strength are achieved.

56项建材行业标准7月1日实施

近日，国家发改委发布第7号《公告》，正式公布56项产品、实验方法和技术行业标准。这些标准将于7月1日起正式实施。

Strength characteristics of modified polypropylene fiber and cement-reinforced loess

The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials.To study the strength characteristics of loess soil reinforced by modified polypropylene(MPP) fiber and cement,samples were prepared with six different fiber contents,three different cement contents,three different curing periods and three kinds of fiber length.The samples were tested under submergence and non-submergence conditions for the unconfined compressive strength(UCS),the splitting tensile strength and the compressive resilient modulus.The results indicated that combined reinforcement by PP fiber and cement could significantly improve the early strength of loess to 3.65–5.99 MPa in three days.With an increase in cement content,the specimens exhibited brittle fracture.However,the addition of fibers gradually modified the mode of fracture from brittle to ductile to plastic.The optimal dosage of fiber to reinforce loess was in the range of 0.3%–0.45% and the optimum fiber length was 12 mm,for which the unconfined compressive strength and tensile strength reached their maxima.Based on the analysis of failure properties,cement-reinforced loess specimens were susceptible to brittle damage under pressure,and the effect of modified polypropylene fiber as the connecting "bridge" could help the specimens achieve a satisfactory level of ductility when under pressure.

Strength of copolymer grouting material based on orthogonal experiment

Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of water-cement ratio （mass fraction of water to cement）, epoxy resin content, and waterborne epoxy curing agent content. By orthogonal range and variance analysis, the orders of three factors to influence the strength, the significance levels of different factors, and the optimized compound ratio scheme of copolymer grouting material mixture at different curing ages were determined. An empirical relationship among the strength of copolymer grouting material, the water-cement ratio, the epoxy resin content, and the waterborne epoxy curing agent content was established by multivariate regression analysis. The results indicate that water-cement ratio is the most principal and significant influencing factor on the strength. Epoxy resin content and waterbome epoxy curing agent content also have a significant influence on the strength. But epoxy resin content has a greater influence on the 7-day and 28-day flexural strength, and waterborne epoxy curing agent content has a greater influence on the 3-day flexural strength and the compressive strength. The copolymer grouting material with water-cement ratio of 0.4, epoxy resin content of 8% （mass fraction） and waterbome epoxy curing agent content of 2% （mass fraction） is the best one for repairing of cement concrete pavement. The flexural strength and the compressive strength have good correlation, and the ratio of compressive strength to flexural strength is between 1.0 and 3.3.

Damage model of fresh concrete in sulphate environment

A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions: an expanded and dense region; a crack-development region; and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks' corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement,but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.

Mechanical properties of fiber and cement reinforced heavy metal-contaminated soils as roadbed filling

The treatment of contaminated soil is a crucial issue in geotechnical and environmental engineering.This study proposes to incorporate appropriate polypropylene fibers and cements as an effective method to treat heavy metal contaminated soil(HMCS).The objective of this paper is to investigate the effects of fiber content,fiber length,cement content,curing time,heavy metal types and concentration on the mechanical properties of soils.To this end,a series of direct shear test,unconfined compression strength(UCS)test,dry-wet cycle and freeze-thaw cycle test are performed.The results confirm that the appropriate reinforcement of polypropylene fibers and cement is an effective way to recycle HMCS as substitutable fillers in roadbed,which exhibits benefits in environment and economy development.

Study on influence factors of cement-stabilized soil compressive strength

The cement dry jet mixing method has been used to reinforce soft cohesive ground to increase the strength of soft cohesive ground and to decrease its deformation. The study briefly introduces the curing mechanism of cement-soil,presents the factors of influencing on compressive strength,mainly analyses the factors including cement mixing ratio,cement strength grade,curing age,moisture content and soil texture and puts forward some rational proposals at last.

Assessment of strength development in cement-admixed artificial organic soil with GX07

To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic matter content was obtained by adding different amounts of fulvic acid into non-organic clay,and then liquid-plastic limit tests were carried out on the artificial organic soil.Meanwhile,unconfined compressive strength(UCS) tests were performed on cement-only soil and composite stabilized soil,respectively.The test results indicate that the plastic limit of soil samples increases linearly,and the liquid limit increases exponentially as the organic matter content increases.The strength of stabilized soil is well correlated with the organic matter content,cement content,stabilizing agent content and curing time.When the organic matter content is 6%,as the cement content varies in the range of 10%-20%,the strength of cement-only soil increases from 88.5 to 280.8 kPa.Once 12.6% GX07 is added into the mix,the strength of stabilized soil is 4.93 times compared with that of cement-only soil.GX07 can obviously improve the strength of cemented-soil and has a good economic applicability.A strength model is proposed to predict strength development.

Application of Geopolymer Cement for Groutless Decorative Building Materials

The present study describes the experiments on the application of geopolymer paste for groutless in situ casting or flooring. The paste was synthesized from fly ash and sodium silicate solution and cured at room temperature, 60 and 80℃ for 24 hours. To simulate flooring application, the geopolymer paste was casted on Portland cement cubes which have been fully hydrated for 28 days. Silica fume was added to reduce cracks but at the same time compressive strength decreased. Averaged compressive strength decreased from 53 MPa to 37 MPa for paste cured at 60℃. Curing at higher temperatures produced stronger geopolymer, with compressive strength of 12 MPa, 53 MPa and 67 MPa for geopolymer cured at room temperature, 60℃ and 80℃ respectively, however, higher curing temperature resulted in more cracking when the geopolymer paste was applied on the Portland cement substrate. Averaged hardness values were 65 and 43 Brinnel scale （BHN）, and wear rate, measured using Ogoshi machine, were 0.66 and 1.80 mm3/min for samples cured at 60 and 80℃ respectively. Unless surface hardening was applied, the material is not suitable for flooring but do so for decorative masonry.

Effect of aggressive pH media on peat treated by cement and sodium silicate grout

The effects of aggressive peat nature (pH) on the strength of peat treated by cement and cement-sodium silicate grout were investigated by evaluating the changes in unconfined compressive strength,moisture content,and scanning electron microscopy (SEM) of samples with time in different pH media.The results indicate that peats treated by cement-silicate have higher strength than peats treated by cement,due to an increase in pH value of the media.Furthermore,cement and cement-silicate are highly effective in reducing the moisture content and void ratio of the treated peats.The microstructures of treated peats support the laboratory test results.