高强再生轻骨料和玻璃微珠配制轻质高强混凝土的研究

采用高强再生轻骨料和玻璃微珠,利用体积法配制出了性能满足预定控制要求的轻质高强混凝土。通过对比试验研究了玻璃微珠、水泥品种、骨料掺量对轻质高强混凝土力学性能和工作性能的影响。结果表明,调节玻璃微珠的粒度和掺量可有效控制混凝土的表观密度,使用高强再生轻骨料可提高混凝土的强度和工作性。试验配制出了表观密度1520kg/m3、28d抗压强度58.9 MPa、比强度1.0667、工作性能较好的轻质高强混凝土。     

无骨料粉煤灰轻质混凝土的研究

本文介绍了无骨料粉煤灰轻质混凝土的原材料及其配比,轮碾工艺、抑制收缩及提高强度的措施、养护制度等。     

粗骨料对高强高性能混凝土的影响

该文研究了石灰石碎石、破碎卵石、玄武岩碎石三种不同粗骨料及粗骨料的体积含量对高强高性能混凝土工作性和强度的影响。结果表明:粗骨料为玄武岩的混凝土工作性最好。粗骨料的体积含量越小,新拌混凝土的工作性越好。混凝土中粗骨料体积含量对混凝土后期强度无影响。混凝土的弹性模量在粗骨料体积含量为45%时最大。     

再生粗骨料在高强泵送混凝土中应用的试验研究

通过对再生粗骨料各项性能试验研究,分析再生粗骨料掺量对高强泵送混凝土性能的影响.通过进一步改善配合比,将再生粗骨料代替天然粗骨料掺量提高到30%,高强泵送再生粗骨料混凝土各项性能指标能够满足施工技术要求,并通过扫描电镜分析高强泵送再生租骨料混凝土的微观结构.     

LC40轻质高强混凝土技术的研究

探索三种不同材质的陶粒作为粗骨料普通砂作为细骨料配制LC40混凝土,结果表明表观密度为1735kg/m3粘土陶粒混凝土28d强度仅达到10.5MPa;表观密度为2004kg/m3粉煤灰陶粒混凝土28d强度45.4MPa;表观密度为1756kg/m3的圆型和表观密度为1806kg/m3碎石型页岩陶粒混凝土28d强度分别是44.8MPa和49.8MPa.出于轻质高强混凝土的要求,粘土陶粒与粉煤灰陶粒混凝土很难符合轻质高强的要求.通过优化配比,陶砂0、30%、50%和100%取代普通砂为粗骨料和1∶1的碎石型、圆型页岩陶粒为粗骨料配制混凝土.结果表明:陶砂50%取代普通砂能较好实现轻质高强的要求,坍落度在120mm,且和易性良好,能较好地克服轻骨料上浮的现象,同时表观密度1526kg/m3且28d强度为44.4MPa,56d强度为45.2MPa     

粗骨料种类对高强混凝土高温爆裂性能的影响

从构成混凝土的基本材料人手,研究改善高强混凝土高温爆裂性能,可降低混凝土的材料成本,简化生产工艺.试验证明粗骨料的品种成为影响高强混凝土高温性能最主要的因素之一,如果粗骨料内含铁元素或其他金属矿物含量高,将加快爆裂出现.以石灰石为骨料可明显提高裂缝出现的温度并推迟裂缝出现的时间,使得采用降温防爆措施成为可能.     

轻质混凝土和轻质骨料

轻质骨料有以下几种。结构级轻质骨料是从合适的页岩、粘土、板岩、粉煤灰或鼓风炉炉渣的原料生产的。隔热级轻质骨料包括低密度、低强度的骨料,如蛭石和珍珠岩。天然形成的轻质骨料采自火山堆积物,包括浮岩及火山熔渣类。越来越多的经处理的结构级轻质骨料的利用是环境上合理计划的证据,因为这些产品利用天然状态下结构应用     

利用废玻璃研制轻粗骨料及轻混凝土

以废玻璃为主要原料试制出堆积密度为760－850kg/m^3的轻粗骨料，用其配制出的轻混凝土各项技术指标接近JGJ51－90《轻集料混凝土技术规程》要求。研究表明，用废玻璃研制的轻粗骨料具有较高的强度、较低的吸水性和较好的抗腐蚀性，适用作建筑混凝土的粗骨料。     

Mechanical properties of high-strength concrete incorporating copper slag as coarse aggregate

Copper slag is a by-product obtained during the matte smelting and refining of copper. Current options of management of this slag are recycling, recovering of metal, production of value added products and disposal in slag dumps or stockpiles. This paper presents the results of a study undertaken to investigate the feasibility of using copper slag as coarse aggregates in high-strength concrete. The effects of replacing limestone coarse aggregate by copper slag coarse aggregate on the compressive strength, splitting tensile strength, and rebound hammer values of high-strength concretes are evaluated in this work. Concrete mixtures containing different levels of silica fume were prepared with water to cementitious materials ratios of 0.40, 0.35, and 0.30. The percentages of the cement replacements by silica fume were 0%, 6%, and 10%. The use of copper slag aggregate compared to limestone aggregate resulted in a 28-day compressive strength increase of about 10–15%, and a splitting tensile strength increase of 10–18%. It can be concluded from the results of this study that using copper slag as coarse aggregate in high-strength concrete is technically possible and useful.     

浅谈采用单粒级粗骨料配制混凝土

通过试验，说明用单粒级粗骨料配制混凝土，完全能够满足混凝土和易性和强度要求，应用在工程实践中能够节约成本，方便施工，降低了工程造价，取得了较好的技术经济效果。     

预填骨料混凝土

预填骨料混凝土就是把粗骨料填在模板中，然后注射水泥砂浆来填满空隙(水泥砂浆中一般都掺有外加剂)。国外也称为“灌浆骨料混凝土”或“注射骨料混凝土”。该种混凝土在工程中的应用较为广泛。     

Properties of self-compacting concrete prepared with coarse recycled concrete aggregate

Self-compacting concrete has significant environmental advantages in comparison to the vibrated concrete: absence of noise and vibrations during installing provides a healthier working environment. In the paper the potential for usage of coarse recycled aggregate obtained from crushed concrete for making of self-compacting concrete was researched, additionally emphasizing its ecological value. On the other hand the issue of the waste disposal sites created by the demolition of old structures is solved. In the experiment, three types of concrete mixtures were made, where the percentage of substitution of coarse aggregate by the recycled aggregated was 0%, 50% and 100%. In the process of mixing, equal consistence of all concrete mixtures was achieved. The obtained results indicate that the properties of these concretes have only a slight difference, and that the recycled coarse aggregate can successfully be used for making of self-compacting concrete.     

The effect of the mineralogy of coarse aggregate on the mechanical properties of high-strength concrete

Tests were carried out to study the effect of the mineralogy of coarse aggregate on the compressive, flexural, and splitting strengths. Two aggregate sizes (10 and 20 mm) were supplied locally from five different areas in Oman; namely Muscat, Bidbid, Sur, Nizwa and Sohar. Petrography analysis was carried out on all these samples. The water/binder ratio (w/b) was kept constant at 0.32 and silica fume and superplasticizers were used in all mixes. The 28-days compressive strength varied between 81.3 and 85.6 MPa for the 10 mm maximum aggregate size, and ranged between 72.5 and 77.5 MPa for the 20 mm maximum aggregate size. Therefore, use of smaller maximum aggregate size would give a higher strength and the mineralogy of the coarse aggregate would affect the strength of concrete.     

Mechanical properties of concrete with recycled coarse aggregate

This paper reports the results of an experimental study on some of the mechanical properties of recycled aggregate concrete (RAC) as compared to those of the conventional normal aggregate concrete (NAC). Ten mixes of concrete with target compressive cube strength ranging from 20 to 50 MPa were cast using normal or recycled coarse aggregates. The development of the cube compressive strength and the indirect shear strength at ages of 1, 3, 7, 14, 28 and 56 days, the compressive strength, the strains at maximum compressive stress and the modulus of elasticity tested by using concrete cylinders at 28 days are reported. The results show that the 28-day cube and cylinder compressive strength, and the indirect shear strength of recycled aggregate concrete were on the average 90% of those of natural aggregate concrete with the same mix proportions. For concrete with cylinder compressive strengths between 25 and 30 MPa, the modulus of elasticity of RAC was only 3% lower than that of NAC. The trends in the development of compressive and shear strength and the strain at peak stress in recycled aggregate concrete were similar to those in natural aggregate concrete.     

陶瓷废料粗骨料混凝土的研究

选取陶瓷废料取代传统的碎石粗骨料进行了混凝土实验,对掺杂了陶瓷废料粗骨料的混凝土的抗压强度、抗拉强度、弯曲强度及弹性模量做了系统研究,并与碎石粗骨料传统混凝土进行了比较,试验结果表明,陶瓷废料粗骨料混凝土的和易性是良好的,并且强度特性与常规混凝土相近。     

低质粗集料水工混凝土性能研究

针对水工混凝土高耐久性要求,研究了优质粉煤灰、萘系减水剂、松香热聚物类引气剂以及粗集料品质对水工混凝土抗渗性、抗碳化性和抗冻融性的影响。研究表明:粗集料的表观密度、吸水率在超出DL/T5144-2001规范的要求时也能配置出高耐久性水工混凝土;粉煤灰掺量为10%、萘系减水剂掺量为1.0%、松香热聚物类引气剂掺量为0.01%时,低质粗集料混凝土抗渗性、抗碳化性和抗冻融性可满足高耐久性水工混凝土的使用要求。     

Quantification of coarse aggregate shape in concrete

The objective of this study is to choose indices for the characterization of aggregate form and angularity for large scale application. For this purpose, several parameters for aggregate form and angularity featured in previous research are presented. Then, based on these established parameters, 200 coarse quartzite aggregates are analyzed herein by using image processing technology. This paper also analyzes the statistical distributions of parameters for aggregate form and angularity as well as the correlation between form and angularity parameters. It was determined that the parameters for form or angularity of coarse aggregates could be fitted by either normal distribution or log-normal distribution at a 95% confidence level. Some of the form parameters were influenced by changes in angularity characteristics, while aspect ratio and angularity using outline slope, area ratio and radius angularity index, and aspect ratio and angularity index were independent of each other, respectively; and consequently, the independent parameters could be used to quantify the aggregate form and angularity for the purpose to study the influence of aggregate shape on the mechanical behavior of concrete. Furthermore, results from this study’s in-depth investigations showed that the aspect ratio and the angularity index can further understanding of the effects of coarse aggregates form and angularity on concrete mechanical properties, respectively. Finally, coarse aggregates with the same content, type and surfaces texture, but different aspect ratios and angularity indices were used to study the influence of coarse aggregate form and angularity on the behavior of concrete. It was revealed that the splitting tensile strength of concrete increased with increases in the aspect ratio or angularity index of coarse aggregates.     

再生粗骨料混凝土强度公式研究

重点研究了水灰比和再生粗骨料强度变化对再生粗骨料混凝土强度的影响规律.结果表明:再生粗骨料混凝土(RGC)和天然粗骨料混凝土(NGC)一样与灰水比(C/W)均呈良好的线性关系,仍遵循水灰比定则;同水灰比时,再生粗骨料混凝土(RGC)抗压强度与天然粗骨料混凝土(NGC)相当或略高(主要是在低水灰比时);再生粗骨料强度对混凝土强度有一定影响,即同水灰比时,再生粗骨料强度越高,混凝土的强度也越高,因此,再生混凝土的水厌比定则应加一修正系数;由试验结果得到的再生粗骨料混凝土水灰比定则公式对其配合比设计及强度推算具有实际意义.