羧基丁苯胶乳聚合物掺量对混凝土性能的影响研究

研究通过试验探讨了羧基丁苯胶乳聚合物掺量对混凝土性能的影响,包括基本力学性能、抗氯离子渗透性能、收缩性能、水份扩散系数等。研究结果表明:提高混凝土中聚合物的掺量将降低混凝土的立方体抗压强度;混凝土静力受压弹性模量受聚合物掺量的影响不显著,抗拉强度和抗氯离子渗透能力随着掺量的增加而增加。随着掺量的提升,混凝土的自生收缩、干燥收缩及水分扩散系数均降低。

聚合物微纤维高性能混凝土力学性能的试验研究

研究了聚合物微纤维的掺量和长度对高性能混凝土力学性能的影响,找出了微纤维的合理掺量及长度范围,并对聚合物微纤维的作用机理进行了初步探讨。

高性能聚合物混凝土在井盖中的应用研究

本文考虑在树脂混凝土中加入增韧剂,配制出高性能聚合物混凝土,并在获得合理的聚合物混凝土配比的基础上,制作符合国家标准(CJ/T211-2005)的防盗检查井盖来代替铸铁井盖;同时,本文推导了此种高性能聚合物混凝土检查井盖的极限承载力,并对不同厚度的井盖极限承载力进行计算.结果表明,采用高性能聚合物混凝土制作的检查井盖与普通检查井盖相比,在相同厚度的条件下,其承载力大幅度提高,同时井盖的制作成本及丢失率均降低,具有较高的经济效益,适合推广应用.

陶瓷废料基绿色UHPGC力学性能及耐热性能分析

超高性能混凝土UHPC已在众多领域得到了应用,但基于安全性和使用寿命考虑,对于以陶瓷废料代替细骨料的超高性能地聚合物混凝土UHPGC力学性能及耐热性能仍有待深入研究。文中设计制备了12种不同配合比的UHPGC试样,通过开展力学性能测试及耐高温测试,分析陶瓷颗粒、钢纤维掺量对UHPGC力学性能及耐热性能的影响。结果表明,UHPGC的流动度和流动直径随着细集料中陶瓷废料含量的增加而降低;高掺量陶瓷颗粒会缩短UHPGC的凝结时间;UHPGC的抗压性能随钢纤维掺量的增加而提高,添加陶瓷颗粒一定程度上会降低UHPGC的抗压性能,陶瓷颗粒含量22.5%的试样抗压强度降低了22.88%;利用陶瓷颗粒制备能够制备56 d强度超过120 MPa的UHPGC,同时保留混凝土的基本特性;含有细陶瓷骨料的UHPGC试样在600℃条件下具有较高的残余抗压强度;UHPGC混合料在700℃下具有热稳定性结构,而掺有陶瓷颗粒的混合料在600℃下具有稳定性。

矿用高性能聚合物改性混凝土的应用研究

为了解决普通混凝土在井巷施工和使用过程中存在脆性大、柔性不足等问题,研制出一种矿用高性能聚合物改性混凝土.通过正交试验研究了聚丙烯酸乳液和苯丙乳液,聚灰比、水灰比、减水剂掺量和砂率对混凝土力学性能的影响,确定了矿用高性能聚合物改性混凝土的配合比,并进行了井下试验,分析了该混凝土修补巷道裂缝的机理.结果表明:聚丙烯酸酯乳液对混凝土有更好的改性作用.与普通混凝土相比,研制的聚合物改性混凝土抗折强度提高了39.3%,劈裂抗拉强度提高了53.1%,黏结强度提高了73.0%,抗渗性提高了83.3%.

Preparation and properties of geopolymer-lightweight aggregate refractory concrete

Geopolymer-lightweight aggregate refractory concrete (GLARC) was prepared with geopolymer and lightweight aggregate. The mechanical property and heat-resistance (950 ℃) of GLARC were investigated. The effects of size of aggregate and mass ratio of geopolymer to aggregate on mechanical and thermal properties were also studied. The results show that the highest compressive strength of the heated refractory concrete is 43.3 MPa,and the strength loss is only 42%. The mechanical property and heat-resistance are influenced by the thickness of geopolymer covered with aggregate,which can be expressed as the quantity of geopolymer on per surface area of aggregate. In order to show the relationship between the thickness of geopolymer covered with aggregate and the thermal property of concrete,equal thickness model is presented,which provides a reference for the mix design of GLARC. For the haydite sand with size of 1.18-4.75 mm,the best amount of geopolymer per surface area of aggregate should be in the range of 0.300-0.500 mg/mm2.

Mechanical properties of pervious cement concrete

Compressive and flexural strength,fracture energy,as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified,were analyzed.Test results show that the strength development of SCM-modified pervious concrete (SPC) differs from that of polymer-intensified pervious concrete (PPC),and porosity has little effect on their strength growth.PPC has higher flexural strength and remarkably higher flexural-to-compressive strength ratio than SPC at the same porosity level.Results from fracture test of pervious concrete mixes with porosity around 19.5% show that the fracture energy increases with increasing the dosage of polymer,reflecting the ductile damage features rather than brittleness.PPC displays far longer fatigue life than SPC for any given failure probability and at any stress level.It is proved that two-parameter Weibull probability function describes the flexural fatigue of pervious concrete.

Bearing capacity of concrete filled bidirectional FRP tube subjected to axial compression

External confinement by fiber reinforced polymer (FRP) is an efficient technique to increase the bearing capacity and ductility of concrete. To better study the mechanical behavior of bidirectional FRP confined concrete, the yield criterion of bidirectional FRP is presented based on the static equilibrium condition in this paper, and a model for calculating the bearing capacity of bidirectional FRP confined concrete is established. The model can capture the character of bidirectional FRP confined concrete. Effects of the confinement effect coefficient, the unconfined concrete strength and the material properties of FRP on bearing capacity are analyzed. Results show that each parameter has different effects on the bearing capacity of bidirectional FRP confined concrete.

State of the art review on the production and bond behaviour of reinforced geopolymer concrete

Geopolymer is produced through the polymerization of active aluminosilicate material with an alkaline activator,leading to the formation of a green,inorganic polymer binder.Geopolymer concrete(GPC)has become a promising low-carbon alternative to traditional Portland cement-based concrete(OPC).GPC-bonded reinforcing bars offer a promising alternative for concrete structures,boasting excellent geopolymer binder/reinforcement bonding and superior corrosion and high-temperature resistance compared to Portland cement.However,due to differences in the production process of GPC,there are distinct engineering property variations,including bonding characteristics.This literature review provides an examination of the manufacturing procedures of GPC,encompassing source materials,mix design,curing regimes,and other factors directly influencing concrete properties.Additionally,it delves into the bond mechanism,bond tests,and corresponding results that represent the bond characteristics.The main conclusions are that GPC generally has superior mechanical properties and bond performance compared to ordinary Portland cement concrete(OPC).However,proper standardization is needed for its production and performance tests to limit the contradictory results in the lab and on site.