水性工业防腐涂料的制备研究

以水性环氧树脂为基料制备工业防腐涂料,分析讨论了水性环氧树脂乳液、水性环氧固化剂、颜填料以及各种助剂的选用对水性工业防腐涂料性能的影响,确定了水性环氧防腐涂料的配方和生产工艺。经工程应用表明,该产品防腐性能良好。     

水性环氧树脂对聚丙烯纤维混凝土性能影响的研究

以改性水性环氧树脂配置聚丙烯纤维混凝土,测试不同水性环氧树脂掺量的聚丙烯纤维混凝土的劈裂抗拉、抗折力学性能,进行了水性环氧树脂增强聚丙烯纤维的水泥附着性能试验和水性环氧树脂的不同掺量下增强聚丙烯纤维混凝土阻裂、抗渗性能效应试验,并对水性环氧树脂掺入聚丙烯纤维混凝土中后对各项性能的增强机理进行了探讨。以番禺大石大桥桥面铺装工程为例,介绍了水性环氧树脂掺入聚丙烯纤维混凝土的工程应用。     

环氧树脂乳液改性水泥砂浆性能研究

分析了水性环氧树脂乳液改性水泥砂浆的力学性能、粘结性能、收缩性能和耐久性能,用SEM和MIP分析了砂浆的结构。结果表明：掺加水泥用量的6％-10％（质量分数,以固含量计）水性环氧树脂乳液可有效提高水泥基修补砂浆的力学性能和与老砂浆的粘结强度,降低水泥砂浆的收缩值;水泥砂浆的抗渗性、抗碳化性以及抗冻性能均随水性环氧树脂掺量的增加而显著提高。较之未经改性的普通砂浆,水性环氧树脂乳液改性水泥砂浆结构更为致密,连通孔的孔隙率和平均孔径小。     

高强环氧树脂混凝土的制备及性能研究

环氧树脂混凝土兼具环氧树脂和普通混凝土的性能优点,研究了胶砂比及固化剂用量对环氧砂浆强度的影响,得出合理胶砂比为0.15～0.30,固化剂乙二胺的合理用量为7%～10%。在合理范围内,胶砂比、固化剂用量越大,环氧砂浆的抗压强度越高。当胶砂比为0.30,乙二胺用量为10%时,环氧砂浆的3 d抗压强度为86.60 MPa。通过正交试验研究固化剂用量、砂、石用量对环氧树脂混凝土强度的影响规律,得出影响环氧树脂混凝土强度的因素主次为:固化剂用量石用量砂用量。最佳试验条件为:乙二胺、砂、石用量分别为环氧树脂质量的10%、240%、260%,制得的环氧树脂混凝土3 d抗压强度高达95.88 MPa。     

高性能水性环氧防腐底漆的研究

文章基于自主开发的水性环氧乳液和固化剂体系制备高性能水性环氧防腐底漆,通过对比研究各种水性环氧树脂乳液与固化剂体系对成膜性能的影响,涂料中颜基比,磷酸锌填料等影响因素的研究,试验结果表明:自主开发的水性环氧树脂体系产品在耐盐雾性能基本接近于国外先进水平,可完全满足钢结构产品对水性漆产品的要求,当PVC含量在25%左右时,磷酸锌在涂料中含量在20%时,获得高性能的水性环氧防腐底漆。     

水性环氧树脂混凝土性能研究

试验主要研究以水性环氧树脂为改性材料的混凝土，测定了不同掺量下的水性环氧树脂混凝土在常温和高温两种情况下各个龄期的力学性能指标，进行了不同掺量下的水性环氧树脂混凝土抗渗性能和干缩性能试验，并对水性环氧树脂增强水泥混凝土各种性能指标的增强机理进行了分析。     

道桥用水性环氧沥青防水涂料研究

研制了一种水性环氧沥青防水涂料,由两个组分组成,A组分为环氧树脂改性水性沥青涂料,B组分为固化剂。该涂料兼具环氧树脂和沥青涂料的双重优点,能提高桥梁的使用寿命。当改性乳液用量为30%、环氧树脂用量为10%时,制得的产品拉拔强度优异,低温柔性和耐高温性能也满足标准要求。     

水泥基水性环氧树脂灌浆材料性能的研究

采用水性环氧树脂乳液和固化剂对水泥基灌浆材料进行改性,对水性环氧灌浆材料的力学性能、粘结性能、抗碳化性能以及氯离子渗透性能进行了研究.结果表明,改性后的水泥基水性环氧灌浆材料具有更好的力学性能、耐氯离子渗透和抗碳化性能.     

高速公路用聚合物灌浆材料的试验研究

针对高速公路混凝土路面存在的裂缝和脱空区的工程问题,采用正交设计方法,研究了聚合物化学灌浆材料的水灰比、环氧树脂含量和水性环氧固化剂含量,以及各因素之间交互作用对该灌浆材料抗折强度的影响,找出了较为理想的优化配方。结果表明,聚合物灌浆材料的最佳配比为水灰比0．4,双酚A型环氧树脂8%,水性环氧固化剂2%     

水性聚氨酯-环氧互穿网络超细水泥复合灌浆材料的制备及性能研究

采用聚醚二元醇(GE-210)、甲苯二异氰酸酯(TDI-80)、二羟甲基丙酸(DMPA)和环氧树脂(E-51)等为主要原料合成了水性聚氨酯-环氧互穿网络聚合物乳液。以该聚合物乳液为主剂加入固化剂、促进剂、超细水泥等制备了三组份水性聚氨酯-环氧互穿网络超细水泥复合灌浆材料,并对其物理性能进行了研究。结果表明:复合灌浆材料的性能与各组份的用量密切相关,聚合物乳液和超细水泥具有协同作用,二者的用量应保持一定的平衡,综合考虑,当聚合物乳液、固化体系和超细水泥的质量比为7.0∶1.0∶1.25时,所制备复合灌浆材料综合性能最佳。     

水性环氧树脂与水泥复合的胶砂强度分析及其咸潮区桥梁墩柱加固应用

采用国标GB/T 17671-1999水泥胶砂强度检验方法(ISO法),对不同掺量的水性环氧树脂与水泥复合胶砂试件进行力学性能试验,研究结果表明,水性环氧树脂与水泥的复合具有较高的早期抗折、抗压强度,其韧性得到了较明显改善.掺量合适时,水性环氧树脂与水泥复合可以发挥各自的优势.但掺量超过40%时,水性环氧树脂与水泥复合性能较差.掺水性环氧树脂的水泥砂浆在咸潮区桥梁墩柱加固中得到应用,效果显著.     

Mechanical properties of polymer-modified concretes containing expanded polystyrene beads

In this study, styrene-butadiene rubber (SBR) latex as a polymeric admixture was applied in lightweight expanded polystyrene (EPS) concrete. The effects of curing conditions and polymer-cement ratio on the compressive and flexural strengths of polymer-modified EPS concretes were investigated. As a result, the strength development of the polymer-modified EPS concretes strongly depends on the curing conditions. Combined dry and wet curings enable to develop both the strengths of cement matrix and SBR films together. Inclusion of SBR latex at a certain polymer-cement ratio in the EPS concrete improves the bonds between the cement matrix and EPS particles due to the SBR films formed in the cement matrix. In addition, SBR modification can significantly improve the flexural strength of the normal EPS concrete. Compared with the EPS concrete, the compressive strength of the polymer-modified EPS concretes can increase gradually even after 28 days.     

The influence of polymer latex modifiers on the properties of concrete

The influence of styrene-butadiene rubber (SBR) and acrylic latices on the properties of Portland cement concrete is investigated. Properties of modified concretes are compared with unmodified samples, on the basis of constant water/cement ratio, and on the basis of constant workability. In samples with constant water/cement ratio, reduction of compressive strength in polymer-modified concretes is statistically significant, and some improvements in flexural and tensile strengths are observed. Scanning electron microscopic examination of the SBR latex modified concrete, using a heavy element tagging technique and energy dispersive analysis of X-rays, demonstrates a non-uniform distribution of polymer modifier in the cement matrix at higher concentrations.     

Effect of electric arc furnace dust on the properties of OPC and blended cement concretes

This paper presents results of a study conducted to evaluate the mechanical properties and durability characteristics of ordinary Portland cement (OPC) and blended cement (silica fume and fly ash) concrete specimens prepared with electric arc furnace dust (EAFD). Concrete specimens were prepared with and without EAFD. In the silica fume cement concrete, silica fume constituted 8% of the total cementitious material while fly ash cement concrete contained 30% fly ash. EAFD was added as 2% replacement of cement in the OPC concrete and 2% replacement of the total cementitious content in the blended cement concretes. Mechanical properties, such as compressive strength, drying shrinkage, initial and final setting time, and slump retention were determined. The durability characteristics were evaluated by measuring water absorption, chloride permeability, and reinforcement corrosion. The initial and final setting time and slump retention increased due to the incorporation of EAFD in both OPC and blended cement concretes. The drying shrinkage of EAFD cement concrete specimens was more than that of concrete specimens without EAFD. The incorporation of EAFD was beneficial to OPC concrete in terms of strength gain while such a gain was not noted in the blended cement concretes. However, the strength differential between the blended cement concretes with EAFD and the corresponding concretes without EAFD was not that significant. The water absorption and chloride permeability, however, decreased due to the incorporation of EAFD in both the OPC and blended cement concretes. The corrosion resistance of OPC and blended cement concrete specimens increased due to the addition of EAFD.     

Effect of environmental conditions on the properties of concretes with different cement types

The paper reports on the changes in properties of concretes with different cement types associated with environmental conditions. Three strength classes with three different cement types (ordinary portland cement PC 42.5 (CEM I 42.5), portland composite cements PKC-A 42.5 (CEM II/A-M 42.5) and PKC-B 32.5R (CEM II/B-M 32.5R)) were used in the study. Also, a mixture was prepared with PC 42.5 and silica fume (SF). The effects of variable ambient conditions on plastic shrinkage of fresh concrete and cement paste, compressive strength, modulus of elasticity, capillary absorption and drying shrinkage of hardened concrete were investigated. In contrast to PC 42.5 cement paste, plastic shrinkage cracks were observed in PKC-B 32.5 and PKC-A 42.5 pastes. Water absorption coefficients of all concretes stored in natural environment were higher at all ages as compared to coefficients of concretes kept in laboratory. Drying shrinkage values of concrete with SF, except the first week, were significantly lower than those of others. Although different behaviors for different cement types were observed, water–cement ratio was one of the dominating factors determining the behavior of concrete. This ratio should be lowered to improve the durability of concrete.     

Betons a hautes performances,a granulats artificiels actifs

High strength concretes, in particular at early ages (more than 40 MPa at 3 days and up to 80 MPa at 7 days), are obtained by replacement of certain granular size ranges of sand or gravel by cement-active artificial aggregates in a given concrete composition elaborated with a local supply of aggregates and cement. The strengthening of the paste-aggregate bond by chemical reactions between the artificial aggregates and the cement also involves an improvement of other concrete performances and not only of mechanical strengths. The cracking ability is decreased, the wear strength is higher, and water permeability is low or even nil for certain compositions. The laboratory results are confirmed by tests on the site and show the possibility of achieving high strength concretes without any particular selection of cement and natural aggregates.     

浸-烘循环作用下橡胶水泥混凝土的性能研究

通过试验,研究了橡胶水泥混凝土在水或Na2SO4／NaCl复合盐溶液中长期浸泡以及在常温浸泡、55℃烘干的浸-烘循环作用下其相对动弹性模量、抗压强度、抗弯强度的变化以及混凝土中的氯离子浓度分布,分析了橡胶水泥混凝土性能劣化的机理．研究表明：橡胶水泥混凝土长期浸泡在水或复合盐溶液中的性能与对比混凝土相当,但在浸-烘循环作用下,橡胶水泥混凝土的性能随循环次数的增加逐渐劣化,复合盐溶液的作用又进一步加剧了橡胶水泥混凝土性能的劣化．因此,橡胶水泥混凝土不宜应用于长期处于干湿交替、干热或有硫酸盐腐蚀的环境中．     

橡胶粉水泥混凝土性能试验的研究

通过掺人不同含量橡胶粉的水泥混凝土物理性能试验、各项力学性能试验和耐久性试验,发现不同掺量橡胶粉对水泥混凝土的工作性、表观密度、立方体抗压强度、劈裂抗拉强度、抗折强度、轴心抗压强度、极限应变和抗冻性等性能的变化情况,从而发现最佳橡胶粉的掺量范围,为进一步研究橡胶粉水泥混凝土特殊性能提供参考.     

Modulus of elasticity of substandard and normal concretes

Modulus of elasticity is an important parameter used for the structural assessment and retrofitting of concrete structures. In this study, an experimental investigation on the modulus of elasticity of concrete was carried out, the results of which is presented. 60 mixtures were prepared, in which the effects of water/cement ratio, maximum size of the aggregate, aggregate type, and fly ash content were investigated. In order to obtain very low quality concrete, the water/cement ratios were increased to as high as 2.2. Modulus of elasticity of the concretes was obtained according to ASTM C469. Compressive strength and ultrasound pulse velocities of the concretes were also recorded. The experimentally obtained modulus of elasticity values were compared with those calculated by using prediction models given in a selection of codes of practice. Dynamic moduli of elasticity of the concretes were also obtained.