矿物掺合料对混凝土耐久性能影响

实践证明,向混凝土中加入一定量的粉煤灰、矿粉等矿物掺合料,可以提高混凝土的耐久性能,同时改善混凝土的抗腐蚀性。本文主要研究了硅灰、超细矿渣、优质粉煤灰以及超细天然沸石粉四种不同的矿物掺合料对混凝土耐久性能的影响,结果表明以这几种矿物作为混凝土掺合料时,不仅能够大大地改善混凝土的耐久性,还能够实现对废旧资源的回收利用,变废为宝,带来了显著的社会效益和经济效益。     

矿物掺合料对混凝土抗酸雨性能研究

随着我国工业化的发展,大气污染日益严重,我国许多地区遭受酸雨的危害.由于酸雨的侵蚀,钢筋混凝土结构承载力退化,导致结构过早退出服役期,给建筑带来严重危害,在混凝土中掺入矿物掺合料不仅可以节约成本、改善混凝土工作性能,而且还能在一定程度上提高混凝土的耐久性能.主要对掺入矿渣、粉煤灰等掺合料后混凝土的力学性能和抗酸雨侵蚀性...     

矿物掺合料对高性能混凝土耐久性的影响

研究了粉煤灰、矿渣粉的不同掺入方式对高性能混凝土(HPC)抗氯离子渗透性能及抗冻性能的影响。结果表明:在相同水胶比条件下,随着矿物掺合料掺量的增加,HPC的抗压强度逐渐降低;掺入适量的矿物掺合料可有效降低HPC的电通量,改善抗氯离子渗透性能;当矿物掺合料掺量为40%,且粉煤灰和矿渣粉质量复掺比例为3∶1时,HPC在28 d与84 d的电通量分别为641.6 C和380.5 C;在水胶比及含气量不变的情况下,随着矿物掺合料掺量的增加,HPC的抗冻性能逐渐变差,而未掺矿物掺合料的HPC抗冻性能最好,抗冻等级为F200。     

矿物掺合料对高耐久性清水混凝土性能的影响

采用扩展度、坍落度、抗压强度及电通量等试验方法,研究单掺矿粉,双掺矿粉和粉煤灰、精细沉珠、石粉、硅粉以及三掺矿粉、粉煤灰和硅粉对清水混凝土工作性能、力学性能及耐久性能的影响,并分析其作用机理.结果表明:单掺矿粉,掺量为20％时混凝土的抗压强度最高,但其工作性能受影响;固定矿粉掺量为20％,分别双掺10％粉煤灰、15％石...     

活性粉末混凝土耐久性能研究

研究了由磨细掺合料如硅灰、粉煤灰等配制的活性粉末混凝土（RPC）抗海水侵蚀和抗冻融的耐久性能，试验结果表明，RPC具有极好的耐化学侵蚀性能和抗冻性能，但存放时间过长的磨细料配制的RPC的耐久性明显变差。     

矿物掺合料对混凝土耐久性的影响及其作用机理

本文主要研究几种矿物掺合料对混凝土耐久性的影响,分析了矿物掺合料的作用机理。研究表明,以硅灰和经细磨处理的水淬矿渣、粉煤灰及天然沸石粉为代表的矿物材料,作为水泥混凝土的掺合料,不仅能够利废和开发资源,而且能明显改善混凝土的耐久性。     

矿物掺合料对高强混凝土断裂性能的影响

本文研究了复掺矿物掺合料对高强混凝土断裂脆性的影响,通过试验检测试件的抗压强度、劈裂抗拉强度,最后计算出劈裂抗拉强度／抗压强度的值,即拉压比。通过试验得出复掺矿物掺合料是改善混凝土断裂脆性的有效途径之一。当硅灰和粉煤灰按1：2掺入,并且总掺量为30％时,对提高混凝土断裂脆性有明显的正效应。     

矿物掺合料对混凝土耐久性能影响

为了改善混凝土的抗腐蚀性能,提高混凝土耐久性,向混凝土中掺入粉煤灰、矿粉等矿物掺合料。进行混凝土流动性、坍落度损失、抗冻、抗渗、抗硫酸盐侵蚀、抗氯离子侵蚀的性能试验研究。研究结果表明：矿物掺合料能够提高混凝土的流动性,改善混凝土工作性能。在耐久性上,掺入矿物掺合料能够改善混凝土抗冻及抗渗性能。提高混凝土抗硫酸盐、抗氯离子等有害离子的侵蚀性能。大掺量矿粉的掺入对混凝土工作性能及耐久性能的改善效果比单掺粉煤灰的改善效果要好。     

珍珠岩掺合料混凝土轨枕制备研究

通过试验测试研究珍珠岩矿物掺合料及其对混凝土主要性能的影响，在混凝土中珍珠岩掺合料替代水泥10％～20％可不同程度地改善工作性能，提高后期强度。该掺合料替代水泥20％制备C60混凝土铁道Ⅲ型轨枕的试验及其检测结果显示其主要性能指标均有所提高。     

矿物掺合料对混凝土耐久性的影响

选择粉煤灰和矿渣作为混凝土矿物掺合料,以不同掺量,采用单掺和复掺的形式设计了7种配合比,研究矿物掺合料对混凝土抗渗性和抗冻性的影响。试验结果表明：粉煤灰、矿渣的掺入可以提高混凝土的抗渗性,掺量小于30％时,随着掺量的增加,混凝土抗渗性提高。粉煤灰和矿渣单掺时,会降低混凝土的抗盐冻性能;复掺时,当掺量小于最佳掺量时,可改善混凝土的抗盐冻性能,超过最佳掺量后,混凝土的抗盐冻性能降低,本试验中最佳掺量值为15％。     

新型复合矿物掺合料对混凝土耐久性影响的研究

介绍一种无硅灰的绿色混凝土用复合矿物掺合料,通过对掺合料混凝土的耐久性能如抗硫酸盐侵蚀性能、抗氯离子侵蚀性能及抑制碱集料等研究,说明该新型复合矿物掺合料能够有效地改善混凝土耐久性能.     

矿物掺合料提高桥梁混凝土耐久性的研究

在混凝土中掺入矿物掺合料不仅可以改善混凝土工作性,而且还可以提高混凝土的力学性能与耐久性能.试验表明:矿物掺合料选择矿粉与粉煤灰复掺方式,其新拌混凝土工作性的效果要好于矿粉或粉煤灰单掺方式,且矿粉与粉煤灰的质量比为2∶1;利用矿物掺合料复掺方式配制的混凝土,其力学性能、抗冻融循环、电通量和氯离子扩散系数都明显好于纯水泥和单掺矿粉或粉煤灰的混凝土.     

矿物掺合料改良混凝土微观结构机理研究

运用显微硬度仪和压汞法研究了不同矿物掺合料对混凝土微观结构的影响,结果表明：矿物掺合料能有效改善混凝土的界面过渡区和孔结构,与“单掺”“不掺”矿物掺合料相比,“双掺”矿物掺合料使混凝土的总空隙率和临界孔径都大大降低,界面过渡区宽度变窄,混凝土微观结构得到明显改善。     

Characteristics of lightweight concrete containing mineral admixtures

This research investigates the properties of fresh and hardened concretes containing locally available natural lightweight aggregates, and mineral admixtures. Test results indicated that replacing cement in the structural lightweight concrete developed, with 5–15% silica fume on weight basis, caused up to 57% and 14% increase in compressive strength and modulus of elasticity, respectively, compared to mixes without silica fume. But, adding up to 10% fly ash, as partial cement replacement by weight, to the same mixes, caused about 18% decrease in compressive strength, with no change in modulus of elasticity, compared to mixes without fly ash. Adding 10% or more of silica fume, and 5% or more fly ash to lightweight concrete mixes perform better, in terms of strength and stiffness, compared to individual mixes prepared using same contents of either silica fume or fly ash.     

Performance of self-compacting concrete containing different mineral admixtures

This paper presents experimental study on the properties of self-compacting concrete (SCC). Portland cement (PC) was replaced with fly ash (FA), granulated blast furnace slag (GBFS), limestone powder (LP), basalt powder (BP) and marble powder (MP) in various proportioning rates. The influence of mineral admixtures on the workability, compressive strength, ultrasonic pulse velocity, density and sulphate resistance of SCC was investigated. Sulphate resistance tests involved immersion in 10% magnesium sulphate and 10% sodium sulphate solutions for a period of 400 days. The degree of sulphate attack was evaluated using visual examination and reduction in compressive strength. The test results showed that among the mineral admixtures used, FA and GBFS significantly increased the workability and compressive strength of SCC mixtures. Replacing 25% of PC with FA resulted in a strength of more than 105 MPa at 400 days. Moreover, the presence of mineral admixtures had a beneficial effect on the strength loss due to sodium and magnesium sulphate attack. On the other hand, the best resistance to sodium and magnesium sulphate attacks was obtained from a combination of 40% GBFS with 60% PC.     

Thermo-mechanical properties of concrete containing high-volume mineral admixtures

This paper reports the results of a study conducted to evaluate the influence of high-volume class C fly ash (FA), blast furnace slag (BFS) and both FA+BFS on the thermal conductivity (TC), compressive strength, water absorption and density of concrete. TC decreased with the increase of FA, BFS and FA+BFS as replacement for Portland cement. The reductions in TC due to FA, BFS and FA+BFS were, respectively, up to 39%, 18% and 31%. The addition of FA, BFS and FA+BFS in the concrete had a decreasing effect on TC. Their addition also decreased compressive strength as a function of replacement percent. However, this reduction in compressive strength decreased with increasing curing period.     

外加剂和掺合料对混凝土耐久性的影响

分析了影响混凝土耐久性的因素，总结了混凝土的抗渗性和抗冻性与耐腐蚀之间的关系，讨论了外加剂和掺合料对混凝土耐腐蚀性能的影响，旨在提高混凝土的密实性和对钢筋的阻锈能力，对节约资源、能源及资金具有重大意义。     

干燥环境条件下大掺量矿物掺合料高强混凝土的抗冻性

用快冻法研究了单掺铝酸盐膨胀剂和钢纤维及其复合对大掺昔矿物掺合料混凝土抗冻性的影响.结果表明:大掺量矿物掺合料高强混凝土(HSC)具有较好的抗冻性,但是其抗冻性对养护环境相对湿度(RH)非常敏感,干燥养护条件下的冻融寿命仅有标准养护的38%～40%.单掺2%钢纤维在保证其抗冻性不变的基础上,可改善其抗冻性对养护环境RH的敏感性.单掺10%膨胀剂能够降低大掺量矿物掺合料HSC的抗冻性对养护环境湿度的敏感性,但是其冻融寿命降低了34%.此外,在改善大掺量矿物掺合料高强混凝土的抗冻性及其湿度敏感性方面,复合掺加膨胀剂和纤维的效果并不比单掺膨胀剂或纤维的效果更好.     

Mechanical properties of reactive powder concrete containing mineral admixtures under different curing regimes

Mechanical properties (compressive strength, flexural strength, and toughness) of reactive powder concrete (RPC) produced with class-C fly ash (FA) and ground granulated blast furnace slag (GGBFS) were investigated under different curing conditions (standard, autoclave and steam curing) in this study. Test results indicate that, compressive strength of RPC increased considerably after steam and autoclaving compared to the standard curing. On the other hand, it was observed that steam and autoclave curing decreased the flexural strength and toughness. Increasing the GGBFS and/or FA content improved the toughness of RPC under all curing regimes considerably. Furthermore, SEM micrographs revealed dense microstructure of RPC.     

冻融环境下矿物掺合料混凝土与钢筋间黏结性能

为了探讨冻融环境下不同矿物掺合料对混凝土与钢筋之间黏结性能的影响,选用粉煤灰、磨细矿渣和硅灰3种混合材设计了4种矿物掺合料钢筋混凝土试件,采用快速冻融试验和黏结拉拔试验方法,研究了随着冻融循环次数增加各组试件的黏结强度及黏结破坏形式的退化规律.试验结果表明:硅灰与磨细矿渣的复合掺入提高了钢筋混凝土的黏结抗冻耐久性能,而粉煤灰的单掺加入对冻融环境下钢筋混凝土之间的黏结强度以及黏结延性都是不利的.因此,对于寒冷地区的钢筋混凝土结构建议粉煤灰与硅灰或磨细矿渣复合掺加使用.