硅酸盐水泥胶砂受热性能的研究

本文研究了水泥胶砂受热温度、加热速度及冷却速度对其强度发展规律的影响。通过外掺粉料的方法使受热水泥胶砂的强度下降大大减少。并通过X衍射及差热分析的方法,探讨了受热水泥胶砂强度下降及外掺粉料减少其强度下降的原因。     

复合外掺料对高性能水泥胶砂性能的影响

以低水胶比高强度水泥胶砂为研究对象,初步探讨了高效减水剂、矿渣、粉煤灰、膨胀剂、高吸水树脂及聚合物纤维等组分构成的复合外掺料对水泥基材料的工作性、早期自收缩和力学性能的影响.通过试验结果的对比,发现同时掺入高效减水剂、矿渣、粉煤灰、膨胀剂和高吸水树脂的水泥胶砂流动性最好,流动度经时损失最慢,早期自收缩最小,同时早期力学性能较好.聚合物纤维的掺入有效地提高了水泥胶砂的韧性和体积稳定性.     

用水量对胶凝砂砾石抗压强度的影响

胶凝砂砾石材料是一新型筑坝材料,拥有广阔的发展前景。用水量是影响胶凝砂砾石强度的重要因素。通过抗压强度试验分析用水量对胶凝砂砾石抗压强度的影响,得出:最优用水量随胶凝材料掺量的增大而增大,随砂率的增大而增大,最优用水量为85~125 kg/m~3;最优水胶比随胶凝材料用量的增加而减小,随龄期的增加呈减小的趋势,最优水胶比为0.95~1.35。用水量对抗压强度的影响仅次于水泥用量,在施工过程中,应将其作为胶凝砂砾石材料的一项重要参数来控制,以保证胶凝砂砾石材料的性能。     

柠檬酸渣掺合料对水泥基胶凝材料性能影响的研究

为探索柠檬酸工业废渣与粉煤灰、矿粉复掺对水泥基胶凝材料基本性能的影响,采用正交试验结合等体积替代方法,研究几种掺合料对胶砂抗折强度、抗压强度、胶砂流动度等基本性能的影响,对其矿物成分、微观形貌等做了进一步分析研究,探索各种掺合料的作用机理.结果表明:不同掺量的柠檬酸渣与粉煤灰、矿粉复掺对胶砂强度及流动度均具有显著的影响...     

纤维增韧水泥基复合材料抗压强度影响因素研究

对多种纤维增韧水泥基复合材料（ECC）进行各个龄期立方体抗压强度试验,对比水胶比、胶砂比、粉煤灰及矿渣含量和龄期对ECC力学性能的影响规律,得到ECC早龄期强度的增长规律及各个因素对ECC强度的影响规律。研究结果表明,粉煤灰及矿渣含量、水胶比是ECC抗压强度的主要控制因素。     

改性压实水泥抗压强度影响因素的研究

采用ＤＳＰ原理和压实技术相结合，掺加硅灰和ＣａＣＯ３等细颗粒矿物外加剂改变压实水泥材料基质，研究了成型压力，细粉掺量，养护制度等因素对压实水泥强度的影响。结果表明，掺加适量硅灰和提高成型压力可显著提高压实水泥的抗压强度，掺加ＣａＣＯ３对强无明显影响；压实水泥存在最佳养护龄期，超过此龄期强度倒缩。     

矿物掺合料对机制砂水泥基自流平砂浆性能的影响

试验选用普通硅酸盐水泥、硫铝酸盐水泥与半水石膏的三元胶凝体系,选用机制砂作为细集料,制备全机制砂水泥基自流平砂浆.选用粉煤灰、石粉与硅灰作为矿物掺合料,并研究矿物掺合料对全机制砂制水泥基自流平砂浆流动度、抗压抗折强度与尺寸变化率的影响.研究结果表明:矿物掺合料的火山灰效应对自流平砂浆力学性能的发展产生积极影响,自流平砂...     

铁板砂作为水泥混合材对水泥强度的影响

研究了铁板砂的粉磨特性、掺杂铁板砂水泥的水化机理及物理性能.结果表明:铁板砂的易磨性好,掺量从20%~40%之间,掺铁板砂的水泥的抗压强度都可以达到40MPa以上.其作为水泥的混合材料是非常理想的.为此种被废弃的当做垃圾的储量丰富的宝贵资源开辟了一条光明的利用途径.     

硫酸铵侵蚀作用下水泥砂浆的抗压强度试验研究

为了研究硫酸铵作用下水泥砂浆受腐蚀劣化的力学性能变化规律,通过室内试验研究,分别探讨了在不同水灰比、不同浓度、不同腐蚀龄期下对水泥砂浆的外观形态、质量变化、应力应变关系和抗压强度的影响.结果表明:硫酸铵对水泥砂浆的侵蚀性比较明显,腐蚀后砂浆抗压强度先有所下降然后上升,再下降;随着腐蚀的进行,水泥砂浆试块表面先开裂、剥落,再失去棱角,最后因膨胀而破坏;而溶液浓度越大,水泥砂浆受腐蚀的程度越深;低水灰比的水泥砂浆抵抗硫酸铵溶液腐蚀的能力越强.     

CA砂浆强度影响因素及强度机理研究

为制得满足高速铁路建设的CA砂浆,制备了不同配比的CA砂浆,通过考查CA砂浆的强度并利用扫描电子显微镜观测微观结构,研究砂的级配、砂灰比、乳化沥青与水泥比等因素对CA砂浆固化体不同龄期强度的影响．研究表明：选择粒径为0．15—0．3mm与0．3—0．6mm的组合砂能有效地降低高强型CA砂浆材料的分离度,而对CA砂浆28...     

D型速凝剂对水泥强度的影响

研究了各种速凝剂对水泥强度的影响 .针对目前国内速凝剂存在的普遍问题 ,在反复试验研究的基础上 ,选出一种辅料 ,制成可降低速凝剂碱性、增加喷射料粘度的复合型水泥速凝剂———D型速凝剂 ,其强度保有率最高 ,同时研究了水灰比对掺有D型速凝剂的水泥强度的影响 ,试验结果水灰比越大 ,强度降低越多 .     

D型速凝剂对水泥强度的影响

研究了各种速凝剂对水泥强度的影响.针对目前国内速凝剂存在的普遍问题,在反复试验研究的基础上,选出一种辅料,制成可降低速凝剂碱性、增加喷射料粘度的复合型水泥速凝剂--D型速凝剂,其强度保有率最高,同时研究了水灰比对掺有D型速凝剂的水泥强度的影响,试验结果水灰比越大,强度降低越多.     

Filler effect of fine particle sand on the compressive strength of mortar

The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%?40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones...     

Effect of strain rate and water-to-cement ratio on compressive mechanical behavior of cement mortar

Effects of strain rate and water-to-cement ratio on the dynamic compressive mechanical behavior of cement mortar are investigated by split Hopkinson pressure bar(SHPB) tests. 124 specimens are subjected to dynamic uniaxial compressive loadings.Strain rate sensitivity of the materials is measured in terms of failure modes, stress-strain curves, compressive strength, dynamic increase factor(DIF) and critical strain at peak stress. A significant change in the stress-strain response of the materials with each order of magnitude increase in strain rate is clearly seen from test results. The slope of the stress-strain curve after peak value for low water-to-cement ratio is steeper than that of high water-to-cement ratio mortar. The compressive strength increases with increasing strain rate. With increase in strain rate, the dynamic increase factor(DIF) increases. However, this increase in DIF with increase in strain rate does not appear to be a function of the water-to-cement ratio. The critical compressive strain increases with the strain rate.     

Size effect on cubic and prismatic compressive strength of cement paste

A series of compression tests were conducted on 150 groups of cement paste specimens with side lengths ranging from 40 mm to 200 mm. The specimens include cube specimens and prism specimens with height to width ratio of 2. The experiment results show that size effect exists in the cubic compressive strength and prismatic compressive strength of the cement paste, and larger specimens resist less in terms of strength than smaller ones. The cubic compressive strength and the prismatic compressive strength of the specimens with side length of 200 mm are respectively about 91% and 89% of the compressive strength of the specimens with the side length of 40 mm. Water to binder ratio has a significant influence on the size effect of the compressive strengths of the cement paste. With a decrease in the water to binder ratio, the size effect is significantly enhanced. When the water to binder ratio is 0.2, the size effects of the cubic compressive strength and the prismatic compressive strength of the cement paste are 1.6 and 1.4 times stronger than those of a water to binder ratio of 0.6. Furthermore, a series of formulas are proposed to calculate the size effect of the cubic compressive strength and the prismatic compressive strength of cement paste, and the results of the size effect predicted by the formulas are in good agreement with the experiment results.     

冻融环境对聚合物水泥砂浆粘结强度的影响

为了分析冻融环境对外墙外保温系统中聚合物水泥砂浆粘结强度的影响,根据寒冷地区温度变化情况,设计了聚合物水泥砂浆的配合比,在冻融环境条件下进行了不同冻融循环次数时聚合物水泥砂浆的粘结强度试验.探讨了冻融循环和胶粉掺量对聚合物水泥砂浆粘结强度的影响,得到了冻融环境条件下粘结强度的变化规律,分析了冻融环境对聚合物水泥砂浆粘结强度的影响机理.结果表明,随着冻融循环次数的增加,聚合物水泥砂浆的粘结强度逐步降低;随着胶粉含量的增加,聚合物水泥砂浆的粘结强度逐步增大.     

The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength

The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength was investigated. Three mineral admixtures (fly ash, ground granulated blast-furnace slag and steel slag) were used. The adding amount of mineral admixture in this study ranges from 22.5% to 60%, and the water-to-binder ratio ranges from 0.34 to 0.50. With equal compressive strength, different mortars can be arranged in such a descending order with their bending strength: cement-fly ash mortar, cement mortar, cement-GGBS mortar, and cement-steel slag mortar. With the same compressive strength, the higher the steel slag content and water-to-binder ratio, the lower the bending strength of mortars. However, the effect of mineral mixture content and water-to-binder ratio on the bending strength of cement-fly ash mortar and cement-GGBS mortar is far inconspicuous.     

氧化石墨烯对矿渣水泥抗压强度及微观结构的影响

为克服矿渣水泥早期强度偏低问题,以氧化石墨烯作为纳米添加剂掺入矿渣水泥中,通过改变氧化石墨烯的掺量,以抗压强度和水化产物为研究对象,进行抗压强度测试试验,并采用X射线衍射、扫描电子显微镜、热分析和纳米压痕等测试方法对水化产物和微观结构进行表征.结果表明:氧化石墨烯可以促进矿渣水泥的水化进程,提高抗压强度,最佳掺量为0.08％;氧化石墨烯在水化过程中起到填充作用和晶核作用,从而提高抗压强度,生成更多水化产物,水化产物中高密度C—S—H凝胶比例增大.该研究结果为改善矿渣水泥早期抗压强度提供了新思路.