An Investigation into the Performances of Cement Mortar Incorporating Superabsorbent Polymer Synthesized with Kaolin

Cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties.This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement mortar.The results show that K-SAP significantly affects the cement mortar’s rheological behavior,with distinct phases of water absorption and release,leading to changes in workability over time.Furthermore,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics.Notably,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage behavior.Moreover,K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP.

Infuences of Different Admixtures on the Drying Shrinkage Characteristics of Metakaolin-based Geopolymer Mortar

To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing conditions.An SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer mortar.Meanwhile,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage coefficient.The experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and time.Finally,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.

Influences of Polypropylene Fiber and SBR Polymer Latex on Abrasion Resistance of Cement Mortar

Influences of polypropylene （PP） fiber and styrene-butadiene rubber （SBR） polymer latex on the strength performance, abrasion resistance of cement mortar were studied. The experimental results show that the flexural strength, brittleness index （σF/σC） and abrasion resistance can be improved significantly by the addition of PP fiber and SBR polymer latex. The relationship between the flexural strength and abrasion resistance was analyzed, showing a good linear relationship between them. The reinforced mechanism of PP fiber and SBR polymer latex on cement mortar was analyzed by some microscopic tests. The test results show that the addition of SBR polymer latex has no significant influence on the cement hydration after 7 d curing. Adding SBR polymer latex into cement mortar can form a polymer transition layer in the interfaces of PP fiber and cement hydrates, which improves the bonding properties between the PP fiber and cement mortar matrix effectively.

Effect of Modified Polymer on Crack Resistance of Mortar

At present, the basic technical principle in China is to adopt polymers to modifying the properties of mortar so as to improve the crack-resistance of construction structures and to strengthen their water-resisting and climate-resisting properties as well. However, how polymer acts on anti-crack mortar is short of systematic research. Theoretical exposition of polymer mortar is basically explained by Ohama Model, which is cement slaking and polymer coating are carried on together and mutually-cross web structure interweaved with liquid and polymer coating. But anti-crack mortar has its own special characteristics because of fewer polymers mixed in it and its high viscosity. So this paper is to showing how different polymers affect its crack-resistance cannot be reflected from this theory. Vinyl-acetate ethylene (VAC/E) has been selected as representation of polymerization, whose property is modified by compounding it from some inorganic components, such as talc, CaCO3 and so on. And then the mechanics property and shrinkage of anti-crack polymer mortar is tested when different amount of polymers is added as admixture of mortar. The result indicates that, the working performance and mechanics property of the polymer mortar are worse mixed VAC/E only. It basically meets the demands for mechanics strength and working performance when mixed both VAC/E and CaCO3 While it achieves much better mechanical property and working performance than the two former when mixed VAC/E, talc and CaCO3; the result of corresponding scanning electron microscopy (SEM) of sample indicates that the internal result of the polymer mortar, compared with classical Ohama Model, has a particularity that its structure is formed by polymer coating instead of filling up the intervals among cement grains.

Studies on Chemical Resistance of PET-Mortar Composites: Microstructure and Phase Composition Changes

Researches into new and innovative uses of waste plastic materials are continuously advancing. These research efforts try to match society’s need for safe and economic disposal of waste materials. The use of recycled plastic aggregates saves natural resources and dumping spaces, and helps to maintain a clean environment. The present articles deals with the resistance to chemical attack of polymer-mortars, which are often used as low-cost promising materials for preventing or repairing various reinforced concrete structures. To gain more knowledge on the efficiency of polymer-mortar composites, four mortar mixtures: one specimen with Portland cement and three mixtures with 2.5, 5, and 7.5 wt% of the substitution of cement by polyethylene terephthalate (PET) were exposed to the influence of aggressive environment (0.5%, 1% and 1.5% HCl acids, 10% NH4Cl, 5% H2SO4 acid and 10% (NH4)2SO4 solutions). The measurements of several properties were carried out, the results were analyzed and the combination of X-ray diffraction, FT-IR spectroscopy, differential thermal analysis (DTA), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) analysis and the composites were also observed by SEM led to the positive identification of the deterioration products’ formation. From this study, it was found that the addition of PET to the modified mortars, means reducing the penetration of aggressive agents. So, the PET-modified mortars exposed to aggressive environments showed better resistance to chemical attack. The new composites appear to offer an attractive low-cost material with consistent properties. The present study highlights the capabilities of the different methods for the analysis of composites and opened new way for the recycling of PET in polymer-mortars.

改性干粉型聚合物水泥砂浆试验研究

本文研究两种不同的可再分散乳胶粉(醋酸乙烯-乙烯共聚物和醋酸乙烯/叔碳酸乙烯酯共聚物)对干粉型聚合物水泥砂浆力学性能、粘结强度、吸水率、干燥收缩的性能影响。结果表明,可再分散乳胶粉的掺量、类型对聚合物水泥砂浆的性能影响较大,力学性能较普通水泥砂浆有明显的提升和改善。可再分散乳胶粉的加入虽然降低了砂浆的抗压强度,但显著提高了抗折强度和折压比,改善了砂浆的柔韧性和抗裂能力;砂浆的干燥收缩、粘结强度和吸水率等性能均有较为明显的改善。

EVA与硅烷乳液改善防水砂浆性能的微观机理

通过四点弯曲强度、黏结强度、冻融循环及热重、压汞和扫描电镜等试验研究了乙烯-乙酸乙烯酯共聚乳液(EVA)和硅烷乳液对高韧性防水砂浆力学性能和抗冻性的影响规律及作用机理.结果表明:EVA基本不影响砂浆后期弯曲性能,但显著提高其与基层的黏结强度;随EVA掺量增加,砂浆孔隙率先增大后减小,抗冻性先降低后提高;硅烷乳液的掺入显著降低了水化产物在聚乙烯醇(PVA)纤维表面的附着,导致砂浆弯曲性能下降;当硅烷乳液掺量较高时,PVA纤维与基体界面粗糙度明显增加,砂浆弯曲性能提高;内掺硅烷乳液增加了毛细孔含量,有助于缓解孔隙水结冰产生的膨胀应力,从而显著提高砂浆抗冻性.

纳米二氧化硅负载丙烯酰胺型SAP内养护性能研究

设计制备了纳米二氧化硅(NS)负载丙烯酰胺型高吸水树脂(SAP),探究了不同NS负载量的SAP对砂浆自收缩、干燥收缩和力学性能的影响。结果表明,丙烯酰胺型SAP能够完全消除砂浆自收缩,而随着NS负载量增加,负载型SAP对自收缩的抑制作用降低,但仍保持在80%以上。SAP及额外水的引入增加了砂浆的干燥收缩,但随着NS负载量增加,负载型SAP对缓解干燥收缩有积极作用。SAP及额外水的引入降低了砂浆的力学性能,但随着NS负载量增加,负载型SAP显著改善了砂浆的力学性能。其中,负载50%(相对于丙烯酰胺的质量分数)NS的SAP对砂浆力学性能影响最小,试样在28 d龄期的抗压强度与抗折强度仅损失5.6%与2.2%。热重(TG)以及背散射扫描电子显微镜(BSE)结果表明,随着NS负载量增加,负载型SAP内养护试样的水化程度显著提高,微观结构明显改善。

钢纤维增强聚合物水泥砂浆性能研究

研究了钢纤维的体积掺量(0、0.5%、1.0%、1.5%、2.0%)对聚合物水泥砂浆力学性能和韧性的影响,并进行了性价比评价。结果表明:随着钢纤维掺量的增加,试件的7 d和28 d抗折、抗压强度基本均呈先增大后减小的趋势,最佳掺量为1.5%,此时,试件的韧性得到显著提升,性价比也达到最高。

聚氨酯类聚合物砂浆-混凝土界面黏结性能与变形特征试验研究

聚合物砂浆(polymer mortar,PM)因其良好的气密性、抗裂性和变形适应性被认为是一种极具发展潜力的建造压缩空气储能(compressed air energy storage,CAES)人工硐室储气库密封层的可选材料之一。为探究聚氨酯类聚合物砂浆(polyurethane polymer mortar,PPM)与人工硐室储气库衬砌混凝土之间的黏结性能和变形适应性,采用室内试验和数值模拟方法,研究了PPM中粉料和聚合物含量以及配比变化对PPM-混凝土界面的黏结性能和变形性能的影响规律,并分析了界面的破坏特征和破坏机制。研究结果表明:PPM-混凝土界面破坏型式主要表现为界面两侧材料的分离;界面剪应力-位移关系在应力峰值前呈现两阶段近似线性变形特征,界面破坏剪切应变最大值可达11.05%;粉料和聚合物含量以及配比变化对界面黏结强度都有重要的影响,最高黏结强度约为1.21MPa,最低平均黏结强度为0.237MPa。PPM-混凝土界面强度和变形性能可满足CAES地下储气库的建库要求。

石粉替代率对聚合物机制砂粘结砂浆性能及微细观结构的影响

为研究凝灰岩石粉在聚合物粘结砂浆中应用的可行性,分析了石粉部分替代水泥对聚合物粘结砂浆工作性能及力学性能的影响规律,并采用压汞法(MIP)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)试验研究砂浆内部孔结构及水化产物微观形貌的变化规律。结果表明:凝灰岩石粉在聚合物粘结砂浆中具有较好的适用性;砂浆强度随石粉替代率的增加呈先增大后减小的趋势,在替代率为15%(质量分数,下同)时,砂浆7 d、28 d抗折强度、抗压强度和粘结强度达到最大值,此时工作性能也较优。当石粉替代率不大于15%时,其对粘结砂浆微细观结构的影响以填充效应和晶核效应为主,可有效改善砂浆内部密实度,且有利于内部孔结构向少害孔和无害孔发展;当石粉替代率为15%时,H_(2)O、OH^(-)、CO_(3)^(2-)等特征振动峰强度最高,即此时内部水化最为充分;当石粉替代率超过15%时,石粉对粘结砂浆工作性能、力学性能和微细观结构均产生不利的影响。

VAE乳胶粉与偏高岭土聚合物改性防水砂浆性能研究

为了提高普通砂浆抗渗性能,提出了一种将有机聚合物与无机矿物相结合、并内掺有机硅赋予普通砂浆优良抗渗性能的试验研究。通过对防水砂浆抗压强度、抗折强度、抗渗强度、吸水率的测定分析,得到了高性能的聚合物改性防水砂浆。研究结果表明:(1)可再分散乳胶粉在水泥砂浆中形成的膜结构,会显著降低抗压强度而提高抗渗强度,适宜掺量应为水泥质量的3%;(2)偏高岭土具有的火山灰活性,可与水化产物发生二次反应,但应注意掺量与力学性能的关系,不宜大于6%;(3)聚硅氧烷在砂浆中形成的有机硅憎水基团,可以赋予防水砂浆优良憎水性,从而提高抗渗强度降低吸水率,掺量为0.5%时综合性能最优;(4)聚合物改性防水砂浆在具有良好力学性能的同时,抗渗强度从最初的1.0 MPa升至2.3 MPa,吸水率从7.7%降至5.2%,各项性能均远超国家规范对聚合物防水砂浆的要求。该研究成果可为防水砂浆的推广使用及改性研究提供参考。

仿生高韧水泥基复合材料制备技术及增韧机理

为了提升混凝土基体的韧性,基于贝壳珍珠层独特“砖-泥”结构,采用水泥石与有机聚合物制备出具有仿生“砖-桥-泥”结构的高韧水泥基复合材料.通过三点弯曲试验、扫描电子显微镜及有限元模拟方法研究了仿生水泥基材料的抗折强度、韧性及增韧机理.结果表明,相较于传统水泥的脆性断裂模式,仿生水泥基材料表现出明显的延性断裂特征,包括峰后曲线渐进下降、跨中挠度大幅增加等.基于有机聚合物的多尺度桥接-伸展效应,仿生水泥基材料内部呈现明显的裂纹偏转及分支现象,体现了仿生“砖-桥-泥”结构的内外协同增韧机制.仿生水泥基材料能够在保证95%抗折强度的基础上,将水泥基体的韧性提高179.45%,可为解决混凝土增韧降脆问题提供新的技术路径.

不同环境溶液下高吸水树脂对水泥基材料的裂缝修复性

混凝土开裂及修复一直是工程界关注的重点问题,高吸水树脂(SAP)具有一定的裂缝自愈合功能。本文测试了不同环境溶液(NaOH、NaCl和蒸馏水)下SAP的吸液性能,以开裂试件的抗压强度恢复率、不同裂缝宽度(0.1、0.2 mm)的自愈合率以及裂缝填充状态为修复指标,分析了不同质量分数(0%、0.5%、1.0%)的SAP在不同环境溶液下对开裂砂浆试件的修复效果。结果表明:SAP在不同环境溶液下的吸液倍率呈先快速增加后缓慢趋于稳定的变化规律,其中SAP在NaOH环境溶液下的吸液倍率最高;SAP的掺入一定程度上提升了开裂砂浆试件在不同环境溶液下的抗压强度恢复率,其中掺入0.5%SAP的试件在NaOH环境溶液修复28 d的抗压强度恢复率最高,高出基准组17%;SAP的掺入提高了不同裂缝宽度的砂浆试件在不同环境溶液下的自愈合性能,随着SAP含量增加,0.2 mm裂缝宽度的砂浆试件在NaOH环境溶液修复28 d的自愈合率显著高于蒸馏水和NaCl溶液,掺入1.0%SAP的试件在NaOH环境溶液下的自愈合率达90%;SAP协同水化产物封堵裂缝口,提高了水泥砂浆的耐久性。

不同类型聚合物对水泥砂浆粘接性能的影响研究

研究了丙烯酸酯聚合物(AC)、聚乙烯醇(PVA)、丁苯橡胶(SBR)和乙烯醋酸乙烯酯(EVA)对聚合物改性水泥砂浆(PCM)力学性能的影响。使用了一种聚合物剂量(3%),并将该剂量对相变材料(PCM)的影响与含有0%聚合物的对照砂浆混合物进行了比较,测量了抗压强度和粘接强度,分析了聚合物的添加对改善聚合物改性水泥砂浆粘接性能的影响。结果表明,含有EVA的相变材料表现出最好的性能,28 d后抗压强度提高了33%。相比之下,AC、PVA和SBR在28 d后粘接强度的提高较小。含有EVA的PCM在7 d时表现出最高的粘接强度;28 d后,粘接强度最高的是含有SBR的PCM,高出对照砂浆约29%。

高黏结低收缩砂浆在船闸闸室墙面层修复中的应用

针对传统聚合物砂浆在机械搅拌时黏结性能大幅下降、干缩率较高等缺点,制备了改性聚合物砂浆,对比研究了传统聚合物砂浆和改性聚合物砂浆在不同搅拌方式下的工作性、力学性能、变形性能及耐久性能,并将改性聚合物砂浆用在江苏省某船闸闸室墙修复试点工程中,对砂浆的强度、立面垂直度、表面平整度、黏结牢固程度进行了现场检查测试。结果表明:改性聚合物砂浆与基层间黏结牢固,结合层无脱层、空鼓等现象,整体修复效果较好。

高岭土改性聚丙烯酸钠型高吸水性树脂对砂浆性能的影响

通过反向悬浮聚合法将无机组分高岭土与有机组分聚丙烯酸钠型高吸水性树脂接枝聚合,分析其粒径分布和吸水倍率,确定较为合适的高岭土添加量。试验探究了不同高岭土含量的改性高吸水性树脂以及不同掺量的高岭土改性高吸水性树脂,对砂浆收缩及抗折强度、抗压强度的影响。结果表明,添加含有高岭土的高吸水性树脂有效降低砂浆的干燥收缩,但是高吸水性树脂的添加普遍降低砂浆的抗折、抗压强度,高岭土改性高吸水性树脂在砂浆中的合适掺量为0.2%。

消泡剂与减缩剂对聚合物改性水泥砂浆干燥收缩和质量损失的影响

研究了单掺消泡剂、单掺减缩剂及二者复掺对聚合物改性水泥砂浆的干燥收缩率和质量损失率的影响。结果表明,单掺消泡剂时,砂浆的干燥收缩率与质量损失率均会降低,且降低幅度与掺量成正比;单掺减缩剂时,砂浆的干燥收缩率降低且降幅与掺量成正比,质量损失率整体降低,但随着掺量的增加,减缩剂对质量损失的抑制作用逐渐降低;二者复掺对砂浆的干燥收缩与质量损失的抑制作用大于各自单掺时,具有明显的协同效应。砂浆的质量损失率与干燥收缩率之间存在幂函数关系,曲线参数受外加剂种类及掺量影响。

融雪盐对蓄盐沥青胶浆高温性能的影响

为探究融雪盐对蓄盐沥青胶浆高温性能的影响,通过针入度、软化点和黏度等常规试验,以及温度扫描、多重应力蠕变与恢复等流变试验对SBS组沥青胶浆和HEA组沥青胶浆的高温性能进行了表征。结果表明,与SBS组相比,HEA组沥青胶浆的针入度更低,软化点和黏度更高。融雪盐掺量越多,沥青胶浆的针入度提高、软化点和黏度降低。沥青胶浆中结构沥青含量可能是导致这一结果的重要因素。沥青胶浆的复数模量和车辙因子随融雪盐掺量的增加而降低,但融雪盐对沥青胶浆的相位角影响较为复杂。沥青胶浆的蠕变能力随融雪盐掺量增加而增加,但高弹聚合物可显着降低蠕变性能。HEA100的抵抗蠕变性能甚至高于SBS00,由此高弹聚合物可弥补融雪盐对沥青胶浆高温性能的负面影响。综上,融雪盐虽然增加了沥青路面融冰雪的潜力,但也降低了沥青胶浆的高温抗车辙能力。蓄盐路面材料可与高弹聚合物结合使用,以减少融雪盐对沥青胶浆高温性能带来的负面影响。