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聚合物水泥砂浆概述聚合物水泥砂浆是一种特殊类型的砂浆，它在传统水泥砂浆基础上添加了聚合物（通常是聚丙烯酸酯或丙烯酸树脂）作为增强材料。
这种砂浆既具备了传统水泥砂浆的优点，又通过添加聚合物改善了其性能，使其具有更好的可塑性、粘结力和耐久性。
聚合物水泥砂浆在建筑、修缮和装饰等领域得到了广泛应用。
特性和优点聚合物水泥砂浆具有以下特性和优点：1.可塑性：聚合物的添加改善了砂浆的可塑性，使其更容易施工和塑造，适用于各种形状和表面的应用。
2.粘结力：聚合物水泥砂浆具有更高的粘结力，能够更好地粘结到不同类型的基材上，如混凝土、砖石、砂浆等。
3.耐久性：聚合物的添加提高了砂浆的耐候性和耐化学性，能够更好地抵抗外部环境的侵蚀和损害，延长建筑物的使用寿命。
4.防水性：聚合物水泥砂浆具有优秀的防水性能，能够有效地阻止水分渗透，保护建筑物的结构和内部空间。
5.抗裂性：聚合物的添加增强了砂浆的抗拉强度，有效地抵抗外部应力和震动引起的裂纹。
6.环保性：聚合物水泥砂浆对环境友好，不含有害物质，符合绿色建筑的要求。
应用领域聚合物水泥砂浆在多个领域都有应用，主要包括以下几个方面：1. 建筑装饰在建筑装饰领域，聚合物水泥砂浆经常被用于墙面和地面的修补、涂料和石材粘贴等工作。
其可塑性和粘结力使得砂浆能够更好地与各种装饰材料结合，创造出美观、坚固的表面。
2. 砌筑和砌块粘结聚合物水泥砂浆在砌筑和砌块粘结方面也有广泛应用。
由于其粘结力和可塑性，能够确保砌体的稳定性和强度，提高建筑结构的质量和耐久性。
3. 地面修补和维护在地面修补和维护领域，聚合物水泥砂浆用于填补裂缝、修复破损的地面以及改善地面平整度。
其耐久性和防水性使得修补后的地面更加坚固和耐用。
4. 防水工程聚合物水泥砂浆的优秀防水性能使其成为防水工程中的重要材料。
它广泛应用于地下室、浴室、水池、水塔等需要防水的场所。
5. 修复和加固聚合物水泥砂浆在结构修复和加固方面有独特的优势。
可以用于修补和增强混凝土结构、填补缺陷、加固和保护建筑物。
水泥建筑胶粉的作用及用途
水泥是建筑材料中非常重要的一种，而建筑胶粉也是广泛应用于建筑行业的材料。
那么，水泥建筑胶粉的作用和用途是什么呢？
首先，我们来看一下水泥建筑胶粉的作用。
建筑胶粉是一种粉末状物质，通常是一种聚合物，可以与水泥混合使用，促进水泥凝固。
建筑胶粉还可以增加混凝土的粘合性、可塑性和强度。
其作用可以帮助水泥更好地凝固，提高水泥的强度和硬度，从而使得建筑更加稳固和耐久。
其次，水泥建筑胶粉的用途非常广泛。
建筑胶粉可以用作建筑水泥的添加剂，是用于修复和重建混凝土结构的理想选择。
在建筑工程中，胶粉被广泛应用于修缮破损的地面、墙壁、屋顶等。
此外，建筑胶粉还可以用作粉刷和涂料中的黏合剂，以增加底漆和涂料的粘附力。
在湿地和高温环境中，建筑胶粉也被广泛应用作为防水材料。
综上所述，水泥建筑胶粉的作用和用途非常广泛。
无论是建筑工程还是涂料和粉刷等方面，都可以发挥重要作用。
因此，建筑胶粉在建筑行业中的应用得到了越来越广泛的关注和应用。
聚乙烯醇在砂浆中的作用随着科技的进步和建筑行业的不断发展，建筑材料的选择和应用越来越受到人们的关注。
其中，聚乙烯醇作为一种功能性高分子材料，在砂浆中的应用逐渐崭露头角。
本文将对聚乙烯醇在砂浆中的作用、性能以及应用进行详细介绍。
一、聚乙烯醇的基本概念与特性聚乙烯醇(Polyvinyl alcohol,简称PVA)是一种具有良好水溶性的高分子化合物，其分子式为(C3H4O2)n。
PVA具有良好的生物相容性、抗炎性、抗菌性、保湿性等特点，因此在医药、食品、化妆品等领域有着广泛的应用。
近年来，人们发现PVA还具有很好的粘结性能，尤其是在砂浆中的应用越来越受到关注。
二、聚乙烯醇在砂浆中的作用1.增强砂浆的粘结力和抗裂性聚乙烯醇在砂浆中的加入可以有效地提高砂浆的粘结力和抗裂性。
这是因为PVA分子链中含有大量的羟基(-OH),这些羟基可以与水泥颗粒表面的硅酸盐离子发生化学反应，形成牢固的水化产物，从而提高砂浆的黏附力。
此外，PVA分子链的柔性使得砂浆在干燥过程中能够产生一定的收缩变形，从而减少砂浆的开裂现象。
2.改善砂浆的耐水性和耐久性聚乙烯醇具有良好的保水性和保湿性，能够在砂浆中形成一层致密的水膜，防止水分的蒸发和砂浆的龟裂。
这对于提高砂浆的耐水性和耐久性至关重要。
在潮湿环境下使用的建筑物，如桥梁、隧道等，采用含有PVA的砂浆能够显著降低渗水和腐蚀的风险。
3.提高砂浆的操作性和施工效率由于PVA具有良好的流动性和可塑性，使得砂浆在使用过程中更加易于操作和施工。
PVA可以与其他添加剂混合均匀，形成稳定的砂浆体系，有利于提高施工效率。
此外，PVA还可以作为增稠剂使用，进一步改善砂浆的流动性和可泵性。
三、聚乙烯醇在砂浆中的应用实例1.高速公路桥梁工程在中国的一些高速公路桥梁工程中，已经采用了含有PVA的砂浆。
这种砂浆具有较高的抗裂性和耐久性，能够有效减少桥梁的维护成本和使用寿命。
2.隧道工程在隧道工程中，由于地下水位较高，传统的水泥砂浆容易出现渗水和腐蚀问题。
什么叫聚合物砂浆
聚合物砂浆是一种特殊类型的水泥砂浆，它在水泥基体中添加了聚合物乳液，从而改善了水泥砂浆的性能和特性。
聚合物砂浆常用于建筑、修缮和装饰工程中，其优越的性能使其在工程施工中备受青睐。
首先，聚合物砂浆与普通水泥砂浆相比，具有更优异的耐久性和抗裂性能。
添加聚合物乳液可以提高砂浆的粘结强度和韧性，有效防止了砂浆开裂和脱落的情况。
这种耐久性和抗裂性能使聚合物砂浆在各种气候条件下都能保持较长时间的良好状态，减少了施工后的维护成本和频率。
其次，聚合物砂浆具有较高的耐水性和耐候性。
由于聚合物乳液可以有效改善水泥基体的性能，聚合物砂浆在潮湿环境下表现出色；同时，其耐候性也使其能够长时间保持在室外环境中不受影响。
这些特性使得聚合物砂浆在各种建筑表面涂料和修缮材料中得到广泛应用。
此外，聚合物砂浆还具有较好的粘附性和施工性能。
添加聚合物乳液可提高砂浆的粘结能力，使其能够更好地附着在各类建筑表面上，同时也提高了涂抹的便捷性。
这种优良的施工性能使得聚合物砂浆在修缮、装饰等施工工程中更易于操作，提高了施工效率和工程质量。
总的来说，聚合物砂浆是一种在建筑工程中应用广泛且性能优越的材料。
其耐久性、抗裂性和耐水性能，以及较好的粘附性和施工性能，使得它在各种建筑工程中都具有重要作用。
未来，随着建筑技术的不断进步和改善，聚合物砂浆有望在更多领域得到应用，为建筑行业带来更多的创新和进步。
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关于VAE的一些资料,欢迎大家来补充VAE乳液是醋酸乙稀－乙烯共聚乳液的简称，是以醋酸乙烯和乙烯单体为基本原料，与其它辅料通过乳液聚合方法共聚而成的高分子乳液。
乙烯与醋酸乙烯共聚物是乙烯共聚物中最重要的产品，国外一般将其统称为EVA。
但是在我国，人们根据其中醋酸乙烯含量的不同，将乙烯与醋酸乙烯共聚物分为EVA树脂、EVA橡胶和VAE乳液。
醋酸乙烯含量小于40％的产品为EVA树脂；醋酸乙烯含量40％～70％的产品很柔韧；富有弹性特征，人们将这一含量范围的EVA树脂有时称为EVA橡胶；醋酸乙烯含量在70％～95％范围内通常呈乳液状态，称为VAE乳液。
VAE乳液外观呈乳白色或微黄色。
国外对乙烯与醋酸乙烯共聚物的研究比较早。
英国帝国化学公司于1938年发表了EV A共聚物的高压自由基聚合专利，美国杜邦公司于1960年实现工业化。
国内从20世纪60年代开始研制EVA树脂，到70年代中期试产成功。
1988年北京有机化工厂首次从美国引进年产1.5万吨VAE乳液装置，1991年四川维尼纶厂再次从美国引进同样一套VAE乳液装置。
江西化工化纤有限公司自建了一套年产1000吨生产线，但一直没有进入实质性生产。
VAE乳液主要用于胶粘剂、涂料、水泥改性剂和纸加工，具有许多优良的性能。
VAE乳液具有永久的柔韧性。
VAE乳液可以看作是聚醋酸乙烯乳液的内增塑产品，由于它在聚醋酸乙烯分子中引入了乙烯分子链，使乙酰基产生不连续性，增加了高分子链的旋转自由度，空间阻碍小，高分子主链变得柔软，并且不会发生增塑剂迁移，保证了产品永久性柔软。
VAE乳液具有较好的耐酸碱性。
VAE乳液在弱酸和弱碱存在条件下均能够保持稳定性能，因此它不论与弱酸或弱碱混合都不会发生破乳现象，产品应用范围较广。
VAE乳液能够耐紫外线老化。
由于VAE乳液是采用乙烯作为共聚物的内增塑剂，使V AE聚合物具有内增塑性，增塑剂不会发生迁移，从而避免了聚合物性能老化。
因此，不仅是VAE乳液对紫外线有很好的稳定性，就是VAE乳液成膜后同样也可保持这一特点。
可再分散乳胶粉用途乳胶粉是由乳胶经过加工而制成的粉状物质，能溶于水形成乳胶溶液，具有良好的胶凝、黏附和可塑性。
乳胶粉具有广泛的应用领域，下面我将就其主要用途进行详细介绍。
1. 建筑领域：乳胶粉在建筑领域中可用作粘结剂，可以用于瓷砖、墙纸、石材等的粘贴，能够提高粘结强度和防水性能。
同时，乳胶粉还可以用于调配水泥砂浆、石膏砂浆等，能够提高砂浆的抗裂性和抗渗性。
2. 木工领域：乳胶粉可作为胶水使用，在木材加工中起粘结作用，能够用于胶合板、多层板、实木家具等的制作。
与传统的骨胶相比，乳胶粉具有使用方便、环境友好等优势。
3. 紙製品：乳液可以以粘合劑的形式應用於紙張和紙箱的生產中，能夠提高紙張的強度和黏合性。
4. 纺织印染：乳胶粉中的乳胶颗粒能够与纺织品表面的纤维产生化学反应，改变纤维的表面性质，增强纤维的染色率和牢度。
因此，乳胶粉可用于纺织印染的增白、固色、皮碱等工艺。
5. 造纸工业：乳胶粉可用作造纸的增白剂和结合剂，能够提高纸张的白度和光泽，同时增加纸张的抗水性、抗磨性和耐久性。
6. 化妆品：乳胶粉可以用作化妆品中的粘结剂和稳定剂，能够提高化妆品的黏性和稳定性，使其更容易涂抹和吸收。
7. 电子产品：乳胶粉可以用作电子产品中的包裹材料，能够起到缓冲和保护电子零部件的作用。
8. 医疗用品：乳胶粉可以用于医疗敷料的制作，具有良好的黏合性和渗透性，在伤口愈合的过程中发挥重要作用。
9. 包装材料：乳胶粉可以用作包装材料的粘合剂，能够提高包装材料的抗冲击性和耐久性，使其更加牢固可靠。
除了上述应用领域外，乳胶粉还可广泛应用于胶粘剂、橡胶制品、陶瓷制品、石材修补等领域。
乳胶粉具有良好的工艺性能和环境友好特点，正逐渐替代传统的胶粘剂和粘结剂，成为众多行业中不可或缺的材料。
可再分散乳胶粉研究报告第一章可再分散乳胶粉产品简介一、可再分散乳胶粉产品概述由聚合乳液通过加入其它物质改性，经喷雾干燥而成，以水作为分散介质可再行程乳液,具有可再分散性的聚合物粉末。
1.2可再分散乳胶粉的组成:通常为白色粉状，但也有少数有其他颜色,它的主要成分包括：聚合物树脂:位于胶粉颗粒的核心部分，也是可再分散乳胶粉发挥作用的主要成分.添加剂（内）：与树脂一起起到改性树脂的作用.添加剂（外）：为进一步扩展可再分散乳胶粉的性能的又另添加材料.保护胶体：在可再分散乳胶粉颗粒的表面包裹的一层亲水性材料，绝大数为聚乙烯醇.抗结块剂：细矿物填料，主要用于防止胶粉在储运过程中结块以及便于干粉流动。
可再分散聚合物胶粉是水溶性的，当这些粉末与水搅拌或在砂浆中与水混合时，会生成与原始乳液性能相似的稳定分散体系，聚合物颗粒自行分散并不会同水泥粘聚，一个粒经在50～300μm 的可再分散聚合物胶粉颗粒中主要包含了许多分散粒子( 每个粒子的直径大约1μm) 。
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3包装与贮存:需储存于阴凉干燥之场所，建议使用期限为六个月，在夏天使用时则请尽量早使用，若保存于温度潮湿之场所则会增加结块之几率，开袋后亦请尽可能一次使用完毕，否则需将袋口封好以避免从空气中吸收水分。
1.4常用的可再分散乳胶粉按聚合物种类进行分类如下表：1。
5分辨可再分散乳胶粉优劣的几种方法：（1)溶解法,取一定量的可再分散性乳胶粉溶解于5倍质量的水中，充分搅拌后静置5分钟后观察.原则上沉淀到底层的不容物越少，可再分散性乳胶粉的质量越好。
这种方法简单易行。
(2)成膜法，取一定质量的可再分散性乳胶粉，溶解于2倍的水中，搅拌均匀后静置2分钟，再次搅拌均匀，将溶液倒在一块平放的洁净玻璃上,玻璃置于通风背阴处。
待充分干燥后，揭下.观察揭下的聚合物膜。
透明度高的质量好。
然后进行适度拉扯，弹力好的质量好.再将膜切割成条状,浸泡到水中,1天后观察，被水溶解的少的质量好.这种方法更加客观。
聚合物水泥砂浆作用
聚合物水泥砂浆是一种由水泥、砂子、聚合物乳液等材料混合制成的混凝土，广泛应用于建筑工程中的墙体、地面、屋顶防水、地下室等工程中。
它具有以下几个方面的作用：
1. 增强抗裂性能：聚合物水泥砂浆中的聚合物乳液可以形成一种强韧的聚合物胶体，能够在混凝土中形成网状结构，提高混凝土的抗裂性能。
2. 提高粘结强度：聚合物水泥砂浆中的聚合物乳液能够与水泥晶体表面形成化学键，提高混凝土的粘结强度，使之更加牢固。
3. 提高耐水性：聚合物水泥砂浆中的聚合物乳液具有良好的耐水性，可以防止水分侵入混凝土中，保证混凝土的长期使用寿命。
4. 提高耐久性：聚合物水泥砂浆中的聚合物乳液可以提高混凝土的耐久性，防止混凝土因气候变化、温差变化、化学腐蚀等原因而出现裂缝和断裂。
总之，聚合物水泥砂浆是一种性能优异、用途广泛的建筑材料，具有很多的优点和作用，能够满足不同工程的需要，为建筑工程的施工质量提供了可靠的保障。
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可再分散胶粉的生产与应用在预拌砂浆产品成本中，添加剂占了很大的比例，而最常用的添加剂如可再分散乳胶粉，价格较贵，导致预拌砂浆的成本大幅提高。
因此，如何选用、选好添加剂，是预拌砂浆的核心，通过调配添加剂来改善预拌砂浆的性能，使之满足工程的需要。
例如，可以通过掺加可再分散乳胶粉使砂浆具有弹性；通过增加流化剂用量使地坪砂浆可以自由流淌，通过掺加纤维使砂浆表面裂缝大幅度减少等等可再分散乳胶粉可大大提高砂浆与基层的粘结性能，但会降低砂浆的耐水性。
憎水剂可提高砂浆抵抗微压力水的能力，但憎水剂可能降低砂浆的粘结性。
因此，在配制预拌砂浆产品时，我们应综合考虑各组分对砂浆各项性能指标的影响，通过试验确定经济合理、技术先进的砂浆配方。
一、国外预拌砂浆的发展历程及发展现状19世纪70~80年代，预拌砂浆在欧美形成了一个新兴的产业。
在欧洲，预拌砂浆产品已经达到几百种，包括砌筑砂浆、抹灰砂浆、粘结砂浆、修补砂浆、装饰砂浆等几大类，每类都有几个到几十个品种。
二、国内预拌砂浆的发展现状1、国内预拌砂浆发展概述我国从上世纪八十年代开始研究引进预拌砂浆技术，九十年代末期开始出现具有一定规模的预拌砂浆生产企业。
进入二十一世纪以来，随着国家相关政策的推动，国外先进理念和先进技术的引进，预拌砂浆行业进入一个快速发展的时期。
自2003年起，上海市开始在建筑工程中应用普通预拌砂浆。
2010年统计数据显示，全国2万吨规模以上的预拌砂浆生产企业200家，设计能力2000万吨，实际生产1100万吨。
预拌砂浆基本组成胶结材料集料添加剂水泥消石灰粉细磨石灰粉石膏粉煤灰砂/粗砂填料/颜料轻集料工业尾矿风积砂引气剂消泡剂促凝剂塑化剂缓凝剂粘结剂防水剂聚合物增稠剂保水剂可再分散乳胶粉（一）制备可再分散乳胶粉是高分子聚合物乳液经喷雾干燥，以及后续处理而成的粉状热塑性树脂，通常为白色粉末，但也有少数含有其它颜色。
主要用于建筑方面，特别是在增加干拌砂浆的内聚力，粘聚力，与柔韧性方面表现出良好的性能。
乳胶粉用途乳胶粉是由乳胶经过加工制成的粉状产品。
乳胶是橡胶树的乳液，主要成分是胶原质、蛋白质和油脂等，具有良好的黏附性和可伸展性。
乳胶粉具有广泛的用途，可以在各个领域中发挥其独特的特性和功能。
一、建筑领域乳胶粉在建筑领域中被广泛应用。
其主要功能是作为建筑材料的增强剂，可以提高建筑材料的抗拉强度、耐久性和抗震性能。
乳胶粉可以用于制作瓷砖胶、防水涂料、防火涂料、壁纸胶等。
它能够增加建筑材料的粘结力和可塑性，提高施工的效率和质量。
二、纺织印染乳胶粉在纺织印染行业中也有较多的应用。
它可以与染料和纤维相结合，形成乳胶乳，用于印花和染色。
乳胶乳具有良好的黏稠度和延展性，能够使染料均匀地附着在纤维上，并增加纤维的柔软度和弹性。
此外，乳胶粉可以用于制作防水涂料，增加纺织品的防水性能，在户外服装、雨具和泳衣等方面有广泛的应用。
三、胶粘剂乳胶粉是一种优质的胶粘剂原料，广泛应用于胶黏剂行业。
由于其所含有的胶原蛋白质能够与物体表面产生较强的附着力，乳胶粉可以用于制作各种胶粘剂，如木工胶、布艺胶、玻璃胶和电子胶等。
乳胶粉胶粘剂具有粘结力强、耐久性好等特点，在家具、装修、工艺品制作以及电子设备的粘接方面有着广泛的应用。
四、水性涂料乳胶粉在水性涂料中的应用也很常见。
水性涂料是将乳胶粉与颜料和稀释剂等混合而成的涂料，主要有墙面漆、木器漆和金属漆等。
乳胶粉可以增加水性涂料的粘结力和附着力，提高涂料的抗气候老化性能和耐磨性。
与传统的溶剂型涂料相比，水性涂料环保无污染，使用起来更加安全，乳胶粉的应用使得水性涂料成为一种主流的涂料产品。
五、医疗器械乳胶粉还可以用于制作医疗器械和外科手套等，以提供良好的手术操作感和防护性能。
乳胶粉的柔韧性和延展性使得手套能够紧密贴合手部，有效防止外界物质的侵入和交叉感染。
此外，乳胶粉在医疗器械中的应用还包括石膏、医用胶带等。
乳胶制成的石膏材料能够固定骨折处，提供支撑和保护。
乳胶粉也常用于制作医用胶带，以固定绷带和敷料。
Action of redispersible vinyl acetate and versatate copolymer powder in cement mortarRu Wang a ,b ,⇑,Pei-Ming Wang aaKey Laboratory of Advanced Civil Engineering Materials of Ministry of Education,School of Materials Science and Engineering,Tongji University,4800Caoan Road,Shanghai 201804,China bDepartment of Civil Engineering and Engineering Mechanics,Columbia University,New York,NY 10027,USAa r t i c l e i n f o Article history:Received 4February 2011Received in revised form 21April 2011Accepted 22April 2011Available online 8May 2011Keywords:Redispersible VA/VeoVa powder Cement mortarPhysical and mechanical properties Shrinkage rateWater capillary adsorption Anti-penetration capacitya b s t r a c tRedispersible polymer powder of vinyl acetate and versatate copolymer (VA/VeoVa)is applied to modify cement mortar.The effect of VA/VeoVa powder on physical and mechanical properties of cement mortar is investigated.VA/VeoVa powder exhibits excellent water-reduction and water-retention effects in cement mortar and improves mortar properties effectively.Due to the air-entrainment effect of VA/VeoVa powder,the air content of fresh mortar is increased and the bulk density is decreased.VA/VeoVa powder makes the compressive strength decrease,but not so significant the effect on the flexural strength is,which results in the ratio of compressive strength to flexural strength goes down sharply with the increase of VA/VeoVa powder,indicating the toughness of cement mortar is improved markedly.Fur-thermore,VA/VeoVa powder reduces the shrinkage rate and improves the hydrophobicity and water impermeability of cement mortar.Ó2011Elsevier Ltd.All rights reserved.1.IntroductionPolymer-modified mortars are good repair materials for excellent properties.Polymers can improve the flowability of fresh mortar,mechanical properties [1],anti-penetrability [2],freezing–thawing resistance [3],anti-corrosion [4],and so on of hardened mortar.Former research shows that polymers change the micro-structure,have physical and chemical interaction with cementi-tious phase,effect the flowability,hydration,setting,hardening,pore structure,and thus physical and mechanical properties of hardened mortar [5–8].In fact,different polymers have different influences on cement mortar.For example,styrene–butadiene rubber (SBR)latex im-proves the flexural strength,tensile bond strength,waterproofing property,carbonation resistance and anti-shrinkage of cement mortar [9–11].Styrene–acrylic ester copolymer (SAE)latex de-creases the elastic modulus and increases the toughness of cement mortar to a larger extent [12,13].Ethylene–vinyl acetate copoly-mer (EVA),the most widely used polymer in mortar,improves the tensile bond strength,flexural strength,and toughness of ce-ment mortar [14,15].Whereas vinyl acetate and versatate copolymer (VA/VeoVa)is a special copolymer that introduces the versatate group with three long a -alkyl molecule side chains into the copolymer.The three long a -alkyl molecule side chains make the copolymer have many superior properties.The ester group of vinyl versatate is stable for the hindering effect of long side chains,resulting in good alkali resistance;the long side chains of vinyl versatate protect neighbor-ing ester group of vinyl acetate too,making the copolymer have good alkali resistance.VA/VeoVa powder is a potential modifier for brittle cement mortar.In Ref.[16],lower degeneration of VA/VeoVa in an alkaline environment rather than other copolymers that contain vinyl acetate group was found.The former researches [17,18]show that with antifoamer together the VA/VeoVa powder increases the strengths of cement mortar.After that,little research on the application of VA/VeoVa powder in cement mortar is pub-lished.This paper focuses on evaluating the action of single VA/VeoVa powder in cement mortar,trying to compare the properties with other polymer powders and dispersions modified mortars those are tested using the same method.2.Experimental 2.1.MaterialsPortland cement type P ÁII 52.5R,according to Chinese standard GB 175,and standard sand,according to ISO 679,were used for preparing the specimens.The chemical composition and physical properties of the cement are listed in Table 10950-0618/$-see front matter Ó2011Elsevier Ltd.All rights reserved.doi:10.1016/j.conbuildmat.2011.04.060⇑Corresponding author at:Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education,School of Materials Science and Engineering,Tongji University,4800Caoan Road,Shanghai 201804,China.Tel.:+862169582140.E-mail address:ruwang@ (R.Wang).and Table2,respectively.The redispersible VA/VeoVa powder(density:0.5g/cm3; average particle size:80l m;minimumfilm formation temperature:6°C)was used in the experiment.2.2.Specimen preparationThe mortar specimens were prepared with VA/VeoVa powder to cement ratio by mass(m p/m c)of0,1%,2%,3%,4%,5%,6%,7%,8%,9%,10%,12%,15%,and20%,con-stantflow of(170±5)mm,and sand to cement ratio by mass of3.The specimens with the dimension of40mmÂ40mmÂ160mm were prepared according to ISO679.The specimens were unmolded after24h.Mixed cure method,1day im-mersed in20°C water followed by1day in air of20°C and RH50%for specimens tested at the age of3days and6days immersed in20°C water followed by21days in air of20°C and RH50%for the specimens tested at the age of28days,was used.2.3.Test methods2.3.1.FlowTheflow table value of fresh mortars was measured according to GB/T2419-2005.A cone-shaped metal ring isfilled with fresh cement mortar on a shock table, and after lifting the ring the mix is subjected to25drops of the table within25s. Thefinal diameter is the so-calledflow table value.The water to cement ratio (m w/m c)of VA/VeoVa powder-modified mortars was determined byfixing theflow table value at a constant of(170±5)mm,as listed in Table3.2.3.2.Water-retention rateThe water-retention rate of fresh mortar was tested according to DIN18555-7. During test,the fresh mortar with settled volume was put on afilter-film allowing waterfilter through,fixed on absorbentfilter papers.Then the water absorbed by thefilter papers(lost water of fresh mortar)was measured after5min.The water-retention rate was calculated based on that.2.3.3.Air entrainment testThe air content of fresh mortars was measured using an air entrainment meter made according to DIN18555/-557,from which the air content can be read directly.2.3.4.Bulk density of fresh mortarsThe bulk density of fresh mortars was tested according to JGJ70-90.One liter container was used during test.After the fresh mortar was cased into the container, it should be vibrated for10s before the mass was measured.pressive andflexural strengthsThe compressive andflexural strengths were determined according to ISO679.2.3.6.Shrinkage rateThe shrinkage rate of mortars was determined according to JGJ70-90.The initial length of mortar was tested right after the specimen was unmolded.The shrinkage rate was calculated according to the length of mortar at different curing ages and the initial length.2.3.7.Water capillary adsorptionThe water capillary adsorption was measured according to DIN52617.Before test,the mortar specimens were dried at70°C for2days.The four around surfaces were sealed with EP resin before the upside of the specimens was dipped into water.The water capillary adsorption was calculated based on the adsorbed water at different times.2.3.8.Anti-penetration capacityThe anti-penetration capacity was measured according to DL/T5126-2001. Conic specimens with upside and underside surface diameters of70mm and 80mm,height of30mm were prepared.The curing is the same as that described in2.2.Before test,the around surface of specimens was sealed with olefin and the underside surface was contacted with water.During test,the water pressure was increased step by step to1.5MPa within8h to observe whether the water pen-etrates through the mortar specimens.If water penetrates through three of six spec-imens under one pressure,then the pressure was determined as the pressure that the mortar survives.3.Results and discussion3.1.Water-reduction effectThe m w/m c of VA/VeoVa powder-modified mortars decreases significantly with the increase of m p/m c when theflow wasfixed at a constant of(170±5)mm(see Table3).So it is apparent that the VA/VeoVa powder has water-reduction effect in cement mor-tar.Water-reduction rate is an important factor to evaluate water-reduction effect,which can be calculated according to the following equation:[13].R¼1Àm w2Áq2Ám1m w1Áq1Ám2;ð1Þwhere R is the water-reduction rate,m w2,q2and m2is water mass, bulk density and mass of fresh VA/VeoVa powder-modified mortars, respectively;m w1,q1and m1is water mass,bulk density and mass of fresh control mortar,respectively.The water-reduction rate of VA/VeoVa powder-modified mor-tars calculated according to Eq.(1)is displayed in Fig.1.A small amount of VA/VeoVa powder addition of1%makes the water-reduction rate rise to about6%.Then the water-reduction rate rises gradually with the increase of m p/m c.When the m p/m c is15%the water-reduction rate increases to about35%.With the m p/m c increasing from15%to20%,no significant change of water-reduc-tion rate was observed.The experimental results explain that VA/ VeoVa powder has good water-reduction effect in mortar,enhanc-ing theflowability of fresh mortar,which is attributed to the dis-persion and air entrainment functions of VA/VeoVa powder.3.2.Water-retention effectGood water-retention property is helpful for the construction and properties of mortar.Water-retention rate is a quantitative in-dex to evaluate the water-retention effect of mortar.Fig.2presents the water-retention rate of VA/VeoVa powder-modified mortars.Table1Chemical composition of PII52.5R Portland cement.Component SiO2CaO Al2O3Fe2O3MgO SO3K2O TiO2BaOContent(%)21.365.1 5.1 2.9 1.1 1.80.70.20.3Table2Physical properties of PII52.5R Portland cement.Specific gravity at20°C(g/cm3)Blaine’s specific area(m2/kg)Setting time(min)Flexural strength(MPa)Compressive strength(MPa)Initial Final3days7days28days3days7days28days3.20385.5125190 6.97.88.439.049.060.6Table3Water to cement ratio(m w/m c)of VA/VeoVa powder-modified mortars with a constantflow of(170±5)mm.m p/m c(%)012345678910121520 m w/m c0.4890.4720.4580.4440.4350.4260.4180.4100.4040.3990.3940.3920.3900.388R.Wang,P.-M.Wang/Construction and Building Materials25(2011)4210–42144211The water-retention rate augments apparently with the increase of m p/m c.It reaches98%with the m p/m c increasing up to6%,and then keeps augmenting stably,indicating the water-retention property of the modified mortar is very good.The good water-retention property may be attributed to following reasons:first,the water-reduction effect of VA/VeoVa powder reduces the unit water usage; second,the VA/VeoVa powder induces water to distribute well in cement mortar;third,the VA/VeoVa powder has blocking effect on the water in cement mortar and makes it more difficult to separate from the system.3.3.Air contentThe relationship between the air content of fresh mortars and the m p/m c is illustrated in Fig.3.A small amount of VA/VeoVa pow-der addition of1%makes the air content of fresh mortar rise from 6%to8.6%.Then a linear increment of air content appears with theincrease of m p/m c up to15%.The air content change indicates that the VA/VeoVa powder has air-entrainment effect in cement mor-tar,making the density of fresh mortar decrease(see Fig.4).The bulk density of fresh mortars reduces gradually with the increase of m p/m c up to15%.It is easy tofind that the bulk density of fresh mortar is closely related to its air content.pressive strengthThe compressive strengths of VA/VeoVa powder-modified mor-tars with curing ages of3days and28days are displayed in Fig.5.The compressive strength of cement mortars depresses with the addition of VA/VeoVa powder.When the m p/m c increases from 0%to3%,the compressive strength falls from30MPa to14MPa for the mortars cured for3days,from72MPa to34MPa for the mortars cured for28days.The compressive strength declines slightly with the m p/m c increasing from3%to5%,and does not decrease any more when the m p/m c is higher than5%.The decrease tendency of compressive strength with the increasing m p/m c of VA/VeoVa powder-modified mortars is similar with that of SBR latex-or PAE latex-modified mortars.But the decrease is faster than that for SBR latex-modified mortars,which4212R.Wang,P.-M.Wang/Construction and Building Materials25(2011)4210–4214decreases to30MPa when the SBR latex/cement-ratio increases to 8%,and then keeps at around this value with the m p/m c range from 8%to20%[10],and slower than that for PAE latex-modified mor-tars,which decreases to20MPa when the PAE latex/cement-ratio increases to5%,and then keeps at around this value with the m p/ m c range from5%to20%[19].The compressive strength of VA/Veo-Va powder-modified mortars is lower than that of SAE latex-mod-ified mortar when the m p/m c is lower than15%[13].3.5.Flexural strengthFig.6presents theflexural strengths of VA/VeoVa powder-mod-ified mortars with curing ages of3days and28days.The change of flexural strength with the m p/m c is similar with that of compres-sive strength except for a smaller changing magnitude.When the m p/m c increases from0%to3%,theflexural strength decreases from7.2MPa to4.8MPa for the mortar tested at the age of3days and from12.5MPa to9.3MPa for the mortar tested at the age of28days.Then theflexural strength of mortars cured for3days de-creases slowly until the m p/m c of8%,followed by an almost con-stantflexural strength value at the m p/m c range from8%to20%. Whereas no significant change offlexural strength of mortars cured for28days appears when the m p/m c is in the range from 3%to8%.When the m p/m c increases from8%to20%,theflexural strength of VA/VeoVa powder-modified mortar rises to almost equal to that of control mortar.That is probably due to the VA/Veo-Va content is high enough to form a continuous network structure in the mortar and also improve the interface structure between the cement hydrates and the aggregates.When the m p/m c is higher than5%,theflexural strength of VA/ VeoVa powder-modified mortar,higher than9MPa,is higher than that of SBR latex-,SAE latex-or PAE latex-modified mortar,8MPa [10],7MPa[13]and7MPa[19],respectively.3.6.ToughnessThe ratio of compressive strength toflexural strength(r C/r F)of mortar is an important factor to judge its toughness.Lower r C/r F indicates better toughness.Several Chinese standards have the rule that the r C/r F of some mortar must be lower than3[20–22]. The r C/r F calculated based on above compressive andflexural strengths is illustrated in Fig.7.The r C/r F of VA/VeoVa powder-modified mortars cured for3days and28days goes down sharply with the increase of m p/m c,indicating the toughness of mortars is improved significantly.Both the rate and magnitude of decrease are larger for the mortars cured for28days than that cured for 3days.When the m p/m c is above5%,the r C/r F for all the modified mortars is below3.To compare with Refs.[10,13,14,19],with low polymer addi-tion,the VA/VeoVa powder is more effective for the improvement of the toughness of cement mortar than SBR latex that makes the r C/r F decrease to4.5when the m p/m c is20%,SAE latex that makes the r C/r F decrease to below3when the m p/m c is higher than15%, redispersible EVA powder that makes the r C/r F decrease to below 3when the m p/m c is higher than10%,and PAE latex that makes the r C/r F decrease to below3when the m p/m c is higher than7%.3.7.Shrinkage propertyThe shrinkage rate of VA/VeoVa powder-modified mortars with different curing ages is presented in Fig.8.An amount of VA/VeoVa powder below6%makes the shrinkage rate enlarge slightly.When the m p/m c reaches7%,the shrinkage rate reduces sharply and then keeps around this value until the m p/m c of20%,lower than that of control mortar.A slight expansion was found for the VA/VeoVa powder-modified mortars at the curing age of3days with the m p/m c higher than7%.The shrinkage reducing effect of the VA/Veo-Va powder in the mortar when the m p/m c is higher than7%is prob-ably due to the polymerfilm formed in the mortar prevents the water escape from the system.3.8.Water capillary adsorptionThe water capillary adsorption of VA/VeoVa powder-modified mortars within48h was measured,as shown in Fig.9.The water capillary adsorption decreases gradually with the increase ofR.Wang,P.-M.Wang/Construction and Building Materials25(2011)4210–42144213m p/m c.When the m p/m c is below7%,the decrease of water capil-lary adsorption with the m p/m c is more evident,indicating at this range a little increase of m p/m c leads to an apparent decrease of water capillary adsorption.However,when the m p/m c is higher than7%,the effect of the increase of m p/m c on the water capillary adsorption is not so marked and the water capillary adsorption va-lue is low.The water capillary adsorption of VA/VeoVa powder-modified mortars with the m p/m c of7%at24h is about0.7kg/m2,which is better than that of redispersible EVA powder-modified mortar 0.8kg/m2[15],similar to that of SAE latex-modified mortar 0.7kg/m2[13],but not so good as that of SBR latex-modified mor-tar0.7kg/m2with SBR latex to cement ratio of5%[23].3.9.Anti-penetration capacityThe experimental results show that the water does not pene-trate through the specimens for all the mortars when the water pressure was increased step by step to1.5MPa within8h.After test,the mortar specimens were broken to observe the penetration depth of water into the specimens,as listed in Table4.It is found that the water penetration depth decreases from12mm to2mm with the increase of the m p/m c from0%to15%.When the m p/m c is20%,no water penetrating into the mortar specimens was ob-served.It can be drawn that the VA/VeoVa powder enhances the anti-penetration capacity of mortar remarkably.4.ConclusionsVA/VeoVa powder has good water-reduction and water-reten-tion effects in cement mortar.The water-reduction rate augments gradually with the increase of m p/m c,reaching about35%when the m p/m c is15%.The water-retention rate rises significantly to about 98%with the increase of m p/m c up to7%.VA/VeoVa powder has air-entrainment effect,making the air content of fresh mortar increase and the bulk density decrease.VA/VeoVa powder depresses the compressive strength of ce-ment mortar,but not so significant the effect on theflexural strength is.That makes the ratio of compressive strength toflex-ural strength goes down to below3when the m p/m c is above5%. The toughness of cement mortar is improved significantly.VA/VeoVa powder has shrinkage rate reducing effect in cement mortar when the m p/m c is higher than7%.VA/VeoVa powder improves the hydrophobicity and water impermeability of cement mortar.The water capillary adsorption decreases with the increase of m p/m c and to about0.7kg/m2at 24h when the m p/m c increases to7%;the water penetration depth decreases from12mm to2mm with the increase of m p/m c from0%to15%when the pressure was increased step by step to 1.5MPa.AcknowledgmentsThe authors acknowledge thefinancial support of the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science&Technology of China(2006 BAJ05B03)and the Specialized Research Fund for the Doctoral Pro-gram of Higher Education(20060247023).References[1]Flavio LM,Vanderley MJ.Bond strength and transversal deformation aging oncement-polymer adhesive mortar.Constr Build Mater2009;23:1022–7.[2]Zhong SY,Chen ZY.Properties of latex blends and its modified cement mortars.Cem Concr Res2002;32:1515–24.[3]Mirza J,Mirza MS,Lapointe boratory andfield performance of polymer-modified cement-based repair mortars in cold climates.Constr Build Mater 2002;16:365–74.[4]Xiong JP,Shen AQ,Qiu YB.A study on road performance and modificationmechanism of polymer cement mortar.Highway2007(5):144–8.[5]Nestle N,Kühn A,Friedemann K,Horch C,et al.Water balance and porestructure development in cementitious materials in internal curing with modified superabsorbent polymer studied by NMR.Micropor Mesopor Mater 2009;125:51–7.[6]Afridi MUK,Ohama Y,Demura K,Iqbal MZ.Development of polymerfilms bythe coalescence of polymer particles in powdered and aqueous polymer-modified mortars.Cem Concr Res2003;33:1715–21.[7]Beeldens A,Monteny J,Vincke W,et al.Resistance to sulphuric acid corrosionof polymer-modified mortars.Cem Concr Compos2001;23:47–56.[8]Kong XM,Li QH.Properties and microstructure of polymer modified mortarbased on different acrylate latexes.J Chin Ceram Soc2009;37(1):107–14. 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