室外花岗岩泛碱原因和处理办法

天然石材以其自然庄重、色彩绚丽及较好的抗风化稳定性、耐磨性、耐酸碱性等特点，被建筑师逐渐认识并广泛采用于建筑物的室内、外墙面装饰，极大地突出了建筑的艺术效果。天然石材的安装施工有干挂法和湿贴法，其中湿贴法具有施工简便，造价较底的优点，但也比较容易产生一些质量通病，突出的一点即是石材表面泛碱现象，产生泛碱后的墙面“水印”斑斑，去之无效，拆之亦难，极大地破坏了建筑装饰效果。广州近年建成的一些标志性公共建筑、广场建筑湿贴花岗岩有泛碱和析白流挂（白胡子）现象，有些甚至十分严重，给这一建筑造成无可挽回的损失和遗憾。为此，分析泛碱成因和作相应的预防措施具有重要意义。一、 泛碱现象 (Alkalization, Efflorescence)湿贴天然石墙面在安装期间，石材板块会出现似“水印”一样的斑块，随着镶贴砂浆的硬化和干燥，“水印”会稍微缩小，甚至有些消失，其孤立、分散地出现在板块中，室内程度不严重，影响外观不大。但是，随着时间推移，特别是外墙反复遭遇雨水或潮湿天气，水从板缝、墙根等部位侵入，天然石的水斑逐渐变大，并在板缝连成片，板块局部加深、光泽暗淡、板缝并发析出白色的结晶体，长年不褪，严重影响外观，此种现象称为泛碱现象。 二、原因分析Analysis1天然石材结晶相对较粗，存在许多肉眼看不到的毛细管，花岗岩细孔率为0.51.5%，大理石细孔率为0.52.0%，其抗渗性能不如普通水泥砂浆，花岗岩的吸水率0.21.7%是较低的，水仍可由通过石材中的毛细管浸入面传到另外一面。天然石材的这种特性及毛细孔的存在，为粘接材料中的水、碱、盐等物质的渗入和析出并形成泛碱提供了通道。1. Natural Stone crystal is relatively thick, there are many naked eye can not see the capillary, granite pore rate of 0.5 1.5%, marble pore rate of 0.5 2.0%, its impermeability is lower than ordinary cement mortar, granite water absorption is as low as 0.2 1.7%, water can still be through the stone from the surface of the capillary immersion reached the other side. This natural stone features and the presence of the pores for the bonding material in the water, alkali, salt, and the infiltration of substances such as precipitation provides the channel for the forming of the Alkalization. 2粘结材料产生含碱、盐等成分物质。主要为镶贴砂浆析出Ca（OH）2（氢氧化钙）并跟随多余的拌合水，沿石材的毛细孔游离入侵板块，拌合水越多，移动到砂浆表面的Ca（OH）2就越多，水分蒸发后，Ca（OH）2就存积在板块里。其他，如在水泥中添加了含有钠Na+的外加剂，粘土砖土壤含有的Na+、Mg2+、K+、Ca2+、C1-、So42-、C032-等，遇水溶解，会渗透到石材毛细孔里，形成“白华”等现象。 粘结材料产生的含碱、盐等成分物质是渗入石材毛细孔产生泛碱的直接物质来源。2. Bonded materials produced alkali, salt and other ingredients material. Precipitation is mainly Xiangtie mortar Ca (OH) 2 (calcium hydroxide) and follow the excess mixing water intrusion along the stones pores free plate, mixing more water, move to the mortar surface of Ca (OH) 2 more and more moisture evaporated, Ca (OH) 2 on the deposit accumulated on the plate inside. Others, such as adding cement admixtures containing sodium Na +, clay soil contains Na +, Mg2 +, K +, Ca2 +, C1-, So42-, C032-, etc., dissolved with water, will penetrate into the stone inside the pores to form a whitish surface and so on. Bonding materials are the source material for alkali, salt and other ingredients to form alkalization.3水的渗入。由于外墙接缝用水泥细砂砂浆勾缝，令防水效果差；地面水（或潮湿）沿墙体或砂浆层侵入石材板；安装时对石材洒水过多等原因，使水入侵石材板，并溶入Ca（OH）2和其他盐类物质进入石材毛细管形成泛碱。可见，水是泛碱物质的溶剂和载体。 3. Water infiltration. As the outer wall joint is made with cement sand mortar resulting poor water proof; surface water (or wet) layer of mortar along the wall, or invasive stone plate; installing the stone watering too much and other reasons, so that the water intrusion stone panels, and integration into the Ca (OH) 2 and other salts into the stone by capillary formation of pan-alkali. This proves that water is the alkalization solvent and carrier.泛碱发生原理。Theory二、 预防措施 Precaution measures针对泛碱现象的成因，可以相应从切断泛碱的途径，减少Ca（OH）2、盐类等生成物及减少水的侵入三方面采取措施，进行预防。 （一）施工前准备 1设计上考虑消除泛碱，尽可能设计成干挂形式；考虑好结构的防水处理；选择吸水率及其他物理性能符合要求的石材板等。 2施工前要充分考虑可能发生泛碱的各施工工艺环节，提前作好预防措施，如无把握应先做样板。 3有关材料应先检验后使用，不但要求外观、尺寸合格，而且其物理性能指标也要合格。 A) pre-construction preparation 1. Use “design” to eliminate the alkalization, as far as possible designed to dry hanging form; considered good water proofing treatment, choose water absorption and other stone panels with physical properties that meet the requirements 2. Prepare mock-up panel. 3. The material should be tested before using and the appearance, size, qualified, and their physical performance should also be qualified.（二）使用防碱背涂剂 1石板安装前在石材背面和侧面背涂专用处理剂，该溶剂将渗入石材堵塞毛细管，使水、Ca（OH）2、盐等其他物质无法侵入，切断了泛碱现象的途径。无背涂处理，泛碱不可避免，经背涂处理的石材的粘接性不受影响。 2在石材板底涂刷树脂胶，再贴化纤丝网格布，形成抗拉防水层，但切不可忘记在侧面作涂刷处理。 (B) the use of anti-alkali- coating Paint 1. Slate stone before installation in the back and side back Tu-specific treatment agent, the solvent would penetrate stone plug the capillary, so that the water, Ca (OH) 2, salt and other substances can not be penetrated, cut off the way the phenomenon of alkalization. If there is no base coating processing, alkalization is inevitable, the adhesion is not affected by applying the base coating. 2. Apply resin glue on the base of the stone panel, and paste with fiber mesh to form water proof layer. Do not forget to apply the side with the same treatment.（三）减少Ca（OH）2、盐等物质生成 1镶贴用的水泥砂浆宜掺入减少剂，以减少Ca(OH)2析出，粘贴法砂浆稠度宜为68cm，灌浆法砂浆稠度宜为812cm。 2室外镶贴可采用水泥基商品胶粘剂（干混料），它具有良好的保水性，能大大减轻水泥凝结泌水。室内镶贴可采用石材化学胶粘剂点粘。 (C) reduction of Ca (OH) 2, salt and other substances generated 1. Xiangtie used for mixing cement mortar should reduce the dose to reduce the Ca (OH) 2 precipitation and paste France mortar consistency might be desirable for 6 8cm, grouting mortar consistency might be desirable for 8 12cm. 2. Cement-based products can be used outdoors Xiangtie adhesive (dry mixture), which has good water retention, can greatly reduce condensation Bleeding of cement. Stone can be used indoors Xiangtie chemical adhesive sticky point.（四）防止水的侵入 1作业前不可大量对石材和墙面淋水。 2地面墙根下应设置防潮层、卫生间、浴室等用水房间的外壁如有石材装饰，其内壁应需作防渗处理。 3外墙石材装饰面，为防止从板缝侵入，墙面板块必须离缝镶贴，缝宽不应小于5mm，使用石材专用硅硐耐候密封胶密封。 4室外施工搭设防雨蓬，处理好门窗框周边与外墙的接缝，防止雨水渗漏入墙。 5镶贴完成后，室外石材全面积喷涂有机硅防水剂或其他无色护面涂剂。 (D) to prevent water intrusion 1. Do not spray too much water on the stone and the wall. 2. Damp proof membrane should be installed on the wall in the washroom. The wall should be treated with water proofing materials3. For outdoor stone walls, in order to prevent water intrusion from the joint, the wall plate to be away from the seam Xiangtie, Joint should not be less than 5mm, the use of st