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混凝土方面翻译
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12.1.6 Effects at exposed surfaces The microstructures of the surface regions of a concrete differ from that of the bulk material, and are important because they have a major effect on durability. The differences have several origins. Settlement and constraints imposed by the formwork may affect aggregate distribution. Moisture gradients can be created if a surface is exposed to a drying atmosphere, retarding or even stopping hydration in the surface layers, altering the pore structure and facilitating carbonation. Water can be lost by absorption in or leakage through formwork. Patel et al. (P57) moist cured blocks of cement pastes of w/c ratio 0-59 for 7 days and then sealed the prism surfaces of each and exposed the ends to air at 20°C and 65% RH. Methanol sorption data showed that, near the exposed surfaces, the pore structure was markedly coarser and the diffusion time lower. TG evidence showed that less hydration had occurred and that carbonation was increased. These effects were detectable even at a distance of 50 mm from the exposed surface. Further work confirmed the marked effect of RH on hydration rates (P33; Section 7.7.1). Crumbie et al. {CIS) moist-cured concrete specimens with w/c 0 4 and 0-6 in steel moulds for 24 h and then cured them in saturated CH solution for 28 days. Slices from the top, bottom, sides and bulk of each specimen were examined by methanol exchange, quantitative determination of coarse and fine aggregate and backscattered electron imaging in the SEM. The largest variations in the aggregate distribution were in the contents of coarse aggregate in the top 5 mm, which were much reduced, especially in the mix with w/c 0-6, for which the content was almost zero. The methanolexchange data showed that the porosity and permeability increased near to all the surfaces. SEM examination of a section cut perpendicular to the top surface confirmed the increase in porosity, which was about twice as high in the outermost 200 /im as in the bulk. The surface region was also depleted in CH, but the content of anhydrous material was little affected. Despite the fact that the specimens had been placed in saturated CH, some leaching appeared to have occurred. |
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charleygan 
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chlgan
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jianliang3(金币+12,VIP+0):谢谢你的关注，但隔行如隔山，你翻译的与原文意思相差太大，不过也辛苦你了。 10-26 16:54
jianliang3(金币+12,VIP+0):谢谢你的关注，但隔行如隔山，你翻译的与原文意思相差太大，不过也辛苦你了。 10-26 16:54
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12.1.6 裸露表面的影响 混凝土表面区域的微观结构与本体材料很不同，因为对材料的使用寿命有很大影响而显得非常重要。这些差别来源于几个方面：由网状结构引起的沉降和局部区域可能影响材料总的分布。如果表面暴露在干燥气候环境下，会产生潮气，从而会减缓甚至会阻止表面的水合作用，改变空的结构和碳酸化反应，水分可能通过网状结构吸收或遗漏而流失。Patel et al. (P57) 在潮湿环境下固化混凝土样块，w/c 比例0-59，固化7天。然后封住每个棱柱表面，把端部暴露在20°C和相对湿度65%的空气中。甲醇吸附数据显示：在接近表面附近，孔的结构明显变得粗糙，扩散时间变得更短。TG 结果显示：水合作用很少，而碳酸化作用增多。这些影响甚至在表面50mm距离的地方也能检测到。进一步实验确定了相对湿度对水合速度具有显著影响。(P33; Section 7.7.1) Crumbie et al. (CIS) 在潮湿环境下固化混凝土样条，w/c比例分别为 0-4 和 0-6，先在钢模里固化24小时，然后在饱和CH 溶液里固化28天。分别从每个样条的顶部、底部、侧面和本体取出试样，进行甲醇交换实验，用SEM 反向电镜照片定量分析粗糙度和精细结构。结果显示聚集结构分布的最大变化是在表面5mm深处的粗糙程度显著减少，特别是对w/c 比例是0-6的样条，粗糙度几乎为零。甲醇交换数据显示：多空性和渗透性都在表面明显增多。沿着垂直于顶部表面切割出来的截面进行SEM检验，确定了多孔性不断增加，最外层(多空率200/ml)几乎是本体材料的2倍。表面区域也被CH饱和液损坏，但是对无水材料的表面影响很小。尽管所有样条浸泡在饱和CH溶液里，但却出现了一些xx（leaching appeared不知道啥意思）情况。 |
2楼2009-10-26 09:38:30
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jianliang3(金币+8,VIP+0): 10-26 16:54
jianliang3(金币+8,VIP+0): 10-26 16:54
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12.1.6 在裸露表面方面的影响 混凝土表面区域的微观结构与本体材料很不同，因为对材料的耐久性有很大影响而显得非常重要。这些差别来源于几个方面。被模板所加强的沉降和约束可能影响集料的分布。如果表面暴露在干燥气候环境下，就会产生湿度梯度，从而会减缓甚至阻碍表层的水化，改变孔结构和易于碳酸化反应，水分可能通过模板的吸收或渗漏而流失。 Patel et al.(P57) 在潮湿环境下养护水灰比为0.59的水泥浆体试块，养护7天，然后密封每个试块的侧面而将底部暴露在温度为20°C和相对湿度为65%的空气中。甲醇吸附数据显示：暴漏的表面附近，孔的结构明显变得粗糙，扩散时间变得更短。TG 结果显示：水化程度较小，而碳化增大。这些影响甚至在距离暴漏表面50mm地方也能检测到。进一步实验证实了相对湿度对水化速度具有显著影响。(P33; Section 7.7.1) Crumbie et al. (CIS) 湿养护的混凝土试样，水灰比为0.4和0.6，先在钢模具里养护24小时，然后在饱和CH溶液里养护28天。分别从每个样条的顶部、底部、侧面和本体取样，通过甲醇交换，粗细集料的定量测定和在SEM中的背散射电子成像对试样进行检测。在集料分布中的最大的变化是5mm以上的粗集料的含量，它们有很大程度的减少，尤其是在水灰比为0.6的混合浆体中，因为它们的含量几乎为零了。甲醇交换数据显示：孔隙率和渗透性都在接近表面的地方增大。从垂直于上表面切割出来的截面的SEM检验，真实了孔隙率的增加，在最外层200μm的孔隙率大约是内部的2倍。表面区域的CH也被大大地减少，但是无水材料的含量受到的影响很小。尽管样条被置于饱和CH溶液中，但也发生了一些浸析作用。 |
3楼2009-10-26 16:50:47