土木工程專業(yè)英語翻譯總匯

1、浙江大學(xué)寧波理工學(xué)院2012-2013學(xué)年第II學(xué)期土木工程專業(yè)英語開課分院： 土木建筑工程分院 學(xué)生姓名： 賀宇寧3110621132 指導(dǎo)教師： 毛江鴻 完成日期： 2014-5-31 ABSTRACTWe report here, for the rst time in the literature, a method to synthesize hydrophobic and super-hydrophobic concrete. Concrete is normally a hydrophilic material, which signi cantly reduces the du

2、rability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (S

3、F) to induce the microroughness and polyvinyl alcohol (PVA) bers to create hierarchical surfaces. Various emulsion types were investigated by using di erent mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical m

4、icroscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-o angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the e ect of

5、 surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA bers treated with MK based emulsion. Since water penetration is the main factor leading to concrete

6、 deterioration, hydrophobic water- repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering.INTRODUCTION Fabrication of hydrophobic concrete is a very important task for many applications. Concrete, a mixture

7、 of portland cement as binder and water as well as aggregates as fillers, is a porous material with pores ranging in size from nanometers to millimeters. There are various pore types within the cement hydration products, including entrapped and entrained air voids up to a few millimeters in diameter

8、, capillary pores in a range of a few micrometers in diameter, and nanoscale gel pores. In most applications, the concrete surface is subjected to external erosion, abrasion, and environmental exposure to aggressive liquids, such as water, mineral solutions, oil, solvents, etc. When dry concrete com

9、es into contact with a liquid such as water,most of the water is absorbed by the pores due to the capillary forces. The capillary forces are dependent on the surface tension of the liquid (typically water), its contact angle (CA) with the pore walls, and the radius of the pores.The durability(i.e.,

10、freezethaw and sulfate attack) of concrete depends on its overall absorption and permeability to aqueous solutions. For example, freezethaw damage occurs when water in saturated concrete freezes due to temperature fluctuations, causing considerable stresses within the material. The cumulative effect

11、 of freezethaw cycles eventually causes expansion, cracking,scaling, and crumbling of the concrete. It is therefore crucial to synthesize water-repellent concrete in order to increase its durability, and, in particular, to produce the ultradurable concrete.The apparent CA is the principal parameter

12、which characterizes the wetting properties of the surface.When the CA is greater than 90°, it indicates the hydrophobicity, while the CA less than 90° shows the hydrophilicity, which is the tendency of a surface to become wet or to absorb water, as shown in Figure 1. Common concrete is hyd

13、rophilic. The super-hydrophobicity corresponds to an apparent CA between 150 and 180°. Furthermore, not only a high apparent CA but also a low hysteresis of contact angle is necessary for true super-hydrophobicity.CA hysteresis is the difference between the advancing and receding CA and serves

14、as a measure of adhesion between water and the solid substrate. Adhesion under various modes of loading can also be measured with the centrifugal adhesion balance.The surfaces that are not quite superhydrophobic but exhibit a high CA between 120 and 150°, which is above typical values for hydro

15、phobic materials, are sometimes called“over-hydro-phobic”. The water CA with a solid surface can be measured by a goniometer or tensiometer. The CA of a water droplet on a smooth solid surface, 0, can be calculated by using the Young equation where SW, SA, and WA are the solidwater, solidair, and wa

16、terair interfacial energies, respectively.However, in practice, the surfaces are not quite smooth and usually possess micro- and nanoroughness. Two analytical models explaining the roughness effect on wetting properties ofthe surfaces were proposed by Wenzel and CassieBaxter. According to the Wenzel

17、 model, wetting is homogeneous because water fills all pores and cavities at the surface (Figure2a). This model states that roughening a hydrophobic solid surface enhances its hydrophobicity by increasing the surface area:where Rf is the roughness factor (the ratio of the real substrate area to its

18、projected area) and is the CA on the rough surface.However, according to the CassieBaxter model, air can be trapped in cavities and the wetting is heterogeneous.In other words, in the CassieBaxter state, a composite interface of solidwaterair can be formed which increases the water repellency of the

19、 surface due to partial contact area of water droplet with air. The CA is given bywhere fSW is the solidwater fractional area.摘要：我們首次在文獻(xiàn)中報(bào)告，一種合成疏水和超疏水性的混凝土的方法?；炷镣ǔＪ怯H水性材料，它顯著降低混凝土結(jié)構(gòu)和路面的耐久性。以合成的防水混凝土，疏水乳液制備和應(yīng)用上的波特蘭水泥砂漿的瓷磚。將乳液富含的聚甲基氫硅氧烷油的疏水劑以及偏高嶺土（MK）或硅灰（SF）以誘導(dǎo)微粗糙度和聚乙烯醇（PVA）纖維，以建立分層的表面。各種乳液類型分別采用不同的混合

20、方法研究，以及單和雙層疏水涂層被應(yīng)用。乳劑和涂層，其特征在光學(xué)顯微鏡和掃描電子顯微鏡（SEM），其潤濕性能，包括對(duì)水的接觸角（CA）和滾動(dòng)角，進(jìn)行了測(cè)定。它被開發(fā)用于涂覆和未涂覆的具體的理論模型，這可以推廣到其它類型的材料，來預(yù)測(cè)表面粗糙度和組合物的CA上的效果。骨料經(jīng)優(yōu)化后的距離被發(fā)現(xiàn)那里的CA具有最高的價(jià)值。測(cè)得的最大的CA為156°，與MK基乳液處理過的PVA纖維試樣。由于水的滲透是導(dǎo)致混凝土劣化的主要因素，疏水防水混凝土具有更長的耐久性然后定期混凝土，可以有廣泛的應(yīng)用在土木工程和材料工程。 引言疏水性混凝土的制造是一個(gè)非常重要的任務(wù)。硅酸鹽水泥，粘合劑和水組成的聚集體作為混凝

21、土混合物的填料，是具有孔尺寸從納米到毫米的多孔材料。有水泥水化產(chǎn)物內(nèi)的各種孔隙類型，包括截留和夾帶的空氣空隙高達(dá)數(shù)毫米的直徑，毛細(xì)管孔的范圍為幾微米的直徑，和納米凝膠的孔隙。在大多數(shù)應(yīng)用中，混凝土表面進(jìn)行外部侵蝕，磨損和環(huán)境暴露于侵蝕性的液體，例如水，礦物溶液，油，溶劑等干燥時(shí)混凝土接觸到的液體，例如水接觸時(shí)，多數(shù)的水通過毛細(xì)管力的氣孔吸收。毛細(xì)管力依賴于液體（通常是水），它的孔壁上的接觸角（CA），和孔的半徑的表面張力?；炷恋哪途眯裕?，凍融和硫酸鹽侵蝕）取決于它的整體吸收和透氣性，比如水溶液，當(dāng)水在飽和的混凝土里結(jié)冰時(shí)，由于溫度波動(dòng)，在材料內(nèi)產(chǎn)生相當(dāng)大的應(yīng)力的發(fā)生，例如，凍融損害。凍融循環(huán)的累積效應(yīng)最終導(dǎo)致混凝土的膨脹，開裂，脫屑，和搖搖欲