毕业的设计参考英文文献.docVIP

参考外文资料原文及译文 学院（部）： 材料科学与工程学院 专业班级： 无机非金属08-2 学 号： 2008300178 学生姓名： 夏雪宜 指导教师： 王庆平副教授 2012年 0月 日 Portland Cement Portland cement is made by heating a mixture of limestone and clay ,or the other materials of similar bulk composition and sufficient reactivity ,ultimately to a temperature of about 1450℃. Partial fusion occurs ,and nodules of clinker are produced .The clinker is mixed with a few percent of calcium sulfate and finely ground ,to make the cement .The calcium sulfate controls the rate of set and influences the rate of strength development .It is commonly descried as gypsum ,but this may be partly or wholly replaced by other forms of calcium sulfate .Some specifications allow the addition of other materials at the grinding stage .The clinker typically has a composition in the region of 67%CaO ,22%SiO2 ,5%Al2O3 ,3%Fe2O3 and 3% other components ,and normally contains four major phases ,called alite , belite ,aluminate and ferrite .Several other phases ,such as alkali sulfates and calcium oxideare normally present in minor amounts .Hardening results from reactions between the major phases and water . Alite is the most important constituent of all normal Portland cement clinkers ,of which it constitutes 50%～70% .It is tricalcium silicate (Ca3SiO5) modified in composition and crystal structure by ionic substitutions .It reacts relatively quickly with water ,and in normal Portland cement is the most important of the constituent phases for strength development ;at ages up to 28 days ,it is by far the most important . Belite constitutes 15%～30% of normal Portland cement clinkers .It is dicalcium silicate(Ca2SiO4) modified by ionic substitutions and normally present wholly or largely as the βpolymorph .It reacts slowly with water ,thus contributing little to the strength during the first 28 days .But substantially to the further increase in strength that occurs at later a