简介：Oneofthechiefmaterialsusedintheconstructionofbuildingsandroadsiseement(水泥),apowdermademainlyfromlimestone(石灰石)andclay(粘土).EventheancientEgyptiansandRomans(罗马人)usedakindofcement,butitwasnotuntil1824thatanEnglishbricklayer(泥瓦匠)developedacementstrongenoughformodemroadsandbuilding.
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