【正文】
below(舉例說明如下) : (a) Concretes made with lightweight aggregates。 (b) Aerated concretes (US gas concretes) foamed(起泡) by whisking(攪拌) or by some chemical process during casting。 (c) Nofines concretes. 另一個例子是輕質混凝土,如今已在全世界快速地發(fā)展,因它們的絕熱性而被采用,其三種類型舉例說明如下: (a)輕質骨料制成的混凝土; (b)通過澆筑時攪拌或一些化學方法起泡而成的加氣混凝土( US加氣混凝土); (c)無細骨料混凝土。 All three types are used for their insulating properties(絕熱性) , mainly in housing, where they give high(非常) fort in cold climates and a low cost of cooling(降溫成本) in hot climates. In housing, the relative weakness of lightweight concrete walls is unimportant, but it matters(有重大關系) in roof slabs, floor slabs and beams. 這三種類型的混凝土都是由于它們的絕熱性而被使用,主要用于房屋,使其在寒冷的氣候中非常舒服,在炎熱的氣候中降溫的成本不高。在房屋中,墻采用較薄弱的輕質混凝土不重要,但是屋面板、樓面板和梁(采用輕質混凝土)則有重大關系。 In some locations, some lightweight aggregates cost little more than(幾乎等于) the best dense(致密) aggregates and a large number of (大量) floor slabs have therefore been built of lightweight aggregate concrete purely for its weight saving, with no thought of(沒考慮) its insulation value. 在某些地區(qū),一些輕質骨料的費用幾乎等于最致密的骨料,因此大量的樓面板采用輕骨料混凝土制作純粹是節(jié)約重量,而沒考慮它的絕熱價值。 The lightweight aggregate reduces the floor dead load(恒載) by about 20 per cent resulting in(導致)considerable savings in the floor(樓蓋結構) steel in every floor and the roof, as well as in the column steel and (less) in the foundations. One London contractor(承包商) prefers to use lightweight aggregate because it gives him the same weight reduction in the floor slab as the use of hollow tiles, with simpler anization and therefore higher speed and profit. The insulation value of the lightweight aggregate is only important in the roof insulation, which is greatly improved(改進) . 輕質骨料使樓面的恒載減少了約 20%,因而大量的節(jié)約了每層樓面以及屋面的樓蓋結構中的鋼材和柱子與基礎中(較少)的鋼材使用量。一位倫敦的承包商寧愿使用輕質骨料,因為這使樓面板上減少的重量與用空心磚相同,且組織更簡單,因而速度和利潤更高。輕質骨料的絕熱價值只在屋面絕熱時顯得重要,它已被大大地改進了。 作業(yè)練習 通過兩篇 Reading Materials 的學習,進一步了解建筑材料中最常用的混凝土材料的一些特點、種類和性能等,從而更多地掌握一些專業(yè)詞匯和句法。