《国际工程英语》课件Structural Material--Concrete.ppt

must be free of harmful substances, esp. organic material, clay, and salts water suitable for drinking ⑶ Water ⑷ Admixtures ① Air-Entraining Admixtures ② Water-Reducing Admixtures ③ Accelerating Admixtures ④ Fly Ash ⑤ Silica Fume ⑥ Blast Furnace Slag Air-Entraining Admixtures Water-Reducing Admixtures Accelerating Admixtures Fly Ash Silica Fume Blast Furnace Slag 2. Properties ⑴ Workability the ease or difficulty fluidity (thick or thin; amount of water) cohesiveness (homogeneity; proportion of C.M. and sand) water retention (stability, type of cement) ⑵ Compressive Strength the maximum compressive load (per unit area) the crushing strength of concrete 3 days, 7 days and 28 days ⑶ Tensile Strength weak in tensile strength steel bars (reinforcement) ⑷ Durability of Concrete resist the influence of exterior corrosive substance maintain good usability and complete appearance ① Anti-Permeability ② Freezing Resistance ③ Carbonation / Neutralization ④ Alkali-Aggregate Reaction 3. Varieties ⑴ High Density Concrete apparent density (表观密度) 3360-3840 kg/m3 (unit weight) 50 percent higher ⑵ Light Weight Concrete 2200-2500 kg/m3 (unit weight) ① Light Weight Aggregate Concrete natural and artificial light weight aggregate ② Aerated Concrete gas or air bubbles ③ No-Fines Concrete only coarse aggregate (10-20 mm); less cement for pipe ⑶ Polymer Concrete pre-polymer with cement as the cementing materials rubber ⑷ Fiber Reinforced Concrete FRC fiber (act as crack arrester) to improve the tensile strength (twice) steel fibers & glass steel fiber ⑸ Ultra High Performance Concrete UHPC RPC (Reactive Powder Concrete 活性粉末混凝土) 3 “High”: durability, workability, compressive strength (six to eight times) no coarse aggregate; silica fume & fibers; more cement a quarry ⑸ Steel one of the most useful of structural materials high strength and elastic; easily to be rusted (must be painted to prevent rusting) ⑹ Plastic some hard and brittle, others soft and exte