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2008年全国材料员考试真题及答案

2015-04-17 17:10:00 来源:无忧考网

2008年全国材料员考试真题及答案

名词解释 (每题2分,共12分)
  吸湿性是指材料在潮湿空气中吸收水分的性质。 吸湿性是指材料在潮湿空气中吸收水分的性质。
  水硬性胶凝材料是指不但能在空气中硬化,还能更好的在水中硬化,保持并继续增长其强度的胶凝材料。
  水泥石腐蚀是在一些腐蚀性介质中,水泥石的结构会遭到破坏,强度和耐久性降低,甚至完全破坏的现象。
  混凝土拌合物离析是指混凝土拌和物由于密度和粒径不同,在外力作用下组成材料的分离析出的现象。
  钢材的屈强比是反映钢材的可利用率和安全性的大小。
  沥青混合料流值是指达到破坏荷重时沥青混合料试件的垂直变形。
  判断题 (对的划√,不对的划×, 每题1分,共15分)

  
  √ 2. × 3. × 4.√ 5. × 6. √ 7. × 8. × 9. × 10. × 11. × 12. × 13. × 14. √ 15.√
  填空题 ( 每题1分,共25分)
  390min , 10h
  3CaO·SiO2 +H2O → 3CaO·2SiO2 ·3H2O+Ca(OH)2, Ca(OH)2, 3CaO·2SiO2 ·3H2O
  水泥质点表面电性 、溶剂化膜使滑动能力增加,分散度提高,流动性和强度增加
  填充、润滑,胶结
  70.7mm × 70.7mm × 70.7mm,标准, 28d,抗压,强度等级
  砌体种类,施工条件
  脆性临界温度以下,降低 ,冷脆性
  粘度、延度、 软化点
  问答题 (共30分)
  after hardening, cement structure development can be divided into three periods: early period, middle period and late period. Various mineral compositions in Portland cement (熟料)will interact with each other and produce hydrates. As hydrates increases, the pores between cement particles will be infilled meanwhile calcium hydroxide crystal and calcium aluminates hydrate crystal flow between calcium silicate hydrate gels. Then it forms the cement with certain strength and moves to the hardening phase (5分)

  (1) Concrete mixture mobility sets slump and Vebe Consistometer as its index. Slump is used for larger mobility concrete mixture while Vebe Consistometer is used for dry and hard concrete mixture.(4分)

  (2) It is recommended to select smaller slump for cement efficiency and high quality concrete under the principle of construction feasibility and dense vibration. In construction the concrete mixture slump is decided upon the component cross section, supporting steel spacing and construction method. It is recommended to select larger slump when the cross section is small or the supporting steel spacing is wider or the concrete mixture is mixed by manual vibration, otherwise smaller slump is recommended when the cross section is larger or the supporting steel spacing is narrower or the concrete mixture is mixed by machine vibration. (6分)

  (1) When mixed with fixed amount of cement, there will be small W/C and dry concrete with small slump, so it is hard to form dense shapes. If W/C is lower, the concrete is easy to be broken and has poor performance in viscidity so that the hardened concrete strength and durability will reduce. If W/C is higher, the concrete not only has thin concentration and larger slump but it is easy to segregate, laminate and bleed as well, therefore the hardened concrete strength and durability will reduce. With proper W/C the concrete can be formed into dense and uniform shapes. (5分)

  (2) Concrete strength depends on W/C on the condition of the same cement type and strength degree. Within the certain range of W/C (the concrete can be formed into dense shapes.), the lower W/C, the higher the compressive strength becomes. As W/C becomes lower (the concrete can not be formed into dense shapes.), the porosity will become larger and the strength will reduce. As W/C becomes higher, the strength will reduce.(5分)

  The following measures can be taken to produce the high strength concrete

  (1) use high strength cement(1分)
  (2) set smaller W/C(1分)
  (3) use machine mixing and vibrating for formation(1分)
  (4) process at high temperature and hunidity(1分)
  (5) use admixture (1分)

  计算题
  解:设该材料干燥状态得质量为 m ,则有
  ρ = m/ V (1)
  ρ0 = m/ V0 (2)
  mw = m水 × 100 % /m (3)
  由式( 1 )和( 2 )得: V孔 = V0 -V=m (ρ - ρ0 ) /ρ0 ρ
  由式( 3 )得: V开 = V水 = m mw / ρ 水
  所以, V开 / V孔= (1 %× 2.56 × 2.65)/(5.65-2.56)
  = 0.75
  V闭 / V孔 = 1-0.75 = 0.25
  该岩石中开口孔隙与闭口孔隙所占的比例分别为 0.75 和 0.25 。(5分)

  解: 1 立方米 拌合物需水泥的量为 C ,按假定体积法有:
  C/3.10+ 0.6C + 2.20C /2.60+ 4.20C /2.50+10=1000
  所以, C= 287kg ; W= 172kg ; S= 631kg ; G = 1205kg 。
  每立方米拌合物所需各材料用量为: C= 287kg ; W= 172kg ; S= 631kg ; G = 1205kg 。 (6分)

  解:按试验室配合比, 1m3混凝土中各种材料得用量为:
  C= 300Kg ; W = 300 × 0.56 = 168Kg ; S = 300 × 1.92 = 576Kg ; G = 300 × 3.97 = 1191Kg ;
  所以,施工配合比为:
  C= 300Kg ; W = 168-576 × 5 % -1191 × 1 %= 127Kg ;
  S = 576 ×(1 + 5 %)= 605Kg ; G = 1191 × (1+1 %) = 1203Kg ;
  施工配合比为: C= 300Kg ; W = 127Kg ; S = 605Kg ; G = 1203Kg 。 (7分)

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