判断题 （对的划√，不对的划×， 每题1分，共15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）
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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