名詞解釋 (每題2分,共12分)
吸濕性是指材料在潮濕空氣中吸收水分的性質(zhì)。 吸濕性是指材料在潮濕空氣中吸收水分的性質(zhì)。
水硬性膠凝材料是指不但能在空氣中硬化,還能更好的在水中硬化,保持并繼續(xù)增長(zhǎng)其強(qiáng)度的膠凝材料。
水泥石腐蝕是在一些腐蝕性介質(zhì)中,水泥石的結(jié)構(gòu)會(huì)遭到破壞,強(qiáng)度和耐久性降低,甚至完全破壞的現(xiàn)象。
混凝土拌合物離析是指混凝土拌和物由于密度和粒徑不同,在外力作用下組成材料的分離析出的現(xiàn)象。
鋼材的屈強(qiáng)比是反映鋼材的可利用率和安全性的大小。
瀝青混合料流值是指達(dá)到破壞荷重時(shí)瀝青混合料試件的垂直變形。
判斷題 (對(duì)的劃√,不對(duì)的劃×, 每題1分,共15分)
√ 2. × 3. × 4.√ 5. × 6. √ 7. × 8. × 9. × 10. × 11. × 12. × 13. × 14. √ 15.√
填空題 ( 每題1分,共25分)
390min , 10h
3CaO·SiO2 +H2O → 3CaO·2SiO2 ·3H2O+Ca(OH)2, Ca(OH)2, 3CaO·2SiO2 ·3H2O
水泥質(zhì)點(diǎn)表面電性 、溶劑化膜使滑動(dòng)能力增加,分散度提高,流動(dòng)性和強(qiáng)度增加
填充、潤(rùn)滑,膠結(jié)
70.7mm × 70.7mm × 70.7mm,標(biāo)準(zhǔn), 28d,抗壓,強(qiáng)度等級(jí)
砌體種類,施工條件
脆性臨界溫度以下,降低 ,冷脆性
粘度、延度、 軟化點(diǎn)
問答題 (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)
計(jì)算題
解:設(shè)該材料干燥狀態(tài)得質(zhì)量為 m ,則有
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開 = V水 = m mw / ρ 水
所以, V開 / V孔= (1 %× 2.56 × 2.65)/(5.65-2.56)
。 0.75
V閉 / V孔 = 1-0.75 = 0.25
該巖石中開口孔隙與閉口孔隙所占的比例分別為 0.75 和 0.25 。(5分)
解: 1 立方米 拌合物需水泥的量為 C ,按假定體積法有:
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為: C= 287kg ; W= 172kg ; S= 631kg ; G = 1205kg 。 (6分)
解:按試驗(yàn)室配合比, 1m3混凝土中各種材料得用量為:
C= 300Kg ; W = 300 × 0.56 = 168Kg ; S = 300 × 1.92 = 576Kg ; G = 300 × 3.97 = 1191Kg ;
所以,施工配合比為:
C= 300Kg ; W = 168-576 × 5 % -1191 × 1 %= 127Kg ;
S = 576 ×(1 + 5 %)= 605Kg ; G = 1191 × (1+1 %) = 1203Kg ;
施工配合比為: C= 300Kg ; W = 127Kg ; S = 605Kg ; G = 1203Kg 。 (7分)