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or signifying the concrete with high work degree, high strength and high durability beginning. This kind of concrete must be designed and possessed high volume stability. For reduce concrete shrink and do fracture produced to contract with temperature, must limit the grout content in the concrete mixture. The highperformance concrete amount of total grout limited of design method of match ratio that Mehta and Actcin put forward is 1/3 of the concrete volume。 Allow some silicate cement spend volcanic ash or have glue person who congeal to mix, shut material replace. AcTcin has been prophesied: Mix slay, fly ash, silica flour, inferior clay, the rice husks dust and three yuan of the lime stone powder and mix cement besides can make the preparation of the highperformance concrete more economic ing, still can give play to exceeding a pile of function of them, improve its property while mixing and hardening newly. performance concrete in modern engineering High performance concrete technology is successfully used in many parts of the world of offshore structures and grew up across the bridge construction, Langley, who described growing up across a few bridges in Canada with the are used in the girder, mound department and mound base, it is 450 Kg/m3 that silica flour mix cement consumption, water 153L/ m3, guide angry pharmaceutical 160mL/ m3 and highefficient waterreducing agent 3L/ m3. Its slump is probably in 200mm。 Toronto39。 g. Applications (1) in the . about 70% of the road pavement using highperformance concrete: one in North Dakota, 1988 and 1989 in the summer, with 20200m3 of concrete paving thickness of 200 mm of the surface, its watercement ratio of , cement consumption 100 Kg/m3, fly ash 220 Kg/m3。挪威于 1986年首先對(duì)此進(jìn)行了研究,在 1990年由美國(guó)國(guó)家標(biāo)準(zhǔn)與技術(shù)研究院( NIST)與美國(guó)混凝土學(xué)會(huì)( ACI)共同主辦的一次研討會(huì)上正式定名。近年來(lái),美國(guó)混凝土學(xué)會(huì)又給出一個(gè)文字上較精練的定義: “ 高性能混凝土是一種要能符合特殊性能綜合與均勻性要求的混凝土,此種混凝土往往不能用常規(guī)的混凝土組分材料和通常的攪拌、澆搗和養(yǎng)護(hù)的習(xí)慣做法所獲得。其坍 落度大約在 200mm;含氣量 %; 1d、 3d、 28d 抗壓強(qiáng)度分別為 3 52和 82 MPa;基礎(chǔ)和其他大塊混凝土的混合水泥用量為 307 Kg/m3,粉煤灰 133 Kg/m3,用水量接近,但引氣劑和高效減水劑摻量大幅度減小,坍落度約在 185mm;含氣量 7%; 1d、 3d、 28d 和 90d抗壓強(qiáng)度分別為 50和 76 MPa。 芝加哥 79層的 Water Tower Place 大樓柱子采用了 60MPa 混凝土;多倫多的 Scotia Plaza Building 和西雅圖的 Two union Square Building 兩座建筑物則分別有 90 和 120MPa 強(qiáng)度的高性能混凝土柱子。使用高性能道面混凝土可以顯著提高道面的承載能力,延長(zhǎng)使用壽命或減薄道面的厚度以降低 工程 造價(jià)。 如: a 汕頭港外深水航道治理工程; b 珠江口伶仃洋深水航道治理工程; c 青島、寧波北侖等港口建成了能靠泊二十萬(wàn)噸級(jí)油輪和礦石船的深水泊位 免振自密實(shí)混凝土 由于免振自密實(shí)混凝土具有十分良好的工作性,使混凝土的填充性、密實(shí)性、均勻性得到顯著的提高,成為混凝土技術(shù)的一項(xiàng)新的進(jìn)展而被列為高性能混凝土一族。新拌免振自密實(shí)混凝土要在沒有外力作用下充分填實(shí)混凝土模板中的一切空隙并達(dá)到密實(shí),更是要兼具良好的流動(dòng)性與穩(wěn)定性。對(duì)于漿體而言,除了要求具有高流動(dòng)性外,還需具有足夠的高粘度,必須成為高粘性的牛頓液體,才能防止離析。 高性能混凝土在性能上尚存在的問題及其改善的途徑 配制高性能混凝土的特點(diǎn)是低水膠比并摻有足夠數(shù)量的礦物細(xì)摻合料和高效減水劑,從而使混凝土具有綜合的優(yōu)異的技術(shù)特性,但由此也產(chǎn)生了兩個(gè)值得重視的性能缺陷:( 1)自干燥引起的自收縮;( 2)脆性。水灰比基本上按所需的混凝土抗壓強(qiáng)度來(lái)確定。其流變性質(zhì)是按流變學(xué)的賓漢姆型用粘度計(jì)來(lái)評(píng)定的,應(yīng)具有低的屈服應(yīng)力和適當(dāng)?shù)乃苄哉扯取? 根據(jù)上述三個(gè)特性的要求,免振自密實(shí)混凝土配制的原理與方法 描 述如下: 新拌混凝土的物相屬粒子懸浮體,其連續(xù)介質(zhì)是水泥漿體,也就是液相而混凝土中的集料則為固相。 (2) 青藏鐵路建設(shè)工程中全面推廣使用 三個(gè)強(qiáng)度級(jí)別的高性能道面混凝土具有極其優(yōu)良的品質(zhì),材料費(fèi)用基本不增加或增加不多,可供不同要求的工程選擇使用,建造長(zhǎng)壽命低維護(hù)的道面、路面,其社會(huì)、 經(jīng)濟(jì) 效益是巨大的,值得大力推廣和不斷研究,促進(jìn)我國(guó)機(jī)場(chǎng)水泥混凝土道面工程和公路路面工程步入新的發(fā)展階段,以適應(yīng)日益增長(zhǎng)的對(duì) 航空 和 交通 運(yùn)輸?shù)男?要。提高混凝土道面表面的致密性、抗?jié)B性都是很重要的,而這是需要通過高性能混凝土來(lái)實(shí)現(xiàn)的。 采用摻 10~15%硅粉甚至更高的混合水 泥配制的超塑化混凝土,具有優(yōu)良的粘附力,因此適用于濕噴的噴射混凝土進(jìn)行結(jié)構(gòu)修補(bǔ),這也是高性能混凝土的應(yīng)用領(lǐng)域之一 . 高性能混凝土在高層建筑中的應(yīng)用 高性能混凝土( 40MPa)首先用于 30層以上高層建筑物的鋼筋混凝土結(jié)構(gòu),因?yàn)檫@種建筑物下部三分之一的柱子,在用普通混凝土?xí)r斷面很大。 濰坊學(xué)院本科畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 10 高性能混凝土在現(xiàn)代工程中的應(yīng)用 高性能混凝土技術(shù)正在世界各地成功地用于很多離岸結(jié)構(gòu)物和長(zhǎng)大跨橋梁的建造,Langley 等人敘述了幾種加拿大一長(zhǎng)大跨橋梁所用的拌合物。十多年來(lái),世界上許多國(guó)家相繼投入了大量的人力、財(cái)力、物力進(jìn)行該項(xiàng)研究與開發(fā)應(yīng)用,使高性能混凝土技術(shù)取得了很大的進(jìn)展,在原料的選擇、配合比設(shè)計(jì)、 物理 力學(xué)性能、耐久性、工作性、結(jié)構(gòu)性能以至應(yīng)用技術(shù)等方面都取得了既有理論基礎(chǔ)又有實(shí)用價(jià)值的科技成果。 (3) Reinforcement and templates in any gap, with a good through capacity, does not produce blocking. According to the requirements of these three characteristics, vibrationfree preparation of selfpacting concrete principles and methods section are as follows: Fresh concrete phase is a particle suspended solids, the continuous medium is a cement paste, which is liquid and Concrete Aggregates, pared with solidphase. All the particles in suspension, mobility and particle balance between segregation is necessary. Free vibration of fresh selfpacting concrete in the absence of external force to be real concrete formwork to give full fill all the gaps and achieve the pact, more importantly, to both good fluidity and stability. In order to obtain high mobility, we must first reduce the friction between the particles. Incorporation of superplasticizer to reduce the surface tension of particles of course is necessary, but vibrationfree performance requirements of selfpacting of view, alone doped superplasticizer was also difficult to achieve, needs to mixed with a certain amount of ultrafine material. To obtain good stability, so that materials are not disintegrate, the liquid must have the appropriate rheology, can not produce bleeding and prevent particle segregation. To achieve this request, also be mixed with an appropriate amount of particle size fine