本文選題：超高性能混凝土 + 礦物摻合料�。� 參考：《東南大學(xué)》2017年博士論文

【摘要】：超高性能混凝土(Ultra-High Performance Concrete, UHPC)是一種新型的土木工程材料,與普通混凝土相比,具有極其優(yōu)異的力學(xué)性能和耐久性能,不僅可作為新型的特殊構(gòu)件,也可以應(yīng)用于基礎(chǔ)設(shè)施的維護(hù)與加固工程。然而傳統(tǒng)的UHPC在實(shí)際工程中并未得到廣泛應(yīng)用,其中主要原因之一是該配合比中只含有大量的水泥(1100-1300 kg/m3) 和硅灰 (200-350 kg/m3) , 使得其生產(chǎn)成本極其昂貴; 并且水泥和硅灰的有效利用率僅為30-40%,這極大地浪費(fèi)了資源和能源。因此利用礦物摻合料取代傳統(tǒng)UHPC配合比中的部分水泥或硅灰,是解決UHPC高成本和高能耗的有效方法之一。然而目前缺乏不同礦物摻合料對(duì)UHPC宏觀性能與微觀機(jī)理的系統(tǒng)性研究,這嚴(yán)重制約了生態(tài)型UHPC的研究與應(yīng)用進(jìn)展。本文針對(duì)上述問(wèn)題,應(yīng)用多種現(xiàn)代測(cè)試技術(shù),系統(tǒng)性地研究了石灰石粉、F級(jí)與C級(jí)粉煤灰、�；郀t礦渣、偏高嶺土與煅燒粘土對(duì)UHPC的宏觀性能、水泥水化和微結(jié)構(gòu)演變的影響。試驗(yàn)研究揭示了:(1)石灰石粉和C級(jí)粉煤灰能夠改善UHPC基體的工作性,降低混凝土的粘度,F級(jí)粉煤灰在超過(guò)一定摻量下會(huì)降低混凝土的流動(dòng)性。�；郀t礦渣和煅燒粘土的應(yīng)用增加了混凝土的粘稠性,降低混凝土的工作性。(2)礦物摻合料的應(yīng)用會(huì)降低單位體積內(nèi)水泥的含量,改變UHPC體系內(nèi)有效水灰比w/c值的大小。過(guò)高摻量的礦物摻合料會(huì)顯著提高w/c,使得體系中缺乏足夠的水泥參與水化反應(yīng),混凝土在后期水化中缺乏足夠的C-S-H凝膠;礦物摻合料取代量過(guò)低時(shí),仍然有大量的水泥未得到有效利用。UHPC體系中水泥含量與總水量需要保持合適的平衡關(guān)系,滿足“完全水化理論”有效w/c值,即0.4左右。滿足該平衡關(guān)系且拌合物工作性較好的UHPC基體,在常溫密封養(yǎng)護(hù)條件下,56天的抗壓強(qiáng)度均能達(dá)到150 MPa左右,例如摻加石灰石粉、F級(jí)粉煤灰和C級(jí)粉煤灰的UHPC抗壓強(qiáng)度值分別為 169.6 MPa、167.4 MPa 和 142.9 MPa。(3) F級(jí)粉煤灰的火山灰反應(yīng)和�；郀t礦渣的水硬性反應(yīng)對(duì)水泥水化的影響較小,然而C級(jí)粉煤灰和鍛燒粘土(特別是偏高嶺土)中可以溶解出大量的鋁離子,在孔溶液中形成大量的鈣礬石AFt和單碳型碳鋁酸鹽AFm-Mc,消耗了體系中大量的自由水。該化學(xué)反應(yīng)與水泥水化產(chǎn)生了對(duì)自由水的競(jìng)爭(zhēng)關(guān)系,水泥的水化受到嚴(yán)重的抑制,這也影響了體系中Ca(OH)2的生成與消耗。石灰石粉的化學(xué)活性取決于UHPC體系中可溶解性鋁離子的含量,CaC03與鋁離子反應(yīng)生成AFm-Mc。鈣礬石和單碳型碳鋁酸鹽相的大量形成能夠顯著降低UHPC的孔隙率,然而對(duì)于摻加C級(jí)粉煤灰的UHPC,由于生成的鈣礬石尺寸較大,與硅灰和水泥水化產(chǎn)物相互混合,對(duì)孔結(jié)構(gòu)的細(xì)化作用并不明顯,但是對(duì)于摻加煅燒粘土的UHPC,由于顆粒堆積體系不同,孔結(jié)構(gòu)一定程度上得到細(xì)化。(4)選擇合適的礦物摻合料取代水泥或硅灰,不僅能夠維持UHPC極其優(yōu)異的力學(xué)性能,提高材料的使用效率,還能改善混凝土的流變性能,降低高效減水劑的使用量,這有助于降低UHPC整體的生產(chǎn)成本和CO2排放量,有利于UHPC的大規(guī)模普及利用和可持續(xù)發(fā)展。
[Abstract]:Ultra-High Performance Concrete (UHPC) is a new kind of civil engineering material. Compared with ordinary concrete, it has excellent mechanical properties and durability. It can be used not only as a new special component, but also in the maintenance and reinforcement engineering of infrastructure. However, the traditional UHPC is in practical engineering. One of the main reasons is that one of the main reasons is that the mixture contains only a large amount of cement (1100-1300 kg/m3) and silica fume (200-350 kg/m3), which makes the production cost extremely expensive; and the effective utilization of cement and silica fume is only 30-40%, which is a great wave of resources and energy. Therefore, the mineral admixture is used instead of the mineral admixture. The traditional UHPC mix proportion cement or silica fume is one of the effective methods to solve the high cost and high energy consumption of UHPC. However, there is a lack of systematic research on the macro and micro mechanism of UHPC with different mineral admixtures, which seriously restricts the progress of the research and application of ecotype UHPC. Test techniques systematically studied the effect of limestone powder, F grade and C grade fly ash, granulated blast furnace slag, high ridge soil and calcined clay on the macro properties of UHPC, cement hydration and microstructure evolution. (1) lime stone powder and C grade fly ash can improve the working property of UHPC matrix, reduce the viscosity of concrete, and F grade pulverized coal. The application of granulated blast furnace slag and calcined clay increases the consistency of concrete and reduces the workability of concrete. (2) the application of mineral admixtures will reduce the content of cement in the unit volume and change the w/c value of the effective water cement ratio in the UHPC system. The admixture will significantly increase the w/c, which makes the system lack enough cement to take part in the hydration reaction, and the concrete lacks sufficient C-S-H gel in the later hydration. When the mineral admixture is too low, a large number of cement still has not been used effectively in the.UHPC system to maintain a proper balance between the cement content and the total water content. The effective w/c value of complete hydration theory, that is about 0.4, is about 0.4. The UHPC matrix that meets the balance and the working property of the mixture can reach about 150 MPa at 56 days under the condition of normal temperature sealing. For example, the UHPC compressive strength of F grade fly ash and C grade fly ash is 169.6 MPa, 167.4 MPa and 142, respectively. The volcanic ash reaction of.9 MPa. (3) F grade fly ash and the hydration of granulated blast furnace slag have little effect on the hydration of cement. However, a large amount of aluminum ions can be dissolved in C grade fly ash and calcined clay (especially in metakaolin), and a large number of alunite AFt and single carbon aluminate AFm-Mc can be formed in the pore solution, which consumes the system. The chemical reaction and hydration of cement produce a competitive relationship with free water, and the hydration of cement is severely restrained, which also affects the formation and consumption of Ca (OH) 2 in the system. The chemical activity of limestone powder depends on the content of soluble aluminum ions in the UHPC system and the reaction of CaC03 with aluminum ions to produce AFm-Mc. calcium Ettringite The formation of a large number of single carbon aluminate phases can significantly reduce the porosity of UHPC. However, for the UHPC doped with C grade fly ash, due to the larger size of the ettringite, the refinement of the pore structure is not obvious with the mixture of silica fume and cement hydration products. But for the UHPC of the calcined clay, the particle accumulation system is due to the addition of the calcined altrite. The pore structure is refined to a certain extent. (4) choosing suitable mineral admixtures to replace cement or silica fume can not only maintain excellent mechanical properties of UHPC, improve the use efficiency of materials, but also improve the rheological properties of concrete and reduce the amount of high efficiency water reducing agent, which helps to reduce the overall production cost and CO2 of the UHPC. Emissions are conducive to large-scale popularization and utilization of UHPC and sustainable development.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

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