本文選題：內(nèi)養(yǎng)護(hù) + 火山灰　； 參考：《北京交通大學(xué)》2017年碩士論文

【摘要】：肯尼亞蒙-內(nèi)鐵路是東非鐵路網(wǎng)的第一段,也是國(guó)際上第一條采用中國(guó)標(biāo)準(zhǔn)修建的國(guó)際現(xiàn)代化鐵路。按照中國(guó)鐵路標(biāo)準(zhǔn)有關(guān)要求,需要在混凝土中摻加礦物摻合料以提高其耐久性。然而東非地區(qū)普遍缺乏粉煤灰、礦粉等礦物摻合料,當(dāng)?shù)貎?chǔ)量豐富的天然火山渣就成為一個(gè)合理的技術(shù)選擇,所以本文采用肯尼亞當(dāng)?shù)氐哪ゼ?xì)火山渣作為礦物摻合料配制耐久性良好的高性能混凝土。由于高性能混凝土普遍存在早期收縮大、易開(kāi)裂的問(wèn)題,在非洲這樣的干燥環(huán)境中,因得不到充分的外部養(yǎng)護(hù),其收縮開(kāi)裂問(wèn)題更加不容忽視�；诖�,內(nèi)養(yǎng)護(hù)技術(shù)對(duì)天然火山灰高性能混凝土早期收縮開(kāi)裂的改善是一個(gè)非常值得研究的課題。本文選取工程現(xiàn)場(chǎng)常用的兩個(gè)強(qiáng)度等級(jí)高性能混凝土:HPC40、HPC60;采用兩種內(nèi)養(yǎng)護(hù)材料:火山渣、高吸水樹(shù)脂(簡(jiǎn)稱SAP);研究了兩種內(nèi)養(yǎng)護(hù)技術(shù)對(duì)天然火山灰高性能混凝土工作性能、力學(xué)性能、收縮性能及耐久性能的影響規(guī)律;并結(jié)合化學(xué)結(jié)合水、混凝土內(nèi)部相對(duì)濕度、水分損失率,分析了內(nèi)養(yǎng)護(hù)對(duì)火山灰混凝土性能的作用機(jī)理。主要工作和研究結(jié)果如下:(1)以流動(dòng)性(坍落度和坍落擴(kuò)展度)、粘聚性、保水性作為工作性能指標(biāo),研究了 SAP摻量、附加水膠比、不同拌合工藝對(duì)火山灰混凝土工作性能的影響規(guī)律;得出了 SAP在天然火山灰混凝土中的理論吸水倍率和適于SAP內(nèi)養(yǎng)護(hù)的火山灰混凝土的拌合工藝。(2)以不同齡期的抗壓強(qiáng)度作為力學(xué)性能指標(biāo),研究了兩種內(nèi)養(yǎng)護(hù)技術(shù)對(duì)火山灰混凝土力學(xué)性能的影響規(guī)律;得出了火山灰混凝土的抗壓強(qiáng)度與內(nèi)養(yǎng)護(hù)水膠比的關(guān)系;通過(guò)測(cè)定化學(xué)結(jié)合水的變化證明了內(nèi)養(yǎng)護(hù)對(duì)膠凝材料水化的促進(jìn)作用,并結(jié)合孔結(jié)構(gòu)分析了內(nèi)養(yǎng)護(hù)技術(shù)對(duì)強(qiáng)度的影響機(jī)理。(3)以自收縮和干燥收縮作為收縮性能指標(biāo),研究了兩種內(nèi)養(yǎng)護(hù)技術(shù)對(duì)火山灰混凝土收縮性能的影響規(guī)律;得出了內(nèi)養(yǎng)護(hù)減縮率與內(nèi)養(yǎng)護(hù)水膠比的關(guān)系以及干燥收縮開(kāi)始產(chǎn)生的臨界水分損失率,并結(jié)合內(nèi)部相對(duì)濕度證明了內(nèi)養(yǎng)護(hù)對(duì)干燥環(huán)境中火山灰混凝土良好的養(yǎng)護(hù)效果。(4)以電通量和碳化深度作為耐久性能的指標(biāo),研究了 SAP內(nèi)養(yǎng)護(hù)對(duì)火山灰混凝土耐久性能的影響規(guī)律;采用顯微鏡觀察了摻加SAP后凈漿斷面微觀結(jié)構(gòu)的變化情況;探討了 SAP內(nèi)養(yǎng)護(hù)對(duì)混凝土耐久性能的影響機(jī)理。
[Abstract]:Kenya's Mongol-Inner Railway is the first section of the East African railway network and the first international modern railway to be built to Chinese standards. According to the requirements of Chinese railway standards, mineral admixtures should be added to concrete to improve its durability. However, there is a general lack of coal ash, mineral powder and other mineral admixtures in East Africa, so the rich natural volcanic slag in the region has become a reasonable technical choice. In this paper, high performance concrete (HPC) with good durability is prepared by using the grinding slag of Kenya as mineral admixture. High performance concrete (HPC) generally has the problem of large early shrinkage and easy cracking. In dry environment such as Africa, the shrinkage cracking problem can not be ignored because of insufficient external curing. Based on this, the improvement of early shrinkage cracking of natural pozzolanic high performance concrete by internal curing technology is a subject worth studying. In this paper, two kinds of strength grade high performance concrete, 1: HPC40 / HPC60, which are commonly used in engineering site, are selected. Two kinds of internal curing materials are adopted: volcanic slag, super absorbent resin (abbreviated as SAP). The working performance of two internal curing techniques for natural pozzolanic high performance concrete is studied. The effect of internal curing on the performance of pozzolanic concrete was analyzed by combining with chemically bonded water, relative humidity of concrete and water loss rate. The main work and results are as follows: (1) taking fluidity (slump and collapse extension, cohesion, water retention) as the working performance index, the content of SAP and the ratio of additional water to binder are studied. The influence of different mixing processes on the performance of pozzolanic concrete; The theoretical water absorption rate of SAP in natural pozzolanic concrete and the mixing process of pozzolanic concrete suitable for curing in SAP are obtained. The compressive strength of different ages is taken as the mechanical performance index. The influence of two internal curing techniques on the mechanical properties of pozzolanic concrete was studied, and the relationship between the compressive strength of pozzolanic concrete and the water-binder ratio of internal curing was obtained. The effect of internal curing on the hydration of cementitious materials was proved by measuring the change of chemically bound water, and the mechanism of influence of internal curing technology on strength was analyzed in combination with pore structure. The effects of two internal curing techniques on the shrinkage properties of pozzolanic concrete are studied, and the relationship between internal curing shrinkage rate and internal curing water-binder ratio and the critical water loss rate at the beginning of drying shrinkage are obtained. Combined with internal relative humidity, it is proved that internal curing has good curing effect on pozzolanic concrete in dry environment. The influence of curing in SAP on durability of pozzolanic concrete was studied. The microstructure of clean slurry section with SAP was observed by microscope, and the mechanism of influence of curing in SAP on durability of concrete was discussed.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

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