本文關(guān)鍵詞：C80高性能混凝土微結(jié)構(gòu)高溫?fù)p傷演化研究　出處：《太原理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 高強(qiáng)高性能混凝土 高溫 損傷 裂縫 孔結(jié)構(gòu) 微觀形貌

【摘要】：高強(qiáng)高性能混凝土因其強(qiáng)度高、承載能力大、性能好的優(yōu)點(diǎn),在現(xiàn)代工程中應(yīng)用廣泛。但高強(qiáng)高性能混凝土結(jié)構(gòu)密實(shí),高溫下極易發(fā)生爆裂,在高強(qiáng)高性能混凝土中添加聚丙烯纖維是較常用的抑制其爆裂的方法。研究高強(qiáng)高性能混凝土內(nèi)部微結(jié)構(gòu)高溫?fù)p傷演化的規(guī)律,對高強(qiáng)高性能混凝土爆裂機(jī)制和聚丙烯纖維抗爆裂機(jī)理的研究有重要意義。本文依托國家自然科學(xué)基金(批準(zhǔn)號:51278325),主要利用X射線CT技術(shù)(CT)對高溫下C80高性能混凝土(以下簡稱HPC)和C80摻聚丙烯纖維高性能混凝土(以下簡稱PPHPC)進(jìn)行細(xì)觀損傷演化研究;使用壓汞測試方法(MIP)對C80 HPC和C80 PPHPC進(jìn)行高溫后微觀損傷演化研究;使用掃描電鏡(SEM)研究高溫后C80 PPHPC的微觀形貌。主要內(nèi)容如下:1.CT圖像的定性分析通過試驗(yàn)得到HPC、PPHPC在不同溫度下的CT圖像,對CT圖像中混凝土內(nèi)部各組分進(jìn)行識別和分析,描述孔隙、裂縫等隨溫度升高的變化情況。觀察發(fā)現(xiàn):HPC、PPHPC中的孔徑隨著溫度的升高而擴(kuò)大。HPC中一般從400℃時開始出現(xiàn)溫度裂縫,裂縫數(shù)量較少。PPHPC自300℃開始出現(xiàn)溫度裂縫,400℃作用下裂縫數(shù)量急劇增多,裂縫數(shù)量多于HPC。2.CT圖像定量分析對HPC、PPHPC的CT圖像進(jìn)行灰度分析,使用Matlab軟件得到HPC、PPHPC CT圖像的灰度直方圖,并進(jìn)行像素數(shù)量統(tǒng)計(jì)。HPC、PPHPC的灰度直方圖形狀隨溫度的升高出現(xiàn)峰值左移或者小灰度像素數(shù)量增多,像素統(tǒng)計(jì)結(jié)果發(fā)現(xiàn)HPC、PPHPC內(nèi)部缺陷隨溫度的升高而逐漸劣化。使用軟件對HPC、PPHPC CT圖像中的裂縫進(jìn)行提取,計(jì)算裂縫的長度、寬度、面積和周長,追蹤裂縫在溫升過程中的發(fā)展情況,結(jié)果顯示:單條裂縫的長度、寬度、面積和周長會隨著溫度的升高而增長。裂縫總數(shù)量、總長度、寬度、總面積和總周長都隨溫度的升高而增大,PPHPC裂縫的總參數(shù)大于HPC。3.孔結(jié)構(gòu)分析利用壓汞測試技術(shù)對不同溫度作用后的HPC、PPHPC試件進(jìn)行孔結(jié)構(gòu)測定。結(jié)果顯示除300℃外,HPC、PPHPC孔隙率變化趨勢相似,HPC、PPHPC平均孔徑隨溫度升高而降低、孔比表面隨溫度的升高而增加�？紫斗植硷@示HPC、PPHPC在400℃作用后劣化嚴(yán)重,在500℃后產(chǎn)生新一輪劣化,600℃、700℃作用后損傷嚴(yán)重。300℃作用后PPHPC劣化開始,HPC劣化已較嚴(yán)重,HPC孔隙形成“蒸養(yǎng)條件”使得孔隙率低于PPHPC,400℃作用后HPC多害孔占比多于PPHPC,摻入聚丙烯纖維改善高強(qiáng)高性能混凝土高溫性能。根據(jù)分形幾何學(xué)知識和壓汞試驗(yàn)結(jié)果,使用兩種數(shù)學(xué)模型計(jì)算孔結(jié)構(gòu)的分形維數(shù)。研究表明:不同數(shù)學(xué)模型計(jì)算出的分形維數(shù)有所不同,HPC、PPHPC的分形維數(shù)在不同溫度段、不同孔徑范圍內(nèi)差別較大,隨溫度變化顯示出不同的分形特征。4.掃描電鏡分析使用掃描電鏡技術(shù)對常溫、300℃、500℃作用后PPHPC微觀形貌進(jìn)行觀察。常溫時,漿體中的C-S-H、Ca(OH)_2、鈣礬石都能顯示出其相應(yīng)的形貌;鈣礬石在300℃時已完全分解,C-S-H逐漸變疏松;500℃作用后,Ca(OH)_2已分解,C-S-H極其松散。微觀層次上物相的變化直接導(dǎo)致了高強(qiáng)高性能混凝土高溫后性能的劣化。
[Abstract]:High strength and high performance concrete with high strength, large bearing capacity, has the advantages of good performance, widely used in modern engineering. But the high strength and high performance concrete dense structure, high temperature easily burst, adding polypropylene fiber in high strength and high performance concrete is more commonly used in the burst suppression. The research of high strength and high performance the concrete internal structure of high temperature damage evolution, it has important significance to study the performance of the Gao Qianggao mechanism and the polypropylene fiber concrete burst spalling mechanism. Based on the National Natural Science Fund (No. 51278325), the main use of X ray CT (CT) of C80 high performance concrete under high temperature (hereinafter referred to as HPC) and C80 polypropylene fiber reinforced high performance concrete (hereinafter referred to as PPHPC) of meso damage evolution research; using test method of mercury (MIP) on C80 HPC and C80 PPHPC after high temperature micro damage evolution Study; using scanning electron microscopy (SEM) morphology of C80 on PPHPC after high temperature. The main contents are as follows: the qualitative analysis of the 1.CT images obtained by HPC test, PPHPC CT images at different temperatures, the concrete CT image components were identified and analyzed, describing the pore, crack changes with temperature rise the observation showed that HPC, PPHPC in diameter with the temperature increasing and expanding.HPC generally from 400 degrees occurred when the temperature cracks, cracks began to appear a small number of.PPHPC temperature cracks from 300 DEG, 400 DEG C under the effect of a sharp increase in the number of cracks cracks, more than the number of HPC.2.CT image quantitative analysis of HPC CT image PPHPC gray scale analysis using Matlab software HPC, PPHPC histogram of CT image, and the number of pixels statistics.HPC, PPHPC histogram shape with the increase of temperature at the peak of the left or small The increase in the number of pixels, the pixel statistical results found that HPC, the internal defects of PPHPC with temperature increasing deterioration. The use of HPC software, PPHPC CT crack in the image extraction, calculation of crack length, width, area and perimeter track, cracks in the temperature rise in the process of development, the results show that the single crack the length, width, area and perimeter will increase with the increase of temperature. The total number of cracks, total length, width, total area and total perimeter are increased with the increase of temperature, the total crack parameter PPHPC is greater than HPC.3. the analysis of pore structure by different temperature on HPC after mercury testing technology, PPHPC test hole determination of structure. The results showed that in addition to 300 DEG C, HPC, PPHPC, HPC, porosity change tendency is similar, the average pore size of PPHPC decreases with the increase of temperature, pore specific surface increases with the increase of temperature. The pore distribution of HPC, PPHPC in 400 The deterioration of the temperature effect, produce a new round of deterioration in 500 DEG C 600 C, 700 C C.300 serious injury effect after PPHPC degradation, HPC degradation is more serious, HPC pore forming "steam curing condition makes the porosity is lower than 400 DEG PPHPC, after HPC and hole accounted for more than PPHPC, polypropylene fiber to improve the high temperature performance of high strength and high performance concrete. According to the fractal geometry knowledge and MIP test results, calculate the fractal dimension of pore structure using two kinds of mathematical models. The study shows that the fractal dimension of different mathematical model to calculate the different, HPC, PPHPC of the fractal dimension in different temperature range. The scope of different pore diameter vary greatly, with the change of temperature shows the fractal characteristics of.4. scanning electron microscope analysis of different temperature, using scanning electron microscopy in 300 DEG, 500 DEG C after PPHPC morphology were observed. At room temperature, slurry in C-S-H, Ca (OH) _2, the ettringite can show the corresponding morphology; ettringite has been completely decomposed at 300 DEG C, C-S-H gradually become loose; 500 DEG C after the action of Ca (OH) _2 decomposition, C-S-H is extremely loose. The micro level changes phase directly leads to the deterioration of high strength and high performance concrete after high temperature performance.

【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU528

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