【摘要】：隨著混凝土膠凝材中收縮裂縫和延遲鈣礬石的致裂影響導(dǎo)致的工程滲漏水問題不斷突顯,常規(guī)修補措施難以及時地發(fā)現(xiàn)和解決這些微裂縫。因此,論文以膠凝基材為研究對象,以硅粉、粉煤灰和礦粉作為主要摻和料,采用壓汞法和低場核磁共振法對不同齡期下復(fù)合膠凝材硬化漿體的孔隙特征進(jìn)行測試,通過Rietveld全譜擬合定量分析水化產(chǎn)物中鈣礬石的含量變化,初步研究了復(fù)合膠凝材硬化漿體的孔隙特征與鈣礬石含量的相互關(guān)系,并結(jié)合對應(yīng)的抗折抗壓強度,選出了孔隙特征和強度更優(yōu)的膠凝材配合比。通過膠凝基材改性研究控制微觀孔隙的產(chǎn)生和發(fā)展,為自修復(fù)混凝土的研究奠定了試驗基礎(chǔ),并得出以下結(jié)論:(1)在適當(dāng)?shù)膿搅肯?復(fù)合膠凝材硬化漿體的抗折、抗壓強度比純水泥高;多摻和料復(fù)合膠凝材硬化漿體的強度總體上比同齡期的單摻和料復(fù)合膠凝材的強度低;復(fù)合膠凝材硬化漿體的強度與孔隙率基本成反比趨勢。(2)壓汞法測出復(fù)合膠凝材硬化漿體的孔隙主要分布在3.5nm～1OOnm的范圍內(nèi),最可幾孔徑隨齡期增加總體向小孔徑移動,且前期減小快,后期變化慢;而低場核磁共振法測得的孔隙分布范圍大多在1nm～300nm之間,最可幾孔徑在7d齡期后幾乎保持不變。(3)不同配合比復(fù)合膠凝材硬化漿體的平均孔徑和孔隙率均隨著齡期的增加而不斷減小,且前期減小快,后期變化慢;隨著某一摻和料摻量的增加,平均孔徑總體減小;多摻和料復(fù)合膠凝材在適當(dāng)?shù)膿搅肯?比單摻時更明顯地降低了硬化漿體的孔隙率、平均孔徑和最可幾孔徑。(4)不同配合比的復(fù)合膠凝材料水化產(chǎn)物中的鈣礬石含量主要分布在0～3%的范圍內(nèi),對應(yīng)的孔隙率則集中分布在15%～30%之間,平均孔徑集中分布在14nm～30nm之間。(5)綜合考慮抗折抗壓強度、平均孔徑和孔隙率的測試結(jié)果,確定了單一摻和料時復(fù)合膠凝材的最優(yōu)摻量范圍:硅粉6%左右,粉煤灰4%～8%之間,礦粉12%左右。多摻和料復(fù)合膠凝材的優(yōu)化摻量范圍:硅粉6%左右,粉煤灰7.5%以下,礦粉4%～8%左右,水泥80%左右。
[Abstract]:With the problems of engineering leakage caused by shrinkage cracks and delayed ettringite cracking in concrete cementitious materials, it is difficult to find and solve these microcracks in time by conventional repair measures. Therefore, taking the cementing base material as the research object, taking silica powder, fly ash and mineral powder as the main admixture, the pore characteristics of the composite cemented paste at different ages were measured by mercury injection method and low field nuclear magnetic resonance method. The change of ettringite content in hydration products was quantitatively analyzed by Rietveld full-spectrum fitting. The relationship between pore characteristics and ettringite content of hardened paste of composite cementing material was studied preliminarily, and the corresponding flexural compressive strength was combined with the relationship between the pore characteristics and the content of ettringite. The best mix ratio of gelling material with better pore characteristics and strength was selected. The formation and development of micro-pores are controlled by the modification research of cementing base material, which lays an experimental foundation for the study of self-repairing concrete, and draws the following conclusions: (1) the bending resistance of the composite cement hardened paste is obtained under the appropriate dosage. The compressive strength is higher than that of pure cement, the strength of multi-admixture composite cementing paste is lower than that of mono-admixture compound cementing material of the same age, and the strength of multi-admixture composite cementing material is lower than that of single-admixture composite cementing material of the same age. The strength and porosity of composite cemented paste are inversely proportional to each other. (2) the porosity of composite cemented paste is mainly distributed in the range of 3.5nm~1OOnm by mercury injection method, and the most suitable pore size moves to small pore size with increasing age. The pore distribution range measured by low field nuclear magnetic resonance (LFS) is between 1nm~300nm, and the change is slow in the later stage, but the pore distribution range measured by low field nuclear magnetic resonance method is mostly between 1nm~300nm. (3) the average pore size and porosity of the composite cementing paste with different mix ratio decreased with the increase of age, and decreased rapidly in the early stage and slow in the later stage; (3) the maximum pore size remained almost unchanged after 7 days of age. (3) the average pore size and porosity of the composite cementing paste with different mix ratio decreased with the increase of age. With the increase of a certain amount of admixture, the average pore size decreases generally, and the porosity of hardened paste decreases more obviously when the amount of multi-admixture compound cementing material is suitable than that of single admixture, and the average pore size decreases with the increase of the amount of admixture, and the average pore size decreases with the increase of the amount of admixture. (4) the content of ettringite in the hydration products of the composite cementitious materials with different mix ratios is mainly distributed in the range of 0 ~ 3%, and the corresponding porosity is concentrated in the range of 15% and 30%. The average pore size is concentrated between 14nm~30nm. (5) considering the test results of flexural compressive strength, average pore size and porosity, the optimum dosage range of composite cementing material is determined: silica fume is about 6%, fly ash is between 4% and 8%. Ore powder is about 12%. The optimum dosage range of multi-admixture compound cementing material is about 6% of silica powder, 7.5% of fly ash, 4% of mineral powder and 80% of cement.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU528

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