本文選題：泡沫混凝土 + 高溫��； 參考：《西南科技大學》2017年碩士論文

【摘要】：物理發(fā)泡泡沫混凝土是一種多孔水泥基材料,其制備工藝簡便、能夠現(xiàn)場澆筑,且同時具備輕質(zhì)、高強、保溫隔熱、吸能吸聲、抗震等多功能,在建筑圍護結(jié)構(gòu)保溫、軟土地基/廢棄礦洞回填、人防工程緩沖等領(lǐng)域有廣闊的應(yīng)用前景。泡沫混凝土主體以無機材料為主,天然具有防火阻燃功能。然而,在火災(zāi)環(huán)境或窯爐使用條件下,泡沫混凝土圍護材料將暴露在高溫環(huán)境中,水泥水化產(chǎn)物失水、組成/結(jié)構(gòu)演化將加速其力學性能和功能的劣化,因此研究高溫熱處理對泡沫混凝土結(jié)構(gòu)和性能影響意義重大。本研究以普通硅酸鹽水泥為主要原料,采用物理發(fā)泡方式制備了密度等級為300-700kg/m~3的泡沫混凝土,研究了高溫熱處理對不同密度等級泡沫混凝土試件外觀、質(zhì)量損失、抗壓強度、導熱系數(shù)及吸水率等的影響,同時分析了泡沫混凝土氣孔結(jié)構(gòu)、物相組成和微觀形貌的演化。在此基礎(chǔ)上,提出優(yōu)化配合比設(shè)計,以提高泡沫混凝土耐高溫性能。研究結(jié)果表明:隨熱處理溫度提高,泡沫混凝土質(zhì)量損失增加、抗壓強度降低,吸水率和導熱系數(shù)增加;密度等級對泡沫混凝土耐高溫性能影響較大,300-400kg/m~3密度等級的泡沫混凝土質(zhì)量和抗壓強度損失更大,吸水率增加更多,導熱系數(shù)先降低后增加;在8 0 0℃時,各密度等級泡沫混凝土基本性能趨于一致,質(zhì)量損失率為2 0%,質(zhì)量吸水率為6 5%-7 0%,導熱系數(shù)為0.3 0-0.3 3,抗壓強度殘余率為20%。高溫熱處理后泡沫混凝土孔隙率增大,通孔率增加,氣孔孔徑無明顯變化;不同溫度高溫處理后各密度等級的泡沫混凝土的水化產(chǎn)物數(shù)量和種類變化基本一致,在200℃以下泡沫混凝土主要發(fā)生自由水的逸出、水化硅酸鈣和鈣礬石的分解,400℃時鈣礬石完全分解,在600℃時氫氧化鈣分解,在800℃時碳酸鈣分解。水灰比的增大在800℃以前增大了泡沫混凝土質(zhì)量損失,但在800℃時影響不大,水灰比0.50-0.55時制備的泡沫混凝土在高溫熱處理后殘余抗壓強度更高。粉煤灰、偏高嶺土的摻入減小了泡沫混凝土在高溫熱處理后的質(zhì)量損失,并提升了強度殘余率,硅灰的加入將降低強度殘余率。
[Abstract]:Physical foamed foam concrete is a kind of porous cement based material. Its preparation technology is simple, it can be poured in the field, and it also has many functions such as light weight, high strength, heat insulation, energy absorption, sound absorption, seismic resistance and so on. Soft soil foundation / abandoned mine hole backfill, civil air defense engineering buffer and other fields have broad application prospects. The main body of foam concrete is inorganic material, which has the function of fire-proof and flame-retardant. However, under the conditions of fire or kiln use, the foam concrete enclosure will be exposed to high temperature, the hydration products of cement will lose water, and the composition / structure evolution will accelerate the deterioration of its mechanical properties and functions. Therefore, it is of great significance to study the influence of high temperature heat treatment on the structure and properties of foam concrete. In this study, ordinary Portland cement was used as the main raw material to prepare foam concrete with density grade 300-700kg/m~3 by physical foaming method. The appearance, quality loss and compressive strength of foam concrete specimens with different density grades were studied by high temperature heat treatment. The influences of thermal conductivity and water absorption are also analyzed. The evolution of pore structure, phase composition and microstructure of foamed concrete are also analyzed. On this basis, the optimum mix ratio design is proposed to improve the high temperature resistance of foam concrete. The results show that with the increase of heat treatment temperature, the mass loss of foam concrete increases, the compressive strength decreases, and the water absorption and thermal conductivity increase. The density grade has a great influence on the high temperature resistance of foamed concrete. The loss of quality and compressive strength of foamed concrete with density grade 300-400kg / mm3 is greater, the water absorption is increased more, and the thermal conductivity decreases first and then increases. The basic properties of each density grade foam concrete tend to be consistent, the mass loss rate is 20%, the mass water absorption rate is 6 5 -7 0, the thermal conductivity is 0.3 0. 3 3, and the residual rate of compressive strength is 20%. After high temperature heat treatment, the porosity of foamed concrete increases, the through porosity increases, the pore pore size does not change obviously, and the quantity and type of hydration products of different density grades of foamed concrete after different temperature and high temperature treatment are basically the same. Free water escape mainly occurs in foam concrete below 200 鈩，

本文編號：1818353