本文選題：混凝土　切入點(diǎn)：氣體滲透性　出處：《吉林大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：多數(shù)混凝土耐久性問(wèn)題是由于有害物質(zhì)通過(guò)混凝土內(nèi)部孔隙侵蝕混凝土內(nèi)部造成的,因此,外界物質(zhì)穿透混凝土的能力,即滲透性,對(duì)于評(píng)估混凝土的耐久性有重要的意義。本文通過(guò)配制不同配比的混凝土試件,測(cè)試了水膠比、粉煤灰含量對(duì)混凝土氣體滲透性的影響,探討了混凝土氣體滲透性的測(cè)試影響因素;分析了混凝土孔隙率、孔隙表面積、孔徑大小與混凝土氣體滲透性的關(guān)系;研究了水膠比、粉煤灰含量對(duì)于混凝土碳化性能的影響,探索了混凝土碳化性能與氣體滲透性的相互關(guān)系;研究了高溫作用和應(yīng)力荷載對(duì)混凝土氣體滲透性的影響。主要得出以下結(jié)論:混凝土試件的氣體滲透性在5.78×10-18-1.90×10-17m2之間,屬于低滲透性介質(zhì);當(dāng)粉煤灰含量在0%和30%之間,混凝土的氣體滲透性隨粉煤灰含量的增大而逐漸減小,而當(dāng)水膠比在0.35到0.55之間,混凝土的氣體滲透性隨水膠比的減小而逐漸減小;混凝土的孔隙率隨水膠比的增大,而不斷變大,隨粉煤灰含量的增加而稍微減小;BET表面積隨著水膠比的逐漸增大,先增大后略微減小,隨著粉煤灰含量的增大,BET表面積逐漸增大;水膠比和粉煤灰含量均對(duì)混凝土最可幾直徑?jīng)]有明顯影響;孔隙率和孔隙直徑對(duì)混凝土氣體滲透性影響較小,相反混凝土孔隙的撓曲度對(duì)混凝土氣體滲透性有重要影響;混凝土碳化深度隨著碳化時(shí)間增長(zhǎng)而逐漸加深,且碳化速度逐漸變緩;對(duì)于粉煤灰含量30%的混凝土,水膠比越小,混凝土的碳化深度越小;對(duì)于水膠比0.45的混凝土,粉煤灰的含量越高,混凝土的碳化深度就越大;相比混凝土氣體滲透性,混凝土的碳化性能受堿性物質(zhì)含量的影響更大;以60℃為基準(zhǔn),在200℃、350℃、500℃溫度作用下,混凝土的氣體滲透性分別提高了3.8、11.7和72.6倍;高溫作用使混凝土氣體滲透性對(duì)圍壓更為敏感,k12MPa/k3MPa由0.87降低至0.41;混凝土的氣體滲透性,在軸向荷載小于0.6P時(shí),隨著軸向荷載的逐漸增加保持穩(wěn)定或者略微下降,在0.7P之后略微增大,并在0.8P時(shí)增速加快。
[Abstract]:Most concrete durability problems are caused by harmful substances eroding the concrete interior through the internal pores of the concrete, so the ability of the external material to penetrate the concrete, that is, the permeability, It is of great significance to evaluate the durability of concrete. In this paper, the effects of water binder ratio and fly ash content on the permeability of concrete are tested. The influence factors of concrete gas permeability testing, the relationship between porosity, pore surface area, pore size and permeability of concrete are discussed, and the effects of water binder ratio and fly ash content on the carbonation performance of concrete are studied. The relationship between carbonation property and gas permeability of concrete is explored, and the effect of high temperature and stress load on gas permeability of concrete is studied. The main conclusions are as follows: the gas permeability of concrete specimen is between 5.78 脳 10-18-1.90 脳 10-17m2. When the content of fly ash is between 0% and 30%, the gas permeability of concrete decreases with the increase of the content of fly ash, but when the water-binder ratio is between 0.35 and 0.55, The gas permeability of concrete decreases with the decrease of water-binder ratio, and the porosity of concrete increases with the increase of water-binder ratio, and decreases slightly with the increase of fly ash content, and the surface area of BET increases with the increase of water-binder ratio. With the increase of fly ash content, the surface area of BET increases gradually, the water / binder ratio and fly ash content have no significant effect on the maximum allowable diameter of concrete, and the porosity and pore diameter have little effect on the permeability of concrete gas. On the contrary, the deflection of concrete pore has an important effect on the gas permeability of concrete; the carbonation depth of concrete gradually deepens with the increase of carbonation time, and the carbonation rate gradually slows down; for the concrete with 30% fly ash content, the water-binder ratio is smaller, The lower the carbonation depth of concrete is, the higher the content of fly ash is, the greater the carbonation depth of concrete is when the water-binder ratio is 0.45. Compared with the gas permeability of concrete, the carbonation performance of concrete is more affected by the content of alkaline substance. On the basis of 60 鈩，

本文編號(hào)：1624867