本文選題：天然浮石混凝土 + 鹽漬溶液��； 參考：《內(nèi)蒙古農(nóng)業(yè)大學(xué)》2015年博士論文

【摘要】：本文充分利用內(nèi)蒙古地區(qū)豐富的浮石資源和工業(yè)廢料,研究和開發(fā)水泥、浮石、砂子、粉煤灰等混合的新型輕質(zhì)節(jié)能寒區(qū)材料——天然浮石混凝土。本文選定內(nèi)蒙古河套灌區(qū)為研究區(qū)域,灌區(qū)用水主要來自黃河,呈堿性,pH值在7.7-8.2之間,主要含有Na+、Mg2+、Ca2+、Cl-、SO42-等侵蝕性介質(zhì),鹽分隨著水流在灌區(qū)中積累,必然會對水工建筑物造成嚴重侵蝕。本文依據(jù)內(nèi)蒙古河套灌區(qū)鹽漬水分的調(diào)查資料和灌區(qū)水工建筑物所處的自然環(huán)境特點(冬季時間長、晝夜溫差大等),配制了五組不同配合比的天然浮石混凝土(LC20、LC25、LC30及兩組引氣天然浮石混凝土),并設(shè)計了四種工況組合：凍融(清水)與鹽漬溶液-凍融循環(huán)、干濕循環(huán)(清水)與鹽漬溶液-干濕循環(huán)、凍融-干濕(清水)與鹽漬溶液-凍融-干濕、清水浸泡與鹽浸試驗。主要進行了以下幾項內(nèi)容的試驗和模擬研究：1.通過對不同工況下的質(zhì)量損失率和超聲波波速的測試,可得到：相對動彈模量作為衡量天然浮石混凝土耐久性的評價指標更準確；天然浮石混凝土強度越大,則質(zhì)量損失率和相對動彈模量的損傷越小,適量引氣劑的加入也可以改善混凝土的耐久性。同時為了使研究更加深入,利用電鏡照片和能譜成分圖分析天然浮石混凝土破壞機理。2.在天然浮石混凝土研究中首次運用核磁共振測試方法,從孔隙度、核磁共振乃譜分布、孔徑分布及核磁共振圖像分析得到凍融前后的內(nèi)部孔隙損傷擴展特征：天然浮石混凝土的核磁共振乃譜分布一般為4個峰,凍融循環(huán)使得天然浮石混凝土內(nèi)部小孔隙逐漸向大孔隙擴展破壞,造成孔隙度、乃譜面積增大,并且在鹽漬溶液中核磁共振信號較強,亮點區(qū)域較大。3.本文運用計算機X射線斷層掃描(CT)、環(huán)境掃描電鏡(ESEM)、超景深三維顯微系統(tǒng)綜合分析天然浮石混凝土的細觀特征,并結(jié)合核磁共振成像,從不同角度分析了凍融前后內(nèi)部孔隙的損傷擴展特征,最終得到一致結(jié)論：在鹽漬溶液中的天然浮石混凝土內(nèi)部損傷較嚴重。4.論文提出利用凍融核磁共振測試天然浮石混凝土孔溶液在凍融過程中的變化規(guī)律,得到了冷凍過程和融化過程中各個溫度下天然浮石混凝土孔溶液的信號量、結(jié)冰量等相關(guān)指標,并由此得出天然浮石混凝土孔溶液結(jié)冰的一般規(guī)律：用冷凍過程中的含冰量來評價由孔溶液結(jié)冰引起的靜水壓比較符合實際情況：天然浮石混凝土發(fā)生凍害主要是-15℃以上。5.最后利用損傷力學(xué)的理論,結(jié)合靜水壓假說,根據(jù)天然浮石混凝士的孔結(jié)構(gòu)、抗拉力學(xué)性能和凍融條件,建立了天然浮石混凝土的抗凍耐久性預(yù)測模型,對天然浮石混凝土凍害的全過程進行了定量描述。
[Abstract]:This paper makes full use of the abundant pumice resources and industrial wastes in Inner Mongolia to study and develop the natural pumice concrete, which is a new type of light energy saving cold zone material, such as cement, pumice, sand, fly ash and so on. In this paper, the Hetao Irrigation area of Inner Mongolia is selected as the study area. The water used in the irrigated area mainly comes from the Yellow River, and the pH value of the irrigated area is between 7.7-8.2, which mainly contains the erosive medium such as Na ~ (2 +) mg _ (2) Ca ~ (2 +) ~ (2 +) -Cl-so _ (4) _ (4-). It is bound to cause serious erosion of hydraulic structures. Based on the investigation data of salinized water in Hetao Irrigation District of Inner Mongolia and the characteristics of the natural environment of the hydraulic structures in the irrigated area, the winter time is long. Five groups of natural pumice concrete (LC20LC25LC30) and two groups of air-entrained natural pumice concrete (LC20LC25LC30) and two groups of air-entrained natural pumice concrete (LC20LC25LC30) were prepared, and four working conditions were designed: freeze-thaw (clear water) and salinized solution-freeze-thaw cycle. Dry and wet cycles (clear water) and salinized solution-dry and wet cycles, freeze-thawing (clear water) and salinized solutions-freeze-thawing, soaking and salt soaking tests. The following experiments and simulations were carried out: 1. Through the measurement of mass loss rate and ultrasonic wave velocity under different working conditions, it can be concluded that the relative dynamic modulus is more accurate as an evaluation index to evaluate the durability of natural pumice concrete, and the greater the strength of natural pumice concrete, the greater the strength of natural pumice concrete. The damage of mass loss rate and relative dynamic modulus is smaller and the durability of concrete can be improved by adding proper amount of air entraining agent. At the same time, the damage mechanism of natural pumice concrete was analyzed by means of electron microscope photos and energy dispersive composition diagram. In the study of natural pumice concrete, nuclear magnetic resonance (NMR) method is used for the first time. Pore size distribution and nuclear magnetic resonance (NMR) image analysis showed that the propagation characteristics of internal pore damage before and after freezing and thawing: the NMR spectrum distribution of natural pumice concrete was generally four peaks. The freeze-thaw cycle causes the small pores in the natural pumice concrete to expand and destroy to the macropores, resulting in the increase of the porosity and the increase of the spectral area, and the nuclear magnetic resonance signal is stronger in the saline solution, and the bright spot region is larger than that in the saline solution. In this paper, the microcosmic characteristics of natural pumice concrete are comprehensively analyzed by means of computer X ray tomography (CTT), environmental scanning electron microscopy (ESM) and superfine depth of field (depth of field) three dimensional microscopic system, and combined with nuclear magnetic resonance imaging (NMR). The damage and propagation characteristics of internal pores before and after freezing and thawing are analyzed from different angles, and a consistent conclusion is obtained: the internal damage of natural pumice concrete in salinized solution is more serious. In this paper, nuclear magnetic resonance spectroscopy (NMR) is used to test the variation of natural pumice concrete pore solution during freeze-thaw process, and the signal quantity of natural pumice concrete pore solution at different temperatures during freezing and thawing is obtained. Ice volume and other related indicators, From this, the general law of freezing in pore solution of natural pumice concrete is obtained: the hydrostatic pressure caused by freezing solution of natural pumice concrete is evaluated by the content of ice in freezing process. The freezing damage of natural pumice concrete is mainly above -15 鈩，

本文編號：2027384