本文關(guān)鍵詞： 納米SiO2 納米CaCO3 纖維 混凝土 力學(xué)性能 高溫 強(qiáng)度計算模型 超聲回彈 應(yīng)力-應(yīng)變曲線 氯離子 SEM　出處：《鄭州大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：本文是國家自然科學(xué)基金項目“纖維納米混凝土及其高溫中和高溫后性能研究”(51178434)的主要內(nèi)容之一。通過試驗研究、理論分析以及掃描電鏡SEM的微觀觀察,重點研究了高溫后纖維納米混凝土基本力學(xué)性能、高溫后纖維納米混凝土軸壓應(yīng)力-應(yīng)變關(guān)系、高溫后纖維納米混凝土氯離子滲透性能以及微觀增強(qiáng)機(jī)理,建立了相應(yīng)的計算模型,主要內(nèi)容如下:(1)通過294個邊長150mm纖維納米混凝土立方體試塊在不同齡期的抗壓和劈拉試驗、147個100mm×100mm×400mm梁式試件的抗折試驗以及工作性能試驗和SEM微觀分析,探討了纖維體積率和納米材料摻量對纖維納米混凝土微觀增強(qiáng)機(jī)理與物理力學(xué)性能的影響。結(jié)果表明:在混凝土中摻入適量的纖維和納米材料,改善了混凝土的微觀結(jié)構(gòu),增加了混凝土的密實性,提高了混凝土的物理力學(xué)性能。隨鋼纖維體積率從0增大到1.5%,纖維納米混凝土拌合物坍落度從40mm逐漸減小到25mm,纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度分別提高12%、32%和12.5%。隨納米Si O2(簡稱NS)摻量從0增大到2%,纖維納米混凝土拌合物坍落度減小95mm,初凝終凝時間分別減小52.3%和35.9%,纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度分別提高9%、24%和14.7%。隨納米Ca CO3(簡稱NC)摻量從0增大到2%,纖維納米混凝土拌合物坍落度減小50mm,初凝終凝時間分別減小35.2%和3.8%,纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度分別提高8%、20%和8.8%。根據(jù)復(fù)合力學(xué)理論,并結(jié)合對本文和相關(guān)文獻(xiàn)試驗結(jié)果的統(tǒng)計分析,分別建立了考慮納米材料和纖維影響的纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度計算方法。(2)通過觀察150個邊長150mm纖維納米混凝土立方體試塊高溫前后宏觀形貌和量測高溫前后質(zhì)量損失,研究了纖維納米混凝土高溫形貌特征變化以及質(zhì)量損失率與溫度的關(guān)系。結(jié)果表明:隨溫度從25℃升高到800℃,纖維納米混凝土表觀劣化程度加劇,質(zhì)量損失率從1%增大約10%。基于對試驗結(jié)果的分析,建立了高溫后纖維納米混凝土質(zhì)量損失率與溫度的關(guān)系式。(3)通過450個邊長150mm纖維納米混凝土立方體試塊高溫后的抗壓和劈拉試驗、300個100mm×100mm×400mm纖維納米混凝土梁式試塊高溫后的抗折試驗,研究了纖維、納米材料和溫度對纖維納米混凝土高溫后抗壓強(qiáng)度、劈拉強(qiáng)度和劈拉荷載-橫向變形曲線、抗折強(qiáng)度和彎曲荷載-撓度曲線的影響。結(jié)果表明:隨鋼纖維體積率從0增大到1.5%,高溫后纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度呈增大趨勢;600℃高溫后,鋼纖維體積率1.0%時的纖維納米混凝土殘余抗壓強(qiáng)度較不摻纖維時提高了43.97%,殘余劈拉強(qiáng)度提高了216.38%,殘余抗折強(qiáng)度提高了84.8%;劈拉橫向變形、劈拉荷載-橫向變形曲線下包面積逐漸增大;彎曲荷載-撓度曲線下包面積、峰值撓度、彎曲韌性指數(shù)和彎曲韌性比均呈增大趨勢。納米材料的摻入使高溫后纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度均有一定程度提高,600℃高溫后,NS和NC摻量分別為1%時的纖維納米混凝土殘余抗壓強(qiáng)度較不摻納米材料時分別提高了45.5%和38.2%,殘余劈拉強(qiáng)度分別提高了63.9%和28.1%,殘余抗折強(qiáng)度分別提高了78.7%和46.3%;隨納米材料摻量增大,彎曲荷載-撓度曲線下包面積和彎曲韌性指數(shù)有一定程度提高。隨溫度從25℃升高到800℃,纖維納米混凝土抗壓、劈拉和抗折強(qiáng)度逐漸減小,劈拉荷載-橫向變形曲線下包面積逐漸減小,彎曲荷載-撓度曲線逐漸趨于扁平,峰值荷載顯著降低,峰值撓度逐漸增大。基于對試驗結(jié)果的統(tǒng)計分析,分別建立了纖維納米混凝土抗壓、劈拉和抗折殘余強(qiáng)度相對值與溫度的關(guān)系式。(4)通過150個邊長150mm纖維納米混凝土立方體試塊高溫前后超聲、回彈和抗壓強(qiáng)度試驗,探討了鋼纖維體積率、NS和NC摻量對高溫前后超聲波速和回彈值的影響以及纖維納米混凝土抗壓強(qiáng)度、經(jīng)歷最高溫度與超聲波速和回彈值的關(guān)系。結(jié)果表明:在混凝土中摻入纖維和納米材料,改善了混凝土微觀結(jié)構(gòu),使高溫前后超聲波速和回彈值均有一定程度提高,800℃高溫后,鋼纖維摻量1.0%的混凝土超聲波速較不摻鋼纖維時提高了45.32%,回彈值提高了36.28%;NS和NC摻量分別為1.0%的混凝土超聲波速較不摻時分別提高了21.66%和22.25%,回彈值分別提高了45.77%和30.85%。纖維納米混凝土高溫后抗壓強(qiáng)度與超聲波速和回彈值具有良好的相關(guān)性,超聲回彈綜合法適用于推定纖維納米混凝土高溫抗壓強(qiáng)度及經(jīng)歷最高溫度。通過對試驗數(shù)據(jù)的統(tǒng)計分析,建立了高溫后纖維納米混凝土超聲回彈綜合測強(qiáng)曲線及推定經(jīng)歷最高溫度的公式。(5)通過306個150mm×150mm×300mm纖維納米混凝土棱柱體試塊在25-800℃后的單軸受壓試驗,探討了鋼纖維、納米材料摻量和高溫對纖維納米混凝土軸壓應(yīng)力-應(yīng)變曲線的影響。結(jié)果表明:纖維納米混凝土軸壓應(yīng)力-應(yīng)變曲線可分為彈性階段、裂縫穩(wěn)定發(fā)展階段、裂縫失穩(wěn)擴(kuò)展階段和破壞階段;隨鋼纖維體積率和納米材料摻量的增大,軸壓應(yīng)力-應(yīng)變曲線逐漸飽滿,峰值應(yīng)力和峰值應(yīng)變均有一定程度的提高,曲線下包面積逐漸增大;隨溫度升高,軸壓應(yīng)力-應(yīng)變曲線趨于扁平,彈性段逐漸變短,峰值應(yīng)力顯著降低,峰值應(yīng)變明顯增大,軸壓應(yīng)力-應(yīng)變曲線下包面積減小。通過對試驗數(shù)據(jù)的綜合分析,建立了考慮溫度、納米材料摻量和鋼纖維含量特征參數(shù)影響的纖維納米混凝土軸壓應(yīng)力-應(yīng)變曲線數(shù)學(xué)模型。(6)通過150個100mm×100mm×200mm纖維納米混凝土棱柱體試塊高溫前后氯鹽溶液浸泡干濕循環(huán)試驗,研究了鋼纖維、納米材料和溫度對纖維納米混凝土氯離子滲透性的影響。結(jié)果表明:隨鋼纖維體積率和納米材料摻量增大,纖維納米混凝土的氯離子含量呈減小趨勢。800℃高溫后,鋼纖維體積率1%時,纖維納米混凝土7.5mm深度的氯離子含量為不摻鋼纖維時的64.2%;NS和NC摻量分別為1%時,纖維納米混凝土7.5mm深度的氯離子含量分別為不摻納米材料時的72.9%和68.1%。隨溫度的升高,纖維納米混凝土的氯離子含量逐漸增大。基于對纖維納米混凝土抗氯離子滲透機(jī)理的分析和對試驗結(jié)果的統(tǒng)計分析,建立了考慮溫度、納米材料摻量和鋼纖維含量特征參數(shù)影響的纖維納米混凝土氯離子含量計算公式。(7)通過混凝土微觀結(jié)構(gòu)SEM觀察,研究了纖維、納米材料和溫度對纖維納米混凝土微觀形貌及其對宏觀力學(xué)性能的影響。結(jié)果表明:納米材料增加了混凝土的密實度,改善了水泥石微觀結(jié)構(gòu);聚丙烯纖維高溫熔解大大降低混凝土的內(nèi)部壓力,防止混凝土高溫爆裂;鋼纖維降低了溫度梯度,其橋接阻裂作用減輕了混凝土內(nèi)部微缺陷的引發(fā)和擴(kuò)展,緩解了混凝土高溫劣化。在混凝土中摻入適量纖維和納米材料,提高了常溫時混凝土的力學(xué)性能,有效緩解了高溫對混凝土的劣化作用,改善了高溫后混凝土的力學(xué)性能。
[Abstract]:This paper is the study of properties of nano fiber concrete and high temperature and high temperature after the National Natural Science Fund Project "(51178434) one of the main content. Through experimental research, theoretical analysis and microscopic observation of scanning electron microscopy SEM, focuses on the research of nano fiber after high temperature mechanical mixing ability of concrete after high temperature nano fiber concrete axial compressive stress strain relationship of concrete after high temperature, chloride ion permeability and micro nano fiber reinforced mechanism, a corresponding model is established, the main contents are as follows: (1) through the 294 side of 150mm nano fiber concrete specimens in different age compressive strength and splitting tensile test, 147 100mm * 100mm * 400mm beam try bending test and performance test and SEM analysis, discusses the fiber volume ratio and nano material content on nano fiber concrete micro mechanism and physical force Effect of performance. The results show that the doped fiber and nano materials in concrete, improve the microstructure of concrete, increase the density of concrete, improve the physical and mechanical properties of concrete. The steel fiber volume ratio increases from 0 to 1.5%, nano fiber concrete mixture slump from 40mm decreased to 25mm, nano fiber concrete compressive, tensile and flexural strength were increased by 12%, 32% and 12.5%. with nano Si O2 (NS) content increased from 0 to 2%, the mixture of nano fiber concrete slump decreases 95mm, 52.3% and 35.9% respectively. Initialcoagulation finalcoagulation time, nano fiber concrete the compressive, tensile and flexural strength were increased by 9%, 24% and 14.7%. with nano Ca CO3 (NC) content increased from 0 to 2%, the mixture of nano fiber concrete slump decreases 50mm, initialcoagulation finalcoagulation time was reduced by 35.2% and 3.8%, nano fiber concrete The compressive, tensile and flexural strength were increased by 8%, 20% and 8.8%. according to the composite mechanics theory, and combined with the statistical analysis of this paper and the test results of literature, considering the influence of nano fiber concrete and fiber nano materials were established respectively, tensile and flexural strength calculation method. (2) through the observation of 150 a length of 150mm nano fiber concrete cube macro morphology and amount of block before and after high temperature high temperature before and after weight loss, the effects of fiber morphology of nano concrete high temperature change and the relationship between quality loss rate and temperature. The results showed that with temperature from 25 degrees rise to 800 DEG C, nano fiber concrete apparent deterioration degree aggravate, quality loss the rate of increase of about 10%. from 1% based on the analysis of test results, the relationship between fiber type nano concrete mass loss rate and temperature of high temperature was established. (3) by 450 150mm length fiber Vinami coagulation The soil test cube after high temperature compressive and splitting tensile test, 300 100mm * 100mm * 400mm nano fiber concrete beam test bending test piece after high temperature, the research of nano fiber, fiber concrete after high temperature compressive strength of nano materials and temperature, tensile strength and splitting tensile loading transverse deformation curves, influence the bending strength and bending load deflection curve. The results show that with steel fiber volume ratio increases from 0 to 1.5%, after high temperature nano fiber concrete compressive, tensile and flexural strength increased; the high temperature of 600 DEG C, Vinami fiber concrete compressive strength of steel fiber volume ratio of 1% is not doped fiber increased by 43.97%, the residual tensile strength increased by 216.38%, the residual flexural strength increased by 84.8%; the splitting of transverse deformation, splitting tensile loading transverse deformation curves under the area gradually increased; the bending load deflection curve area under the peak, deflection Degree of flexural toughness index and flexural toughness ratio increased. Nano material doped nano fiber concrete after high temperature compressive, tensile and flexural strength were increased to a certain extent, the high temperature of 600 DEG C, NS and NC content respectively. The residual compressive strength of nano fiber concrete 1% is not mixed with nano materials were increased by 45.5% and 38.2%, 63.9% and 28.1% increased residual splitting tensile strength, flexural strength were increased by 78.7% and 46.3%; with the increase of content of nano materials, the bending load deflection curve and the area under flexural toughness index to a certain extent increased. With the temperature from 25 degrees to 800 degrees. Nano fiber, concrete compressive strength, splitting tensile and flexural strength decreased, splitting tensile loading transverse deformation curves under the area gradually decreases and the bending load deflection curve tends to be flat, the peak load decreased significantly and the peak deflection increases gradually . statistical analysis of the test results based on the nano fiber concrete compression were established, and the relationship between flexural tensile type residual strength and temperature. The relative value (4) through the 150 side of 150mm nano fiber concrete specimens before and after high temperature ultrasonic rebound and compression strength test of steel fiber volume ratio. The influence of ultrasonic velocity and rebound value before and after high temperature and nano fiber concrete compressive strength of NS and NC content, experience the highest temperature and ultrasonic velocity and rebound value. The results show that the incorporation of fiber and nano materials in concrete, improve the microstructure of concrete, the temperature before and after ultrasonic velocity and rebound value to a certain extent improve the high temperature of 800 DEG C, ultrasonic concrete steel fiber content of 1% speed is not mixed with steel fiber increased by 45.32%, the rebound value increased by 36.28%; the content of NC and NS were 1% of the super concrete The acoustic velocity is not mixed were increased by 21.66% and 22.25%, the rebound value were increased by 45.77% and 30.85%. nano fiber concrete after high temperature compressive strength and ultrasonic velocity and rebound value have a good correlation, ultrasonic rebound method applied to the presumption of nano fiber concrete high temperature compressive strength and maximum temperature. Through statistical analysis of experimental data, built after high temperature nano fiber concrete ultrasonic rebound strength curve and the maximum temperature presumption formula. (5) by 306 150mm * 150mm * 300mm nano fiber concrete prism specimens under uniaxial compression test at 25-800 deg.c, discusses the steel fiber, and high temperature nano materials doped with nano fiber concrete axial compressive stress-strain curves. The results show that the stage can be divided into elastic stress-strain curve of nano fiber reinforced concrete under axial compression, the crack development stage, crack Crack instability expansion stage and failure stage; with the increase of volume ratio of steel fiber and nano materials, uniaxial compressive stress-strain curve became full, the peak stress and peak strain were improved to a certain extent, the area under curve increases; with the increase of temperature, axial compressive stress-strain curve tends to be flat the elastic segment, gradually shorter, the peak stress decreased significantly, the peak strain increases obviously and the axial compressive stress strain curve under the area decreased. Through comprehensive analysis of test data, considering temperature, fiber axis nano material content of nano concrete and steel fiber content characteristic parameters affecting the compressive stress - strain a mathematical model of curve. (6) by 150 100mm * 100mm * 200mm nano fiber concrete prism specimens before and after high temperature chlorine salt solution immersion dry wet cycle test, the effects of steel fiber, nano materials and nano fiber temperature of concrete chloride The sub permeability effect. The results show that with the amount of volume ratio of steel fiber and nano material increase, chloride ion content of nano fiber concrete was decreased after high temperature of.800 DEG C, steel fiber volume ratio of 1%, chloride ion content of nano fiber concrete 7.5mm depth for steel fiber is 64.2%; NS and NC the admixture of 1% respectively, chlorine ion content of nano fiber concrete 7.5mm depth were not doped nano materials at 72.9% and 68.1%. with the increase of temperature, chloride ion content of nano fiber concrete increases gradually. The fiber nano concrete anti chloride ion penetration mechanism analysis and the statistical analysis of the test results based on the established considering the temperature calculation formula of nano material content and content of the fiber characteristic parameters affecting fiber nano concrete chloride ion content. (7) through the concrete microstructure observation of SEM, study the fiber, nano materials And the temperature on the fiber morphology of nano concrete and its influence on macroscopic mechanical properties. The results showed that the nano material increases the compactness of concrete, improve the microstructure of cement stone; polypropylene fiber high temperature melting greatly reduce the internal pressure of concrete, to prevent concrete spalling; steel fiber can reduce the temperature gradient, the bridge crack resistance effect of reducing concrete micro defect initiation and propagation, alleviate the deterioration of concrete at high temperature. Adding fiber and nano materials in concrete, improve the mechanical properties of concrete at room temperature, effectively alleviate the bad effect of high temperature on concrete, the mechanical properties of concrete after high temperature is improved.

【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU528

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2 張華;鋼纖維混凝土強(qiáng)度與彎曲韌性研究[D];鄭州大學(xué);2011年

3 孟宏睿;高溫作用后混凝土力學(xué)性能及無損檢測的試驗研究[D];西安建筑科技大學(xué);2005年

4 李翔宇;高溫后纖維礦渣微粉混凝土力學(xué)性能研究[D];鄭州大學(xué);2009年

5 汪鵬;納米高性能混凝土斷裂性能試驗研究[D];鄭州大學(xué);2012年

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