本文選題：水泥基材料約束收縮試驗(yàn) + 外方內(nèi)圓偏心約束試驗(yàn)方法��； 參考：《天津大學(xué)》2015年博士論文

【摘要】：混凝土裂縫產(chǎn)生的原因有很多,大致可分為荷載裂縫、次荷載裂縫和非荷載裂縫。在非荷載裂縫中,自由狀態(tài)下的收縮對混凝土并無不良影響,但實(shí)際工程中,處于不同約束狀態(tài)下的混凝土結(jié)構(gòu)往往因收縮大而產(chǎn)生收縮裂縫,收縮裂縫會削弱混凝土的質(zhì)量,影響其耐久性,甚至影響結(jié)構(gòu)的整體性。檢測水泥基材料收縮開裂性能的試驗(yàn)方法很多,其中圓環(huán)法使用最為廣泛,被各國普遍采用,此法具有原理清晰和模具簡單等特點(diǎn),但是圓環(huán)法存在三個問題:(1)由于試件具有高度的對稱性,使得收縮裂縫隨機(jī)出現(xiàn),不便于裂縫的觀察;(2)混凝土圓環(huán)試件壁厚大多在30mm~35mm范圍內(nèi),而粗骨料的最大粒徑為10mm~15mm,這樣的試件和骨料尺寸并不能真實(shí)的反應(yīng)混凝土的收縮開裂性能;(3)砂漿圓環(huán)試件的最大壁厚為75mm,如果混凝土試件使用75mm的壁厚,則試件幾乎是不開裂的,極大的降低了混凝土收縮開裂的時效性和敏感度。針對于以上三個問題,文中提出了外方內(nèi)圓偏心約束試驗(yàn)方法和雙圓偏心約束試驗(yàn)方法:通過數(shù)值分析確定了試驗(yàn)?zāi)＞叩某叽?通過數(shù)理方法對試驗(yàn)結(jié)果(裂縫分布位置和開裂時間)做了統(tǒng)計分析,通過試驗(yàn)驗(yàn)證了外方內(nèi)圓偏心約束試驗(yàn)方法的開裂敏感度,通過Weiss理論模型估算了混凝土試件的開裂應(yīng)力。為了更直接和簡單的檢測試件收縮開裂時間,提出了一套水泥基材料收縮開裂時間檢測裝置,具體闡述如下:(1)凈漿和砂漿外方內(nèi)圓偏心約束收縮試驗(yàn)方法。外方內(nèi)圓偏心約束試驗(yàn)方法是改變圓環(huán)法外邊界的圓形為方形,同時將約束鋼環(huán)沿其中兩條對邊的中線向一邊移動,形成偏心,試件尺寸為170mm×170mm×35mm,最佳偏心距為20mm,通過對凈漿和砂漿外方內(nèi)圓偏心約束試件開裂時間和裂縫位置的數(shù)理統(tǒng)計發(fā)現(xiàn):外方內(nèi)圓偏心約束試件的平均開裂時間明顯早于圓環(huán)試件,縮短了凈漿和砂漿的收縮試驗(yàn)周期;98%的裂縫偏移量在預(yù)期開裂截面左右15.35mm以內(nèi),因此可以認(rèn)為外方內(nèi)圓偏心約束試驗(yàn)方法基本能起到限定收縮裂縫產(chǎn)生位置的作用。通過對比外方內(nèi)圓試件和圓環(huán)試件在完全密封條件下收縮裂縫的發(fā)展路徑發(fā)現(xiàn),圓環(huán)試件從內(nèi)側(cè)先開裂而外方內(nèi)圓偏心試件從外側(cè)先開裂,驗(yàn)證了文中有限元計算結(jié)果的正確性,也說明外方內(nèi)圓偏心約束試驗(yàn)方法提高了試件的開裂敏感度。(2)混凝土外方內(nèi)圓偏心約束試驗(yàn)方法�；炷镣夥絻�(nèi)圓偏心約束試驗(yàn)方法與凈漿(砂漿)外方內(nèi)圓偏心約束試驗(yàn)方法原理相同,區(qū)別在于其尺寸,為了更真實(shí)的反映混凝土的收縮開裂性能,粗骨料最大尺寸選用25mm,試件尺寸為600mm×600mm×75mm,最狹窄處橫截面尺寸為75mm×75mm,其中,約束鋼環(huán)外直徑為300mm,厚度為20mm,經(jīng)過數(shù)值分析發(fā)現(xiàn),外方內(nèi)圓偏心約束試驗(yàn)方法能夠形成一個預(yù)期的開裂位置,試驗(yàn)結(jié)果表明:0.5水灰比的混凝土外方內(nèi)圓偏心約束試件不但開裂時間在兩周之內(nèi),而且裂縫位置偏移量不大,而壁厚為75mm的圓環(huán)試件幾乎是不開裂的。通過完全密封條件下外方內(nèi)圓偏心約束試件的裂縫發(fā)展和開裂應(yīng)力估算,證明了混凝土外方內(nèi)圓偏心約束試驗(yàn)方法的開裂敏感度,以0.5水灰比的混凝土為例,混凝土外方內(nèi)圓偏心約束試件在完全密封條件下依然能夠開裂,而且裂縫從試件外側(cè)向內(nèi)側(cè)發(fā)展,明顯的提高了混凝土收縮開裂的敏感度。通過試件開裂應(yīng)力估算可知,外方內(nèi)圓偏心約束試件最大開裂應(yīng)力大致為3.7MPa-4.2MPa。(3)雙圓偏心約束試驗(yàn)方法。試件外邊界為圓形,直徑為600mm,高75mm,約束鋼環(huán)直徑為300mm,厚度為20mm,鋼環(huán)沿模型直徑向邊框的某一點(diǎn)偏移,保證鋼環(huán)外邊緣與模具邊框內(nèi)邊緣距離為75mm,雙圓偏心約束試驗(yàn)方法同樣能夠有效的限制收縮裂縫的產(chǎn)生位置,通過試件開裂時間統(tǒng)計發(fā)現(xiàn),雙圓偏心約束試驗(yàn)方法能夠提高混凝土收縮開裂的敏感度,但是效果不如外方內(nèi)圓偏心約束試驗(yàn)方法。為了直接和簡單地檢測混凝土的收縮開裂時間,受到電路回路和斷路的啟發(fā),提出了一套新的開裂時間檢測裝置,裝置由導(dǎo)電性粘附材料、導(dǎo)線和指針型鐘表組成,把導(dǎo)電性粘附材料涂抹在預(yù)期的開裂位置一定的范圍內(nèi),導(dǎo)電材料干燥之后,與導(dǎo)線和鐘表連接成回路,每12h觀察一次鐘表走動情況,如果試件開裂則電路由回路變?yōu)閿嗦?鐘表停止轉(zhuǎn)動,此時鐘表指針?biāo)赶虻奈恢眉礊樵嚰拈_裂時刻,此方法能極大節(jié)省觀察裂縫出現(xiàn)的時間,試驗(yàn)裝置簡單,操作方便,特別在凈漿和砂漿試驗(yàn)中效果最為顯著。
[Abstract]:There are many reasons for concrete cracks, which can be divided into load cracks, secondary load cracks and non load cracks. In non load cracks, the shrinkage of free state has no adverse effect on concrete, but in practical engineering, concrete structures in different confinement conditions often produce shrinkage cracks due to large shrinkage and shrink cracks. To weaken the quality of concrete, affect its durability and even influence the integrity of the structure. There are many testing methods for testing the shrinkage and cracking properties of cement based materials, in which the ring method is most widely used and is widely used by all countries. This method has the characteristics of clear principle and simple mold, but there are three problems in the ring method: (1) because the specimen is high The symmetry of the degree makes the shrinkage crack random and not easy to observe the crack; (2) the wall thickness of the concrete ring specimen is mostly in the range of 30mm~35mm, and the maximum size of the coarse aggregate is 10mm~15mm. The size of the specimen and aggregate can not reflect the shrinkage and cracking performance of the concrete; (3) the maximum wall thickness of the mortar ring specimen is 75mm, If the concrete specimen uses the wall thickness of 75mm, the specimen is almost no crack, which greatly reduces the aging and sensitivity of concrete shrinkage cracking. For the above three problems, the external eccentricity constraint test method and the double circle eccentric constraint test method are put forward in the paper. The size of the test die is determined by numerical analysis. Through the statistical analysis of the test results (the location of the crack distribution and the cracking time) through the mathematical method, the cracking sensitivity of the external eccentricity constraint test method is verified by the test. The cracking stress of the concrete specimen is estimated by the Weiss theoretical model. In order to more direct and simple single test specimen, a set of shrinkage cracking time is put forward. The testing device for shrinkage and cracking time of cement based materials is described as follows: (1) the test method of eccentric constriction of the inner circle and eccentricity of the mortar and mortar. The outer circle eccentric constraint test method is to change the circle of the outer boundary of the circular ring to the square, while the restrained steel ring moves along the middle line of the two sides to form the eccentric, and the specimen ruler is formed. The optimum eccentricity is 170mm x 170mm x 35mm, and the optimum eccentricity is 20mm. Through the mathematical statistics of the cracking time and the crack position of the eccentric confinement of the inner circle of the mortar and mortar, it is found that the average cracking time of the outer square eccentric restraint specimen is earlier than the ring specimen, and the shrinkage test period of the net pulp and the mortar is shortened; 98% of the crack offset is in the case. It is expected that the crack section is less than 15.35mm, so it can be considered that the outer inner circle eccentric constraint test method can basically play the role of limiting the position of the shrinkage crack. By comparing the development path of the contraction crack in the complete seal condition, the circular specimen and the circular specimen are cracked from the inside first and the outer square is round. The core specimen is cracked from the outside first, which verifies the correctness of the results of the finite element calculation in the article, and also shows that the external eccentricity constraint test method improves the cracking sensitivity of the specimen. (2) the eccentric constraint test method for concrete outer circle inner circle constraint test method and the external square eccentric constraint test of the concrete outer circle eccentric constraint test and the slurry (mortar) The method is the same, and the difference lies in its size. In order to reflect the shrinkage and cracking performance of concrete more truly, the maximum size of the coarse aggregate is 25mm, the size of the specimen is 600mm x 600mm x 75mm, the cross section size of the most narrow section is 75mm * 75mm, of which the outer diameter of the restrained steel ring is 300mm and the thickness is 20mm. Through numerical analysis, it is found that the outer circle is eccentric and eccentric. The test method can form a desired position of cracking. The test results show that the cracking time of 0.5 water cement concrete inner circle eccentricity restraint specimen is not only within two weeks, but the displacement of the crack position is small, and the circle specimen with the thickness of 75mm is almost not open. The crack development and the crack stress estimation of the restrained specimens prove the cracking sensitivity of the concrete outer circular eccentric constraint test method. Taking the concrete of 0.5 water cement ratio as an example, the concrete outer inner circular eccentric restraint test still can crack under the condition of complete seal, and the crack is developed from the outside of the specimen to the inside, and it is obviously improved. The sensitivity of concrete shrinkage cracking is estimated by the crack stress estimation of the specimen. It is found that the maximum crack stress of the outer inner circular eccentric constraint specimen is 3.7MPa-4.2MPa. (3) double circular eccentric constraint test method. The outer boundary of the specimen is round, the diameter is 600mm, the height is 75mm, the diameter of the restrained steel ring is 300mm, the thickness is 20mm, and the steel ring is along the model diameter to the frame. At a certain point, the distance between the outer edge of the steel ring and the inner edge of the die frame is 75mm, and the double circular eccentric constraint test method can also effectively limit the position of the shrinkage crack. The double circular eccentric constraint test method can improve the sensitivity of the shrinkage cracking of the coagulant soil, but the effect is not as good as the external side. In order to detect the shrinkage and cracking time of concrete directly and simply, inspired by circuit circuit and circuit breakage, a new set of cracking time detection device is put forward, which consists of conductive adhesive material, wire and pointer type clocks, and the conductive adhesive material is applied to the expected cracking position. Within the range, after the conductive material is dry, the circuit is connected with the wire and the clock, and every 12h watches a clock moving. If the specimen is cracked, the circuit turns from the circuit to the circuit breaker, the clock stops turning. At this time, the position of the clock pointer is the cracking time of the specimen. This method can greatly save the time for the observation of the crack. Test The device is simple and easy to operate, especially in the test of paste and mortar.

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

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 張立華,許祥俊;水泥基材料水化產(chǎn)物的研究發(fā)展?fàn)顩r評述[J];河南建材;2002年03期

2 李相國,梁文泉,馬保國,葉群山,王信剛;水泥基材料開裂敏感性評價方法分析[J];混凝土;2004年07期

3 張鵬;趙鐵軍;Wittmann F.H.;Lehmann E.;;基于中子成像的水泥基材料毛細(xì)吸水動力學(xué)研究[J];水利學(xué)報;2011年01期

4 蔣家奮;;水泥基材料的科技發(fā)展近況[J];上海建材學(xué)院學(xué)報;1990年04期

5 ;先進(jìn)水泥基材料[J];中國建材科技;1999年01期

6 文寨軍;顏碧蘭;;淺談重大工程用水泥基材料的未來發(fā)展[J];中國建材;2014年04期

7 劉志勇;聚合物水泥基材料研究綜述[J];新型建筑材料;2000年01期

8 楊醫(yī)博,文梓蕓;水泥基材料的微波養(yǎng)護(hù)技術(shù)[J];低溫建筑技術(shù);2001年03期

9 陳美祝,何真;彩色水泥基材料著色穩(wěn)定性研究[J];新型建筑材料;2002年02期

10 鄭克仁,孫偉,楊鼎宜,劉志勇;用于圖像分析的水泥基材料樣品制備技術(shù)[J];建筑材料學(xué)報;2004年03期

相關(guān)會議論文 前10條

1 姚武;吳科如;;水泥基材料損傷自愈合的理論與方法[A];2000年材料科學(xué)與工程新進(jìn)展（下）——2000年中國材料研討會論文集[C];2000年

2 吳中偉;;特高強(qiáng)纖維水泥基材料[A];纖維水泥制品行業(yè)纖維增強(qiáng)水泥及其制品論文選集（1）（1960～2009）[C];2009年

3 趙順增;劉立;吳勇;曹淑萍;;電磁功能水泥基材料性能初探[A];中國硅酸鹽學(xué)會2003年學(xué)術(shù)年會論文摘要集[C];2003年

4 趙順增;劉立;吳勇;曹淑萍;;電磁功能水泥基材料性能初探[A];中國硅酸鹽學(xué)會2003年學(xué)術(shù)年會水泥基材料論文集（下冊）[C];2003年

5 馮奇;巴恒靜;梁傳棟;;二級界面對水泥基材料孔結(jié)構(gòu)和性能的影響[A];中國硅酸鹽學(xué)會2003年學(xué)術(shù)年會水泥基材料論文集（上冊）[C];2003年

6 姚武;劉小艷;伍建平;;碳纖維水泥基材料溫-阻效應(yīng)研究[A];先進(jìn)纖維混凝土 試驗(yàn)·理論·實(shí)踐——第十屆全國纖維混凝土學(xué)術(shù)會議論文集[C];2004年

7 余小燕;賈治龍;于良;陳宜亨;;短切纖維在不同環(huán)境下對水泥基材料斷裂韌性的影響[A];《硅酸鹽學(xué)報》創(chuàng)刊50周年暨中國硅酸鹽學(xué)會2007年學(xué)術(shù)年會論文摘要集[C];2007年

8 崔素萍;徐西奎;汪瀾;;水化環(huán)境對水泥基材料吸附重金屬離子性能的影響[A];第十屆全國水泥和混凝土化學(xué)及應(yīng)用技術(shù)會議論文摘要集[C];2007年

9 謝友均;馬昆林;龍廣成;;硫酸鹽對水泥基材料物理侵蝕的試驗(yàn)研究[A];第七屆全國混凝土耐久性學(xué)術(shù)交流會論文集[C];2008年

10 于利剛;余其俊;劉嵐;;雜化改性廢橡膠粉在水泥基材料中的水化作用[A];2011中國材料研討會論文摘要集[C];2011年

相關(guān)重要報紙文章 前10條

1 本報記者 劉莉;顯微鏡下看水泥[N];科技日報;2007年

2 樊躋宇;拉法基探討水泥基材料可持續(xù)發(fā)展[N];中華建筑報;2011年

3 駐江蘇記者杜小衛(wèi);江蘇水泥基材料創(chuàng)新成果累累[N];中國建材報;2011年

4 賀元棟;肥城米山公司攜手同濟(jì)大學(xué)建立水泥基材料研發(fā)實(shí)踐基地[N];中國建材報;2006年

5 本報記者 周芳燕;水泥基礎(chǔ)研究緣何受寵[N];中國高新技術(shù)產(chǎn)業(yè)導(dǎo)報;2002年

6 本報記者　 胡春明;水泥基材料應(yīng)用技術(shù)成室內(nèi)防水發(fā)展趨勢[N];中國建設(shè)報;2006年

7 王驊;法國高泰集團(tuán)與同濟(jì)大學(xué)簽署合作協(xié)議[N];中國建材報;2010年

8 中國建筑材料工業(yè)規(guī)劃研究院;應(yīng)對產(chǎn)能過剩關(guān)鍵在于轉(zhuǎn)變發(fā)展方式[N];中國建材報;2012年

9 中國建筑材料集團(tuán)有限公司總經(jīng)理 中國建筑材料科學(xué)研究總院院長 姚燕;低碳技術(shù)引領(lǐng)水泥混凝土行業(yè)科學(xué)發(fā)展[N];中國建材報;2011年

10 駐天津記者 郭關(guān)朝 特約記者 王寶芬;天津建材科研所取得良好業(yè)績[N];中國建材報;2006年

相關(guān)博士學(xué)位論文 前10條

1 龐曉，

本文編號：1871007