高體積率鋼纖維自密實(shí)混凝土靜態(tài)斷裂性能研究
發(fā)布時(shí)間：2018-07-20 21:32
【摘要】：自密實(shí)混凝土中可以通過摻入鋼纖維來改善其強(qiáng)度和韌性。以往研究都主要集中為普通鋼纖維增強(qiáng)自密實(shí)混凝土,所選用的鋼纖維主要集中在長(zhǎng)度為15~35mm,長(zhǎng)細(xì)比為40~65且體積摻量通常不超過1.5%。盡管普通鋼纖維對(duì)自密實(shí)混凝土的強(qiáng)度和韌性均有一定程度的提高,但提高幅度有限,完全可以通過調(diào)整配合比配制出同等強(qiáng)度等級(jí)的普通自密實(shí)混凝土。此外,當(dāng)纖維體積摻量超過1.5%后,纖維分散性變差,混合料攪拌難度大易出現(xiàn)結(jié)團(tuán)、流動(dòng)性降低難以達(dá)到自密實(shí),材料基本性能持續(xù)提高難以實(shí)現(xiàn)。論文以斷裂力學(xué)阻裂增強(qiáng)機(jī)理為基礎(chǔ),以滿足自密實(shí)混凝土工作性為前提,提出一種剛性纖維改性水泥基復(fù)合材料的研究方法,實(shí)現(xiàn)傳統(tǒng)鋼纖維自密實(shí)混凝土難以實(shí)現(xiàn)的鋼纖維高摻量,得到一種具有高強(qiáng)度和高韌性特性的高摻量微細(xì)平直型鋼纖維自密實(shí)混凝土(SFRSCC),并針對(duì)高強(qiáng)特性可能導(dǎo)致的缺陷敏感性開展斷裂性能試驗(yàn),即高強(qiáng)材料存在初裂紋的條件下,其高強(qiáng)優(yōu)勢(shì)會(huì)不會(huì)導(dǎo)致其缺陷敏感性也倍增。論文在大量的工作性和基本力學(xué)性能試驗(yàn)的基礎(chǔ)上,通過三點(diǎn)彎曲缺口小梁試驗(yàn)研究了其靜態(tài)斷裂性能。具體展開了以下工作:①基于斷裂力學(xué)原理設(shè)計(jì)的SFRSCC混合料工作性能良好,當(dāng)鋼纖維體積摻量達(dá)到6%時(shí),微細(xì)平直型鋼纖維自密實(shí)混凝土混合料的塌落擴(kuò)展度SP達(dá)到了600mm以上,鋼纖維亂向均勻分布于混合料中,無明顯骨料堆積現(xiàn)象�？闺x析性能極好,篩余率為1.3%。對(duì)于3×40mm的鋼筋間隙,當(dāng)體積摻量為0~3.0%時(shí),通過性良好H2/H1能達(dá)到90%以上,當(dāng)體積摻量為4.5%~6.0%時(shí)會(huì)出現(xiàn)輕微堵塞現(xiàn)象。②與C40、C50基準(zhǔn)自密實(shí)混凝土相比,基本力學(xué)性能指標(biāo)隨著纖維體積摻量的增加而提高,當(dāng)纖維體積摻量達(dá)到6%,C40組(A組)SFRSCC立方體抗壓強(qiáng)度提高111.4%,抗折強(qiáng)度提高214.2%,劈拉強(qiáng)度提高133.2%,壓縮彈性模量提高13.1%,彎拉彈性模量提高9.3%,初裂強(qiáng)度提高217.1%,等效彎曲強(qiáng)度提高1083.3%,彎曲韌性比提高300%;C50組(B組)SFRSCC立方體抗壓強(qiáng)度提高73.0%,抗折強(qiáng)度提高143.2%,劈拉強(qiáng)度提高173.6%,壓縮彈性模量提高16.5%,彎拉彈性模量提高9.8%,初裂強(qiáng)度提高125.0%,等效彎曲強(qiáng)度提高了1080.3%,彎曲韌性比提高264.7%。③三點(diǎn)彎曲缺口小梁斷裂性能測(cè)試表明,預(yù)裂相同情況下,與C40、C50的素基準(zhǔn)自密實(shí)混凝土相比,C40組(A組)SFRSCC有效裂縫高度平均提高51.8%,斷裂韌度平均提高193.7%,起裂韌度平均提高139.6%,失穩(wěn)韌度平均提高195.7%,加載點(diǎn)最大位移平均提高1002.4%,斷裂能增益比平均為23.0。C50組(B組)SFRSCC有效裂縫高度平均提高102.6%,斷裂韌度平均提高236.5%,起裂韌度平均提高98.1%,失穩(wěn)韌度平均提高285.6%。加載點(diǎn)最大位移平均提高1071.1%。斷裂能增益比平均為23.27。當(dāng)纖維層≥60mm,隨著纖維層厚度的提高,有效裂紋長(zhǎng)度增長(zhǎng)緩慢,趨于穩(wěn)定,達(dá)到1/3梁截面高度(包括預(yù)裂縫長(zhǎng)度),斷裂韌度值也趨于穩(wěn)定。SFRSCC試件的P-CMOD曲線和荷載-位移曲線呈現(xiàn)明顯的塑性特征,素自密實(shí)混凝土達(dá)到峰值荷載后曲線迅速下降,失去承載能力。SFRSCC不僅具有非線性彈性階段,在達(dá)到峰值荷載后具有較長(zhǎng)的塑性階段,曲線緩慢下降,裂縫穩(wěn)定擴(kuò)展時(shí)間長(zhǎng),裂紋尖端張開位移提高明顯,具有高強(qiáng)韌特性。④運(yùn)用ANSYS有限元分析軟件得出的斷裂韌度值與試驗(yàn)研究得出的斷裂韌度值隨著纖維層厚度增大而變化的規(guī)律一致,驗(yàn)證缺口小梁的斷裂韌度的準(zhǔn)確性。綜上所述,與普通自密實(shí)混凝土相比,試驗(yàn)研究配制出的高體積率鋼纖維自密實(shí)混凝土工作性能及力學(xué)性能良好,具有廣闊的應(yīng)用前景。
[Abstract]:The strength and toughness of self compacting concrete can be improved by adding steel fiber. The previous study was mainly concentrated on steel fiber reinforced self compacting concrete. The steel fiber selected mainly concentrated in the length of 15~35mm, the length and slenderness ratio of 40~65 and the volume content usually not more than 1.5%., although the strength of the self compacting concrete was stronger than that of the ordinary steel fiber. The degree and toughness are improved to a certain extent, but the increase in the range is limited, and the ordinary self compacting concrete with the same strength grade can be prepared by adjusting the mix ratio. In addition, when the volume of the fiber is more than 1.5%, the dispersion of the fiber becomes worse and the mixing is difficult to be mixed, and the flow property is difficult to achieve self compacting, and the material is difficult to achieve self compacting. It is difficult to realize the continuous improvement of basic performance. Based on the strengthening mechanism of fracture mechanics, this paper puts forward a research method of rigid fiber modified cement based composite on the premise of satisfying the working property of self compacting concrete, and realizes the high admixture of steel fiber which is difficult to be realized by the traditional steel fiber self compacting concrete, and obtains a high strength. The high admixture of high admixture and high tenacity steel fiber self compacting concrete (SFRSCC), and to carry out the fracture performance test for the defect sensitivity of high strength properties, that is, under the condition of the initial crack in the high strength material, its high strength will not cause the defect sensitivity to be doubled. On the basis of the performance test, the static fracture performance of the three point bending notch trabecula was studied. The following work was carried out: (1) the working performance of the SFRSCC mixture based on the principle of fracture mechanics was good. When the volume of steel fiber volume reached 6%, the collapse expansion of the self compacting concrete mixture was S P reaches more than 600mm, and the steel fiber is uniformly distributed in the mixture without obvious aggregate accumulation. The anti segregation performance is excellent, the sieve residual rate is 1.3%. for 3 x 40mm steel bar gap, when the volume content is 0~3.0%, the good H2/H1 can reach more than 90%. When the volume content is 4.5%~6.0%, there will be a slight clogging phenomenon. (2) and C40, C50 Compared with the base self compacting concrete, the basic mechanical performance index increases with the increase of the volume of fiber volume. When the volume of fiber volume reaches 6%, the compressive strength of SFRSCC cube in group C40 (A group) is increased by 111.4%, the flexural strength is raised by 214.2%, the splitting tensile strength is increased by 133.2%, the elastic modulus of compression is increased by 13.1%, the flexural modulus is increased by 9.3%, and the initial crack strength is strong. The equivalent bending strength is raised by 217.1%, the equivalent bending strength is increased by 1083.3%, the flexural toughness is 300%, the compressive strength of the SFRSCC cube in group C50 (B group) is increased by 73%, the flexural strength is raised by 143.2%, the splitting tensile strength is increased by 173.6%, the compression modulus is raised by 16.5%, the flexural modulus is raised by 9.8%, the initial crack strength is increased by 125%, the equivalent bending strength is increased 1080.3%, the bending strength is 1080.3%, bending. The fracture performance test of the flexural toughness ratio (264.7%.) three point bending notched trabecula shows that the effective crack height of C40 group (A group) is increased by 51.8%, the fracture toughness increases by 193.7%, the crack toughness increases by 139.6% and the instability toughness increases 195.7%, and the instability toughness increases by 195.7%. The point maximum displacement is increased by 1002.4%, the fracture energy gain is higher than the average 23.0.C50 group (B group), the effective crack height of SFRSCC is increased by 102.6%, the fracture toughness increases by 236.5%, the crack toughness increases by 98.1%, the instability toughness increases averaging the maximum displacement of the 285.6%. loading point and the 1071.1%. fracture energy gain ratio is 23.27. as the average fiber. As the layer is more than 60mm, with the increase of the thickness of the fiber layer, the effective crack length increases slowly and tends to stable, reaching the height of the 1/3 beam section (including the length of the pre crack). The fracture toughness values also tend to be stable in the P-CMOD curve and load displacement curve of the.SFRSCC specimen, and the curve of the self compacting concrete is rapidly under the peak load. .SFRSCC not only has nonlinear elastic phase, but also has a long plastic stage after reaching the peak load. The curve slows down slowly, the crack growth time is long, the crack tip opening displacement increases obviously and has high toughness characteristics. (4) the fracture toughness value obtained by using the ANSYS finite element analysis software and experimental study The fracture toughness values are consistent with the increase of the thickness of the fiber layer, and the accuracy of the fracture toughness of the notched trabecula is verified. In summary, compared with the ordinary self compacting concrete, the high volume rate steel fiber self compacting concrete has a good working performance and good mechanic performance, which has a broad application prospect.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528
[Abstract]:The strength and toughness of self compacting concrete can be improved by adding steel fiber. The previous study was mainly concentrated on steel fiber reinforced self compacting concrete. The steel fiber selected mainly concentrated in the length of 15~35mm, the length and slenderness ratio of 40~65 and the volume content usually not more than 1.5%., although the strength of the self compacting concrete was stronger than that of the ordinary steel fiber. The degree and toughness are improved to a certain extent, but the increase in the range is limited, and the ordinary self compacting concrete with the same strength grade can be prepared by adjusting the mix ratio. In addition, when the volume of the fiber is more than 1.5%, the dispersion of the fiber becomes worse and the mixing is difficult to be mixed, and the flow property is difficult to achieve self compacting, and the material is difficult to achieve self compacting. It is difficult to realize the continuous improvement of basic performance. Based on the strengthening mechanism of fracture mechanics, this paper puts forward a research method of rigid fiber modified cement based composite on the premise of satisfying the working property of self compacting concrete, and realizes the high admixture of steel fiber which is difficult to be realized by the traditional steel fiber self compacting concrete, and obtains a high strength. The high admixture of high admixture and high tenacity steel fiber self compacting concrete (SFRSCC), and to carry out the fracture performance test for the defect sensitivity of high strength properties, that is, under the condition of the initial crack in the high strength material, its high strength will not cause the defect sensitivity to be doubled. On the basis of the performance test, the static fracture performance of the three point bending notch trabecula was studied. The following work was carried out: (1) the working performance of the SFRSCC mixture based on the principle of fracture mechanics was good. When the volume of steel fiber volume reached 6%, the collapse expansion of the self compacting concrete mixture was S P reaches more than 600mm, and the steel fiber is uniformly distributed in the mixture without obvious aggregate accumulation. The anti segregation performance is excellent, the sieve residual rate is 1.3%. for 3 x 40mm steel bar gap, when the volume content is 0~3.0%, the good H2/H1 can reach more than 90%. When the volume content is 4.5%~6.0%, there will be a slight clogging phenomenon. (2) and C40, C50 Compared with the base self compacting concrete, the basic mechanical performance index increases with the increase of the volume of fiber volume. When the volume of fiber volume reaches 6%, the compressive strength of SFRSCC cube in group C40 (A group) is increased by 111.4%, the flexural strength is raised by 214.2%, the splitting tensile strength is increased by 133.2%, the elastic modulus of compression is increased by 13.1%, the flexural modulus is increased by 9.3%, and the initial crack strength is strong. The equivalent bending strength is raised by 217.1%, the equivalent bending strength is increased by 1083.3%, the flexural toughness is 300%, the compressive strength of the SFRSCC cube in group C50 (B group) is increased by 73%, the flexural strength is raised by 143.2%, the splitting tensile strength is increased by 173.6%, the compression modulus is raised by 16.5%, the flexural modulus is raised by 9.8%, the initial crack strength is increased by 125%, the equivalent bending strength is increased 1080.3%, the bending strength is 1080.3%, bending. The fracture performance test of the flexural toughness ratio (264.7%.) three point bending notched trabecula shows that the effective crack height of C40 group (A group) is increased by 51.8%, the fracture toughness increases by 193.7%, the crack toughness increases by 139.6% and the instability toughness increases 195.7%, and the instability toughness increases by 195.7%. The point maximum displacement is increased by 1002.4%, the fracture energy gain is higher than the average 23.0.C50 group (B group), the effective crack height of SFRSCC is increased by 102.6%, the fracture toughness increases by 236.5%, the crack toughness increases by 98.1%, the instability toughness increases averaging the maximum displacement of the 285.6%. loading point and the 1071.1%. fracture energy gain ratio is 23.27. as the average fiber. As the layer is more than 60mm, with the increase of the thickness of the fiber layer, the effective crack length increases slowly and tends to stable, reaching the height of the 1/3 beam section (including the length of the pre crack). The fracture toughness values also tend to be stable in the P-CMOD curve and load displacement curve of the.SFRSCC specimen, and the curve of the self compacting concrete is rapidly under the peak load. .SFRSCC not only has nonlinear elastic phase, but also has a long plastic stage after reaching the peak load. The curve slows down slowly, the crack growth time is long, the crack tip opening displacement increases obviously and has high toughness characteristics. (4) the fracture toughness value obtained by using the ANSYS finite element analysis software and experimental study The fracture toughness values are consistent with the increase of the thickness of the fiber layer, and the accuracy of the fracture toughness of the notched trabecula is verified. In summary, compared with the ordinary self compacting concrete, the high volume rate steel fiber self compacting concrete has a good working performance and good mechanic performance, which has a broad application prospect.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528
【參考文獻(xiàn)】
相關(guān)期刊論文 前3條
1 易成,沈世釗;局部高密度鋼纖維混凝土靜態(tài)斷裂性能研究[J];哈爾濱建筑大學(xué)學(xué)報(bào);2001年02期
2 陳春珍;張金喜;陳煒林;金珊珊;李建軍;;自密實(shí)混凝土配合比設(shè)計(jì)方法適用性的研究[J];混凝土;2009年12期
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