本文選題：鋼纖維輕骨料混凝土 + 拌合物性能��； 參考：《鄭州大學(xué)》2014年博士論文

【摘要】：輕骨料混凝土具有輕質(zhì)、高強(qiáng)、抗震性能和耐久性能好等優(yōu)點(diǎn)，越來越多地被應(yīng)用于土木工程中。在輕骨料混凝土中摻入鋼纖維配制的鋼纖維輕骨料混凝土(簡(jiǎn)稱SFRLC)，不僅具有輕骨料混凝土的各種優(yōu)點(diǎn)，而且能顯著提高輕骨料混凝土的抗拉、抗裂性能和韌性，改善混凝土結(jié)構(gòu)的延性、抗疲勞性能和耐久性能。因此，開展鋼纖維輕骨料混凝土材料與構(gòu)件性能試驗(yàn)與理論研究具有重要的應(yīng)用價(jià)值與理論意義。為充分利用鋼纖維輕骨料混凝土和普通混凝土的優(yōu)點(diǎn)，作者提出了一種新型結(jié)構(gòu)形式：在下部一定高度的鋼纖維輕骨料混凝土上同期現(xiàn)澆普通混凝土組成的疊澆梁。本文采用不同配合比方法進(jìn)行鋼纖維輕骨料混凝土配合比設(shè)計(jì)，，通過系列試驗(yàn)研究了不同參數(shù)對(duì)鋼纖維輕骨料混凝土基本性能的影響，對(duì)所提出的新型鋼纖維輕骨料混凝土疊澆梁（簡(jiǎn)稱SFRLCB）開展了系統(tǒng)試驗(yàn)研究和理論分析，所完成的主要工作和取得的結(jié)論： （1）采用松散體積法對(duì)鋼纖維機(jī)制砂輕混凝土和鋼纖維全輕混凝土(簡(jiǎn)稱SFRFLC)進(jìn)行配合比設(shè)計(jì)，系統(tǒng)研究了水灰比、水泥用量、砂率及鋼纖維體積率等參數(shù)對(duì)混凝土性能的影響。結(jié)果表明：機(jī)制砂輕混凝土的抗壓強(qiáng)度及彈性模量、劈裂抗拉強(qiáng)度和軸心抗拉強(qiáng)度均隨水灰比的增大而減小，但抗彎強(qiáng)度受水灰比的影響不明顯；當(dāng)水泥用量較高時(shí)，砂率對(duì)混凝土軸心抗拉強(qiáng)度和抗彎強(qiáng)度的影響較��；當(dāng)水泥用量較低時(shí)，混凝土的軸心抗拉強(qiáng)度和抗彎強(qiáng)度受砂率和水泥用量的關(guān)聯(lián)影響，砂率對(duì)混凝土劈裂抗拉強(qiáng)度的影響不明顯。全輕混凝土的強(qiáng)度受砂率、水灰比及水泥用量的關(guān)聯(lián)影響，其強(qiáng)度值主要取決于水泥砂漿及陶粒強(qiáng)度的強(qiáng)弱；存在使混凝土各強(qiáng)度指標(biāo)達(dá)到最佳值的水泥用量、水灰比及砂率。摻加鋼纖維顯著增強(qiáng)了機(jī)制砂輕混凝土的劈裂抗拉強(qiáng)度和軸心抗拉強(qiáng)度，明顯提高了全輕混凝土的抗彎強(qiáng)度。 （2）采用考慮鋼纖維裹漿厚度的直接設(shè)計(jì)方法進(jìn)行高強(qiáng)鋼纖維全輕混凝土配合比設(shè)計(jì)，系統(tǒng)研究了鋼纖維體積率、水灰比、鋼纖維裹漿厚度及砂率對(duì)高強(qiáng)鋼纖維全輕混凝土性能的影響。結(jié)果表明：按考慮裹漿厚度的直接設(shè)計(jì)方法配制的高強(qiáng)鋼纖維全輕混凝土，能滿足拌合物工作性能、干表觀密度和強(qiáng)度的要求。隨著鋼纖維體積率的增加，高強(qiáng)鋼纖維全輕混凝土立方體抗壓強(qiáng)度、軸心抗壓強(qiáng)度和軸心抗拉強(qiáng)度均有所提高，劈裂抗拉強(qiáng)度顯著提高。經(jīng)綜合分析，確定鋼纖維全輕混凝土最佳鋼纖維裹漿厚度為1.0mm。 （3）對(duì)試驗(yàn)中采用不同配合比方法的鋼纖維輕骨料混凝土的劈裂抗拉強(qiáng)度和軸心抗拉強(qiáng)度的關(guān)系進(jìn)行了分析研究，結(jié)果表明：該類輕骨料混凝土劈裂抗拉強(qiáng)度與軸心抗拉強(qiáng)度的比值隨輕骨料性質(zhì)和鋼纖維特征含量的變化而變化，建議輕骨料混凝土和鋼纖維輕骨料混凝土抗拉強(qiáng)度采用軸心抗拉強(qiáng)度法測(cè)定。 （4）考慮水泥用量、水灰比及鋼纖維體積率變化，進(jìn)行了鋼纖維全輕混凝土抗凍性能試驗(yàn)研究。結(jié)果表明：鋼纖維全輕混凝土的抗凍性能受水泥用量及水灰比的影響，摻入鋼纖維可顯著提高全輕混凝土的抗凍性能。與相對(duì)動(dòng)彈性模量相比，抗彎強(qiáng)度損失率對(duì)凍融循環(huán)更為敏感。建議對(duì)承受彎曲作用為主的鋼纖維輕骨料混凝土構(gòu)件，采用抗彎強(qiáng)度損失率作為抗凍性能的1個(gè)評(píng)價(jià)指標(biāo)。 （5）系統(tǒng)進(jìn)行了42根鋼筋鋼纖維全輕混凝土疊澆梁、12根鋼筋混凝土梁和4根鋼筋鋼纖維全輕混凝土梁的受彎性能試驗(yàn)。結(jié)果表明：3類試驗(yàn)梁的破壞形態(tài)基本相似，均為適筋破壞；鋼纖維摻量、疊澆高度對(duì)試驗(yàn)梁極限承載力具有較大影響，且變化規(guī)律與配筋率相關(guān)；縱筋配筋率顯著影響試驗(yàn)梁的極限承載力，受壓區(qū)混凝土強(qiáng)度等級(jí)對(duì)疊澆梁的極限承載力影響較小。根據(jù)理論分析和試驗(yàn)結(jié)果，建立了鋼筋鋼纖維全輕混凝土疊澆梁受彎承載力的計(jì)算模型和計(jì)算方法，提出了疊澆梁鋼纖維全輕混凝土最小高度和最佳高度計(jì)算公式。 （6）結(jié)合試驗(yàn)梁的研究成果，分析了鋼纖維體積率、普通混凝土強(qiáng)度等級(jí)、縱向受拉鋼筋配筋率和鋼纖維全輕混凝土截面高度等參數(shù)對(duì)疊澆梁正截面抗裂彎矩的影響規(guī)律。結(jié)果表明：疊澆梁受壓區(qū)混凝土與受拉區(qū)鋼纖維全輕混凝土的截面高度存在較優(yōu)值，受壓區(qū)高強(qiáng)混凝土保障了疊澆梁正截面的較高抗裂彎矩；適當(dāng)?shù)目v向受拉鋼筋配筋率有利于提高疊澆梁的正截面抗裂彎矩；鋼纖維對(duì)疊澆梁正截面抗裂彎矩的提高與其對(duì)全輕混凝土抗拉強(qiáng)度的提高是一致的。結(jié)合理論計(jì)算分析，提出了鋼筋鋼纖維全輕混凝土疊澆梁正截面抗裂計(jì)算方法以及充分發(fā)揮鋼纖維全輕混凝土抗拉能力的截面高度計(jì)算公式。 （7）根據(jù)疊澆梁在正常使用荷載作用下的裂縫分布情況，明確了疊澆梁裂縫分類統(tǒng)計(jì)原則，進(jìn)行了各類裂縫數(shù)量、平均裂縫間距、平均裂縫寬度及最大裂縫寬度分布規(guī)律的統(tǒng)計(jì)分析，建立了疊澆梁縱向受力鋼筋重心水平位置處平均裂縫間距、平均裂縫寬度和最大裂縫寬度的計(jì)算模型和計(jì)算方法。
[Abstract]:Lightweight aggregate concrete has many advantages, such as light weight, high strength, good seismic performance and good durability. It is more and more used in civil engineering. Steel fiber lightweight aggregate concrete (SFRLC) mixed with steel fiber in lightweight aggregate concrete not only has various advantages of lightweight aggregate concrete, but also significantly improves lightweight aggregate concrete. Tensile, crack resistance and toughness improve the ductility, fatigue resistance and durability of concrete structures. Therefore, it is of great applied value and theoretical significance to carry out the performance test and theoretical study of steel fiber lightweight aggregate concrete materials and components. The author proposes to make full use of the advantages of steel fiber lightweight aggregate concrete and ordinary concrete. A new type of structural form: a superimposed cast-in-place beam of steel fiber lightweight aggregate concrete at a certain height at the lower level. The mix proportion of steel fiber lightweight aggregate concrete is designed by different mix ratio methods. The basic properties of steel fiber lightweight aggregate concrete are studied by a series of experiments. A new type of steel fiber reinforced concrete composite cast-in-place beam (SFRLCB) is carried out in a systematic test and theoretical analysis, and the main work and conclusions are achieved.
(1) the loose volume method is used to design the mix ratio of steel fiber reinforced lightweight concrete and steel fiber all light concrete (SFRFLC). The effects of water cement ratio, cement dosage, sand rate and steel fiber volume rate on the concrete performance are systematically studied. The results show that the compressive strength and modulus of elasticity of the machine made sand lightweight concrete, splitting resistance The tensile strength and the axial tensile strength decrease with the increase of water cement ratio, but the bending strength is not obviously influenced by the ratio of water to cement. When the cement content is high, the sand ratio has little effect on the tensile strength and bending strength of concrete axle center. When the cement dosage is low, the axial tensile strength and bending strength of the concrete are affected by the sand rate and cement. The effect of sand ratio on the splitting tensile strength of concrete is not obvious. The strength of all light concrete is influenced by the correlation of sand ratio, water cement ratio and cement content. The strength of the concrete mainly depends on the strength of cement mortar and the strength of the ceramsite, and the cement dosage, water cement ratio and sand ratio that make the concrete strength indexes reach the best value. The tensile strength and axial tensile strength of the machine-made sand lightweight concrete are significantly increased by adding steel fiber, and the flexural strength of all lightweight concrete is obviously improved.
(2) using the direct design method considering the thickness of steel fiber, the mix ratio design of high strength steel fiber full light concrete is designed. The effect of steel fiber volume rate, water cement ratio, thickness of steel fiber and sand ratio on the performance of high strength steel fiber lightweight concrete is systematically studied. The results show that the direct design method considering the thickness of the steel fiber is made up. The high strength steel fiber full light concrete can meet the requirements of the working performance of the mixture, the density and strength of the dry surface. With the increase of the steel fiber volume rate, the compressive strength of the high strength steel fiber full light concrete cube, the axial compressive strength and the axial tensile strength of the axle are improved, and the splitting tensile strength is greatly improved. The steel fiber is determined by comprehensive analysis. The best steel fiber wrapped thickness of all lightweight concrete is 1.0mm.
(3) the relationship between splitting tensile strength and axial tensile strength of steel fiber lightweight aggregate concrete with different mix ratio methods was analyzed. The results showed that the ratio of splitting tensile strength to axial tensile strength of this kind of lightweight aggregate concrete varies with the change of light aggregate quality and steel fiber characteristic content. The tensile strength of lightweight aggregate concrete and steel fiber reinforced lightweight aggregate concrete is determined by axial tensile strength method.
(4) considering the amount of cement, the ratio of water to cement and the change of the volume ratio of steel fiber, the frost resistance performance of the steel fiber full light concrete is studied. The results show that the frost resistance of the steel fiber full light concrete is affected by the cement dosage and the water cement ratio, and the frost resistance of the whole light concrete can be greatly improved by the addition of steel fiber. The flexural strength loss rate is more sensitive to the freezing and thawing cycle. It is suggested that the flexural strength loss rate is used as the 1 evaluation index for the frost resistance of the steel fiber lightweight aggregate concrete members.
(5) the flexural performance tests of 42 steel fiber reinforced steel fiber fully lightweight concrete beams, 12 reinforced concrete beams and 4 steel fiber full light concrete beams are carried out. The results show that the failure modes of the 3 type test beams are basically similar, all of which are suitable for reinforcement, and the steel fiber content and superposition height have great influence on the ultimate bearing capacity of the test beams. And the change rule is related to the reinforcement ratio; the longitudinal reinforcement ratio has a significant influence on the ultimate bearing capacity of the test beam, and the concrete strength grade of the compression zone has little influence on the ultimate bearing capacity of the superimposed beam. Based on the theoretical analysis and test results, the calculation model and calculation method of the bending bearing capacity of the steel fiber reinforced steel fiber full light concrete superposition beam are established. The formula for calculating the minimum height and optimum height of steel fiber reinforced lightweight concrete is presented.
(6) combining with the research results of the test beam, the influence of the steel fiber volume rate, the strength grade of the ordinary concrete, the reinforcement ratio of the longitudinal reinforced bar and the height of the steel fiber full light concrete section on the bending moment of the cross section beam is analyzed. The results show that the section of the concrete and the steel fiber full light concrete in the compression zone of the cast in place beam is cut. There is a better value in the height of the surface, and the high strength concrete in the compression zone ensures the high cracking bending moment of the cross section of the beam, and the proper reinforcement ratio of the longitudinal reinforced bar is beneficial to the improvement of the bending moment of the cross section of the beam, and the improvement of the crack resistance of the steel fiber to the cross section of the cast beam is consistent with the increase of the tensile strength of the full light concrete. On the basis of rational calculation and analysis, the calculation method for the crack resistance of steel fiber reinforced steel fiber full light concrete superposition beam and the calculation formula for full play of the tensile capacity of the steel fiber full light concrete are put forward.
(7) according to the distribution of the cracks under the normal use load of the superimposed beam, the classification statistics principle of the cracks of the superimposed beam is clarified, and the statistical analysis of the number of cracks, the average crack spacing, the average crack width and the distribution law of the maximum crack width is carried out, and the average crack between the horizontal position of the center of gravity of the longitudinal stress bar of the superimposed cast-in-place beam is established. The calculation model and calculation method of the average crack width and the maximum crack width are given.

【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU528.2;TU37

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