【作者】 丁庆军；

【导师】 胡曙光；

【作者基本信息】 武汉理工大学 ， 材料学， 2006， 博士

【摘要】 高强次轻混凝土是指表观密度为1950 kg／m³～2300kg／m³，强度在50MPa以上，弹性模量可设计的新型混凝土材料。因其具有轻质、高强、优良的体积稳定性和耐久性，在高层建筑、海洋工程和大跨度桥梁等工程建设中具有巨大的经济优势和广阔的应用前景。本文围绕高强次轻混凝土的组成、结构与性能之间的关系，以及在桥梁工程应用中的关键技术开展了深入系统的研究工作，研究成果为高强次轻混凝土材料的设计、制备与应用提供理论依据和技术支撑。本文进行的主要工作和取得的重要成果有：在系统研究高强混凝土内部湿度与自收缩关系的基础上，提出高强混凝土内部湿度补偿理论与设计方法，揭示了轻集料的湿度补偿作用和普通集料的限制收缩作用是高强次轻混凝土具有优良体积稳定性的本质原因；建立高强次轻混凝土的强度设计理论模型，并提出高强次轻混凝土的配合比设计方法。建立了高强次轻混凝土抗拉强度（f_t）与抗压强度(f_cu)之间的关系式f_t=0.0519f_cu^1.0467，及弹性模量（E）与其表观密度（ρ）和抗压强度(f_cu)的关系式E=0.02554×f_cu^1.44ρ^0.23。为高强次轻混凝土的设计、制备及工程应用奠定了理论基础。系统地研究了次轻混凝土流变性能和工作性能的主要影响因素及其规律，探明了次轻混凝土拌合物具有随着普通集料体积率的增加，屈服剪切应力和粘度系数降低，坍落度和扩展度增加的流变特性；提出了次轻混凝土的匀质性评价方法以及泵送高强次轻混凝土的工作性能控制指标，实现了钢纤维增韧高强次轻混凝上的泵送施工，为次轻混凝土的原材料选择与工作性能设计提供依据。采用XRD、SEM、EDXA等测试手段，结合耐久性试验，研究了高强次轻混凝土的组成、结构与耐久性之间的关系，揭示了水泥石及其与轻集料和普通集料组成的两种界面过渡区在轻集料湿度补偿作用下，水化程度提高、空隙率降低、界面处Ca（OH）₂含量与取向指数减小、混凝土结构密实是高强次轻混凝土具有优良耐久性的重要原因。系统研究了SC60高强次轻混凝土梁的抗弯和抗剪力学性能。结果表明：高强次轻混凝土梁和普通混凝土梁受压区混凝土具有相似的破坏特征，高强次轻混凝土梁的挠度、极限承载力与相同强度等级普通混凝土梁接近，裂缝间距小、分布均匀；高强次轻混凝土与钢筋之间的粘结性好，变形协调同步；随着配筋率的增加，高强次轻混凝土梁的极限承载力提高，延性降低；箍筋对斜裂缝的开裂和挠度影响较小；高强次轻混凝土梁的挠度随剪跨比增大而增大。研究成果为高强次轻混凝土的结构工程设计提供参考依据。创新性地开展了高强次轻混凝土在桥梁工程中的应用研究，首次提出了基于高强次轻混凝土的钢箱梁桥面铺装层结构优化设计方法和预应力轻质空心板梁结构材料梯度设计方法。采用有限元法，深入地分析了钢箱梁桥面铺装层和预应力轻质空心板梁端部的受力特性，创建了一种与钢箱梁协同变形的高耐久性钢箱梁桥面铺装层新型组合结构体系和锚固端抗裂性能优良的新型预应力轻质空心板梁的结构形式。研究成果成功应用于孝襄高速公路随州团山河大桥、武汉市中环线钢箱梁高架桥和绕城公路东西湖钢箱梁桥，解决了轻集料混凝土空心板梁端部锚固区易开裂和钢箱梁桥面铺装层易发生推移、拥包、破损等病害的世界性难题，形成了具有自主知识产权的成套技术。更多还原

【Abstract】 High strength semi lightweight concrete （HSSC） is a kind of new concretematerial which refers to the coarse aggregates compounded with normal weightaggregate and lightweight aggregate. Its dry apparent density between 1950 kg/m³and 2300kg/m³ and compressive strength higher than 50Mpa and modulus can bedesigned. HSSC has many merits such as high compressive strength, small dead load,good volume stability and excellent durability. So it is economic to use ttSSLC inhigh-rise buildings and long-span bridges, and the prospect of its application is veryextensive. The relation between the composition, construe and performance of HSSCand the key application technology of HSSC in the practical engineering werestudied systematically in this paper. The research achievement supplied the theoryand technology for the design, preparation and application of HSSC.The originality innovation of this thesis is summarized as following:The relation between the inner humidity and self-shrinkage of high strengthconcrete was studied systematically. Based on the relation, the compensated theoryand design method of inner humidity of high strength concrete were presented. It canbe concluded that the HSSC possessed the good volume stability because thelight-weight aggregate and normal aggregate played the roles as the humiditycompensation and confining shrinkage, respectively. At the same time, the strengthdesign theory model of HSSC was established and the mixture proportion designmethod was presented. The equation for the relation between compressive strengthand tensile strength of HSSC is as following, f_t=0.0519f_cu^1.0467. The equation for therelation between compressive strength, appearance density and elastic modulus ofHSSC is as following, E=0.02554×f_cu^1.44×ρ^0.23. This laid a theory foundation forthe design, preparation and application of HSSC.The rheologic and workability performance of HSSC was studiedsystematically by means of the different effecting factors. And the rule was provedup: the yield value of shear stress and the viscosity of cement paste decreased withthe increasing of volume ration of normal aggregate in the concrete: but thedivergence and the slump constant were inversed. Then the experimental methodsfor the uniform performance of HSSC and the workability index of the pumpingHSSC were established. It realized, the application of the pumping HSSC andsupplied the rule for raw materials and workability performance designing of HSSC. The composition, construction and durability of HSSC were studied by theXRD, SEM, EDXA and durability experiment. The excellent durability of HSSCresulted from the higher hydrated degree and more dense construction of the cementstone and the lower content and orientation index of Ca（OH）₂ in the interfacebetween the stone and aggregate because of the inner humidity compensation oflight-weight aggregate.It is studied systematically on the flexural and shearing mechanical propertiesof the SC60 HSSC beams. The results showed that HSSC beam has the similardestructive characteristic to the normal concrete beams. The flexivity and limiterload of HSSC is close to of the normal concrete beams with the same strength grade.Comparing the crack of the HSSC beams with the normal concrete beams, the spacebetween them is smaller and the distribution is more homogeneous, which isindicated that the bonded strength between HSSC beams and reinforcing steel bar ishigher and the synchronize distortion capability is better. With increasing of the ratioof reinforcement, the ductility of HSSC beams decreases and the limited load withcracking increases slightly. The stirrup of HSSC beams has few effects on theslanting crack and flexivity. The flexivity of HSSC beam increased with the shearspan ratio increasing. This laid a theory foundation for the design of HSSC appliedin the practice engineering.It was originality reported on the engineering practice of HSSC. It was firstlypresent for the optimum design method of steel-box beam bridge surfacingconstruction base on HSSC and the gradient design method of lightweight hollowbeam used HSSC. The characteristic of the surfacing system of steel-box beambridge and the prestressed lightweight hollow beam was analyzed by finite-elementmethod. A new unit-construction system for the pavement of steel-box beambridge was established, which make the surfacing system with the consistentdistortion and high durability performance. Another new construction form was alsoestablished, which make the stress of both ends of the prestressed lightweight hollowbeam is obviously improved so that the split phenomenon of ends can be voided andthe using performance and safety of the construction get improvement.The research achievement was successfully applied in the engineering ofTuanshan river bridge of Xiao-Xiang highway and of steel-box beam bridge of theWuhan middle circle line and of Wuhan east-west lake road. The world puzzleincluding traction, bellying and breakage of the steel-box beam bridge surfacing pavement and the dehiscence of both ends of the prestressed lightweight hollowbeam was solved completely. At the same time, we have possess a unitizedtechnology with independence knowledge property right for the steel-box beambridge and prestressed lightweight hollow beam.更多还原