【作者】 张敏；

【导师】 王树伟； 代志宏；

【作者基本信息】 广西大学 ， 土木工程（专业学位）， 2024， 硕士

【摘要】 超高性能混凝土(UHPC,Ultra-high Performance Concrete)凭借其卓越的强度、耐久性和良好的抗蚀抗冲刷性,在海洋工程建设中展现出显著的应用价值。将贝类等海洋废弃物资源适当处理后作为粗骨料同时应用海水海砂进行制备超高性能混凝土材料,有助于解决沿海陆域、近海区域、远海岛礁等建材匮乏、建设成本高的难题,减轻对生态环境的压力。本研究聚焦于研发一种含有锥螺壳粗骨料的超高性能混凝土(UHPC-SCA,UHPC with Shell as Coarse Aggregate),旨在通过对比分析,探究其与传统使用花岗岩粗骨料、河砂、淡水制备的UHPC-CA(UHPC with Coarse Aggregate)在基本力学性能上的差异。(1)选择的水胶比为0.16,粗骨料掺量500kg/m~3,结合普通河砂、P·O42.5水泥和4.75-9.5mm粒径的花岗岩碎石,研究钢纤维(SF)、聚乙烯醇纤维(PVA)和聚丙烯纤维(PP)及其掺量对UHPC-CA的流动性和抗压强度的影响,获得最佳纤维类型与最优纤维掺量。(2)使用牡蛎壳和锥螺壳骨料替代花岗岩碎石,研究了SF在0%和1.5%含量下对粗骨料UHPC的流动性和抗压强度的影响。发现锥螺壳配置的UHPC-SCA抗压强度达到106MPa,优于牡蛎壳,并且与UHPC-CA相当。(3)通过对UHPC-SCA和UHPC-CA的宏观破坏与微观形貌进行分析,发现试件内部存在大量空隙是导致开裂的主要因素。基于这一发现,对细骨料级配进行了优化,并添加了P·O52.5水泥和消泡剂来改善UHPC-SCA基本力学性能不足的问题。将UHPC-SCA与同条件的UHPC-CA进行了抗压强度、轴心抗压强度、劈裂抗拉强度和抗折强度的对比。结果显示,锥螺壳UHPC-SCA的28天抗压强度和轴心抗压强度均高于UHPC-CA。而劈裂抗拉强度、应力-应变曲线关系、弹性模量、抗折强度和弯曲挠曲与UHPC-CA相近。此外,还建立了轴压比、拉压比和压折比的数学模型,并通过两种典型公式对试验的应力-应变曲线进行拟合,预测效果较好。更多还原

【Abstract】 Ultra-high Performance Concrete(UHPC)has demonstrated significant value in marine engineering construction due to its exceptional strength,durability,and resistance to corrosion and erosion.Utilizing marine waste resources such as shellfish as coarse aggregate and seawater sand in the production of UHPC materials can help address the challenges of limited building materials and high construction costs in coastal areas,offshore locations,and islands,while also reducing the impact on the ecological environment.This study focuses on the development of a type of UHPC-SCA(UHPC with a coarse aggregate of spiral shells).Its objective is to investigate the differences in basic mechanical properties between UHPC-CA(UHPC with a coarse aggregate of granite,river sand,and freshwater)and UHPC-SCA through comparative analysis.(1)The water-binder ratio chosen is 0.16,and the coarse aggregate content is 500 kg/m~3.When combined with ordinary river sand,P.O 42.5cement,and granite crushed stone with a particle size of 4.75-9.5 mm,the study examines the impact of steel fiber(SF),polyvinyl alcohol fiber(PVA),and polypropylene fiber(PP)and their content on the fluidity and compressive strength of UHPC-CA.The goal is to determine the best fiber type and its effect on compressive strength.(2)The study examined the impact of substituting granite gravel with oyster shell and snail shell aggregate on the fluidity and compressive strength of coarse aggregate UHPC,with a focus on the influence of 0%and 1.5%SF content.The results showed that the compressive strength of UHPC-SCA containing conical snail shells reached 106MPa,outperforming oyster shells and matching UHPC-CA.(3)Upon analyzing the macro-damage and micro-morphology of UHPC-SCA and UHPC-CA,it was discovered that many voids in the specimens are the main factors leading to cracking.As a result of this finding,the gradation of fine aggregate was optimized,and P.O 52.5 cement and defoamer were added to enhance the basic mechanical properties of UHPC-SCA.The compressive strength,axial compressive strength,splitting tensile strength,and flexural strength of UHPC-SCA and UHPC-CA were compared under the same conditions.The results indicate that the 28-day compressive strength and axial compressive strength of UHPC-SCA are higher than those of UHPC-CA.However,the splitting tensile strength,stress-strain curve,elastic modulus,flexural strength,and bending deflection are similar in both types.Additionally,mathematical models for axial compression ratio,tension-compression ratio,and compression-folding ratio were established,and two typical formulas effectively fit the stress-strain curve of the test,with good predictive results.更多还原