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第九期
贾丽莉1,高育欣1,赵日煦1,彭 园1,黄义雄1,霍 亮2
摘 要:用磨细白云石、白云石-水淬矿渣共磨物料作为混凝土矿物掺合料,研究了单掺白云石粉、白云石-水淬矿渣复合矿物掺合料对混凝土耐久性的影响。研究结果表明,单掺白云石粉使C30混凝土的电通量值增加15%,同时使碳化深度增加,并使100次冻融循环后的动弹模量损失率最大达到37.6%,弱化了混凝土的抗氯离子侵蚀性和抗碳化和抗冻性能;而单掺白云石粉使混凝土的抗硫酸盐侵蚀系数提高1.7%,抗硫酸盐侵蚀性能改善。白云石-水渣复合矿物掺合料与单掺白云石粉相比,改善了混凝土的抗氯离子渗透性、抗碳化、抗冻融性能;当水淬矿渣与白云石比例为3.5:6.5时,混凝土的耐久性包括抗氯离子侵蚀性、抗碳化、抗冻性能最好。
Abstract: The ground dolomite and co-grinding powders of dolomite and water-quendched granulated blost furnace slag were used as concrete admixtures, and the influence of admixture on the durability of concrete are studied. The results show that by single-mixed with dolomite powder, the electric flux of C30 concrete increase by 15%, the carbonation depth increase, and the loss rate of dynamic elastic modulus can reach up to 37.6% after 100 freeze-thaw cycles, the properties of chloride ion penetration-resistant, anti-carbonization and anti-freeze of concrete are weakened; however, the sulphate resistance coefficient of concrete increase by 1.7%, the sulfate resistance is improved. Compared with single-mixed dolomite powder, mixing dolomite-slag composite mineral admixture can improve properties of chloride ion penetration-resistant, anti-carbonization and anti-freeze of concrete, especially when the ratio of slag and dolomite is 3.5∶6.5, the durability of concrete will be the best.
张卫东1,王振波2
摘 要:通过对不同废弃混凝土掺入率、块体粒径的再生混凝土立方体抗压强度试验,研究了两者对立方体试件的破坏形态、抗压强度的影响。结果表明,掺有废弃混凝土块体的混凝土与普通再生混凝土破坏形态不尽相同,其中掺有废弃混凝土块体的混凝土的破坏形态呈不规则凹凸面,脆性破坏;掺入率对抗压强度有较大的影响;随着掺入率的加大,立方体抗压强度下降。通过对试验数据的分析,验证了现行公式,通过引入粘结力降低系数,提出了掺有废弃混凝土块体混凝土立方体抗压强度的简化计算公式。
Abstract: Based on cubic compressive strength tests of concrete with different replacement rate and size of waste concrete, the influence of the two factors on failure mode and compressive strength of concrete cubic specimen were studied. The test results demonstrate that the failure mode of recycled concrete with waste concrete blocks is different from that of common recycled concrete, and the failure mode of waste recycled concrete blocks presents irregular surface and brittle failure; the replacement rate has great influence on cube compressive strength of the concrete, cubic compressive strength declines when replacement rate inclines. Based on test results, the formula is verified, and simplified calculation formula put forward by considering reduction factor of bond force, and the calculating results agrees with test data.
姚 翔1,林长农2,邓 敏1,阳勇福1,曹黎颖2
摘 要:分析了转炉钢渣的矿物组成和胶凝性能,研究了Na2SO4、CaCl2、NaCl和海水对钢渣浆体和钢渣水泥浆体强度的影响。结果表明,钢渣粉3d的水化放热量仅为P·O42.5水泥的7.5%,钢渣浆体7d和90d抗压强度只有0MPa和15.1MPa,所以钢渣粉自身水化能力很低,胶凝性很差。Na2SO4和CaCl2对于钢渣浆体有一定的激发效果,掺0.9%Na2SO4时激发效果最好,浆体3d和90d抗压强度比不掺激发剂的空白组提高了19.1%和8.2%。对于钢渣水泥浆体,掺1.2%CaCl2的浆体强度最高,浆体3d和90d抗压强度分别比空白组提高了53.6%和16.9%。NaCl和海水对钢渣浆体和钢渣水泥浆体3d强度有明显的激发作用,但会使90d强度出现较明显的倒缩。Abstract:Themineralcompositionandcementitiouspropertiesoftheconvertersteelslagareanalyzed.TheinfluenceofNa2SO4,CaCl2,NaClandseawateronthestrengthofsteelslagslurryandsteelslagcementslurryisevaluated.Theresultsshowthatthehydrationheatofsteelslagpowderisonly7.5%ofP·O42.5cementat3days,andthecompressivestrengthofsteelslagslurryis0MPaat7daysand15.1MPaat90days.Soconvertersteelslaghaslowpotentialhydraulicpropertyandpoorcementitiousactivity.Na2SO4,CaCl2,NaClandseawatermaypromotetheearlystrengthofsteelslagslurryandsteelslagcementslurry.NaNa2SO4 andCaCl2hadgoodactivationeffectsonthesteelslagslurry.CaCl2isthemosteffectiveactivatorandthecompressivestrengthofsteelslagcementslurryaddedwith1.2%CaCl2isincreasedby19.1%at3daysand8.2%at90daysrespectively.Thestrengthofsteelslagcementslurryisthehighestwhentheslurryisaddedwith1.2%CaCl2andthecompressivestrengthisincreasedby53.6%at3daysand16.9%at90daysrespectively.NaClandseawaterhavesignificantactivationonthestrengthofsteelslagslurryandsteelslagcementslurryat3days,howeverthestrengthat90daysdecreasesremarkably.
李志国,邵永健
摘 要:大体积混凝土结构在施工初期容易受到自身水化热升温和外界环境温度变化的影响,从而在结构内部产生温度应力。温度应力是大体积混凝土开裂的主要原因,为了控制混凝土温度裂缝的发展,有必要对大体积混凝土柱施工期的温度进行监测,进而分析其内部温度应力变化规律。基于实际工程的现场监测数据,得出大体积混凝土柱施工期的内外温度与最大温差变化规律,并与大型有限元软件ANSYS模拟的施工期温度场结果进行对比。通过计算混凝土内部的最大温度应力,提出了大体积混凝土柱施工阶段的工艺改进措施。
Abstract:Because of the influence of hydration heat temperature of cement and the external environment temperature, the temperature stress is easily occurred within the mass concrete structure at the starting stage of the construction. Temperature stress is the main reason for the mass concrete cracking, so it is necessary to monitor the temperature of mass concrete column during construction period and analyze its internal thermal stress change rule in order to control the development of concrete temperature crack. Based on some data by actual engineering field monitoring, the change rule mentioned above is concluded and compared with simulate results of temperature field by the finite element software ANSYS during the construction. In addition, according to the calculation of concrete internal maximum temperature stress, some technology improvement measures of mass concrete column are put forward during construction period.
苑举卫1,孙邦宾2,郭 彤3,姚 兵2
摘 要:预应力管桩水泥土复合挡墙支护技术(简称PCMW工法)采用PHC管桩作为挡土构件,其抗弯刚度的合理选取对设计结果和支护安全影响较大。本文引入刚度降低系数,通过开展PHC管桩和钻孔桩的抗弯刚度对比分析研究,建立了面向设计的PHC管桩抗弯刚度和弯矩取值原则;结合工程实例,验证了PHC管桩抗弯刚度计算方法的适用性。研究结果表明:由于预应力的存在,使得预应力管桩开裂后的刚度衰减速度远低于钻孔灌注桩;采用本文推荐的PHC管桩抗弯刚度方法得到的计算结果与基坑监测结果规律性吻合良好。
Abstract: In PCMW (Prestressed Concrete Tube-pile Soil-cement Mixed Wall), the precast tube-pile is used to withstand soil pressure, whose bending stiffness has great influence on design of supporting structure in deep excavation and deformation predication. Based on analysis of stiffness reduction coefficient between PHC pile and cast-in-place concrete pile, the result shows that prestress makes PHC pile keep relatively higher bending stiffness after cracking, which benefits for lateral deformation control of foundation pit. A successful project example of PHC pile with PCMW demonstrates the applicability of the method.
杨正民,王 旭
摘 要:通过2组配置普通强度箍筋与高强度箍筋的混凝土短柱的轴心受压试验,研究了高强箍筋约束混凝土柱的破坏过程及其形貌,分析了箍筋强度对轴心受压性能的影响及其作用机理。
Abstract: The axial compression experiments on two groups of concrete short columns with ordinary-strength stirrups and high-strength stirrups are carried out. Damage process and their morphology of concrete columns confined with high-strength stirrups are studied, and the influence of stirrup strength on axial compression performances of the concrete short columns and relevance mechanism are analyzed.