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第十一期

周云开,闫 健,罗炳均,何贵安,陈泽浩,陈锦宏,骆 标

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摘 要:传统水泥砂浆保水性、黏聚性差,导致砂浆的收缩性大,抹面易开裂,施工性能差。加入一定量的橡胶粉,虽然在一定程度上降低水泥砂浆的强度,但是其抗裂性能得到大幅提升,同时有效利用了废旧橡胶。研究了橡胶粒径、掺量对水泥砂浆强度、抗裂性能的影响,结果表明,橡胶粒径对水泥砂浆的影响起伏较大;一定范围内,橡胶掺量越大,水泥砂浆的抗压、抗折强度下降越大,但抗裂性能越强。 Abstract: The traditional cement mortar has a poor water retention and cohesiveness, which leads to a large shrinkage, easily cracking for plastering and a poor construction performance. Although adding a certain amount of rubber powder may reduce the strength of cement mortar to a certain extent, its crack resistance gets significantly improved and meanwhile, the waste rubber is made good use. The influence of rubber particle size and rubber content on the strength and crack resistance of cement mortar were studied, the results showed that, the influence of the rubber particle size on the cement mortar fluctuates strongly; within a certain range, the larger dosage of rubber, the bigger reduction in both compressive strength and flexural strength, the stronger in crack resistance of cement mortar.

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摘 要:砖块作为再生混凝土粗骨料的成份之一,其含量高低可显著影响混凝土拌合物的工作性能。为此,通过测定砖块孔隙特征、不同砖块含量的水泥浆体流变参数以及不同水灰比的水泥浆体中砖块的吸、放水行为,掌握砖块的影响规律。结果表明,砖块特有的孔结构导致其对水泥颗粒吸附量可忽略不计,仅可能与水发生交换行为。在不同水灰比的浆体中,砖块自身含水率将显著影响其吸、放水行为。当浆体水灰比为0.3~0.5时,砖块的平衡含水率约为9%~17%,且浆体水灰比越高,则砖块平衡含水率越高。预示着当配制低强度等级混凝土时,可以提前对再生骨料进行饱水处理。砖块掺量为10%以下时,砖块饱水后掺入水泥浆中不会对水泥浆体的流变性能产生显著影响。 Abstract: Brick is one of the coarse aggregate of recycled concrete; its content will probably effect the working performance of the concrete mixture. Therefore, the effect law can be known by the measure of brick pore feature, rheological parameters of cement pastes with different bricks content and the suction and drainage behavior of bricks in cement pastes with different water cement ratio. The results showed that, the unique pore structure of the brick leads to no adsorption of cement particles, which can only be exchanged with water. With different water cement ratio, the water content of the brick will significantly affect its suction and drainage behavior. When the water cement ratio is 0.3 to 0.5, the equilibrium moisture content of the bricks is 9% to 17%. The higher the water cement ratio, the higher equilibrium moisture content of bricks, which shows that, when prepare low strength concrete, pre-full-water treatment can be carried out on the recycled aggregate. When the content below 10%, bricks with full water have no effect on the mobility of the cement paste.

张向冈1,2,汪 昉2,杨健辉1,2,陈 真2,吴 帆2

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摘 要:以再生细骨料取代率和温度作为影响参数,设计并制作了45个标准立方体试块进行抗压强度试验。观察了试块的破坏过程和破坏形态,实测了试块的极限抗压强度,分析了不同温度下立方体抗压强度与再生细骨料取代率的关系以及不同取代率下立方体抗压强度与温度的关系,讨论了影响参数对于立方体抗压强度的影响规律。结果表明:再生水泥砂浆的破坏过程和形态与天然水泥砂浆相似;当温度达到400℃时,试块无爆裂现象,但试块的颜色变成了暗粉红色;随着再生细骨料的增加,试块质量损失率增大;在恒温3h的条件下,不同的温度对立方体试块抗压强度的影响规律并不明显。 Abstract: Taking the replacement rate of recycled fine aggregate and temperature as the affect parameters, 45 standard cube test blocks were designed and produced to carry out compressive strength test. The failure process and failure mode of test blocks were observed. The limit of the cube compressive strength of test blocks were measured, the relations between cube compressive strength and recycled fine aggregate under different temperatures and the relations between cube compressive strength and temperatures under different replacement rates were also analyzed, the influence law that the parameters made on the cube compressive strength was discussed. The results showed that, the failure process and the failure mode of recycled fine aggregate cement mortar and the failure process and the failure mode of nature is similar; when the temperature reached 400℃, the block has no burst phenomenon, but the color of block turned into a dark pink; with the increase of recycled fine aggregate, the mass lose rate of block increase; the influence law that different temperature making on cube compressive strength of test block is not obvious when temperature keeps same for 3h.

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摘 要:针对坑外邻近刚性桩复合地基条件下侧向土压力的计算,规范采用的是朗肯土压力作图法按天然地基计算,未能考虑桩体的荷载传递效应及附加应力随深度的变化。基于桩侧摩阻力分布假设,采用Mindlin解和Boussinesq解分别求得桩体与桩间土产生的竖向附加应力,并结合Mohr-Coulomb强度准则,依据极限平衡法推导出既有刚性桩复合地基条件下主动土压力强度计算公式,并将本文算法与规范算法和朗肯主动土压力进行对比分析。结果表明,本文计算土压力强度分布大于朗肯主动土压力而远小于规范计算值,并随深度呈非线性分布,桩体的荷载传递效应会对桩端附近土体产生附加土压力,0.5倍桩长范围内仅考虑桩间土的附加土压力。最后,通过室内模型试验结果与本文计算结果进行对比,证明了所提算法的合理性与有效性。 Abstract: The Rankin’s active pressure calculated method of the standard under the condition of natural foundation is used to compute the lateral earth pressure adjacent to rigid pile composite foundation. It ignores the deep transfer function of pile load and the change of additional stress along depth. Based on the assumption of the lateral frictional resistance distribution, this paper combined M-C criterion and limit equilibrium method, use Mindlin solution and Boussinesq solution to calculate the vertical additional stress between piles and soil, meanwhile, the active earth pressure adjacent to rigid pile composite foundation is computed. This method is compared with the standard method and the Rankin’s active pressure. The results showed that the active pressure intensity is smaller than that is calculated by standard, and the distribution curve is nonlinear. At the same time, the active pressure intensity of pile tip is influenced by the transfer function of pile load, and with the scope of the 0.5 times of pile length only considers the influence of vertical addition stress of soil between piles. Finally, comparing the result of the indoor model test and calculation method in this article can verify the rationality and effectiveness of this method.

张 良1,王艳莉1,韩彦军1,张 凯2

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摘 要:为了提高混凝土预制构件生产线效率,以台湾新代的HC10A一体化控制器为控制核心,采用开放式数控系统的结构形式,设计了四轴置模机械手的控制系统。分析了机械手的结构与功能,在此基础上设计了控制系统的硬件组成,实现了伺服电机的闭环控制,根据机械手工作流程的特点,完成了控制器的软件编写。该控制系统具有性能稳定、控制精度高、操作简单、可靠性高、使用维护方便,易于实现机电一体化等优点,能满足置模需求,符合工业应用要求。 Abstract: To improve the production efficiency of the concrete prefabricated parts production line, a control system for four axis motion of the manipulator is designed which uses the structure form of open CNC and takes HC10A integrated controller of SYNTEC as the control core. The structure and function of the manipulator are analyzed, and the hardware structure of the control system is designed on the basis of this. The software system is completed according to the requirement of the characteristic of the work flow. The control system has the advantages of simple operation, safe, efficient and stable, strong anti-interference ability, safe and stable performance, high control precision, which can meet the demand scale, in line with the industrial application requirements.

田晗旭,邓跃全,汪彬彬,李光华

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摘  要:以水泥和白肥作为复合胶凝体系,研究了水泥-白肥-硫酸渣生产建筑砌块的可行性。当白肥和水泥掺量均为20%~60%时,随白肥与水泥质量比从1∶3逐步上升到3∶1,水泥-白肥-硫酸渣基建筑砌块用水量从240mL逐步上升到342mL,干密度从1816kg/m3逐步下降到1410kg/m3,7d强度呈现先增长后下降趋势,抗压、抗折强度最高值分别为16.7MPa、3.0MPa,其机理为白肥与水泥水化产物Ca(OH)2反应生成羟基磷灰石,与C-S-H协同形成稳定的复合胶凝体系,可应用于砌块生产中,变废为宝。Abstract:Usingcementandwhitephosphorusfertilizerasthecompositioncementingsystem,thefeasibilityofproducingbuildingblocksbasedoncement,whitephosphorusfertilizerandpyritecinderwerestudied.Whencontentsofwhitephosphorusfertilizerandcementinblockswerebothfrom20%to60%,withwhitephosphorusfertilizercementratiorisingfrom1∶3to3∶1gradually,waterconsumptionofthebuildingblocksbasedoncement,whitephosphorusfertilizerandpyritecinderincreasedfrom240mLto342mL,drydensityoftheblocksdecreasedfrom1816kg/m3to1410kg/m3and7dstrengthpresentedafirstgrowingafterdecreasingtend,themaximumsofcompressivestrengthandflexuralstrengthoftheblockswere16.7MPaand3.0MParespectively.ThemechanismisthatwhitephosphorusfertilizerreactwithcementhydrationproductCa(OH)2 togenerateCa10(PO4)6(OH)2,whichcouldformstablecompositegelledsystemcombinedwithC-S-H.Whenappliedsuccessfullyinblocks,thatcouldtransformwasteintotreasure.