Abstract: The effect of iron tailings sand replacement rate on the workability, mechanical properties and durability of machined sand concrete was studied. The results show that when the iron tailings sand replacement rate is 40%, the particle size gradation and fineness modulus of the mixed sand are similar to those of river sand. The concrete prepared by the mixed sand shows good workability and mechanical properties. In addition, as the iron tailings sand replacement rate increases within a certain range, the impermeability and the resistance to chloride ion erosion of concrete are gradually improved.
LIU W Y,ZHANG Y L,LI S C,et al.Research on the Influence of Iron Tailings Sand on the Performance of Machined Sand Concrete[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):84-86.
Abstract: The porosity and high water absorption of recycled concrete aggregate (RCA) surface mortar are detrimental to the mechanical properties and durability of recycled aggregate concrete. Removal and modification of RCA surface mortar are the two main ways to improve RCA performance. Based on this, the progress on various modification approaches of RCA surface mortar such as polymer coating, sodium silicate modification, micro-powder filling, CO2 carbonation and microbial carbonate deposition is summarized, the advantages and disadvantages of each RCA modification method are analyzed, and the problems to be further studied are put forward to promote the application of recycled concrete.
LIANG C F,DU X M,QIU J Y,et al.Research Progress on Modification Methods of Recycled Concrete Aggregate[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):87-91.
摘 要：分析了生活垃圾焚烧炉渣的各项性能指标，并将其经多道水洗、筛分等工艺制成再生骨料，利用再生骨料取代天然砂石制备了透水混凝土。结果表明：生活垃圾焚烧炉渣的粒径分布较优，基本满足Ⅱ类建设用砂标准要求；再生骨料透水混凝土的抗压强度均低于基准组，透水系数均大于10 mm/s；随着再生骨料（处理后）取代率的增加，试件的28 d抗压强度逐渐降低；在取代率为100%的情况下，与未处理再生骨料透水混凝土相比，处理后再生骨料透水混凝土的抗压强度提高了43.1%。
Abstract: The various indicators of the domestic waste incinerator slag were analyzed, and it was prepared into recycled aggregate through multiple washing, screening and other processes, and the pervious concrete was prepared by using recycled aggregate instead of natural sand. The results show that the domestic waste incinerator slag basically meets the requirements of Type Ⅱ construction sand standard, and the particle size distribution is better. The compressive strength of recycled aggregate pervious concrete is lower than that of reference group. The permeability coefficient of recycled aggregate pervious concrete is greater than 10 mm/s. With the increase of the replacement rate of recycled aggregate (after treatment), the 28 d compressive strength of specimen gradually decreases. When the replacement rate is 100%, compared with the untreated recycled aggregate pervious concrete, the compressive strength of the treated recycled aggregate pervious concrete is increased by 43.1%.
ZHANG L L,XIE Y F,LIU Z X,et al.Experimental Research on Application of Domestic Waste Incinerator Slag in Pervious Concrete[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):92-95.
摘 要：利用ASTM C1202法、NT Build 492/RCM法及NEL法对三种市售超高性能混凝土（UHPC）基体预混料的渗透性进行了检测，以分析其适用性。结果表明：ASTM C1202电量法的测试结果均在100 C以下，难以进行更加细致的区分；NT Build 492/RCM电迁移法即使在60 V下通电500 h，试件中的氯离子显色深度也多在2 mm以内，由显色深度读数引起的测试误差较大；NEL饱盐电导率法的测试结果与现有研究结果基本吻合，考虑测试结果的区分度，该法仍是UHPC渗透性检测的首选之法，但其可靠性仍需更多的实践检验；对于无需测试氯离子扩散系数的场合，可直接采用规定测试条件下的试件电导率（或电阻率）来比较材料的渗透性高低。
Abstract: The ASTM C1202, NT Build 492/RCM and NEL test methods were used to compare the permeability of three commercial ultra-high performance concrete(UHPC) matrix premixes, and the applicability of these methods was analyzed. The results show that the ASTM C1202 electric charge method is mostly below 100 C, and it is difficult to make a more detailed distinction. For the NT Build 492/RCM electric migration test method, the chloride penetration depths after 500 h at 60 V are mostly within 2 mm together with large reading errors causing unavoidable fluctuations. The results of the NEL salt saturated conductivity method are basically consistent with the data reported in the literature, and considering the principle and the resolution, the NEL method is currently the preferred method for UHPC permeability evaluation even though its reliability still needs further practical inspections. For those cases the chloride diffusivities unnecessary, the electrical conductivity or resistivity of the UHPC can be directly employed to compare its permeability under the same testing conditions.
WANG Z H,WEI Y T,LU X Y.Comparison of Three Electrical Testing Methods for Evaluation of Permeability of Ultra-high Performance Concrete[J].CHINA CONCRETE AND CEMENT PRODUCTS,(12):79-83.
Abstract: In order to meet requirements of production process and considering characteristics of the original workshop, the expandable combined long line pedestal prefabricated component production line is developed. The structural requirements of movable equipment such as vibration and rollover integrated equipment, mobile equipment ferry equipment, self-propelled side formwork and integrated equipment for steel transportation and installation are elaborated to provide a reference for remodeler and application of traditional prefabricated component production line.
YANG J L,ZHU M T,ZHOU Q.Research and Application of Expandable Combined Long Line Pedestal Prefabricated Component Production Line[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):76-78.
Abstract: In combination with the developed automatic group vertical mold equipment, the key technologies such as rapid mold forming, embedded part positioning, formwork deformation and slurry leakage control, casting and vibration,automatic curing are studied and optimized, and the technical difficulties in precast concrete inner wall panel manufacturing technique by using the vertical mold are solved. Through the engineering application, it is shown that the quality of the inner wall panel produced by the vertical mold is significantly improved compared with that of the flat mold.In addition to greatly saving space, the use of the vertical mold greatly improves production efficiency, significantly reduces energy consumption, and has significant social and economic benefits.
ZHAO Z G,YANG S Z,REN C C,et al.Research and Application of Precast Concrete Inner Wall Panel Manufacturing Technique by Using the Vertical Mold[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):59-62.
Abstract: Based on ABAQUS finite element simulation software, 18 groups of stainless steel tie-in pieces with different thickness and size were simulated, and their shear capacity was determined by numerical calculation and analysis, and the stress development process of the plate type stainless steel tie-in parts was obtained. The results show that the plate type stainless steel tie-in parts have large in-plane shear bearing capacity. When the size of the tie-in parts is the same, the shear bearing capacity increases with the increase of the thickness. The longer the stainless steel tie-in pieces of the same thickness and height, the greater the shear bearing capacity. When the thickness and length of stainless steel pull-out pieces are the same, the shear bearing capacity has little change with the increase of height. The yield strength can be taken as the basis in the design, and the safety factor is taken as 3.0 to determine the allowable shear strength of plate type stainless steel tie-in parts.
ZHENG X,ZHENG Y,LIU H C,et al.Study on Shearing Capacity of Stainless Steel Connector with Sandwich Wall [J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):63-67.
Abstract: The typical full-scale test models were selected and verified by ABAQUS software from the aspects of skeleton curve, load and displacement, so as to obtain the reliability of the finite element method. Based on this, the seismic behavior of ECC frame joints with high axial compression ratio (0.5, 0.7, 0.9) under cyclic load was analyzed. The results show that when the design axial compression ratio is 0.9, the frame joints are prone to serious shear failure in the core area, and the energy consumption is about 11.2% lower than that of the 0.5 axial compression ratio, which leads to serious plastic deformation. When the design axial compression ratio is 0.5, μ reaches 5.37, and the average μ of all specimens reaches above 3.0, and the failure mode is ductile failure.
DING J,ZHOU X,HUANG K.Seismic Performance Analysis of Cross ECC Frame Joints Under Cyclic Load [J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):68-72.
Abstract: The carbonation performance and mechanical properties of different grades of sand aerated concrete were studied under specific conditions by means of depth measurement, SEM and XRD. The results show that the compressive strength of sand aerated concrete decreases obviously with the increase of carbonation depth because of the tobermorite formed by hydration of sand aerated concrete gradually transforms into calcite.
XUE X Y,YANG P,LI J Q,et al.Study on Carbonation Performance of Different Grades of Sand Aerated Concrete[J].CHINA CONCRETE AND CEMENT PRODUCTS,2020(12):73-75,95.