摘   要：基于由常温（20 ℃）降至给定低温（-40、-80、-120、-160、-190 ℃）、经历低温再直接或以1 ℃/min匀速回至常温3种工况下的混凝土受压试验，研究了不同低温作用下混凝土的受压强度及其离散性。结果表明：随着低温温度的降低，混凝土的受压强度变化率高于常温时的受压强度变化率，且整体呈增大趋势，其离散性也明显变大；而经历低温再直接和以1 ℃/min匀速回至常温时混凝土的受压强度变化率相比常温时均有所提高，但与低温温度关联度较低，其离散性也均减小。 Abstract: The compressive strength and its discreteness of concrete subjected to different low temperatures were discussed through compressive experiment of concrete under three temperature conditions: cooling to given low temperatures(-40, -80, -120, -160, -190 ℃) from room temperature, and returning to room temperature directly and at a rate of 1 ℃/min after experiencing given low temperatures. The results show that the change rate of compressive strength of concrete at low temperature is higher than that at room temperature without experiencing action from low temperature and generally increases with the decrease in the low temperature, and its discreteness increases obviously. Compared with the change rate of compressive strength of concrete at room temperature, the change rate of compressive strength of concrete for returning directly and at the rate of 1 ℃/min to room temperature from low temperatures still increases, but the correlation with the low temperature is low and the compressive strength discreteness is also reduced.

时旭东,韩大全,崔一丹.不同低温工况下混凝土的受压强度研究[J].混凝土与水泥制品,2023(1):1-4,10. SHI X D,HAN D Q,CUI Y D.Study on Compressive Strength of Concrete Under Different Low Temperature Action Conditions[J].China Concrete and Cement Products,2023(1):1-4,10.

摘   要：基于细菌反硝化作用诱导碳酸盐沉积原理，建立了松散细颗粒材料与矿化胶结液注浆修复的混凝土裂缝三维多孔介质渗流数值模型。考虑混凝土断面的分形特征，选取Darcy速度驱动模型和Brinkman压力驱动模型下两种边界条件进行模拟，研究了两种驱动方式对修复过程的影响，得出了混凝土裂缝修复过程中灌浆液葡萄糖浓度、CaCO3生成量、裂缝内胶结颗粒孔隙率随反应时间变化的关系，给出了反应过程中模型内压力场和速度场分布云图。结果表明：随着分形维数的增加，反应用时减少，且在反应结束时，对于分形维数2.8的最光滑裂缝断面，注浆入口处的孔隙率为0.12，渗透系数为9.02×10-13 m/h，分别为混凝土修复前的30%和2.2%。 Abstract: Based on the theory of bacterial denitrification induced carbonate precipitation, the three-dimensions numerical models of porous media seepage were established, which aimed to simulate the process of concrete damage repairs via grouting mineralization solutions mixed with loosely fine grain materials. Considering the fractal characteristics of concrete section, two boundary conditions under Darcy velocity-driven model and Brinkman pressure-driven model were selected for simulation, the influence of the two driving methods on the repair process was studied, and the relationship between the concentration of glucose in the grouting solution, the generation amount of CaCO3 and the porosity of cemented particles in fractures in the concrete crack repair process with reaction time were obtained. The cloud picture of pressure and velocity within the crack models during the process of simulation reaction were also researched. The results show that with the increasing of fractal dimension, the reaction time is continue decreasing, and at the end of reaction, for the smoothest crack section with fractal dimension 2.8, the porosity at the grouting entrance of models is 0.12 and the permeability quotient is 9.02×10-13 m/h, which are 30% and 2.2% of the concrete before grouting repair, respectively.

兰春晖,王楠星,田叶,等.混凝土损伤修复过程流体动力学特性数值模拟[J].混凝土与水泥制品,2023(1):5-10. LAN C H,WANG N X,TIAN Y,et al.Numerical Modelings Study on Characteristic of Fluid Dynamics of Grouting Fluid on Process of Concrete Cracks Repair[J].China Concrete and Cement Products,2023(1):5-10.

摘   要：以聚乙二醇单甲醚（MPEG-2000）作为主链，磷酸作为末端吸附基团，合成了低分子磷酸基减水剂PM-2，分析了红外吸收光谱、凝胶渗透色谱，并研究了PM-2的分散性能、黏土敏感性、水泥对其的吸附性、对水泥水化热的影响及在混凝土中的应用效果。结果表明：与聚羧酸减水剂PCE-1相比，所制备的PM-2的分散性保持能力强，黏土敏感性低，水泥颗粒对其的吸附量少，同时具有一定的延缓水泥水化的效果，但减水效果相对较低；通过PCE-1和PM-2复配可以显著提升混凝土的坍落度及其保持能力，且不会降低混凝土强度。 Abstract: A low molecular weight phosphate based water reducer was synthesized by using polyethylene glycol monomethyl ether (MPEG-2000) as the main chain and phosphoric acid as the terminal adsorption group. The molecular structure and molecular weight were determined by IR and GPC. The dispersion property of PM-2, clay sensitivity, adsorption of cement, influence on cement hydration heat and application effect in concrete were studied. The results show that, compared with polycarboxylic acid water reducer PCE-1, the prepared PM-2 has strong dispersion retention ability, low clay sensitivity, less adsorption capacity of cement particles, and has a certain effect of delaying cement hydration, but the water reducing effect is relatively low. By mixing PCE-1 and PM-2, the concrete slump and its retention capacity can be significantly improved without reducing the concrete strength.

韩正,黄振,王兵,等.低分子量磷酸基减水剂的合成、性能及应用研究[J].混凝土与水泥制品,2023(1):11-14,20. HAN Z,HUANG Z,WANG B,et al.Synthesis, Properties and Application of Low Molecular Weight Phosphate Group Water Reducer[J].China Concrete and Cement Products,2023(1):11-14,20.

摘   要：基于聚羧酸减水剂的作用机理，从原材料（大单体的分子量和封端基团、小单体的亲疏水性、单体的官能团活性）、制备方法（合成工艺、复配方式）方面总结了近年来国内外关于降黏型聚羧酸减水剂制备技术的研究进展，分析了降黏机理，并对降黏型聚羧酸减水剂的可行性研究进行了展望。 Abstract: Based on the mechanism of action of polycarboxylic acid superplasticizer, from raw materials (molecular weight and sealing group of large monomer, hydrophilicity and hydrophobicity of small monomer, functional group activity of monomer), preparation method(synthetic process, compounding means), the research progresses on the preparation technology of viscosity-reducing polycarboxylic acid superplasticizer are reviewed at home and abroad in recent years. The viscosity reducing mechanism is analyzed, and the feasibility research of viscosity-reducing polycarboxylic acid superplasticizer is prospected.

赵潜,孟祥杰,邹亮,等.降黏型聚羧酸减水剂的制备技术研究进展[J].混凝土与水泥制品,2023(1):15-20. ZHAO Q,MENG X J,ZOU L,et al.Research Progress in Preparation Technology of Viscosity-reducing Polycarboxylic Acid Superplasticizer[J].China Concrete and Cement Products,2023(1):15-20.

摘   要：开展了不同循环加卸载（荷载分别为单轴抗压强度20%、30%、40%、50%、60%、70%和80%）作用下的三轴试验，研究了不同循环荷载作用对灌注桩混凝土力学性能的影响，并分析了混凝土的损伤特征。结果表明：在各级循环加卸载作用下，混凝土的应力-应变曲线出现内凹和右移推进现象；弹性模量随循环次数的增加先增加后减小；在各级循环内，泊松比呈“减小-稳定-增大”的变化规律，第90次循环后超过名义泊松比，混凝土损伤逐渐积累加深，轴向和横向不可逆应变均随循环次数的增加而增加；屈服阶段前混凝土的累计损伤小，屈服阶段后混凝土的横向累计损伤参数比轴向大。 Abstract: Triaxial tests were carried out under different cyclic loading and unloading (loads were 20%, 30%, 40%, 50%, 60%, 70% and 80% of the uniaxial compressive strength), and the effects of different cyclic loads on the mechanical properties of cast-in-place pile concrete were studied, and the damage characteristics of the concrete were analyzed. The results show that the stress-strain curves of concrete specimens appear concave and right shift in the cyclic loading and unloading conditions at all levels. The elastic modulus first increases and then decreases with the increase of the number of cycles. The internal Poisson′s ratio of each cycle shows a change law of "decreasing-stabilizing-increasing". After the 90th cycles, it exceeds the nominal Poisson′s ratio and the concrete damage gradually accumulates and deepens. The axial and transverse irreversible strains increase with the increase of the number of cycles. The concrete cumulative damage before the yield stage is small, and the cumulative damage parameters after the yield stage are larger than those in the axial direction.

吴建福,胡力绳,田亚洲,等.三轴循环荷载作用下混凝土的力学性能及损伤特征研究[J].混凝土与水泥制品,2023(1):21-24. WU J F,HU L S,TIAN Y Z,et al.Study on Mechanical Properties and Damage Characteristics of Concrete Under Triaxial Cyclic Loading[J].China Concrete and Cement Products,2023(1):21-24.

摘   要：研究了不同粒径、掺量的石灰石粉对水泥胶砂工作性和力学性能的影响以及石灰石粉掺量对清水混凝土力学性能和耐久性能的影响，对比优选了清水混凝土施工脱模剂和模板。结果表明：水泥胶砂早期强度受石灰石粉细度和掺量的影响较大，在相同掺量时，粒径小的石灰石粉制备的胶砂流动性小、抗压、抗折强度大；清水混凝土的抗压强度随着石灰石粉掺量的增加而增大，电通量和氯离子扩散系数则随着石灰石粉掺量的增加而减小；当石灰石粉掺量为15%时，清水混凝土的力学性能和耐久性能最优；水性脱模剂的脱模效果优于油性脱模剂和模板漆，不锈钢模板的脱模效果优于普通钢模板。 Abstract: The influence of the particle size and amount of limestone powder on the workability and mechanical properties of mortar were investigated, and the effects of amount of limestone powder on the mechanical properties and durability of fair-faced concrete were studied, and the release agent and formwork for fair-faced concrete construction were optimized. The results show that the early strength of mortar is greatly affected by the particle size and amount of limestone powder. The mortar with small particle size shows a smaller fluidity and higher compressive strength at the same amount. The compressive strength of fair-faced concrete increases with the increase of the amount of limestone powder, while the electric flux and chloride diffusion coefficient decrease with the increase of the amount of limestone powder. The mechanical properties and durability of fair-faced concrete are the best when the amount of limestone powder is 15%. The appearance quality of waterborne release agent is better than that of oily release agent and template paint, and the appearance quality of stainless steel template is better than that of ordinary template.

蔡昱,盖珂瑜,陈露一,等.掺石灰石粉的清水混凝土性能与工艺研究[J].混凝土与水泥制品,2023(1):25-29. CAI Y,GE K Y,CHEN L Y,et al.Study on Properties and Technology of Fair-faced Concrete Mixed with Limestone Powder[J].China Concrete and Cement Products,2023(1):25-29.