既有裂缝对混凝土热湿物性参数的影响分析

为解决既有裂缝对混凝土热湿物性参数影响的问题，通过3D打印技术制作裂缝模型，以裂缝体积与混凝土试块体积比值作为变量，针对不同裂缝体积占比混凝土的导热系数、吸水系数、水分扩散系数和水蒸气渗透系数展开研究。结果表明：混凝土的导热系数随着含湿量的增大而增大，随着裂缝体积占比的增大而减小，且导热系数对裂缝体积的敏感性逐渐减小。裂缝体积占比0.1%～0.3%的干燥混凝土相较于无裂缝混凝土，导热系数增大比例最小为7.96%，最大为30.9%。拟合得到混凝土吸水系数、水分扩散系数与裂缝体积占比的关系曲线，两者皆随着裂缝体积占比的增大而增大。拟合得到不同裂缝体积占比的混凝土的水蒸气渗透系数与含湿量的变化曲线，曲线的斜率逐渐增大，其随裂缝体积占比的增大而增大，且含湿量越大，水蒸气渗透系数随裂缝体积增大的幅度越大。     

pH值对工程废浆稳定、絮凝及固结特性的影响

在影响药剂真空预压法处理工程废弃泥浆效果的诸多因素中,pH值是其中最重要的因素之一。文中关于pH值对工程废弃泥浆稳定、絮凝和固结特性的影响进行了研究。首先探讨不同pH值时废浆中土颗粒Zeta电位的变化规律;然后研究泥浆不同pH时絮凝剂APAM的最佳添加量和不同pH值调节方式时废浆的絮凝效果;最后通过固结试验分析了在絮凝剂APAM添加量相同情况下不同pH值导致废浆的不同固结特性。研究结果表明：①土颗粒表面Zeta电位的绝对值随废浆pH值的增大而减小,颗粒粒径随pH值的减小呈增大趋势,特别是在酸性条件下,废浆中土颗粒更容易发生聚沉,小于0.01mm的土颗粒多变为0.01~0.02mm的土颗粒;②不同pH值的废浆在达到最佳絮凝状态时各条颗分曲线相差不大,但是APAM的最优添加量随着废浆的pH值变化而变化;③pH值的不同调节方式对废浆的絮凝效果有较大影响,相同pH值时,采用CaO调节方式得到的废浆絮体粒径要比采用NaOH调节方式得到的废浆絮体粒径要大;④固结试验表证明pH值接近中性泥浆絮体的固结系数最大,建议在药剂真空预压处理工程废弃泥浆时将pH值调节至中性。研究成果对药剂真空预压乃至压滤、离心法处理工程废弃泥浆实践均具有一定的实际指导意义。     

CO_2在页岩中的吸附解吸性能评价

利用自主设计的页岩中气体吸附解吸实验装置,在不同温度和压力条件下研究CO2在不同页岩中的吸附解吸性能。结果表明:CO2在页岩上的等温吸附曲线属于典型的Ⅰ型等温曲线,可采用Langmuir模型对吸附及解吸数据进行拟合;相同温度下,CO2在页岩中的吸附量随着压力的升高而增大;相同压力下,CO2在页岩中的吸附量随着温度的升高而减小;相同温度压力条件下,CO2解吸过程中存在解吸滞后现象,且解吸附曲线表征的最大吸附能力低于吸附曲线表征的最大吸附能力;CO2在页岩上最大吸附量随有机碳含量增加而增大,随石英含量增加而减小。     

PVA纤维增强超高性能混凝土的力学性能研究

为探究PVA纤维对超高性能混凝土（UHPC）工作性能与力学性能的影响，试验通过设置5组不同的纤维掺量探究了UHPC的力学性能。结果表明，低掺量的纤维有利于提高UHPC的流动度，当纤维掺量超过0.5%后，纤维对流动性能产生不利影响，流动度开始下降，最低为164 mm；而抗压强度随纤维掺量的变化为先上升后降低，PVA1.0组抗压强度最大，为132.89 MPa；抗折强度与抗拉强度与纤维掺量成正比，PVA2.0组试验梁抗折强度最大，为13.27MPa；随着纤维掺量的增加，荷载-挠度曲线围成的面积也逐渐增大，能量吸收值也明显增大，PVA2.0组能量吸收值最高，为78.62 kN·mm。     

掺矿渣水泥水化反应特性的试验研究

通过抗压强度、非蒸发水量、矿渣反应度的试验测定及XRD分析,研究了掺矿渣水泥浆体的水化反应进程.结果表明,在相同龄期下,抗压强度随矿渣掺量与水胶比的增加呈减小趋势,矿渣的化学活性在28d前比较显著;掺矿渣水泥浆体的非蒸发水量高于纯水泥浆体非蒸发水量;矿渣的反应度则随其掺量的增加而减小,随水胶比的增加而增大.     

水性聚脲的合成与性能研究

以异佛尔酮二异氰酸酯(IPDI)、聚醚胺和乙二胺基乙磺酸钠(AAS)为主要原料,不需加热,只需30min,合成水性聚脲;研究了IPDI与聚醚胺D2000比值、—NCO与总—NH2比值、乙二胺基乙磺酸钠含量和亲水多异氰酸酯固化剂加入量等因素对水性聚脲性能的影响。涂膜机械强度随IPDI与D2000比值的提高而增大;—NCO与—NH2比值越接近1,乙二胺基乙磺酸钠含量为5%以上乳液越稳定;固化剂加入量越大,涂膜力学性能和耐水性越好,本实验加入3%效果最好。     

聚丙二醇掺量对碱矿渣水泥砂浆性能和水化过程的影响

研究了不同掺量聚丙二醇对碱激发矿渣(AAS)水泥砂浆流动度、力学性能和干缩的影响,并通过电化学交流阻抗法(EIS)探讨了其对砂浆水化过程的影响。结果表明,聚丙二醇的掺入能够显著提高AAS水泥砂浆的流动性,且掺量越大,流动性提高越明显,但砂浆密度有轻微降低。聚丙二醇的掺入降低了AAS水泥砂浆的抗折、抗压强度,但是随着龄期的增长,抗折、抗压强度均有所提高。掺入聚丙二醇能有效降低AAS砂浆的干缩。当聚丙二醇掺量为1%～3%时,各龄期的孔溶液电阻值(R1)较基准组有所减小,聚丙二醇抑制了AAS砂浆的水化反应。当掺量为5%～9%时,各龄期的R1大于基准组,AAS砂浆水化反应加快,且R1随着聚丙二醇掺量的增加而增大。     

碱激发偏高岭土/矿渣复合胶凝体系反应水平及影响因素分析

考察了碱激发偏高岭土/矿渣复合胶凝体系中各原料和反应产物在不同pH值盐酸溶液中的溶解率,并通过X射线荧光光谱（XRF）、X射线衍射（XRD）和傅里叶变换红外光谱（FTIR）等测试方法分析了偏高岭土及其碱激发硬化浆体的酸溶剩余物.结果表明：偏高岭土在pH=0的盐酸溶液中几乎不溶解,碱激发偏高岭土的酸溶剩余物（盐酸溶液pH=0～2）为偏高岭土,由此得到偏高岭土的地质聚合反应水平（以下简称反应水平）;矿渣在碱激发条件下几乎完全反应,其在多数情况下可提高偏高岭土的反应水平;当矿渣掺量一定时,偏高岭土的反应水平随碱激发剂模数的增大而降低,随液固比的增大而提高,且低矿渣掺量条件下,增大液固比所产生的促进作用更加显著;低碱激发剂质量分数条件下,偏高岭土反应水平随矿渣掺量的增加而提高;高碱激发剂质量分数条件下,偏高岭土的反应水平随矿渣掺量的增加先升后降,且与偏高岭土最高反应水平相对应的矿渣掺量逐渐减小.     

水胶比、超细粉煤灰掺量对高性能混凝土钢筋握裹力的影响

试验研究了水胶比、超细粉煤灰(以下简称UFA)掺量对高性能混凝土(以下简称HPC)钢筋握裹力的影响。结果表明当超细粉煤灰掺量一定时，HPC钢筋握裹力随水胶比增大而减小，当水胶比一定时，HPC钢筋握裹力随超细粉煤灰掺量的增加而减小。分析发现，当抗压强度相同时，掺UFA的HPC钢筋握裹力要大于不掺UPA混凝土钢筋握裹力。作者用回归分析方法建立了HPC钢筋握裹力与抗压强度之间的关系式，该关系式表明HPC钢筋握裹力随抗压强度的增大而线性增大。     

水胶比及超细粉煤灰掺量对高性能混凝土钢筋握裹力的影响

本文通过试验研究了水胶比，超细粉煤灰（以下简称UFA）掺量对高性能混凝土（以下简称HPC）钢筋握裹力的影响，试验结果表明当UFA掺量一定时，HPC钢筋握裹力随水胶比增大而减少，当水胶比一定时，HPC钢筋握裹力随UFA掺量的增加而减少，对试验结果进行分析发现，当抗压强度相等时，掺UFA的HPC钢筋握裹力要大于不掺UFA混凝土钢筋握裹力，作者用回归分析的方法建立了HPC钢筋握裹力与抗压强度之间的关系式，该关系式表明HPC钢筋握裹力随抗压强度的增大而线性增大。     

Chemical transformation of pet waste through glycolysis

PET bottle grade material makes up a significant portion of the feedstock in plastics recycling. Theoretically, there are many end users however there are few applications for less purified grades of recycled PET. The current work is aiming to investigate the transformation of recycled PET into its chemical building blocks using glycolysis to produce unsaturated polyester resin. In this regard, PET waste has been collected from different sources, mainly, beverages and bottled water. Chemical transformation has been achieved through degrading glycolysis reaction with different glycols namely, propylene glycol, diethylene glycol, triethylene glycol and mixture of diethylene glycol with propylene glycol or triethylene glycol in equal amounts. The glycolized products have been converted into unsaturated polyester (UP) after the reaction with maleic anhydride. Finally, styrene was added as a crosslinker and the obtained UP has been characterized. Factors affecting the curing process of the obtained unsaturated polyester resin have been investigated.     

Strength characteristics of polymer mortar and concrete using different compositions of resins derived from post-consumer PET bottles

The recycled polyethylene terephthalate (PET) plastic waste was depolymerized through glycolysis to produce unsaturated polyester resin (UPER). The UPER so produced was then used as a binding agent to produce polymer mortar (PM) and polymer concrete (PC). Eight different sets of PM and PC were produced by varying PET to glycol ratio, dibasic acids and initiator promoter combinations. The PET to glycol ratio used in the present study was 1:1 and 2:1. The initiator promoter combinations taken were Methyl ethyl ketone peroxide (MEKP) and cobalt naphthanate (CoNp) in one group of sets while Benzoil peroxide (BPO) and N, N-diethyl aniline (NNDA) in other group of sets. For each set, microscopic studies were conducted on neat resin and polymer mortar.The cube compressive strength of PM and PC so produced was found to vary from 15 to 28 MPa and from 20 to 42 MPa, respectively. The tensile strength of polymer concrete was either at par or more than the tensile strength of equivalent grade of cement concrete. The results of different sets have been compared and sets showing better performance have been identified.     

Decay properties of the foamed bitumens

This paper presents study on decay properties of two foamed bitumens. Foaming tests under various conditions were carried out to investigate decay properties of two types of bitumen: Penetration-grade 60 (PG 60) and Penetration-grade 100 (PG 100). Decay data were recorded and analyzed. It is found that water content has a significant effect on the bitumens’ decay, and the time at which the maximum expansion ratio appears advances with an increase of temperature. PG 60 achieves the maximum expansion ratio at an earlier time than PG 100. The effect of viscosity on the two bitumens’ decay properties was discussed and explained; and the observation of the tests confirms this explanation is rational. For developing the bitumens’ decay functions, a four-parameter power function and a three-parameter exponential function were selected to fit the testing data of PG 60 and PG 100 bitumen, respectively. Two bitumens’ decay functions were established by a two-stage method. Non-linear fitting analysis exhibits that two functions can well fit the data of the foaming tests. Decay functions’ parameters were obtained by using the best subset regression method. Two decay functions can be used to calculate the maximum expansion ratios and half-lives of PG 60 and 100 bitumen under various conditions.     

建筑用聚烯烃聚氨酯胶粘剂研制

以端羟基聚丁二烯 (HTPB)、甲苯二异氰酸酯 (TDI)以及有关配合剂为原料 ,制备了无溶剂单组分的聚烯烃聚氨酯胶粘剂 ,对扩链剂种类以及含量、胶粘剂中NCO和白碳黑的含量作了试验 ,测试了胶粘剂的外观、粘度、粘接强度和力学性能。测试结果表明 ,以 1,4丁二醇作为扩链剂 ,与HTPB的羟基含量摩尔比例是 3,控制胶粘剂中NCO含量在 4 .87%左右 ,白碳黑的含量为 10g ,可以获得粘接性能比较优越的聚烯烃型聚氨酯胶粘剂。     

Optimization of the formulation of micro-polymer concretes

This research investigates the optimization of micro-polymer concretes (MPC) formulations in order to produce a construction material that has excellent physical and mechanical properties, such as minimum void content, high Young’s modulus and excellent strength properties. An epoxy resin reinforced with a graded mixture of coarse and fine sands is used as a binder to design the micro-polymer concretes. Effects of curing time and binder contents were evaluated through ultrasonic wave propagation method and flexural, compressive, direct and tensile tests, performed at room temperature. The porosity of different MPC formulations as well as the distribution of the voids size is investigated as a function of curing time using mercury intrusion porosimeter (MIP). Results show that with increasing the binder content, the total pore volume and the maximum pore size are reduced significantly. The kinetics and the mechanisms of diffusion of water in MPC depend strongly on the mass fraction of resin. All the mechanical properties of MPC stabilize after 3 days curing at ambient temperatures. The micro-polymer concrete designed with a polymer content of 9% shows the highest physical and mechanical characteristics such as strengths, rigidity, the lower voids content and thus the best durability. The experimental results reveal that the mechanical behavior of MPC is time dependent. Scanning Electronic Microscopy (SEM) was applied to observe the microstructure and the porosity and to understand the failure mechanism of MPC.     

谈基于防滑性能的碎石沥青混合料的设计

碎石沥青混合料是根据贝雷法和粗骨料空隙填充法设计的.最佳沥青用量根据试验确定.碎石沥青混凝土表面纹理深度有着不同空隙率,利用磨损试验机对碎石沥青混合物和普通沥青混合物进行磨损试验.测实结果表明,表面纹理深度随着沥青石油比例的降低而增加.最佳沥青用量的碎石沥青混合物具有良好的防滑性.沥青混合料的BPN穿用时间的增加而减小,但减小的程度是不同的.随着磨损时间的增加,碎石沥青混合物比普通沥青混合物衰减的慢,表明碎石沥青混合物防滑性的衰减量较小.碎石沥青混合物的其它性质显示劈裂强度和模量均比普通沥青的高,其高温性能和水稳定性也能满足技术要求.     

The using of waste phosphogypsum and natural gypsum in adobe stabilization

The best known disadvantages of adobe are its low mechanical properties and poor resistance to water damage. In this research waste phosphogypsum (PG) and natural gypsum were used as stabilization material to improve the properties of adobe soil and to reduce its disadvantages at least partially. The compressive and flexural strength, softening in water, drying shrinkage and unit weight values were determined on adobe samples. The strength values of adobe samples increased with both gypsum additions. The most resistance of the adobe samples against softening in water was obtained with 25% PG addition. Drying shrinkage of test samples reduced with increasing PG content. The dry unit weight of the specimens was not in the recommended range specified in the standards. Test results showed that PG can be used as alternative material in adobe stabilization to bring economy and to reduce environmental pollution.     

Biodegradation of propylene glycol and associated hydrodynamic effects in sand

At airports around the world, propylene glycol (PG) based fluids are used to de-ice aircraft for safe operation. PG removal was investigated in 15-cm deep saturated sand columns. Greater than 99% PG biodegradation was achieved for all flow rates and loading conditions tested, which decreased the hydraulic conductivity of the sand by 1-3 orders of magnitude until a steady-state minimum was reached. Under constant loading at 120 mg PG/d for 15-30 d, the hydraulic conductivity (K) decreased by 2-2.5 orders of magnitude when the average linear velocity of the water was 4.9-1.4 cm/h. Variable PG loading in recirculation tests resulted in slower conductivity declines and lower final steady-state conductivity than constant PG feeding. After significant sand plugging, endogenous periods of time without PG resulted in significant but partial recovery of the original conductivity. Biomass growth also increased the dispersivity of the sand.     

Kinetics of adenovirus type 2 inactivation with free chlorine

The objective of this study was to elucidate the effects of pH, temperature, and other relevant water quality parameters on the kinetics of adenovirus serotype 2 inactivation with free chlorine. Over a pH range of 6.5-10, a temperature range of 1-30 °C, and in a variety of water types, free chlorine was highly effective against adenovirus type 2. Its disinfection efficacy decreased with increasing pH and decreasing temperature, yet was unaffected by hardness and buffering species. Under the most challenging conditions investigated in this study (pH 10, 1 °C), a four-log reduction of adenovirus viability would be achieved at a CT value of 2.6 mg Cl₂ min/L. The inactivation kinetics was characterized by three phases of inactivation under most conditions. The first phase resulted from a reaction involving primarily the hypochlorous acid species and was characterized by rapid inactivation of viruses to a limit that increased with decreasing pH and increasing temperature. After reaching this limit, adenovirus exhibited two subsequent phases of inactivation at lesser rates that were not affected by temperature or pH. As with the first phase of kinetics, a limit of inactivation was approached in the second phase that decreased with increasing pH, and after which the kinetics was characterized by a third and final phase. An inactivation model consistent with these observations was found to provide adequate representation for the free chlorine inactivation of adenovirus serotype 2 as well as that reported in the literature for other adenovirus serotypes.     

废弃黏土砖再生骨料对混凝土性能的影响研究

配制了4组不同水泥用量的黏土砖再生骨料混凝土,通过试验测试和分析了4组混凝土物理、力学和变形方面基本性能的变化规律.试验结果表明.在骨料用量和水灰比不变的情况下,水泥用量的增加,可以在一定程度上提高黏土砖再生骨料混凝土强度、弹性模量和导热系数,降低其干表观密度、吸水率、干燥收缩率和泊松比.适当选择骨料和设计配合比,黏土砖再生骨料混凝土可以用于保温轻骨料混凝土和结构保温轻骨料混凝土制品.