EPS混凝土静态力学性能研究

对不同粒径、不同体积含量EPS混凝土进行了静态压缩和静态劈裂试验.EPS混凝土静态压缩应力.应变曲线表明:EPS混凝土抗压强度随EPS颗粒体积含量的增加而显著降低;对于体积含量小于10%的EPS混凝土表现出准脆性材料特性;对于体积含量较高的EPS混凝土,表现出明显不同于低含量的EPS混凝土和EPS材料的特性;分析了EP...     

EPS材料动三轴试验研究

通过室内多功能三轴试验,研究了EPS材料在不同围压,不同频率,不同循环次数的EPS材料的工程性状和循环荷载作用对EPS的静力学工程性状的影响。     

EPS轻质混凝土配合比设计及性能研究

为提出合理的EPS轻质混凝土设计方法,对泡沫混凝土设计方法进行改进.设计了不同密度不同掺合料的多种EPS轻质混凝土配合比.测试了不同配合比、不同龄期下EPS轻质混凝土干密度和抗压强度.结果表明这种配合比设计方法应用于EPS轻质混凝土设计是可行的.     

EPS轻质混凝土收缩性能与抗氯离子渗透性能试验研究

通过掺入不同比例的EPS轻质骨料和不同水灰比配制EPS轻质混凝土,研究EPS颗粒对混凝土收缩性能与抗氯离子渗透性能的影响。试验结果表明,随着EPS颗粒掺量的增加,EPS轻质混凝土的干燥收缩值增大,而电通量降低。与普通混凝土相比,EPS轻质混凝土的收缩性能略差,抗氯离子渗透能力增强。     

EPS颗粒轻质混合二灰土强度性质的试验研究

采用相似材料模型试验对相同EPS颗粒含量不同土灰比二灰土以及相同土灰比不同EPS掺量二灰土通过无侧限抗压试验和直剪实验对其强度性质进行了研究。结果表明:EPS颗粒二灰土试样与纯二灰土试样无侧限抗压强度接近。EPS颗粒混合轻质土的粘聚力随EPS颗粒掺入量和土灰比的增大而减小,但是当土灰比和EPS掺量较小时,对轻质土抗剪性能影响不大。     

粘结剂与EPS掺量对保温砂浆性能影响

主要研究废弃EPS颗粒制备的保温砂浆力学性能与导热性能,不同粘结剂种类对EPS保温砂浆抗压强度与导热系数的影响.通过掺入对不同量的EPS聚苯颗粒,得出EPS颗粒的掺量对保温砂浆的影响.     

EPS保温砂浆的性能与施工

本文比较了不同容重的EPS保温砂浆和膨胀珍珠岩砂浆的基本性能，介绍了不同容重EPS保温砂浆的配方及其施工方法。经工程应用表明，EPS保温砂浆完全可用于外墙外保温。     

EPS外墙装饰构件专用砂浆配合比试验研究

通过砂浆配合比试验,对不同的EPS外墙装饰构件进行了称重和外观检测,分析了砂浆配合比对EPS外墙装饰构件质量及经济性的影响,并得到了EPS构件专用砂浆的最佳配合比,有助于优化EPS外墙装饰构件的生产工艺。     

挡土墙后EPS板减压性能模型试验研究

在刚性挡土墙后设置柔性垫层能有效减小墙背土压力。聚苯乙烯土工泡沫(EPS)是一种常见的柔性材料,具有受力易压缩的特性。通过开展室内挡土墙模型箱试验,对铺设不同弹性模量以及不同厚度的EPS板的各工况下墙背土压力分布规律进行了研究,详细分析了弹性模量和厚度对EPS板在不同填土表面荷载作用下的减压性能的影响;并通过FLAC3D建立有限差分数值模型,对不同压缩量情况下土压力分布规律进行了分析。研究结果表明:EPS板能有效地减小挡土墙墙后土压力;EPS板的弹性模量越小、厚度越大、墙后填土表面的外荷载越大,EPS板的减压效果越明显;EPS板厚增加到一定程度后,EPS板的减压效果不会再有明显提升,EPS板厚达到0.1倍墙高即可获得最佳减压效果。     

EPS轻质混凝土强度模型

通过对EPS轻质混凝土进行配合比试验和抗压强度试验,研究了不同水灰比对EPS轻质混凝土强度的影响.试验结果证明EPS轻质混凝土抗压强度与水灰比值密切相关,水灰比越大,EPS轻质混凝土的强度越低.对试验数据统计分析得出EPS轻质混凝土28d强度与灰水比、EPS掺量及颗粒粒径尺寸之间的关系公式.该强度公式计算值与实测数据值比较,相关性系数为0.99.     

EPS颗粒对混凝土的增韧效应

配制了聚苯乙烯(EPS)颗粒体积分数分别为10%,20%,30%,40%,50%的EPS混凝土,采用100分离式霍普金森压杆(SHPB)试验装置,以比能量吸收作为指标,研究了EPS颗粒对混凝土的增韧效应,探讨了EPS颗粒对混凝土的增韧机理.结果表明:冲击荷载作用下,由于应变率效应,相同体积分数的EPS混凝土冲击韧性随应变率的增加而提高,具有显著的应变率相关性;由于EPS颗粒的微结构效应,在EPS颗粒体积分数为10%～30%时,其韧性较未掺EPS颗粒的混凝土有不同程度的提高,EPS颗粒体积分数为20%时对混凝土韧性的改善效果最佳.当EPS颗粒体积分数达到40%～50%时,其韧性有所降低.     

厌氧污泥胞外聚合物(EPS)对水中U(Ⅵ)的吸附试验研究

通过试验,探讨了以厌氧污泥胞外聚合物(EPS)为吸附材料,在溶液中的pH、EPS投加量、初始铀质量浓度及透析温度等因素影响下,该EPS对水中U(Ⅵ)的吸附效果与作用机制。试验结果表明:EPS吸附铀的最佳pH值为6,最高吸附量为0.891 mg/g EPS;当铀的初始质量浓度为20 mg/L,EPS投加量为56.1 g/L时,可以达到最佳去除率98.3%。     

EPS混凝土单轴冲击压缩试验及破坏形态分析

为研究EPS颗粒体积掺量对混凝土单轴动态抗压强度和破坏形态的影响,采用直径74 mm的分离式霍普金森压杆装置,对4种EPS颗粒体积掺量的EPS混凝土进行单轴冲击压缩试验,分析了应变率和EPS颗粒体积掺量对EPS混凝土单轴动态抗压强度和破坏形态的影响。试验结果表明,EPS混凝土单轴动态抗压强度随应变率的增加而增大,随EPS颗粒体积掺量的增加而降低,当EPS颗粒体积掺量在20%~30%之间,EPS混凝土单轴动态抗压强度降低幅度较小;EPS混凝土试件破坏形态具有明显的高掺量低应变率效应;当EPS颗粒体积掺量达到30%之后,EPS混凝土试件裂而不碎。     

Characterization of extracellular polymeric substances of aerobic and anaerobic sludge using three-dimensional excitation and emission matrix fluorescence spectroscopy

In this study three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy was applied to characterize the extracellular polymeric substances (EPS) extracted from aerobic and anaerobic sludge in wastewater treatment. Three fluorescence peaks were identified in EEM fluorescence spectra of the EPS samples. Two peaks were attributed to the protein-like fluorophores, and the third to the humic-like fluorophores. The effects of both pH and EPS concentration were significant on EEM fluorescence spectra of EPS, but the ionic strength had no substantial effect on EEM spectra of the EPS. The differences in the EPS fluorescence parameters, e.g., peak locations, intensities and ratios of various peak intensities, indicate the difference in the chemical structures of the EPS from various origins. EEM spectroscopy was proven to be an appropriate and effective method to characterize the EPS from various origins in wastewater treatment systems.     

Influence of shear on the production of extracellular polymeric substances in membrane bioreactors

Shear is used to control fouling in membrane bioreactor (MBR) systems. However, shear also influences the physicochemical and biological properties of MBR biomass. The current study examines the relationship between the level of shear and extracellular polymeric substance (EPS) production in MBRs. Two identical MBRs were operated in parallel where the biomass in one reactor was exposed to seven times greater shear forces. The concentrations of floc-associated and soluble EPS were monitored for the duration of the experiment. The stickiness of extracted floc-associated EPS from each reactor was also characterized using atomic force microscopy. A mathematical model of floc-associated and soluble EPS production was applied to quantitatively describe changes in EPS production with shear. Biomass grown in a high shear environment has lower floc-associated EPS production compared to biomass grown in a lower shear environment. This decrease in floc-associated EPS production also corresponds to a decrease in soluble EPS production, which can be explained by both the lower concentration of floc-associated EPS and the production of stickier floc-associated EPS that is more erosion resistant in the high shear reactor. This research suggests that mechanical stresses can have a significant impact on the production rates of floc-associated and soluble EPS—key parameters governing membrane fouling in MBRs.     

EPS混合土的动模量和阻尼比特性

作为一种路堤填料,EPS混合土在动力荷载作用下的模量和阻尼比是进行路堤动力稳定性分析的重要参数。开展了15个循环扭剪试验研究EPS混合土的动力特性,分析了EPS混合土的骨干曲线、模量以及阻尼比特性,重点讨论了配合比和初始固结条件的影响。结果表明,EPS混合土具有典型的动力非线性特征,受水泥土强度和初始应力状态控制;EPS掺入比对混合土的初始剪切模量几乎无影响,但土体进入非线性阶段后,EPS颗粒对混合土强度的削弱作用明显;EPS颗粒与水泥土间薄弱接触面的动力行为导致"结构阻尼"效应,是混合土阻尼机制的重要组成;EPS混合土的初始剪切模量随试样初始小主应力增大而增大,其模量衰减特性与初始小主应力和EPS掺入比显著相关。基于试验结果,给出了描述EPS混合土骨干曲线、模量衰减和阻尼比增长特性的经验模型。     

Spatial configuration of extracellular polymeric substances of Bacillus megaterium TF10 in aqueous solution

Configuration of extracellular polymeric substances (EPS) excreted by microorganisms is related greatly to the inherent properties of EPS, and has a significant effect on the physicochemical characteristics of microbial aggregates, such as activated sludge for wastewater treatment, as well as their interaction with other substances in aqueous systems. In this work, the spatial configuration of microbial EPS is characterized using laser light scattering (LLS) technique, with EPS extracted from Bacillus megaterium TF10 as an example. The combined utilization of static light scanning (SLS) and dynamic light scanning (DLS) offers an effective avenue to explore the EPS configuration in aqueous solution, thus enables a better understanding about the physicochemical properties of EPS. The results show that EPS exist in the form of colloids in neutral aqueous solution (pH 7.0) and that their shape is random coil with incompletely extending chains. The attraction interaction between EPS colloids is related with the high flocculability of B. megaterium TF10. The cryo-electron microscopy image further confirms the spherical shape of EPS colloids. The LLS approach offers a powerful and convenient tool for characterizing microbial EPS configuration and understanding their behaviors in biological wastewater treatment systems.     

EPS混凝土静态压缩和劈裂性能

试验研究了4种(表观)密度的EPS(发泡聚苯乙烯)混凝土的静态压缩性能和劈裂性能,建立了较低密度EPS混凝土的应力-应变关系模型,赋予了各参数相应的物理意义.结果表明:当EPS混凝土密度较高时,其呈现出明显的准脆性材料特性;当EPS混凝土密度较低时,其呈现出明显的泡沫吸能材料特性.所建立的较低密度EPS混凝土应力-应变关系模型能较好地拟合试验结果.相同相对密度的EPS混凝土,其相对劈裂强度表现出明显的粒子尺寸效应.随EPS混凝土相对密度的降低,其相对劈裂强度粒子尺寸效应逐渐减小.     

改性聚苯板与传统聚苯板的性能特点分析

解释了膨胀聚苯乙烯泡沫板(EPS板)、石墨模塑聚苯乙烯泡沫塑料板(SEPS板)和热固性改性聚苯乙烯泡沫塑料板(热固性EPS板)的定义,对6个不同厂家生产的EPS板、SEPS板、热固性EPS板的主要物理性能进行了研究,得出了一些有实用价值的结论。     

污泥龄对胞外聚合物组分与表面性质的影响

分别采用超声波法与阳离子交换树脂法提取好氧活性污泥絮体中疏松结合的EPS与紧密结合的EPS,考察了污泥龄(SRT)对两种EPS组分与表面性质的影响.结果表明,污泥龄对疏松结合EPS的组分与表面性质的影响相对较大,而对紧密结合的EPS的影响相对较小;不同污泥龄下,紧密结合的EPS较疏松结合的EPS均表现出更强的疏水性.SRT为15 d时,对疏松结合EPS的提取量最少,其带有较少的负电荷且疏水性较强;随着SRT的增大,紧密结合EPS的产量略有增长,其疏水性逐渐增强,电荷密度与Zeta电位逐渐降低.