玄武岩石粉-矿渣碱激发胶凝材料的制备研究

制备了掺玄武岩石粉的碱激发矿渣胶凝材料,研究了玄武岩石粉掺量、液固比、碱激发剂的固含量和模数对碱激发矿渣胶凝材料抗压强度的影响。结果表明:随着玄武岩石粉掺量的增加,碱激发矿渣胶凝材料的抗压强度呈下降趋势;碱激发剂的固含量由18.00%增大至35.58%时,所制材料的抗压强度呈提高趋势,但碱激发剂的固含量进一步提高至41.35%时,碱激发矿渣胶凝材料的抗压强度反而较低;碱激发剂的固含量为25.08%～35.58%、模数为1.50～1.00时,可制得强度较理想的玄武岩石粉-矿渣碱激发胶凝材料。     

高流动性3D打印水泥基材料制备及性能研究

为了制备性能良好的3D打印胶凝材料,用碱激发剂对粉煤灰/矿渣胶凝材料进行激发得到了满足可打印性和力学性能的基础材料,并分析了影响胶凝材料性能的最主要因素,基于微观试验结果分析了粉煤灰和碱激发剂对胶凝材料性能的影响机理。结果表明:基础材料的合适掺量和组成为:粉煤灰30%、碱胶比0.56%、碱含量5%、激发剂模数1.0;宜选用CaO含量适中的矿渣,激发剂静置时间应为48 h;影响胶凝材料流动性和力学性能的最主要因素为碱含量;相比于纯矿渣胶凝材料,粉煤灰的掺入使材料表面出现微裂缝,使其强度降低,而碱激发剂的掺入,增强了胶凝材料的密实性,提高了强度。     

碱激发胶凝材料研究进展

介绍了碱激发胶凝材料的制备技术和碱激发反应机理，总结了碱激发胶凝材料的工作性能、力学性能、耐久和耐高温特性。分析表明：激发剂的掺量和水玻璃模数是影响碱激发胶凝材料凝结时间和流动度的关键参数，凝结时间介于13~183min之间，终凝时间介于15~215min之间，流动度介于133~230mm之间，可通过改变激发剂的掺量和水玻璃模数使凝结时间和流动性满足不同要求；碱激发胶凝材料具有早强、高强的特点，28d抗压强度可达到60MPa以上，3d抗压强度可达到稳定强度的70%以上；碱激发胶凝材料高温下性能较稳定，在600~800℃的高温下抗压强度可达到常温状态下的60%以上；碱激发胶凝材料具有优异的抗冻融性能，其抗冻等级可达到F300以上；碱激发胶凝材料中由于没有极易遭受侵蚀的水化产物存在，故抗酸腐蚀能力强；碱激发胶凝材料由于孔结构致密，具有良好的抗渗性能。并针对碱激发胶凝材料优选配比和应用所需要解决的收缩、泛霜等问题，对未来研究的方向进行了展望。     

碱激发胶凝材料研究进展

介绍了碱激发胶凝材料的制备技术和碱激发反应机理,总结了碱激发胶凝材料的工作性能、力学性能、耐久和耐高温特性。分析表明:激发剂的掺量和水玻璃模数是影响碱激发胶凝材料凝结时间和流动度的关键参数,凝结时间介于13～183 min之间,终凝时间介于15～215 min之间,流动度介于133～230 mm之间,可通过改变激发剂的掺量和水玻璃模数使凝结时间和流动性满足不同要求;碱激发胶凝材料具有早强、高强的特点,28 d抗压强度可达到60 MPa以上,3 d抗压强度可达到稳定强度的70%以上;碱激发胶凝材料高温下性能较稳定,在600～800℃的高温下抗压强度可达到常温状态下的60%以上;碱激发胶凝材料具有优异的抗冻融性能,其抗冻等级可达到F300以上;碱激发胶凝材料中由于没有极易遭受侵蚀的水化产物存在,故抗酸腐蚀能力强;碱激发胶凝材料由于孔结构致密,具有良好的抗渗性能。并针对碱激发胶凝材料优选配比和应用所需要解决的收缩、泛霜等问题,对未来研究的方向进行了展望。     

碱激发胶凝材料研究进展

介绍了碱激发胶凝材料的制备技术和碱激发反应机理,总结了碱激发胶凝材料的工作性能、力学性能、耐久和耐高温特性。分析表明:激发剂的掺量和水玻璃模数是影响碱激发胶凝材料凝结时间和流动度的关键参数,凝结时间介于13～183 min之间,终凝时间介于15～215 min之间,流动度介于133～230 mm之间,可通过改变激发剂的掺量和水玻璃模数使凝结时间和流动性满足不同要求;碱激发胶凝材料具有早强、高强的特点,28 d抗压强度可达到60 MPa以上,3 d抗压强度可达到稳定强度的70%以上;碱激发胶凝材料高温下性能较稳定,在600～800℃的高温下抗压强度可达到常温状态下的60%以上;碱激发胶凝材料具有优异的抗冻融性能,其抗冻等级可达到F300以上;碱激发胶凝材料中由于没有极易遭受侵蚀的水化产物存在,故抗酸腐蚀能力强;碱激发胶凝材料由于孔结构致密,具有良好的抗渗性能。并针对碱激发胶凝材料优选配比和应用所需要解决的收缩、泛霜等问题,对未来研究的方向进行了展望。     

赤泥制备碱激发胶凝材料的性能

分别以拜耳法赤泥、烧结法赤泥为原料,进行碱激发胶凝材料的制备研究,并对其制备碱激发胶凝材料的可行性进行了评价。研究结果表明,拜耳法赤泥的胶凝活性极低,不适宜用作碱激发胶凝材料的制备原料;烧结法赤泥因含有具有一定胶凝活性的β-硅酸二钙,因此可用作碱激发胶凝材料的制备原料。以烧结法赤泥和矿渣组成二元复合体系,以模数2.40的液体水玻璃为激发剂制备碱激发胶凝材料,在矿渣掺量30%、赤泥掺量70%的条件下,激发剂的最佳掺量为5.0%。所制备碱激发砂浆试样的3d、28d抗压强度可分别达到35.0 MPa、65.0 MPa以上。     

碱激发矿渣胶凝材料综述

本文总结了近几年来碱激发矿渣胶凝材料研究的各类成果,涉及碱激发矿渣胶凝材料中发生的碱硅反应,碱激发矿渣胶凝材料的耐久性、干缩特性、膨胀性能、水玻璃的模数对碱激发矿渣胶凝材料性能的影响。     

碱激发矿渣-钢渣复合胶凝体系的性能研究

以氢氧化钠和水玻璃为激发剂制备矿渣-钢渣复合胶凝材料,研究矿渣掺量、碱当量和水玻璃模数对复合胶凝材料抗压强度的影响,并采用XRD、SEM对硬化试样的显微形貌和水化产物组成进行了分析。结果表明：随矿渣掺量减少,抗压强度降低。随碱当量的增加,抗压强度先提高后降低,碱当量为11%时强度达到最高。随水玻璃模数的增大,抗压强度先提高后降低,当水玻璃模数为1.2时强度达到最高。水化产物主要为CaCO3、C-S-H凝胶、C-A-S-H凝胶、托贝莫来石及RO惰性相。     

CFBC固硫灰地质聚合物强度性能研究

100%以CFBC(Circulating Fluidized Bed Combustion)固硫灰为胶凝材料,采用碱激发方法,选取水玻璃模数、激发剂含碱量、养护温度、养护时间和碱液陈化温度等为变量,系统研究了其对CFBC固硫灰地质聚合物砂浆试块强度性能的影响。结果表明当水玻璃模数为1,养护温度60℃,养护时间3 h,陈化温度为50℃时,砂浆块的抗压强度最高。     

碱激发矿渣混凝土配合比设计研究

以矿粉、粉煤灰为胶凝材料,以水玻璃、氢氧化钠配制激发剂,激发剂模数调配至1.5进行碱激发矿渣混凝土材料试验,混凝土成型过程顺利,混凝土坍落度和扩展度分别为190mm和423mm,和易性较好,测得3d立方体抗压强度为30.70 MPa。     

Rate constants of reactions of ozone with organic and inorganic compounds in water—III. Inorganic compounds and radicals

Second-order rate constants for reactions of ozone with 40 inorganic aqueous solutes are reported. Included are compounds of sulfur (e.g. H₂S, H₂SO₃, HOCH₂SO₃H), chlorine (e.g. Cl⁻, HOCl, NH₂Cl, HClO₂, ClO₂), bromine (e.g. Br⁻, HOBr), nitrogen (e.g. NH₃, NH₂OH, N₂O, HNO₂) and oxygen (e.g. H₂O₂), as well as free radicals (e.g. O₂⁻, OH^•). Most of these compounds exhibit an increase in rate constant with increasing pH corresponding to their degree of dissociation. Rate constants are based on ozone consumption rates measured by conventional batch-type or continuous-flow methods (10⁻³-10⁺⁶ M⁻¹ s⁻¹ range) and determinations of stoichiometric factors. Also listed are data determined by pulse-irradiation techniques using kinetic spectroscopy (10¹⁰ M⁻¹ s⁻¹ range). Additional literature data are reviewed for completeness. Results are discussed with respect to water treatment and environmental processes.     

Formation of disinfection by-products in indoor swimming pool water: the contribution from filling water natural organic matter and swimmer body fluids

The contribution and role of different precursors in the formation of three class of disinfection by-products (DBPs) [trihalomethanes (THMs), haloacetic acids (HAAs), and halonitromethanes (HNMs)] in swimming pool waters were examined using filling waters obtained from five drinking water treatment plant (WTP) effluents and three body fluid analogs (BFAs). BFAs exerted higher chlorine demands as compared to natural organic matter (NOM) in filling waters. BFAs exhibited higher HAA formation potentials than THM formation potentials, while the opposite was observed for the filling water NOM. There was no appreciable difference in the HNM formation potentials of BFAs and filling water NOM. Different components in the BFAs tested exhibited different degree and type of DBP formation. Citric acid had significantly higher THM and HAA yields than other BFA components. The effect of temperature was greater on THM formation, whereas the effect of contact time had more impact on HAA formation. Experiments with filling waters collected from WTP effluents at three different times showed more variability in HAA than THM formation at the WTPs studied.     

Behavior of alkylphenol polyethoxylate metabolites during soil aquifer treatment

The attenuation of alkylphenol polyethoxylates (APEOs) metabolites was studied at a soil aquifer treatment (SAT) site located in Arizona, USA. Two parcels of water were monitored during infiltration; one parcel was predominantly oxic while the other was predominantly anoxic. In this study, only alkylphenol ethoxycarboxylates (APECs) and carboxyalkylphenol ethoxycarboxylates (CAPECs) were detected, no short-chained APEOs were observed-even under anoxic conditions. APEO metabolites were rapidly (<7 days) removed under both aerobic and anoxic conditions. In general, the length of the ethoxycarboxylate chain decreases with depth--at depths greater than 3m, only alkylphenoxy acetic acids (AP1ECs), carboxyalkylphenoxy acetic acids (CAP1ECs), and alkylphenols (APs) remain. Under aerobic conditions, octylphenol and nonylphenol concentrations decreased by approximately 80% (w/w) within 3m of the ground surface. Under anoxic conditions however, alkylphenol concentrations increased by approximately 200% during the first 1.5m and then decreased during the next 1.5m; overall, under anoxic conditions, alkylphenol concentrations increased by approximately 38% within 3m. During infiltration, APEC and CAPEC concentrations decrease by more than 95% within 3m of SAT. Alternate flooding and drying cycles appear to enhance overall APEO metabolite removal efficiencies.     

Removal of VUV pre-treated natural organic matter by biologically activated carbon columns

A potential alternative water treatment process using VUV (185 nm+254 nm) irradiation followed by a biological treatment is described. The system uses sufficient VUV radiation (16J cm(-2)) to significantly enhance the production of biologically degradable moieties prior to treatment with biologically activated carbon (BAC). Two similar activated carbons were used, one virgin and one taken from a water treatment plant with an established biofilm. The VUV-BAC process decreased the overall dissolved organic carbon (DOC) concentration of a natural water sample by 54% and 44% for the virgin carbon and previously used BAC, respectively. Furthermore, VUV-BAC treatment decreased the trihalomethane (THM) formation potential (THMFP) by 60-70% and the haloacetic acid (HAA) formation potential (HAAFP) by 74%. The BAC systems effectively removed the hydrogen peroxide residual produced by VUV irradiation. Although nitrite formation can result from VUV treatment of natural organic matter (NOM), none was detected before or after BAC treatment.     

750kV GIS中金属氧化物避雷器对VFTO影响的研究

随着超高压气体绝缘变电站(GIS)的广泛使用,由隔离开关(DS)和断路器(CB)操作引起的快速暂态过电压(VFTO)的危害越加明显。以西北地区750 kV官亭GIS变电站为计算原型,利用电磁暂态程序(EMTP)对不同运行方式下GIS设备上的VFTO进行数值仿真计算和分析。重点在于对不同运行方式下金属氧化物避雷器(MOA)的限制过电压效果进行分析。计算结果表明:DS无分合闸电阻时,MOA防护效果更明显;MOA主要的抑制效果体现在MOA附近的设备上,对于远离MOA的设备上的VFTO的抑制效果较小;由于VFTO持续的时间极短,通过MOA的能量很小。     

膨润土对重金属离子Pb~(2+),Zn~(2+),Cr(VI),Cd~(2+)的吸附性能

试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb2 ,Zn2 ,Cr(VI)和Cd2 的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb2 ,Zn2 ,Cd2 的吸附效果均优于其对Cr(VI)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式.     

建筑西向房间夏季室内热环境改善

以国内某大学综合实验大楼为例,实测了其中一间西向房间的室内外空气温度与壁面温度,分析了其夏季室内热环境。为了在经济合理地使用能源的情况下,满足它对夏季冷量与冬季热量的需求,根据实测的数据,利用建筑热平衡原理,对其夏季室内热环境特性进行了分析,指出了其热工设计缺陷,并对其进行了热舒适性的改造。通过软件模拟出改造后房间室内空气温度值,对比改造前后室内空气温度值,结果显示改造后的温度值明显降低,热舒适性得到了改善。     

An energy-based partial pushdown analysis procedure for assessment of disproportionate collapse potential

A disproportionate (or progressive) collapse is triggered by localized structural damage that propagates throughout a large portion of a structural system. The current guidelines issued by the US Department of Defense use the alternative path method to assess the vulnerability of a structural system to disproportionate collapse. In this method, the capability of a structure to sustain local damage is evaluated by notionally removing primary load-bearing elements and checking whether the local damage can be absorbed. The assessment can be performed using linear or nonlinear static structural models or a nonlinear dynamic model. Although nonlinear dynamic analysis gives the most accurate results, it is computationally intensive and requires considerable skill to implement properly. In this paper, the vulnerability of three steel frames to disproportionate collapse is assessed using an energy-based nonlinear static pushdown analysis. The predictions are sufficiently close to the results of a nonlinear dynamic time history analysis that the method would be useful for disproportionate collapse-resistant design of buildings with regular steel framing systems.     

聚硅铁混凝去除腐殖酸的研究

考察了聚硅铁(PSF)对腐殖酸(HA)的去除效果及影响因素,并与聚合硫酸铁(PFS)、硫酸铁[Fe_2(SO_4)_3]进行了比较.结果表明,当5相似文献   

Understanding soluble microbial products (SMP) as a component of effluent organic matter (EfOM)

Formation of soluble microbial products (SMP) during biological degradation of organic compounds in a sequencing batch reactor (SBR) was investigated using high performance liquid chromatography--size exclusion chromatography (HPSEC) as well as other organic matter characterization tools. Results showed that carbon compounds in a glucose feed solution were totally transformed to other organic products classified biomass-associated products (BAP). The SMP-BAP contained in the SBR effluent consisted mainly of high-molecular weight (MW) fractions of organic matter, possibly originating from cell lysis. These compounds exhibited a low specific ultraviolet absorbance (SUVA) and a hydrophilic character. In addition, the characteristics of bulk effluent organic matters (EfOM) samples from wastewater treatment facilities were studied. It was observed that EfOM consisted of humic-like and hydrophobic (HPO) compounds, derived from the corresponding drinking water source, in addition to SMP-BAP. A superimposition of SEC chromatograms of the SMP-BAP and humic-like compounds represented a fingerprint of EfOM.