Al粉增强淤泥陶粒及其机理的研究

单纯的淤泥原料常常难以制备出性能理想的轻质高强陶粒,通过向淤泥中掺加Al粉或Al2O3粉,制备轻质高强陶粒。结果表明,Al2O3粉和Al粉皆能有效提高陶粒的强度,掺加Al粉效果更显著,Al粉较适宜掺量为5%;此时通过合适的焙烧制度能制得表观密度为1.27 g/cm3、吸水率为2.5%、颗粒强度为5.4 MPa的轻质高强陶粒,以及表观密度为1.53 g/cm3、吸水率2.1%、颗粒强度为11.7 MPa的优质高强陶粒;SEM、XRD分析发现,Al粉的掺入减少了陶粒内部孔隙的形成,反应所生成的刚玉相对陶粒增强具有重要作用,同时原位生成的Fe金属相使材料获得了一定的延性断裂特征,改善了陶粒的韧性     

对轻集料粒型的思考

从我国对轻集料的研究发展以来,除天然轻集料（例如浮石、火山渣等）和工业废料轻集料（例如自燃煤矸石等）为碎石型轻集料外,大多数人造轻集料（例如黏土陶粒、页岩陶粒和粉煤灰陶粒）均为圆球型轻集料。虽然《轻集料混凝土技术规程》 ＪＧＪ１５－９０把轻粗集料分为圆球型、普通型和碎石型,但其主要是按生产工艺进行的划分,而这里不考虑生产工艺,只按颗粒形状分为碎石型和圆球型。而国外大多采用碎石型轻集料。这固然和我国轻集料的生产工艺有关,但两种粒型哪种对轻集料混凝土的性能特别是商品混凝土的泵送性能更为有利,目前我国…     

轻骨料吸水返水特性及其对轻骨料混凝土抗裂性能的影响

采用U型管微压测定装置测定页岩陶粒的吸水返水过程,采用带隔板环形约束收缩装置测定轻骨料混凝土的抗裂性能。研究表明:未预湿页岩陶粒在陶粒混凝土中的吸水返水过程分为3个阶段:吸水、吸水返水、返水。陶粒混凝土在龄期10d左右在隔板处突然出现贯通性裂缝,而普通混凝土内部微裂缝在龄期10d后逐渐发展;28d龄期时,陶粒混凝土的裂缝宽度比普通混凝土的大。     

Durability of lightweight concretes with lightweight fly ash aggregates

This paper presents the effects of aggregate properties such as strength, porosity, water absorption, bulk density and specific gravity on the strength and durability of lightweight fly ash aggregate concrete (LWAC). The influence of properties of four aggregates (sintered lightweight fly ash aggregates, cold-bonded lightweight fly ash aggregate and normalweight aggregate) on mechanical and durability properties of concrete is discussed. Experimental results revealed that durable high-strength air-entrained lightweight concretes could be produced using sintered or cold-bonded lightweight fly ash aggregates, having comparable performance with the normalweight concretes. The use of lightweight aggregates (LWA) instead of normalweight aggregates in concrete production decreased the strength and stiffness due to the higher porosity and lower strength of the aggregate included in the concrete. However, permeability of sintered fly ash aggregate lightweight concretes was comparable and slightly lower than normalweight concrete whereas permeability of cold-bonded fly ash lightweight concrete was greater than the others. All concretes had a durability factor greater than 85, which met the requirements by showing quite perfect resistance to freeze–thaw.     

Effects of fly ash properties on characteristics of cold-bonded fly ash lightweight aggregates

The study presented herein provides a new insight into the effects of physical and chemical properties of the fly ash on the characteristics of the cold-bonded fly ash lightweight aggregates. LWAs were manufactured through the cold-bonding pelletization of two fly ashes differing in their physical and chemical properties. Moreover, one type of the LWAs was surface treated by water glass. The produced fly ash aggregates were then examined by means of ESEM micrograph, EDX spectrum, and XRD pattern to resolve the microstructural and the mineralogical characteristics of the LWAs. The findings of the study revealed that the fly ash with higher specific surface and with lower CaO content yielded higher strength LWAs. Furthermore, the surface treatment with water glass provided a marked increase in the aggregate strength and a reduction in the water absorption. The LWCs made with such LWAs had a compressive strength of as high as 60 MPa.     

普通混凝土与采用不同陶粒的轻质混凝土的水渗性和氯离子渗透性比较

通过比较采用高强或普通陶粒的轻骨科混凝土和普通混凝土在不同强度等级下水渗性和氯离子渗透性的差异,研究轻骨科混凝土渗透性的规律。试验结果表明：混凝土强度等级相同时,采用高强或普通陶粒的轻质混凝土渗透性均远远低于普通混凝土。当混凝土体积配合比相同时,使用高强轻骨科的轻质混凝土渗透性在强度等级较低时(LC30)低于普通混凝土,在强度等级较高时(LC50)略高于普通混凝土;而使用普通陶粒的轻质混凝土渗透性在两种强度等级下均仅仅略高于普通混凝土。使用半干陶粒的轻质混凝土渗透性低于使用完全预湿陶粒的轻质混凝土,但这种差异随着强度等级的提高趋于减小。     

集料干涉对轻质混凝土匀质性的影响

在构建"集料干涉假说"的理论基础下,作者用动量守恒定理建立了集料干涉的数学模型,揭示了集料干涉的本质机理,提出了改善轻质混凝土匀质性的技术途径;并在此基础上分别研究了集料的相对体积比例、集料的颗粒级配对轻质混凝土匀质性的影响规律,最后提出了集料之间发生明显干涉的条件.     

包壳轻集料的试验研究

文章研究利用粉煤灰进行免烧结绿色轻集料工艺的探索，通过系统的试验得出．以粉煤灰为主要原料，掺入激发剂和化学复合剂，经配料、成球、裹浆、养护等工艺，能够得到一种用灰量大、堆积密度低、筒压强度高的绿色轻集料。文章还重点研究了绿色轻集料的高强度机理。经过性能测试，该集料的性能完全符合高强度轻集料的国标规定，这对其进一步推广应用，将会产生可观的经济价值和明显的社会效益．     

我国众筹融资平台持续督导制度构建——基于平台法律定位视角

随着互联网金融的不断发展,众筹融资作为互联网金融创新的代表,以网络平台为媒介,以创新金融为载体,打破了传统融资地域窄、时间长、风险集中的壁垒,为我国初创及中小微企业融资提供了新途径,为投资者开辟了新渠道。然而,由于目前我国相关法律规范严重缺位,众筹融资领域融资者欺诈、平台跑路等现象屡见不鲜。为有效缓解投资人信息不对称状况,规范融资企业经营管理,确保众筹融资项目顺利完成,保护投资者权益,推动众筹平台良性竞争,众筹平台作为众筹融资的核心枢纽,必须加强持续督导制度建设,在项目发起阶段,优化项目筛选机制,落实对融资方信息的基本审核;在项目筹资阶段,强化信息披露,严格项目与平台资金的隔离;在项目筹资成功后的管理阶段,加强融资方信息的持续披露,保障投资者权益。     

Microstructure and mineralogy of lightweight aggregates manufactured from mining and industrial wastes

The microstructure and mineralogy of lightweight aggregates manufactured with washing aggregate sludge, sewage sludge and a clay-rich sediment have been studied. The mineralogical analysis revealed the neo-formation of plagioclase and pyroxene group minerals and a minor presence of gehlenite. Some relationships may be established: (i) heating temperature and dwell time affect the formation of new porosity; (ii) the disappearance of pyroxenes could produce changes in the density of the solid material in the lightweight aggregates; (iii) when an external glassy film is not present, water absorption values depend on the size and number of each type of pore.     

Effect of Granulated Blast Furnace Slag and fly ash addition on the strength properties of lightweight mortars containing waste PET aggregates

In this work, the effect of Granulated Blast Furnace Slag (GBFS) and fly ash (FA) addition on the strength properties of lightweight mortars containing waste Poly-ethylene Terephthalate (PET) bottle aggregates was investigated. Investigation was carried out on three groups of mortar specimens. One made with only Normal Portland cement (NPC) as binder, second made with NPC and GBFS together and, third made with NPC and FA together. The industrial wastes mentioned above were used as the replacement of cement on mass basis at the replacement ratio of 50%. The size of shredded PET granules used as aggregate for the preparation of mortar mixtures were between 0 and 4 mm. The waste lightweight PET aggregate (WPLA)–binder ratio (WPLA/b) was 0.60; the water–binder (w/b) ratios were determined as 0.45 and 0.50. The dry unit weight, compressive and flexural–tensile strengths, carbonation depths and drying shrinkage values were measured and presented. The results have shown that modifying GBFS had positive effects on the compressive strength and drying shrinkage values (after 90 days) of the WPLA mortars. However, FA substitution decreased compressive and flexural–tensile strengths and increased carbonation depths. Nevertheless a visible reduction occurred on the drying shrinkage values of FA modifying specimens more than cement specimens and GBFS modified specimens. The test results indicated that, GBFS has a potential of using as the replacement of cement on the WPLA mortars by taking into consideration the characteristics. But using FA as a binder at the replacement ratio of 50% did not improve the overall strength properties. Although it was thought that, using FA as binder at the replacement ratio of 50% for the aim of production WPLA concrete which has a specific strength, would provide advantages of economical and ecological aspects.     

Effects of sediment addition on macrobenthic invertebrates in a Northern Canadian River

Two channels built into the Harris River, Northwest Territories were used to study responses of invertebrates to sediment addition. Sediment was added to one channel continuously for approximately 5 h. The other channel was used as a control. In August, 28.27 kg of sediment or 1.38 kg m⁻² of channel bottom were added. Values for September were 35.88 kg or 1.53 kg m⁻².As a result of sediment addition, numbers of macrobenthos drifting from the sediment addition channel (S) increased significantly over those drifting in the control (C) in August (= summer) and September (= fall). Total drift from S was > 3 times higher in August and > 2 times higher in September than from C. Significantly higher numbers of macrobenthos drifted in fall than summer. Numbers of macrobenthos drifting during sediment addition were significantly related to time in September but not in August, indicating a seasonal difference in temporal response to sediment addition. Two explanations are proposed for the response of the September community, as indicated by shape of a polynomial regression curve, to sediment addition. No significant difference existed in standing crops of macrobenthos in the substrate in C and S after sediment addition.Sediment addition caused (1) higher numbers of Oligochaeta and Simuliidae to drift in August and September; (2) higher numbers of Plecoptera and Ephemeroptera to drift in September but not in August; and (3) higher numbers of Hydracarina and Chironomidae to drift in August but not September.We suggest that future work try to relate amounts of settled rather than suspended sediments to quantitative responses of stream macrobenthos. We recommend that highway and pipeline construction undertaken in watersheds of Mackenzie Valley streams during the open-water period, resulting in sediment addition to these streams, should be done during summer rather than spring or fall, providing river discharge is adequate to transport the added sediment.     

Use of aggregates produced from marble quarry waste in asphalt pavements

More than 95% of asphalt pavement materials (by weight) consist of aggregates. The highway and construction industries consume a huge amount of aggregates annually causing considerable energy and environmental losses. The aggregates are usually produced from neighborhood aggregate quarries or from natural aggregate sources. As a result of the increasing demands for new aggregate quarries, the general texture of earth's surface has been steadily deteriorating, causing environmental concerns. The use of marble wastes from marble quarries as aggregates might help meet the increasing demands and slow down any detrimental effects on the environment. In this study, recycled aggregates produced from homogeneous marble and andesite quarry wastes in Afyonkarahisar–Iscehisar region were compared to two other aggregate specimens currently used in Afyonkarahisar city asphalt pavements. Los Angeles abrasion, aggregate impact value, freezing and thawing, flakiness index and Marshall stability flow tests were carried out on the aggregate specimens. The test results indicate that the physical properties of the aggregates are within specified limits and these waste materials can potentially be used as aggregates in light to medium trafficked asphalt pavement binder layers.     

不同轻骨料吸水特性及其对混凝土性能的影响

高性能轻骨料（HPLWA）强度高而吸水率低,即使在负压或正压条件下,吸水率仅5％左右,而表观密度为0．9kg/m^3的HPLWA1．2g/cm^3具有更低的吸水率;普通轻骨料（NLWA）则比较敏感,特别在负压或正压条件下,吸水率高达40％以上,对于表观密度为1．2g/cm^3的HPLWA,即使不预先湿水,所配制的混凝土,在1．5小时内仍能满足泵送所需要的坍落度要求。对于NLWA,则必须在负压或正压下预湿处理,方可使其坍落度在90分钟内保持泵送所需要的坍落度,但此处理对于混凝土的强度是不利的,而常压泡水30分钟,对HPLWAC和NLWAC的强度均不利影响。     

利用地基基础工程淤泥制备冷结型再生粗骨料

台湾地区将营建剩余土石方区分为9大类,其中地基基础工程淤泥被归类为B6类营建剩余土石方,系一可再利用资源。基于资源可循环利用,本研究根据材料互制性,配合水泥化学,并导入复合材料的观念,采用冷结技术,开发以地基基础工程淤泥为母材(Matrix)的再生粗骨料,期望提高地基基础工程淤泥之再利用率及经济价值。试验结果显示,利用地基基础工程淤泥所制备的再生粗骨料性质:烘干比重约1.83;面干内饱和比重约2.12;吸水率约15.5%;单位重约1215kg·m-3;空隙率约33.5%;筒压强度介于12～18MPa;其它性质亦符合ASTMC33之要求。因此利用地基基础工程淤泥及冷结技术所开发的再生骨料,不仅符合绿建材的精神,亦可降低生产烧结型再生骨料所消耗之能源与CO2排放对环境的冲击。     

Optimisation of using lightweight aggregates in mitigating autogenous deformation of concrete

Experiments were conducted to determine the effects of using dispersed saturated lightweight aggregates (LWAs) as water reservoirs in mitigating the autogenous deformation of high performance concrete and to establish the optimum solutions as a combination of a number of factors affecting the fracture and mechanical characteristics of concrete. For this purpose, in concretes prepared with a constant low water to cement ratio, normal aggregates were replaced by natural LWAs with size fractions of 2–4 mm or 4–8 mm at three different volume fractions such as 10%, 20% and 30% of the total aggregate volume of concrete. The results indicate that the inclusion of fine fraction of LWAs in concrete reduces the autogenous deformation significantly compared to that of the coarse fraction. It is also shown that concretes with fine fraction of LWAs have enhanced fracture and mechanical properties compared to those with coarse fraction of LWAs. Increasing the replacement ratio of LWAs mitigates autogenous deformation, while having an unfavourable effect on fracture and mechanical properties of concrete for both size replacements. A multi-objective simultaneous optimisation technique, in which the response surface method (RSM) is incorporated, is used to optimise the mitigation ratio of autogenous deformation and fracture parameters of high strength concretes in an effort to obtain a more ductile concrete with less autogenous deformation.     

Characteristics of self-consolidating concrete using two types of lightweight coarse aggregates

This paper presents the development of lightweight aggregate self-consolidating concrete (SCC) using two types of lightweight aggregates having different densities. Lightweight aggregate SCC properties have been evaluated in terms of flowability, segregation resistance and filling capacity of fresh concrete as per the standards of the Japanese Society of Civil Engineering (JSCE). The measurement of the mechanical properties of hardened lightweight aggregate SCC, including compressive strength, splitting tensile strength, elastic moduli and density, as well as its specific strength were also carried out. The characteristics of lightweight aggregate SCC at the fresh state showed that as the density of the lightweight coarse aggregate decreases, the flowability improves but the segregation resistance tends to decrease. The 28-days compressive strength of the lightweight SCC was found to be 32 MPa or higher. The relationship between the compressive strength and the splitting tensile strength was found to be similar to the expression presented by CEB-FIP, and the relationship between the compressive strength and the elastic moduli was found to be similar to the expression suggested by ACI 318-05 which takes into consideration the density of concrete. The density of the lightweight aggregate SCC decreased by up to 14% compared to that of the control SCC, and the specific strength decreased by up to 20%.     

Influence of volume fraction and characteristics of lightweight aggregates on the mechanical properties of concrete

The influence of lightweight expanded clay and shale aggregates on the mechanical performances of concrete is studied through their volume fractions and aggregate qualities. A very thorough characterisation of a series of LWAs is completed. The impact of aggregates is not only related to its particle density but also to the shell thickness, the percentage of large pores and broken grains. A reverse determination of the elastic modulus of LWA is carried out based to the experimental data. The comparison with values measured ultrasonically confirms the part played by the aggregate stiffer shell in mechanical properties of LWA.     

模拟油田采出水中硫化氢的脱除研究

硫化氢是油气田伴生气中的有害组分。在含硫油气田的采出水中,硫化氢的存在对于安全生产和和油田环境均会产生危害。采出水经处理后通常需作为地层回注水使用,由于油气生产的特殊性,常用的硫化氢脱除方法在使用中受到限制,探索适合于油气田生产的水处理方法十分必要。本文探讨了通常可用于油田水中硫化氢脱除的各种方法,对比了各类方法的优缺点,提出以次氯酸钠为主要脱硫剂的水处理方法,通过对模拟采出水的室内试验,证明次氯酸法可以快速有效地去除采出水中的硫化氢,并提出了消除过量氧化剂的后续处理方法。实验表明经处理后的水质可以达到油气田回注水质要求,处理成本较低。