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Influence of mineral admixtures on the residual mechanical properties and durability characteristics of self-compacting concrete subjected to high temperature 矿物掺合料对高温自密实混凝土残余力学性能和耐久性的影响
IF 1.3 Q2 Engineering Pub Date : 2021-07-21 DOI: 10.1080/14488353.2021.1953682
T. Kiran, M. E. Mathews, A. N, U. J. Alengaram, A. Andrushia
ABSTRACT Structural engineers must be cautious about fire accidents in buildings, as a result critical deterioration occurs in the strength and serviceability of concrete structures. Self-Compacting Concrete (SCC) is an efficient material developed using Supplementary Cementitious Materials (SCM). This research intends to evaluate the effect of mineral admixtures such as Metakaolin (MK), Silica Fume (SF) and Fly Ash (FA) on the mechanical and durability characteristics of SCC exposed to elevated temperature. Two SCC mixes satisfying the European Federation of National Associations Representing for Concrete (EFNARC, 2005) workability stipulations developed to achieve 20MPa and 50MPa. The specimens were exposed to elevated temperatures following the ISO 834 standard fire curve. Compressive strength, water absorption, acid resistance and Rapid Chloride Penetration Test (RCPT) tests were carried out on heat-affected SCC specimens exposed to elevated temperature. A reduction in strength of 48% and 64% were obtained for the M20 and M50 grade SCC specimens, respectively.
摘要结构工程师必须小心建筑火灾事故,因为火灾会导致混凝土结构的强度和可用性严重恶化。自密实混凝土(SCC)是利用补充胶凝材料(SCM)开发的一种高效材料。本研究旨在评估偏高岭土(MK)、硅灰(SF)和粉煤灰(FA)等矿物掺合料对高温SCC力学和耐久性特性的影响。两种SCC混合料满足欧洲混凝土代表协会联合会(EFNARC,2005)的和易性规定,分别达到20MPa和50MPa。根据ISO 834标准火灾曲线,将试样暴露在高温下。对暴露于高温下的热影响SCC试样进行了抗压强度、吸水性、耐酸性和快速氯离子渗透试验(RCPT)。M20和M50级SCC试样的强度分别降低了48%和64%。
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引用次数: 9
Evaluation and identification of parameters affecting the penetration of emulsion bitumen on aggregates 影响乳化沥青对集料渗透的参数评价与识别
IF 1.3 Q2 Engineering Pub Date : 2021-07-20 DOI: 10.1080/14488353.2021.1945258
Mohsen Aboutalebi Esfahani, Seyed Mohammad Navid Khoddami
ABSTRACT More penetration of the prime coat increases the stabilisation thickness of the sub-asphalt layer and makes it more difficult for water to penetrate. Therefore, the purpose of this study is to identify the effective parameters on the penetration of Cationic Emulsion Bitumen (CEB) and investigate their effects. Short and long-term penetration tests are used. For better evaluation, two types of silica and limestone aggregates are selected in dry and wet conditions. To better compare the results of penetration, the penetration of MC250 cutback bitumen was also measured. The results show that among the identified parameters, the maximum penetration increase is influenced by the time of penetration, the material of aggregates, aggregate humidity, type of prime coat, kerosene percentage, and colloid mill speed which is equal to emulsifier percentage and the percentage of pure bitumen. Also, the least effect is observed for increasing soap temperature. Another result is that the CEB penetration in limestone aggregates is inappropriate in all cases. However, the penetration of CEB in silica aggregates in almost all cases provides minimum requirement so that the moisture being most effective to increase it. The value of MC250 penetration in limestone aggregates is only appropriate for wet and long-term conditions.
底漆的渗透性增加了亚沥青层的稳定厚度,使水更难渗透。因此,本研究的目的是确定影响阳离子乳液沥青(CEB)渗透的有效参数,并研究它们的影响。使用了短期和长期渗透测试。为了更好地评价,在干燥和潮湿条件下选择了两种类型的二氧化硅和石灰石骨料。为了更好地比较侵彻结果,还测量了MC250沥青的侵彻度。结果表明:在确定的参数中,最大渗透增量受渗透时间、骨料材料、骨料湿度、底漆类型、煤油含量和与乳化剂含量和纯沥青含量相等的胶体磨速度的影响。此外,提高肥皂温度的影响最小。另一个结果是CEB在石灰石骨料中的渗透在所有情况下都是不合适的。然而,在几乎所有情况下,CEB在硅骨料中的渗透提供了最低要求,因此水分是最有效地增加它。MC250在石灰石骨料中的渗透值仅适用于潮湿和长期条件。
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引用次数: 0
Slag-based geopolymer concrete incorporating ash: effects on thermal performance 含灰矿渣基地聚合物混凝土:对热工性能的影响
IF 1.3 Q2 Engineering Pub Date : 2021-07-19 DOI: 10.1080/14488353.2021.1953234
S. Oyebisi, A. Ede, F. Olutoge, H. Owamah, T. Igba
ABSTRACT The thermal performance (TP) of concrete structures is vital to the evaluation of the fire response. Thus, this study examined the thermal properties slag-based geopolymer concrete (GPC) incorporating corncob ash (CCA). Corncob was valorised and partially used as a substitution for slag under the ambient curing conditions. Sodium hydroxide (SH) solution and sodium silicate (SS) gel were used as alkaline activators at 12, 14, and 16 M concentrations. The TP of GPC was compared with that of Portland cement concrete (PCC). Thermal predictions were developed based on the thermal properties. Based on the findings, GPC exhibited lower thermal conductivity (TC) and thermal diffusivity (TD) with increasing specific heat capacity (SHC), indicating good thermal insulation properties (TIP) compared with PCC. The TIP increased with increasing CCA content in the mixture at all levels of alkaline activators. Thus, CCA improves the insulating capacity of the GPC. In addition, a good correlation exists between the GPC produced and thermal properties. These findings can be beneficial in the hot climate regions and utilised for structural insulating construction concrete. Finally, the proposed models can be used in the assessment of GPC structures incorporating supplementary cementitious materials (SCMs) to enhance the TIP of construction materials.
摘要:混凝土结构的热工性能(TP)对火灾响应的评估至关重要。因此,本研究考察了含玉米芯灰(CCA)的渣基地聚合物混凝土(GPC)的热性能。在常温固化条件下,玉米芯被固化并部分代替矿渣。氢氧化钠(SH)溶液和硅酸钠(SS)凝胶分别在12、14和16 M浓度下作为碱性活化剂。比较了GPC与波特兰水泥混凝土(PCC)的TP。热预测是根据热性质发展起来的。结果表明,GPC具有较低的导热系数(TC)和热扩散系数(TD),且比热容(SHC)增大,与PCC相比具有较好的保温性能(TIP)。在不同水平的碱性活化剂下,TIP随CCA含量的增加而增加。因此,CCA提高了GPC的绝缘性能。此外,制备的GPC与热性能之间存在良好的相关性。这些发现在炎热气候地区是有益的,并用于结构绝缘施工混凝土。最后,该模型可用于含有补充胶凝材料(SCMs)的GPC结构的评估,以提高建筑材料的TIP。
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引用次数: 8
Evaluation of waste engine oil rejuvenation for highly short term aged asphalt binder 废机油对高短期老化沥青粘结剂的回用效果评价
IF 1.3 Q2 Engineering Pub Date : 2021-07-03 DOI: 10.1080/14488353.2021.1896124
Biruk Tadele, Emer Tucay Quezon
ABSTRACT The ageing property of the asphalt binder is time-dependent. A time-dependent short term ageing property of 80/100 penetration grade bitumen and the possibility of waste engine oil rejuvenation for the highly aged asphalt binder performance were investigated. Four specimens of equal weight from the penetration grade-80/100 bitumen are collected. The first specimen was checked for quality requirements. The other three specimens were aged using rolling thin film oven for 85, 115, and 145 minutes to simulate the delay during hot mix asphalt production, hauling, and compaction. The highly aged bitumen was rejuvenated with 2%, 5%, and 10% Waste Engine Oil by weight. Results indicated that as the ageing time increased, penetration and ductility decreased, softening point, flash point, fire point, and mass loss increased. A conventional test showed that highly aged bitumen from the trial period was 145 minutes and 10% waste engine oil obtained the optimum dosage. Further, multiple stress creep recovery analyses indicated the rejuvenated binder is prone to pavement rutting above 70°C, and rejuvenation is effective for pavement temperature below 70°C. Hence, exposing the asphalt binder for temperature for a more extended period affects pavement performance.
摘要沥青结合料的老化性能与时间有关。研究了80/100渗透级沥青的随时间变化的短期老化性能,以及高老化沥青结合料性能中废机油再生的可能性。从渗透等级为80/100的沥青中收集了四个同等重量的试样。检查了第一个样品的质量要求。其他三个试样使用滚动薄膜烘箱老化85、115和145分钟,以模拟热拌沥青生产、运输和压实过程中的延迟。用2%、5%和10%(重量)的废机油使高度老化的沥青再生。结果表明,随着时效时间的增加,渗透性和延展性降低,软化点、闪点、燃点和质量损失增加。常规试验表明,试验期的高老化沥青为145分钟,10%的废机油获得了最佳用量。此外,多重应力蠕变恢复分析表明,再生粘结剂在70°C以上容易产生路面车辙,再生对70°C以下的路面温度有效。因此,沥青结合料在温度下暴露更长时间会影响路面性能。
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引用次数: 2
Double corrosion protection of sewage tunnel linings 污水隧道衬砌的双重防腐
IF 1.3 Q2 Engineering Pub Date : 2021-06-24 DOI: 10.1080/14488353.2021.1941597
Keith W. K. Kong
ABSTRACT In sewer environments, there are complex chemical and microbiological processes with a reaction between the hydrogen sulphide, a gas produced by the used water, and aerobic feeding microorganism. This resulted in production of sulphuric acid which would cause long-term corrosion on cement based concrete structures. This corrosion process is known as “Microbiologically Influenced Corrosion“. Generally, the ordinary Portland cement-based concrete is not considered as a suitable material for direct exposure to acidic sewer environments. As such, it is necessary to prevent the aggressive environments from developing, as well as to prevent the corrosive environments from coming in contact with the concrete elements. A robust corrosion protection system must be specified and provided for the tunnels and underground structures to ensure the durability of these structures under the aggressive sewer environments and able to withstand a design life span of 100 years. Case example with discussion on seven proven corrosion protection lining systems based on current technology. Past experience of the tunnels is provided with further exploratory study in terms of cost effectiveness and quantity analysis for these seven lining systems to be investigated. A technical specification for Portland cement–based Microbiologically Influenced Corrosion resistant concrete is provided.
在下水道环境中,污水产生的气体硫化氢与好氧饲养微生物之间发生了复杂的化学和微生物过程。由此产生的硫酸会对水泥基混凝土结构造成长期腐蚀。这种腐蚀过程被称为“微生物影响腐蚀”。一般来说,普通硅酸盐水泥基混凝土不被认为是直接暴露在酸性下水道环境中的合适材料。因此,有必要防止侵略性环境的发展,以及防止腐蚀性环境与混凝土元件接触。必须为隧道和地下结构指定并提供强大的腐蚀保护系统,以确保这些结构在恶劣的下水道环境下的耐久性,并能够承受100年的设计寿命。实例分析了基于现有技术的7种行之有效的防腐衬里系统。本文提供了以往隧道的经验,并对这七个衬砌系统的成本效益和数量分析进行了进一步的探索性研究。提出了硅酸盐水泥基抗微生物影响腐蚀混凝土的技术规范。
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引用次数: 0
Shear behaviour of concrete wide beams with spiral lateral reinforcement 螺旋侧配筋混凝土宽梁的抗剪性能
IF 1.3 Q2 Engineering Pub Date : 2021-06-23 DOI: 10.1080/14488353.2021.1942405
Ahmed A. Elansary, Yasser Y. Elnazlawy, H. Abdalla
ABSTRACT Wide beams are commonly used in reinforced concrete (RC) structures for architectural considerations such as facilitating the placement of services and providing adequate clear height. However, behaviour of these beams is not as efficient as normal width beams due to the small structural depth. Motivated by the lack of guidelines for wide RC beams with spiral reinforcement, this paper investigates their shear behaviour using innovative lateral reinforcement configurations. A comprehensive experimental program was conducted by testing nine beams under four-point loading. The effect of different parameters on the behaviour of such beams was investigated. These parameters included number, dimensions, and configurations of spirals. The experimental program also included testing of 18 standard cylinders spirally reinforced under compression to study the performance of confined concrete in the compression zone of wide beams. The results showed that the spiral lateral reinforcement is an efficient alternative for traditional closed stirrups for shear resistance in wide beams. Compared to regular closed stirrups, using spiral reinforcement or inclined links with regular closed stirrups can greatly improve the shear capacity and deformation. Also, reduction in the amount of lateral reinforcement can be achieved if the proposed lateral reinforcement is adopted instead of traditional stirrups. Based on the test results and the ACI 318–19 code, an equation is proposed and validated to estimate the shear strength of wide beams with regular/spiral lateral reinforcement.
宽梁通常用于钢筋混凝土(RC)结构,以方便设施的安置和提供足够的净高度。然而,由于结构深度小,这些梁的性能不如正常宽度梁有效。由于缺乏螺旋钢筋宽钢筋混凝土梁的指导方针,本文利用创新的横向钢筋配置研究了它们的剪切行为。通过对9根梁在四点荷载作用下的试验,进行了全面的试验方案。研究了不同参数对此类梁性能的影响。这些参数包括螺旋的数量、尺寸和结构。实验程序还包括18个标准螺旋增强圆柱体在压缩下的测试,以研究宽梁受压区约束混凝土的性能。结果表明,螺旋侧箍筋是一种有效的替代传统封闭箍筋的宽梁抗剪能力。与常规封闭箍筋相比,采用螺旋配筋或斜杆与规则封闭箍筋可以大大提高抗剪能力和变形能力。此外,如果采用拟议的侧向加固而不是传统的马镫,则可以减少侧向加固的数量。根据试验结果和ACI 318-19规范,提出了规则/螺旋配筋宽梁抗剪强度的计算公式,并进行了验证。
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引用次数: 5
Waterproof performance of non-curable rubber modified asphalt material at deformation joints 不硫化橡胶改性沥青材料在变形缝处的防水性能
IF 1.3 Q2 Engineering Pub Date : 2021-06-15 DOI: 10.1080/14488353.2021.1930639
Zhiqiang Wang, Z. Lei
ABSTRACT In order to study the waterproof performance of non-curable rubber modified asphalt material at deformation joints, the grouting situation of non-curable rubber modified asphalt material in the deformation joint was simulated through the test, the maximum opening amount of deformation joint under the action of constant water pressure was studied, and the corresponding waterproof performance was evaluated. The results show that under water pressures of 0.25 MPa, 0.3 MPa and 0.4 MPa, the widths of deformation joints that the non-curable rubber modified asphalt material can bear are about 11.5 mm ~ 12 mm, 11 mm ~ 11.5 mm and 10 mm ~ 11 mm, respectively. Meantime, the failure types of deformation joints under different water pressures are further clarified. When the water pressure is high, if there is water leakage in the deformation joint, cracks may appear along the direction of deformation joint, which will lead to the failure of deformation joint and gradually expand the failure range along the direction of deformation joint. When the water pressure is low, the occurrence probability of cracks is small and the failure range is relatively limited. The research has considerable guiding significance to the waterproofing of tunnel engineering.
摘要为了研究不可固化橡胶改性沥青材料在变形缝处的防水性能,通过试验模拟了不可固化胶改性沥青在变形缝中的灌浆情况,研究了在恒定水压作用下变形缝的最大开度,并对相应的防水性能进行了评价。结果表明,在0.25MPa、0.3MPa和0.4MPa的水压下,不固化橡胶改性沥青材料可承受的变形缝宽度分别为11.5mm~12mm、11mm~11.5mm和10mm~11mm。同时,进一步阐明了不同水压下变形缝的破坏类型。当水压高时,如果变形缝漏水,可能会沿变形缝的方向出现裂缝,从而导致变形缝失效,并沿变形缝方向逐渐扩大失效范围。当水压较低时,裂缝发生的概率较小,破坏范围相对有限。该研究对隧道工程防水具有重要的指导意义。
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引用次数: 1
Simulating the passive confinement of circular concrete cylinders allowing for size effect 考虑尺寸效应的混凝土圆柱体被动约束模拟
IF 1.3 Q2 Engineering Pub Date : 2021-05-24 DOI: 10.1080/14488353.2021.1926072
X. Hao, P. Visintin, D. Oehlers
ABSTRACT There are innumerable tests on small stocky circular cylinders with either internal passive encasement of the concrete with circular stirrups or spirals, or external passive encasement through fibre-reinforced polymer (FRP) wrapping or through the use of FRP tubes or steel tubes. These tests have shown that passive confinement can increase the strength but, in particular, can substantially increase the ductility of concrete cylinders. Because of these important benefits, the effect of passive confinement on the concrete stress/strain in a particular cylinder section is invariably derived from tests such that substantial member testing is required. In this paper, it is shown how the passive stress/strain of the concrete for a particular circular member can theoretically be determined directly from their partial-interaction shear-friction and partial-interaction bond-slip material properties for any reinforcement arrangement and geometry of the circular cylinder. This procedure provides tools for designing for the benefits of passive confinement directly without the need for member testing.
摘要:有无数的小型圆形圆柱体的试验,要么是用圆形箍筋或螺旋线对混凝土进行内部被动包裹,要么是通过纤维增强聚合物(FRP)包裹或使用FRP管或钢管进行外部被动包裹。这些试验表明,被动约束可以提高强度,但特别是可以显著提高混凝土圆柱体的延性。由于这些重要的好处,被动约束对特定圆柱体截面中混凝土应力/应变的影响总是来自于测试,因此需要进行实质性的构件测试。在本文中,展示了特定圆形构件的混凝土的被动应力/应变如何在理论上直接由其部分相互作用剪切摩擦和部分相互作用粘结滑移材料特性来确定,适用于任何钢筋布置和圆柱体几何形状。该程序提供了无需构件测试即可直接设计被动约束的工具。
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引用次数: 1
Effect of fine aggregate replacement with expanded perlite and pumice on the development of lightweight concrete 膨胀珍珠岩和浮石替代细骨料对轻量化混凝土发展的影响
IF 1.3 Q2 Engineering Pub Date : 2021-05-24 DOI: 10.1080/14488353.2021.1930635
Bharvi Sharma, Raju Sharma, P. Bansal
ABSTRACT In the present study, an attempt has been made to produce lightweight concrete (LWC) by replacing fine aggregates with expanded perlite and pumice. The first set of LWC is prepared by replacing the fine aggregates with expanded perlite at varying proportions, i.e. 0%, 25%, 50%, and 100%. The second set of the mix is prepared to study the effect of replacement of natural sand with equal proportionality of dual particles (expanded perlite and pumice). The replacement of fine aggregate with lightweight aggregates (expanded perlite and pumice) efficiently developed the LWC based on the density specified by Eurocode 2 Part 1–1 (density < 2200 kg/m3). The incorporation of expanded perlite efficiently brought down the density of developed LWC lower than 2200 kg/m3. However, the density of the mix prepared using expanded perlite and pumice exhibited slightly greater than the density of only expanded perlite contained LWC. The incorporation of pumice in the LWC imparts the pozzolanic reactivity and shows better strength and durability properties than the only expanded perlite contained LWC. Furthermore, the microstructure properties revealed that the presence of porous lightweight material unable to improve the interfacial transition zone (ITZ) compared to conventional concrete.
摘要本研究试图用膨胀珍珠岩和浮石代替细骨料生产轻质混凝土。第一套LWC是通过用不同比例的膨胀珍珠岩代替细骨料来制备的,即0%、25%、50%和100%。制备第二组混合物是为了研究在双颗粒(膨胀珍珠岩和浮石)比例相等的情况下更换天然砂的效果。用轻质骨料(膨胀珍珠岩和浮石)代替细骨料有效地开发了基于欧洲规范2第1部分规定的密度(密度<2200 kg/m3)的LWC。膨胀珍珠岩的掺入有效地将开发的LWC的密度降低到2200 kg/m3以下。然而,使用膨胀珍珠岩和浮石制备的混合物的密度略大于仅含有LWC的膨胀珍珠岩的密度。在LWC中掺入浮石赋予了火山灰反应性,并显示出比仅含膨胀珍珠岩的LWC更好的强度和耐久性。此外,微观结构性能表明,与传统混凝土相比,多孔轻质材料的存在无法改善界面过渡区(ITZ)。
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引用次数: 3
Marble waste and recycled concrete aggregates in self compacting concrete (SSC): an evaluation of fresh and hardened properties 自密实混凝土(SSC)中的大理石废料和再生混凝土骨料:新鲜和硬化性能的评估
IF 1.3 Q2 Engineering Pub Date : 2021-05-09 DOI: 10.1080/14488353.2021.1921342
O. Ofuyatan, Kayode-Thomas Enoch, Oluwafuminiyi Ogundeji, David O. Omole
ABSTRACT Abundant waste is being generated in the demolition or renovation in the construction industry. Improper disposal of this waste creates environmental concern as they form huge landfills without proper use. This study examined the fresh, hardened, durability, and microstructural analysis of self-compacting concrete made with recycled aggregates (RA) and marble waste as a 10–30% granite substitute. Slump flow test, T50cm test, V-funnel test, and L-box test were conducted on the fresh concrete. Compressive strength, split tensile strength, flexural strength, microstructural properties, and carbonation of the hardened concrete were determined. The physical tests revealed that though the recycled aggregates and marble waste do not have properties as good as the natural coarse aggregates, recycled aggregates were observed to exhibit a better strength than marble waste. SCC with marble waste had better fresh state properties than those with recycled aggregates. SCC with recycled aggregates had better-hardened state properties than those with marble waste. It can be inferred from the microstructural analysis that the utilisation of partial granite replacement improved the interaction between the concrete constituents. However, the sample with recycled aggregate was still better than that with marble waste in this regard.
摘要建筑业在拆迁或改造过程中产生了大量的垃圾。这些废物的不当处理造成了环境问题,因为它们在没有得到适当利用的情况下形成了巨大的垃圾填埋场。本研究考察了用再生骨料(RA)和大理石废料作为10-30%花岗岩替代品制成的自密实混凝土的新鲜度、硬化度、耐久性和微观结构分析。对新拌混凝土进行了坍落度流动试验、T50cm试验、V型漏斗试验和L型箱试验。测定了硬化混凝土的抗压强度、劈拉强度、抗弯强度、微观结构性能和碳化性能。物理测试表明,尽管再生骨料和大理石废料的性能不如天然粗骨料,但观察到再生骨料比大理石废料表现出更好的强度。大理石废料SCC比再生骨料SCC具有更好的新鲜状态性能。使用再生骨料的SCC比使用大理石废料的SCC具有更好的硬化状态性能。从微观结构分析可以推断,部分花岗岩置换的使用改善了混凝土成分之间的相互作用。然而,在这方面,使用再生骨料的样品仍然优于使用大理石废料的样品。
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引用次数: 3
期刊
Australian Journal of Civil Engineering
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