In recent years, the implementation of sustainable concrete systems has been a topic of great interest in the field of construction engineering worldwide, as a result of the large and rapid increase ...in carbon emissions and environmental problems resulting from traditional concrete production and industry. For example, the uses of supplementary cementitious materials, geopolymer binder, recycled aggregate and industrial/agricultural wastes in concrete are all approaches to building a sustainable concrete system. However, such materials have inherent flaws due to their variety of sources, and exhibit very different properties compared with traditional concrete. Therefore, they require specific modifications in preprocessing, design, and evaluation before use in concrete. This reprint, entitled “Advances in Sustainable Concrete System”, covers a broad range of advanced concrete research in environmentally friendly concretes, cost-effective admixtures, and waste recycling, specifically including the design methods, mechanical properties, durability, microstructure, various models, hydration mechanisms, and practical applications of solid wastes in concrete systems.
Many existing and newly constructed bridges are composed of reinforced and prestressed concrete. Advanced concrete materials play an increasingly important role in concrete bridges to facilitate the ...strengthening and repair of existing bridges, to facilitate a (fast) replacement solution for (part of) an existing bridge, and for the design of new challenging bridge projects. The development of advanced concrete materials and their structural applications is thus an important topic in the built environment.This reprint brings together research and practical applications from the perspective of material scientists and bridge engineers for applications to new and existing bridges.
The building industry, and especially the concrete industry, consumes a considerable proportion of the natural resources extracted from the lithosphere and is responsible for a large part of the ...solid waste generated worldwide. Unfortunately, this fact has not yet generated a movement to counter the trend; rather, a huge increase in the use of concrete in new structures can be observed. It is imperative to counteract this development by optimally exploiting the material properties of concrete in order to improve its efficiency. One strategy being pursued at the University of Natural Resources and Life Sciences, Vienna and TU Wien is to reduce the amount of concrete and reinforcement in structures by using high‐performance materials such as carbon‐fibre‐reinforced polymers (CFRP) in ultra‐high‐performance concrete (UHPC) members. This permits a crucial reduction in the self‐weight and allows for the design of very lightweight precast concrete elements. The authors' goal is to use CFRP rods as bending reinforcement and a combination of flat and preformed CFRP textiles as shear and structural reinforcement. In the first part of this paper, the research approach is introduced and a comprehensive overview of the state of the art of UHPC and CFRP reinforcement is given. The second part contains a description of the conceptual design of some structural members (one floor element and two T‐beams), starting with the development of a suitable UHPC mixture. Furthermore, preliminary uniaxial tensile tests of textile‐reinforced UHPC strips are described and evaluated. In the final part of this paper, the authors present parameter studies for different reinforcement types, values, additional prestressing of the rod reinforcement and the first prototypes. They are used to give an estimation of the feasibility, the load‐bearing and deflection behavior of the proposed building components.
Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by ...contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.
This book reports on cutting-edge research within the new field of active rheology control of cementitious materials, presenting new ideas developed within the ERC Advanced Grant Project, SmartCast ...(hosted at Ghent University), which extend the possibilities of admixtures and additions beyond current options. The research presented here develops a new method of actively controlling the rheology of fresh concrete during casting operations by incorporating specially designed responsive components. This results in real-time changes to the rheological behaviour of the cementitious material, allowing the user to intervene actively after the cementitious material has left the mixing phase. This newly gained agility contributes to increased processing speed and placement reliability in the case of traditional casting methods and can also facilitate advanced 3D concrete printing. The different routes followed to achieve this Active Rheology Control are explained within. The book suits researchers and innovative practitioners and is the first comprehensive text to present these new findings. The Open Access version of this book, available at http://www.taylorfrancis.com, has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 license.
Alkalization technology and its application to obtain high-performance concrete compositions is an urgent scientific problem that opens opportunities for improving building structures. The article is ...devoted to the new technology of manufacturing reinforced concrete structures with low energy consumption, resource, and labor intensity based on the improved variatropic configuration of vibro-centrifuged concrete using activated water with high pH. The synergistic effect of the joint use of the proposed novel solutions has been theoretically and experimentally proved. Thus, growth in physical and mechanical characteristics of up to 15–20% was obtained, the structure and its operational ability were improved (the effectiveness of structural improvement, expressed as a percentage, reached values over 70%, concerning control samples). A positive effect on the properties of vibro-centrifuged concrete over the entire thickness of the annular section has been revealed. A method for controlling the integral characteristics of concrete has been obtained. The possibility of regulating the variatropic structure and controlling the differential characteristics of vibro-centrifuged concrete has been established. An assessment of the constructive quality and variatropic efficiency of vibro-centrifuged concrete was carried out, and new calculated dependencies were proposed, expressed in the form of relative coefficients.
•Drop-weight impact tests were performed on steel or GFRP bars RC slabs.•Effects of bar type, reinforcement ratio and arrangement were investigated.•Effects of concrete strength and slab thickness ...were also investigated.•Singly RC slab with higher tensile bars than doubly RC slab perform better.•The results obtained from experiment and numerical simulation are in good agreement.
Reinforced concrete slabs are common structural elements that could be exposed to impact loading. Although use of reinforced concrete slabs and utilization of Fiber Reinforced Polymer (FRP) as alternative to traditional steel reinforcement slabs are growing, but the influence of various parameters on their response under impact loads is not properly evaluated. This study investigated the effect of rebar’s material, amount and arrangement of reinforcements, concrete strength and slab thickness on dynamic behavior of reinforced concrete slabs using both laboratory experiments and numerical simulations. Performance of fifteen 1000 × 1000 mm concrete slabs, including two 75 mm thick plain slabs, five 75 mm thick steel reinforced concrete slabs, six 75 mm thick reinforced concrete slabs with Glass Fiber Reinforced Polymer (GFRP) bars and two 100 mm thick steel reinforced concrete slabs under drop weight impact loads was experimentally investigated. Failure mode, crack development, displacement-time, strain-time, and acceleration-time responses were studied and compared between various slabs. Finite element analyses and simulation of specimens were conducted using LS-DYNA explicit software. The results obtained from experiments and numerical models are in good agreement, and they indicate that increasing the reinforcement ratio or the slab thickness enhance the behavior of RC slabs under impact loads. By adjusting the amount and arrangement of GFRP, better performance in GFRP slabs than steel reinforced slabs can be achieved, which considering the corrosion resistance of this material, can make it an appropriate selection of reinforcement material.
Abstract
Efficient supplementary materials flourish the structural performance and sustainability of reinforced concrete structures. Steel fiber is one of these materials that have significant ...influence on enhancing tensile and flexural strengths and ductility of high strength reinforced concrete columns. This paper presents a review study on the structural performance of steel fiber reinforced concrete columns. The studied case was related to the columns that subjected to concentric or eccentric compression loads or combined compression loads and cyclic lateral loads. The current survey is divided into two branches; the first is related to fibreless HSC columns, while the other is specialized by SFRHSC ones. In addition to the prime actuator (steel fiber content), the investigated parameters were included concrete strength, transverse reinforcement properties, and axial load ratio. The results of this investigation showed that the positive influence of adding steel fiber on improving the flexural strength, fatigue life and resistance, delaying spalling failure of the exterior concrete shell and outward buckling of the longitudinal steel reinforcing bars. The optimum volume fraction of steel fiber used is 0.5% to 2% (by weight) and when 2% of steel fibers are introduced into the concrete mix, the columns’ cover didn’t spall away.
The innovations in construction materials that have been made due to the development of different varieties of concrete have led to innovations in structural applications and design. This Special ...Issue mainly focuses on state-of-the-art research progress in high-performance concrete, including the effect and characteristics of fibers on the properties of high-performance concrete, the CO2 curing efficiency of high-performance cement composites, and the effect of nano materials when used in ultra-high-performance concrete. This Special Issue also contains two comprehensive review articles covering the following topics: the role of supplementary cementitious materials in ultra-high-performance concrete and recent progress in nanomaterials in cement-based materials. Readers working towards conducting research on innovative construction materials will be exposed to findings related to this topic in this Special Issue.
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