A REVIEW ON STUDIES OF THE MECHANICAL PROPERTIES OF SELF COMPACTING CONCRETE

In this study ,We have reviewed many researches and papers that have recently been interested in the self-compacting concrete, its properties and additives, some of the studies focused on the use of specific additives in the self compacting concrete and the study of the effectiveness of these additives and their impact on the different properties of the concrete and its durability and performance, and we summarized the most important results, especially the results related to mechanical properties. Through the data available in recent previous studies, we studied the mechanical properties of self compacted concrete compared to normal vibrated concrete. the comparison was for compressive strength and tensile strength. We also presented a summary of the effect of use of various admixtures on the mechanical properties of self-compacted concrete, which may be useful in comparing the additives on the basis of their effect on the properties of self compacting concrete And to know the characteristics that need to be studied or increased research around them

Microstructure and Dimensional Stability of Slag-Based High-Workability Concrete with Steelmaking Slag Aggregate and Fibers

Four high-workability (pumpable and self-compacting) concretemix designs are presented that incorporate steelmaking slagswith additions of both metallic and polymeric fibers. Electric arcfurnace slag (EAFS) as aggregate, and ladle furnace slag (LFS) andground granulated blast furnace slag (GGBFS) as supplementary cementitious material (SCM) are applied to optimize the sustainability ofthe mix design. The main variables in the microstructural analysis, theporosity and the pore structure of the hardened mixes, were assessedwith mercury intrusion porosimetry (MIP), X-ray computed tomography (XCT) and water capillary penetration analysis. Moreover,shrinkage was observed to decrease when adding metallic fibers and LFS. In general, scanning electron microscopy (SEM) observationsrevealed good quality concrete microstructures. Accelerated aging tests at a moderate temperature (72°C) produced a slight lengthening,which affected the dimensional stability of all the mixtures, which was also conditioned by their micro-porosity. The internal damageinduced by this test decreased the brittle fracture strength of the concrete mixes, although the use of GGBFS and LFS moderated thatdamage, due to the increased compliance of the cementitious matrix.The authors wish to express their gratitude for funding this researchwork to the Spanish Ministry of Universities, MInisterio de Cienciae INNovaci ́on (MICINN), Agencia Estatal de Investigaci ́on (AEI),European Union (EU), and European Regional Development Fund(ERDF) (PID2020-113837RB-I00, PID2021-124203OB-I00,RTI2018-097079-B-C31, 10.13039/501100011033, FPU17/03374);ERDF and the Junta de Castilla y Le ́on (BU119P17; UIC-231);European Social Fund (ESF) and Youth Employment Initiative(JCyL) (UBU05B_1274); Sustainable And Resilient ENvironment(SAREN) research group (IT1619-22, the Basque Government);and the University of Burgos [Y135.GI]. Our thanks also go to thecompanies Chryso Additives and Hormor-Zestoa for their ongoingcollaboration with research group members

Study on Performance, Strength and Durability Of Metallic And Non-Metallic Fibre Reinforced Concrete With Inclusion Of Waste Ceramic Aggregates – A Review

Every year, the world generates millions of tons of waste, much of which cannot be recycled due to the high energy consumption and pollution involved in the recycling process. Ceramic is increasingly used in modern construction, especially in the production of tiles, but the material's fragility causes significant waste during processing, transportation, and installation. Even recycling the waste ceramic for further processing is currently not feasible. However, by using waste ceramic as a material in concrete production in the right way, we can eliminate waste and improve the properties of concrete. As the sustainable or green concrete industry continues to expand, many metallic and non-metallic wastes are generated in each processing and usage stage. This review article examines the utilisation of alternative materials in concrete to find solutions for waste disposal and provides construction contractors and developers with a vast range of ideas to improve and adopt new construction methods. The paper also gives a brief review of the properties from concrete produced from waste ceramic can be utilised as replacement for coarse aggregates by metallic and non-metallic fibers, and the resulting hardened concrete properties are studied

Recycled Fibers for Sustainable Hybrid Fiber Cement Based Material: A Review

Reinforcing fibers have been widely used to improve physical and mechanical properties of cement-based materials. Most fiber reinforced composites (FRC) involve the use of a single type of fiber to improve cement properties, such as strength or ductility. To additionally improve other parameters, hybridization is required. Another key challenge, in the construction industry, is the implementation of green and sustainable strategies based on reducing raw materials consumption, designing novel structures with enhanced properties and low weight, and developing low environmental impact processes. Different recycled fibers have been used as raw materials to promote circular economy processes and new business opportunities in the cement-based sector. The valuable use of recycled fibers in hybrid FRC has already been proven and they improve both product quality and sustainability, but the generated knowledge is fragmented. This is the first review analyzing the use of recycled fibers in hybrid FRC and the hybridization effect on mechanical properties and workability of FRC. The paper compiles the best results and the optimal combinations of recycled fibers for hybrid FRC to identify key insights and gaps that may define future research to open new application fields for recycled hybrid FRC.TRUEComunidad de Madridpu

THE EFFECT OF FINE RECYCLED CONCRETE AGGREGATES ON THE MECHANICAL AND DURABILITY PROPERTIES OF CONCRETE

The fast increase of construction and demolition (C&D) operations has resulted in the creation of massive amounts of garbage, which must be cleared. Reusing C&D waste is of significant importance for environmental conservation and resource utilization. One such alternative for structural concrete is recycled concrete aggregate obtained from building and demolition debris. In this context, the present study aims to comprehensively review the current state of the art in fine recycled concrete materials (fRCA), including their physical properties, technological advantages, mechanical properties, and durability characteristics. The study establishes a paradigm for evaluating the quality of fRCA, whether created in a lab, acquired via controlled breaking and screening of recovered materials, or collected from field buildings

High-Performance Eco-Efficient Concrete

This book is dedicated to “High-Performance Eco-Efficient Concrete” and concrete fatigue behavior, more sustainable construction materials, capable of complying with quality standards and current innovation policies, aimed at saving natural resources and reducing global pollution. The development of self-compacting concretes with electric arc furnace slags is a further achievement. In addition, the technical and economic viability of using coarse recycled aggregates from crushed concrete in shotcrete, enhanced quality and reduced on-site construction time are the basic features of prefabricated bridge elements and systems, biomass bottom ash as aluminosilicate precursor and phosphogypsum were discussed. On the other hand, basalt fiber improving the mechanical properties and durability of reactive powder concrete, alkali-activated slag and high-volume fly ash and the potential of phosphogypsum as secondary raw material in construction industry, the effects of fly ash on the diffusion, bonding, and microproperties of chloride penetration in concrete were studied. Increasing amounts of sustainable concretes are being used as society becomes more aware of the environment. Finally, the circular economy as an economic model of production and consumption that involves reusing, repairing, refurbishing, and recycling materials after their service life are presented in this book

POLYVINYL ALCOHOL (PVA) FIBER-REINFORCED RUBBER CONCRETE AND RUBBERIZED SELF-COMPACTING CONCRETE

This study experimentally investigates the mechanical performance and durability of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete and the rubberized self-compacting concrete. The waste rubber particles were introduced as a partial replacement of fine aggregate in the plain concrete. In addition, the waste tire rubbers were pre-treated with alkali surface treatment method to enhance the performance. The PVA fibers were added to the concrete mixes to enhance the post-failure resistance and thus fracture energy. Rubberized fiber concrete samples were prepared with different fine aggregate replacement ratios and the optimum fiber content. At the same time, the rubber particles had been used to partially replace the fine aggregate in normal self-compacting concrete (SCC). The rubberized self-compacting concrete (RSCC) had also been prepared with different rubber contents. The effects of NaOH treatment method had been evaluated in the self-compacting concrete. For these samples, the mechanical performance including compressive strength, indirect tensile strength, and flexural behavior was measured to compare with control samples. The transport property was also detected by electrical resistivity test. The durability performance such as alkali-silica reaction (ASR) expansion and drying shrinkage were evaluated and compared with control samples. The test results of the PVA-fiber reinforced rubber concrete showed that it could achieve a high fracture energy and maintain xvi a high mechanical performance after addition of recycled rubber and PVA-fiber, furthermore, the modified specimens showed a better performance in durability than control samples. At the same time, the results from rubberized self-compacting concrete (RSCC) also indicated that after using of NaOH surface treated rubbers can successfully achieve high-strength requirement and improve durability performance. Overall, the polyvinyl alcohol (PVA) fiber could be considered to improve the mechanical performance and durability in normal rubberized concrete. In addition, the NaOH surface treatment method for rubber particles could improve the performance of rubberized self-compacting concrete (RSCC), thus achieve a high-strength and good durability with the recycled tire aggregate

Experimental and numerical analysis of short sisal fiber-cement composites produced with recycled matrix

"Published online: 02 Jan 2017"The proper use of renewable or recycled source materials can contribute significantly to reducing the environmental impact of construction industry. In this work, cement based composites reinforced with natural fibers were developed and their mechanical behavior was characterized. To ensure the composite sustainability and durability, the ordinary Portland cement matrix was modified by adding metakaolin and the natural aggregate was substituted by 10% and 20% of recycled concrete aggregate. Compression and splitting tensile tests indicated that mechanical strength did not seem to be affected by recycled content. Flat sheets were cast in a self-compacted cement matrix and bending tests were performed to determine the first crack, postpeak strength and cracking behavior of the composites. The use of short sisal fiber as reinforcement of recycled cement matrices results in a composite with multiple cracking and increment of strength after first crack. The modeling of composites using finite element method allowed to determine the tensile stress-strain behavior of material and to design possible applications of this new sustainable material.This research was supported by CAPES (PVE Program: Project 047/2012) and CNPqinfo:eu-repo/semantics/publishedVersio

Structural use of fiber-reinforced self-compacting concrete with recycled aggregates: case study of a foundation wall in Spain

This paper is focused on the use of mixed recycled-aggregates (RA), replacing 100% of the natural coarse aggregates, for producing steel fiber reinforced self-compacting concrete (FR-SCC-RA) oriented to the construction of foundation walls. To this end, an extensive experimental program dedicated to the mechanical characterization of FR-SCC-RA foundation walls from the material and structural level was carried out. The former was developed on both molded specimens and cores extracted from the in-situ constructed FR-SCC-RA walls in Barcelona, Spain. The results lead to confirm that the use of RA resulted satisfactorily from both the concrete manufacturing and the mechanical performance, since no affectations on the design mechanical variables (i.e., compressive and flexural tensile strengths) were detected. Likewise, the results derived from the full-scale test evidenced that the residual loads of the slabs tested were significantly higher than those calculated based on the test results of the prismatic core samples. The main outcome derived from the experimental research program is that FR-SCC-RA might be a suitable material for this structural typology and that the tested slabs presented a sufficient post-cracking residual capacity -due to the incorporation of structural fibers- for avoiding fragile failures. These conclusions could be extended to other countries where similar restrictive regulations and standards are present, regarding the use of RA and FRC for structural applications.The authors would like to thank the Agency for Management of University and Research Grants (AGAUR), Barcelona, Spain and the company ESCOFET 1886, S.A., Barcelona, Spain, for the economic support within the Industrial Doctorate Programme of Dr. Francisco Mena. This study was also fund by the Spanish Ministry of Science and Innovation under the scope of project CREEF (PID2019-108978RB-C32). Likewise, the authors wish to thank the Structure Technology Laboratory Luis Agulló Lab Staff, belonging to Barcelona Tech, Spain.Peer ReviewedPostprint (published version

Eco-Efficient Preplaced Recycled Aggregate Concrete Incorporating Recycled Tire Waste Rubber Granules and Steel Wire Fibre Reinforcement

With increasing world population and urbanization, the depletion of natural resources and generation of waste materials is becoming a considerable challenge. As the number of humans has exceeded 7 billion people, there are about 1.1 billion vehicles on the road, with 1.7 billion new tires produced and over 1 billion waste tires generated each year. In the USA, it was estimated in 2011 that 10% of scrap tires was being recycled into new products, and over 50% is being used for energy recovery, while the rest is being discarded into landfills or disposed. The proportion of tires disposed worldwide into landfills was estimated at 25% of the total number of waste tires, which represents fire hazards and grounds for breeding of disease carrying mosquitoes. Moreover, waste generated during construction and demolition in the United States in 2014 was about 353.6 million tons. This is expected to increase worldwide with ageing civil infrastructure. Recycling tire rubber and demolition concrete as recycled concrete aggregate (RCA) poses technological challenges. Tire rubber tends to float during concrete mixing and placing due to its lower density, while RCA tends to absorb mixing water, causing loss of workability and shrinkage stresses. In the present study, tire rubber and tire steel-wire along with RCA can be preplaced in the formwork, eliminating the problems above. Subsequently, a flowing grout is injected to fill inter-granular voids. This preplaced aggregate concrete (PAC) offers multiple sustainability advantages. It incorporates about 50% more coarse aggregate than normal concrete, thus reducing the demand for cement and the associated greenhouse gas emissions from cement production. The dense granular skeleton of PAC has a unique stress transfer mechanism, which better resists shrinkage and thermal contraction stresses due to the physical contact between granular particles. Moreover, the mixing and pumping energy of concrete and the associated labour are greatly reduced since only the smaller grout fraction is mixed and injected. In this experimental study, 21 eco-efficient preplaced aggregate concrete mixtures were made with recycled concrete aggregate, along with 10%, 20%, 30%, 40% and 50% of scrap tire rubber, and 0%, 0.25%, 0.5% and 1.0% of tire steel-wire fibre. The mechanical properties of specimens from each mixture were explored, including compressive, tensile and flexural strengths, elastic modulus, post-crack behaviour, and impact resistance. While tire rubber decreased the mechanical strength and elastic modulus, combined tire rubber and steel-wire fibres provided the preplaced aggregate concrete with superior post-crack behaviour, higher toughness and better impact resistance. The Weibull distribution was found to be an effective tool for predicting the impact resistance of PAC mixtures. It is believed that the proposed sustainable technology of preplaced recycled aggregate concrete incorporating recycled tire rubber and tire steel-wire fibres can offer an eco-efficient construction procedure for pavements, sidewalks, road barriers, and other non-structural concrete. Further refinements, including the use of effective supplementary cementitious materials or geo-polymer grout can further enhance the mechanical strength and overall eco-efficiency of this technology