Aggregates In Concrete Production Research Articles

The Influence of Recycled Coarse Aggregate Content on the Properties of High-Fly-Ash Self-Compacting Concrete

In Vietnam, solid waste from construction activities significantly impacts environmental pollution. Recycled concrete aggregate (RCA), derived from waste concrete, can serve as a coarse aggregate in concrete production. However, compared to natural aggregates, RCA exhibits distinct characteristics, including lower strength, higher water absorption, and an increased angular and rough surface. These properties may influence concrete’s workability, compressive strength, and durability. This research investigates the influence of RCA on the properties of High-Fly-Ash Self-Compacting Concrete (SCC). The study explores various replacement levels of natural coarse aggregate with RCA (0%, 50%, 75%, and 100%), alongside a 50% volume fraction of fly ash. Key concrete properties evaluated include workability, compressive strength, flexural strength, and chloride ion permeability. The findings reveal that using 100% RCA in combination with a high fly ash content (50%) produces SCC that meets workability requirements according to EFNARC standards. However, there are trade-offs: the compressive strength decreases by 4.61%, the flexural strength decreases by 3.1%, and chloride ion permeability increases by 57.57% compared to the control sample (using natural aggregates). Notably, the chloride ion permeability of SCC using 100% RCA falls into the category of low permeability. Doi: 10.28991/CEJ-SP2024-010-04 Full Text: PDF

Copper heap leach residue aggregates in concrete: Properties and performance

This study assesses the feasibility of using copper heap leach residue (CHLR) as a sustainable alternative to natural aggregates in concrete production. The CHLR possesses flaky-angular shape grains with rough surface texture and microcracks, crystalline silica of 51.6 %, 6.1 mg/g silt-clay with a median particle size of 4.3 mm, and it becomes suitable for the partial replacement of natural fine and coarse aggregates after removing 4.2 mg/g fines through 60-minute wash. Concrete containing 25–75 % CHLR aggregates met design slump and air content of 125±25 mm and 2±0.5 %, respectively, while also demonstrating a negligible 2.9 % reduction in fresh density and 2.8 % increase in compaction factor. Concrete containing 50 % CHLR as a partial replacement of natural coarse and fine aggregates achieved compressive strengths of 47.3 MPa and 45.1 MPa at 28 days, while the compressive strength of control mix was 46.7 MPa. The mechanical properties significantly declined at 75 % CHLR incorporated concretes. The BSE-EDS analysis highlighted improved interfacial transition zone for CHLR aggregates with minimal microcracks at early age compared to the natural aggregates but developed interfacial transition zone microcracks with prolonged curing leading to a decline in mechanical strength development.

Alkali-silica reaction of ferronickel slag fine aggregate in Portland cement and alkali-activated slag mortars: Pessimum effect investigation

Ferronickel slag (FNS) with dense and hard nature exhibits great potential to be utilized as recycled aggregate in concrete production. This study investigated the alkali-silica reaction (ASR) and the pessimum proportion of FNS fine aggregate in Portland cement (PC) and alkali-activated ground granulated bast furnace slag (AAS) mortars as a substitute for river sand. Over a 120-day period, the accelerated mortar bar test revealed that the addition of FNS fine aggregate in both cases resulted in harmless ASR expansion. In PC mortars, the ASR expansion consistently decreased from 0.569 % to 0.114 % as the FNS content increased. In comparison, AAS mortars with higher pore solution alkalinity had the pessimum proportion of 30 % FNS. The ASR expansion values initially increased from 0.472 % to 0.554 % with an increase in FNS content from 0 % to 30 %, but then decreased to 0.146 % as the FNS content was further raised to 100 %. The amorphous ASR gel was identified as a hydrated alkali silicate gel and present within the existing veins in the river sand grain. The ASR reaction of FNS fine aggregate exhibited a self-mitigating effect on the deleterious expansion through its pessimum behavior. Additionally, the addition of FNS fine aggregate yielded a beneficial outcome by reducing the cumulative pore volume in the mortars, and thus enhanced the compressive strengths.

EXPERIMENTAL STUDY ON LIGHTWEIGHT CONCRETE USING LECA MATERIALS

This study investigates the feasibility of incorporating Lightweight Expanded Clay Aggregate (LECA) materials into concrete to produce lightweight concrete with improved mechanical properties. The experimental approach involves varying proportions of LECA aggregate in concrete mixes and assessing their compressive strength, density, workability, and durability. Additionally, the study examines the effect of LECA aggregate on the thermal and acoustic properties of lightweight concrete. Results from the experiments demonstrate the potential of LECA as a viable lightweight aggregate in concrete production, offering insights into optimizing mix designs for enhanced performance and sustainability in construction applications.

Evaluating the Structural Performance of Concrete Beams Made of Waste Plastic Aggregates

Abstract: This study investigates the potential of using plastic waste as a partial replacement for aggregates in concrete production, aiming to address the dual challenges of unsustainable construction practices and the global accumulation of plastic waste. With an emphasis on sustainability and waste management, the research explores the effects of incorporating different percentages of plastic waste (0%, 5%, 10%, 15%, and 20%) on the mechanical properties, durability, workability, and thermal behavior of concrete. The methodology encompasses the collection and preparation of plastic waste, formulation of concrete mixes with varying levels of plastic waste replacement, and comprehensive testing of the prepared specimens for compressive strength, flexural strength, split tensile strength, workability (slump test), durability (freeze-thaw cycles), impact resistance, and thermal conductivity. The analysis of results reveals that while the inclusion of plastic waste in concrete leads to a reduction in mechanical strengths, it simultaneously improves workability, durability against freeze-thaw cycles, impact resistance, and thermal insulation properties

Review of Treatment Methods for Enhancing Recycled Concrete Aggregates Properties

Abstract: The use of recycled concrete aggregates (RCA) as a potential substitute for natural aggregates in concrete production has been recommended by many research studies due to the environmental and cost benefits associated with it. However, due to RCA’s high-water absorption, its engineering properties are lower than natural aggregates (NA). Therefore, researchers have also suggested various pretreatment methods to enhance RCA's mechanical and durability properties, including thermal, mechanical, and chemical treatment. In this study, an attempt has been made to investigate the combined effect of heat, abrasion, and fly ash slurry pretreated RCA on the workability and compressive strength of recycled aggregate concrete (RAC) using superplasticizer for 0.4, 0.5, and 0.6 w/c ratio. The study results show that pretreatment of RCA along with the addition of superplasticizer can lead to higher workability and compressive strength of recycled aggregate concrete (RAC) compared to untreated RCA.

Recycling of Oil Palm Shell as Aggregate in Concrete: A Review

The consideration of using alternative materials as coarse aggregates in construction industry is to conserve the natural resources, reduce undesirable carbon dioxide (CO2) and environmental degradation related to conventional aggregate. Oil palm shell (OPS) which is a by-product from oil palm industry has shown potentials as an alternative to the conventional aggregate in concrete production. This paper reviews the previous studies on the application of OPS as a construction material and has been extensively used in tropical countries. The performance of OPS meets the minimum requirements for lightweight aggregates. It is suitable material for the production of structural lightweight aggregate concrete with 28-day compressive strength more than 25 MPa. The various improvement techniques employed OPS concrete that resulted in improved OPS concrete performance are also highlighted in this review.

Concrete containing recycled concrete coarse aggregate and crushed glass sand: Mitigating the effect of alkali–silica reaction

AbstractThe utilization of recycled concrete and glass aggregates in concrete production has emerged as a highly promising method to significantly increase the recycling rate of waste materials. However, the interaction between alkaline environment and silica present in concrete detrimentally impacts mechanical properties and durability of the concrete due to the significant silica content of the aggregates. This study aims to develop a high‐performance and sustainable concrete to resist alkali–silica reaction (ASR). The study focuses on the use of a blend of ground granulated blast furnace slag (GGBS) and fly ash (FA) as binder materials to mitigate negative effects of the ASR on the mechanical properties and and durability of concrete made with crushed glass sand and coarse recycled concrete aggregate (RCA). Various tests, including ASR expansion, flow, slump, density, compression, three‐point bending, water absorption, and chloride attack, were conducted. Furthermore, microanalysis using scanning electron microscopy and energy‐dispersive x‐ray spectroscopy was performed. Based on the results, it is found that the GGBS is less effective than the FA in reducing the ASR expansion of the concrete, with only 3%, 9%, and 12% decreased expansion as a result of the addition of 20%, 40%, and 70% GGBS to the concrete containing 30% FA, respectively. It is also shown that combining 20% GGBS with 30% FA in the RCA concrete containing glass sand develops similar compressive and flexural strengths and water absorption compared to that containing natural sand. This can be related to the pozzolanic reaction of the FA and GGBS, which helps to retain the alkalis for reducing the crack development and propagation in the concrete. However, further GGBS content leads to a decrease in the strengths and an increase in the water absorption of the concrete. The results of this study point to the significant potential of combining FA and GGBS at an optimum ratio to mitigate the ASR effect on RCA concretes containing crushed glass sand. This approach helps in minimizing the emission of greenhouse gases and other pollutants generated during cement production, thereby mitigating environmental pollution. Additionally, it helps the preservation of natural resources by reducing the depletion of natural sand and coarse aggregate.

Performance of recycled aggregate concrete composite metal decks under elevated temperatures: a comprehensive review

ABSTRACT This comprehensive review explores the performance of composite metal decks and structural elements incorporating recycled aggregate concrete (RAC) at elevated temperatures. Despite the acknowledged environmental benefits of using recycled aggregates in concrete production, there is a notable gap in the literature regarding their behaviour under fire conditions. The investigation delves into studies encompassing fire resistance, physio-thermal properties, mechanical attributes, and structural performance of composite metal decks constructed with RAC. The analysis reveals that the inclusion of recycled aggregates has both positive and negative impacts on these elements when exposed to high temperatures. The fire resistance of metal decking composite slabs is significantly influenced by material properties, composition, and RAC mix design. Experimental findings indicate that RAC slabs showed larger midspan deflection under load and fire exposure compared to their counterpart NC slabs. After 120 min. of duration, the mid-span deflection of RAC-0 was recorded to be 19 % higher than the corresponding deflection of NC-0 slab. While temperature-time curves show comparable performance between RAC and natural concrete (NC) slabs, RAC slabs exhibit a notably lower ratio of soffit temperature to the upper surface temperature, resulting in increased spalling. In conclusion, this study advocates for the broader utilization of RAC in constructing structural elements, particularly composite slabs facing extreme temperatures. However, it emphasizes the need for additional research to optimize fire resistance and gain a comprehensive understanding of their behaviour. The findings provide essential guidance for structural engineers and researchers involved in the design of sustainable and fire-resistant structures.

Evaluation of Compressive Strength of Concrete with Various Proportions of Stone Dust as Fine Aggregate

Concrete is the most dynamic engineering material in construction due to its durability and strength properties, which have been used in almost all types of physical infrastructure construction. Crushed stone dust is a supplementary material that can be utilized to produce sustainable concrete. The concept of replacing natural fine aggregate in concrete production with stone dust (SD) could enhance the consumption of stone dust produced during aggregate production as well as reduce the requirement for landfill area for stone dust management. The study aims to compare the compressive strength of nominal mixed M20 and M25-grade concrete by replacing fine aggregates with stone dust. The results reveal that compressive strength increases with an increase in stone dust, but the rise in SD percentages beyond a certain level has a negative impact on the strength of concrete. However, fresh density has a similar trend of compressive strength, and the workability of concrete shows a declining trend with a rise in SD levels. From the results of the experimental investigations conducted, it is concluded that the SD can be used as a replacement for fine aggregate. It is found that 40% replacement of fine aggregate by SD gives a maximum compressive strength than normal M20 and M25 grade concrete, which starts decreasing beyond 40% replacement. The compressive strength of the concrete has been quantified by replacing sand with varying percentages of stone dust and found that it does not satisfy the specification except for 40% replacement for M20 grade concrete, though it can be used for low and medium strength concrete production. The cost savings for M20 and M25-grade concrete at 40% sand replacement are 8.23% and 7.62%, respectively.

WITHDRAWN: Utilization of waste coffee ground ash as fine aggregates in concrete: Enhancing shear strength through activated carbon reinforcement

This study addresses burgeoning environmental concerns amid rising global coffee consumption amid rising global coffee consumption by exploring the viability of utilizing waste coffee ground ash (SCG) as a sustainable fine aggregate in concrete production. Significant improvements are noted by investigating the impact of SCG on the shear strength of standard concrete and enhancing properties through activated carbon reinforcement derived from SCG via physical activation. Experimental results reveal that incorporating up to 1.5% activated carbon by weight markedly boosts early shear strength. Moreover, composites with a small inclusion of activated carbon demonstrate superior shear power during curing compared to conventional mixes. The study employs Teaching-Learning Optimization (TLBO) and Extreme Learning Machine (ELM) techniques to forecast shear strength accurately. ELM emerges superior, showcasing heightened accuracy, lower RMSE, and superior r and R2 values compared to TLBO. Conclusively, leveraging waste coffee ground ash as a fine aggregate in concrete not only presents an effective method for enhancing shear strength but also underscores a promising pathway toward sustainable waste management and reduced environmental impact, reflecting a pivotal stride in harmonizing concrete performance enhancement with eco-friendly practices.

Utilization of Plant Waste Materials as a Partial Replacement of Cement and Fine Aggregates in Concrete Production

The research focused on possibility of producing high quality concrete by the way of adding plant waste materials like sugarcane bagasse ash (SBA), rice husk (RH) and cassava starch (CS) to concrete mixtures. Varying percentages of SBA (0, 5, 10, 15% - weight of the cement), rice husk (0, 5, 10, 15% - weight of the fine aggregates) and cassava starch (0, 1, 2, 3% - weight of the cement) were incorporated into the concrete mixtures design. Comprehensive laboratory investigations were done on the concrete’s workability (slump), density and mechanical strength, to establish the impact of these organic materials on the mechanical parameters of the concrete produced. The laboratory test results show that SBA and CS augmented the concrete slump rate whereas, the rice husk retarded the concrete’s workability. The result of the density indicated that the rice husk and SBA reduced the concrete’s density; however, the cassava starch caused substantial increment in the concrete’s density. On the concrete mechanical properties, it was noted from the results that the compressive strength was boosted by the incorporation of SBA and CS. The maximum compressive strength (23.7 N mm-2) was recorded through by substituting the cement with 10 and 2% of SBA and cassava starch respectively, in the presence of 10% RH as partial replacement of the sand. This study findings had revealed the potential of SBA, rice husk and cassava starch combinations in the right mixture design, to produce light-weight concrete material having sustainable high compressive strength.

Crack Resistance of Concrete Using Granulated BlastFurnace Slag Sand under Flexural Stress

AbstractGranulated blast‐furnace slag sand (BFS) has the potential to be used as an alternative to fine aggregates in concrete production. The interface between the cement paste and the aggregate in concrete is densified when BFS is used, due to the hydrates that are generated by its latent hydraulicity. This fact suggests that the crack resistance of concrete, which is closely related to the conditions at the aggregate interface, would be enhanced by the use of BFS. The fracture energy (GF) of concrete under flexural stress is here measured to evaluate the crack resistance of concrete made using BFS. BFS samples from three different steel mills in Japan are used as the fine aggregates for concrete production, and mountain sand is used as a natural sand for comparison. Compressive strength, static modulus of elasticity, and fracture energy tests are conducted at the material ages of 28 and 91 days. The GF of the BFS concretes increase with increasing compressive strength; on the other hand, the GF of the concrete made using mountain sand decrease. Thus, it is concluded that BFS concrete has superior properties to concrete made using natural sand in terms of the crack resistance under flexural stress, especially in high‐strength regions for large material ages.

Structural Sustainable Recycled Aggregate Concrete Production Under Environmental Conditions

Structural Sustainable Recycled Aggregate Concrete Production Under Environmental Conditions

Development of low-carbon recycled aggregate concrete using carbonation treatment and alccofine

AbstractSince the construction industry is one of the major sectors responsible for the overexploitation of natural resources and the production of greenhouse gases, there is an urgent need to adopt a sustainable and environmental friendly approach to mitigate climate degradation. Research has explored the potential of recycled aggregate (RA) as a viable alternative to natural aggregate in concrete production. Currently, several treatment methods are being employed to enhance the efficient incorporation of RA into concrete, aiming to address this issue. However, the effective utilization of RA in place of NA remains uncommon. In this study, an effort has been made to develop a low-carbon recycled aggregate concrete by utilizing 100% carbonation treated recycled coarse concrete aggregate (CRCCA) in place of natural coarse aggregate (NCA) and alccofine as mineral admixture. A comprehensive analysis was performed, comparing the properties of CRCCA to those of untreated recycled coarse concrete aggregate. This analysis covered changes in weight, bulk density, water absorption, crushing value, and microstructure. Furthermore, five different concrete mixes were prepared, each varying in the proportion of natural coarse aggregate (NCA), untreated RCCA, and CRCCA. These mixes also incorporated alccofine as a mineral admixture. The evaluation process involved assessing the effectiveness of carbonation treatment and alccofine addition through tests on the workability, water absorption, density, and compressive strength of the concrete mixes. The study demonstrated that carbonation treatment of RCCA resulted in substantial improvements in crushing value and water absorption of CRCCA, alongside enhanced workability, reduced water absorption, and increased density in CRCCA concrete. Moreover, CRCCA concrete exhibited notable compressive strength gains at both 28 and 90 days compared to untreated RCCA concrete. Furthermore, the use of CRCCA and alccofine contributed to reducing GHG emissions associated with cement production, emphasizing the environmentally friendly attributes of this low-carbon concrete formulation.

Influence on Physical and Mechanical Properties of Concrete Using Crushed Hazelnut Shell

Concrete production requires a significant amount of natural resources, with aggregates comprising between 55% and 80% of the total volume. However, the over-exploitation of natural aggregates has led to the exploration of alternative materials for use in concrete production. In this study, crushed hazelnut shells were investigated as a partial replacement for fine aggregate, addressing the problem of natural resource depletion and offering a second use for this important agricultural waste product available in Chile. Hazelnut shells were incorporated in percentages of 2.5%, 5%, and 10% by weight of sand for water/cement ratios of 0.4 and 0.5. The compressive strength at 7 and 28 days and bending strength at 28 days were determined, alongside physical properties such as the workability, temperature, air content, fresh density, and hardened density of the concrete. Our findings showed that replacing 2.5% of the fine aggregate with hazelnut shells led to a higher compressive strength at 28 days, exceeding the strength of the standard specimens by 9.5%, whereas replacing 5% of the fine aggregate led to the highest bending strength, exceeding the strength of the standard specimens by 3.5%. Moreover, the 0.4 w/c ratio consistently led to better results for both compressive and bending strength, with fewer and lower reductions in mechanical strength compared to the standard mixture. Our results suggest that concrete mixes with hazelnut shells as a replacement for fine aggregate at a percentage of up to 2.5% can be used in construction systems with a compression strength lower than 17 MPa, and mixtures with up to 10% hazelnut shell replacement can be used in structures with tensile bending stress requirements lower than 6 MPa. Overall, the use of hazelnut shells as a partial replacement for fine aggregate in concrete production presents an environmentally friendly and cost-effective solution for the construction industry.

Characterization of Recycled Aggregates of Concrete and Bricks in the Central Region of Burkina Faso

Aggregates used in the construction of civil engineering works have an impact on the properties of concrete. For several years the central region is famous because of the effects of extraction of natural aggregates on the environment. We conducted laboratory tests on several recycled aggregates of concrete and bricks to determine their mechanical properties. This choice was guided by a concern to identify and analyze the characteristics of natural and recycled aggregates of concretes that impact the properties of concrete on the one hand and to show the importance of increased use of recycled aggregates in concrete production to better preserve the environment and move towards sustainable development moreover. To better understand the qualities of these aggregates, it is necessary for us to carry out experimental tests in the laboratory.
 The objective also guided the choice of the different types of recycled aggregates selected for the measurement of mechanical properties in the central region: Crushed Natural Gravel, Rolled Natural Gravel, Crushed Recycled Gravel, Recycled Spinning Gravel, Alluvionary Natural Sands, Recycled Brick Sands.
 The results show that recycled aggregates of concrete and bricks in the central region can be used for high-quality concretes on the one hand and reduce the impact of artisanal extraction of non-recycled aggregates on the environment on the other hand.
 In short, we retain that the characteristics of recycled aggregates are a function of the rate of mortar gangues glued to the mother aggregates.

Application of Steel Slag as an Aggregate in Concrete Production: A Review.

Steel slag is a solid waste produced in crude steel smelting, and a typical management option is stockpiling in slag disposal yards. Over the years, the massive production of steel slags and the continuous use of residue yards have led to vast occupation of land resources and caused severe environmental concerns. Steel slag particles can potentially be used as aggregates in concrete production. However, the volume stability of steel slag is poor, and the direct use of untreated steel slag aggregate (SSA) may cause cracking and spalling of concrete. The present research summarizes, analyzes, and compares the chemical, physical, and mechanical properties of steel slags. The mechanism and treatment methods of volume expansion are introduced, and the advantages, disadvantages, and applicable targets of these methods are discussed. Then, the latest research progress of steel slag aggregate concrete (SSAC) is reviewed. Using SSA leads to an increase in the density of concrete and a decrease in workability, but the mechanical properties and durability of SSAC are superior to natural aggregate concrete (NAC). Finally, future research in this field is proposed to motivate further studies and guide decision-making.

Performance evaluation on bond, durability, micro-structure, cost effectiveness and environmental impacts of fly ash cenosphere based structural lightweight concrete

The production of huge fly ash waste from thermal power plants and gradual depletion of natural aggregates due to their high consumption in concrete making are two major threats to the sustainability of the environment. The strategic utilization of this waste as a replacement of natural aggregate in production of concrete can solve both the problems simultaneously. Hence, this study aims to evaluate the performance of structural lightweight concrete (LWC) containing fly ash cenosphere (FAC), a by-product of fly ash, in order to check its suitability for construction. In this study, one control concrete mix, i.e., without FAC, and other ten concrete mixes utilizing FAC as the replacement of natural fine aggregate (NFA) at the increment of 20% and with/without superplasticizer (SP) are prepared. The Mechanical properties (compressive and bond strength), durability aspects (sulphuric acid, magnesium sulphate and sodium chloride resistance) and the microstructural characteristics from X-ray diffraction and scanning electron microscope analyses of these mixes are evaluated. Moreover, the environmental impact assessment and cost-effective analysis are also conducted. From this investigation, it is found that the structural LWC can be produced by utilizing high volume FAC with/without SP with the acceptable mechanical and durability performances. Further, the concrete with 80% FAC and SP is found to be optimum having compressive strength of 32.59 MPa, which satisfies M25 grade concrete as per IS 456 (2000), meets ACI 213 (2014) requirements of structural LWC and has also acceptable durability properties. The microstructure studies have also supported the strength and durability results of these mixes. Moreover, these mixes are found to be cost effective and environmentally friendly. Hence, structural LWC prepared with a high volume of FAC and SP can be recommended for construction, which reduces the cost and environmental impacts significantly and preserves natural resources for the future generations.

Properties and Behavior of Rubberized Concrete Enhanced with PVA Fibers

Due to growing populations, approximately one billion scrap tires are generated annually worldwide. This is a problem particularly in more developed countries where the per-head share of scrape tires is much higher than the global average. The adverse environmental impacts associated with landfilling scrap tires made it imperative to promote eco-friendly solutions such as utilizing them in civil engineering applications. This paper explores the use of tire-derived aggregates (TDAs) with large particle sizes that require less energy to produce as a substitute for traditional aggregates in concrete production. A comprehensive experimental program was conducted to study the effects of the TDA content on the density, compressive strength, elastic modulus, strain at failure, splitting tensile strength, and flexural strength of rubberized concrete at 28 days. Furthermore, with the aim of improving the tensile and flexural properties of rubberized concrete, the use of polyvinyl alcohol (PVA) fibers was also investigated in this study. A total of 126 specimens, half of them containing PVA fibers, were prepared from fourteen different concrete mixtures with varying percentages of TDAs replacing coarse aggregates. Results indicate that a reasonable TDA content of less than 20% can be used to produce concrete with comparable or even superior properties for specific applications requiring moderate strength and higher deformability while reducing waste tires in landfills. In addition, adding 1% PVA fibers to the mixtures was found to enhance the specimens’ compressive, tensile, and flexural strengths and reduce the observed loss of strength rate in rubberized concrete, especially at higher TDA contents. Overall, this research suggests that TDAs can be a sustainable and cost-effective solution for applications that do not require great concrete compressive strength but a more accommodating plastic behavior.