Self-compacting Concrete Mixtures Research Articles

Study on the performance of hydrophilic curing agent and environmentally friendly non-pozzolanic filler for the development of self-curing self-compacting concrete.

Self-compacting concrete (SCC) is often used when compaction is difficult, requiring special attention to the curing process. However, traditional curing methods usually fail in practice. Despite taking precise measures to control water evaporation, surface water on vertical structure elements can still be problematic. To address these challenges, this study seeks to investigate the possibility of creating self-curing self-compacting concrete (SCSCC). Since the curing agent used has a significant impact on the production of SCSCC, this study examines the effects of using polyethylene glycol (PEG), a hydrophilic agent, at varying rates of 0.5%, 1%, 1.5%, and 2% on the fresh, hardened, and durability characteristics of the material. Additionally, to improve the sustainability properties of SCSCC, manufactured sand (M-sand) acquired from crushing rocks is used as a filler. Overall, the results indicate that the use of superplasticizer and M-sand is enough to achieve the required flowability for SCC mixtures without requiring specific fillers, and this method is effective in immediately controlling bleeding and segregation while maintaining the necessary compressive strength at all ages. The hardened properties of SCSCC were found to be improved by increasing the PEG content up to 1.5%, with an optimal range of 0.75% superplasticizer. Furthermore, the results demonstrate that the self-cured specimen, cured with PEG, has greater acid resistance than the conventionally cured one.

Self-compacting concrete using molybdenum mineral tailings: materials and mechanical property

Recycling mineral tailings poses significant challenges, but one effective solution is their incorporation into self-compacting concrete (SCC) mixtures. This research explores the material and mechanical properties of SCC by integrating mineral tailings at three different ratios: 10%, 20%, and 30%. The primary aim is to determine the optimal replacement ratio that preserves key characteristics such as flowability and viscosity. To assess the material properties of fresh SCC, we conduct various tests, including rheological, V-funnel, U-box, and air content tests. These evaluations focus on how the addition of mineral tailings at different levels impacts flowability and viscosity. In terms of mechanical performance, we analyze compressive strength relative to the increasing proportion of mineral tailings. The results indicate that higher proportions of mineral tailings negatively affect flowability and viscosity. As a result, the optimal replacement ratio for mineral tailings is identified as up to 20% of the total cement content. These findings suggest that mineral tailings can effectively replace conventional cement, making them a promising option for producing environmentally friendly self-compacting concrete.

Carbonation and chloride penetration performance of self-compacting concrete with masonry and concrete wastes

In this research, masonry and concrete construction and demolition wastes (CDWs) were used as supplementary cementitious material (25% vol. residue of masonry, RM) and recycled coarse aggregate (RCA) in increasing levels (0%, 50% and 100% vol. residue of concrete), respectively, in the development of self-compacting concrete (SCC). The performance of SCC mixtures was evaluated in terms of fresh properties, compressive strength, resistance to both accelerated (1% CO2, 65% R.H. and 23 °C temperature) and natural carbonation as well as chloride penetration. Experimental results showed a monotonic workability reduction associated to the incorporation of increasing levels of RCA. In compressive strength, the SCC with RCA showed the greatest increase in this mechanical property after 28 days of accelerated exposure in the carbonation chamber, when compared to its water-cured counterpart. Yet, at 360 days of accelerated carbonation exposure, all SCCs showed compressive strength reductions compared to their water-cured counterparts. On the other hand, the chloride permeability resistance of the SCCs was low and very low at the ages evaluated. Thus, the findings of this study indicate that the use of CDW can generate SCCs with adequate fresh properties, compressive strength and carbonation and chloride penetration performance, which offers benefits for the environment.

Technical and Economic Efficiency of Using the Self-Compacting Concrete Mixtures in Monolithic Construction

Introduction. The technical effect attained during construction of the monolithic reinforced concrete structures made of self-compacting concrete mixtures, which results in the increase of the actual strength of concrete, can be put to use to reduce the cross section of the structures and to cut down the consumption of the reinforcement. The paper aims to assess the technical and economic efficiency of the monolithic reinforced concrete structures made of high-strength self-compacting concrete, with the use of the construction waste, in meeting the goals of green construction.Materials and Methods. To assess the efficiency of the monolithic structure concreting options, the vibratory-compacting concrete mixture БСТ В25 П4 and the self-compacting mixture БСТ В40 РК1 were prepared using the Portland cement CEM0 42.5N. The crushed stone of fraction 5–10 mm was used as a coarse aggregate and natural sand and crushed sand from construction waste (concrete scrap) were used as a fine aggregate. To ensure the high fluidity of the mixtures, the additive Polyplast PK— a universal ester-based polycarboxylate superplasticizer was used. The calculation of the parameters of the reinforced concrete structures depending on the compressive strength of concrete was performed in the LIRA software package. The estimated cost of the works on construction of the reinforced concrete structures was determined for two alternative options that differed in the type of concrete mixture used, the method of its delivery to the place of concreting and in the method of compaction.Results. The calculation of the parameters of the reinforced concrete structures has been carried out, which showed that for the structures made of high-strength B40 class concrete, the cross-section thickness can be uniform along the entire height — 200 mm, whereas the amount of concrete can be 20% less than for B25 class concrete. The calculation of reinforcing parameters along the structures’ height in correlation to the strength of concrete showed that when using the self-compacting B40 class concrete, it is possible to reduce the design diameter and to cut down the consumption of the reinforcement. The expected economic effect of using the self-compacting high-strength concrete, calculated for concreting the structures of the volume of 433 m3 , can be 1639.5 rubbles.Discussion and Conclusion. The technical and economic efficiency of using the high-strength self-compacting concrete for concreting the monolithic reinforced concrete structures has been substantiated. As a result of using the self-compacting mixture and concrete pumping technology, the estimated cost of constructing the structures is reduced, the manpower inputs and labour costs are decreased, and, due to the use of the construction waste and refusal from utilising the electrical equipment for the vibratory compaction, the ecological effect is achieved.

The effect of Dolomite powder and Fly ash on durability properties of self-compacting concrete

Abstract This study aims to assess the effectiveness of dolomite mineral admixture in the production of self-compacting concrete (SCC). The characteristics of concrete at 7 and 28 days of hardening were evaluated. SCC mixtures with different amounts of dolomite powder and fly ash (FA) at a constant composition were made. It has been noted that the flow ability of SCC mixes gets better with increasing percentages of dolomite. In addition to its mechanical characteristics, the durability of mixes containing SCC has been studied, including water absorption, sorptivity, and permeability to chloride ions and acid attack. After 28 days, a strength of 61 MPa was achieved with a 20% DP replacement level mixture, which is 31.38% higher than the control SCC mix. Along with the compressive strength of SCC, parameters affecting the durability of SCC such as Rapid chloride penetration test (RCPT), Sorptivity, water absorption and hydrochloric acid attack were also studied at 28 days. The utmost resistance to permeability of chloride ions was attained.

Characteristics of self-compacting green concrete

Locally, conventional concrete is still created utilizing river sand and crushed stone as filer materials. The massive quarry dust by-product remain untapped in the production of concrete. The coal-fired power station produce significant quantities of Type F fly ash. Self-compacting concrete (SCC) provides many advantages for creating high-quality concrete. Consequently, the main objective of this research is to create a mix design for high-strength SCC utilizing a binary blends, hybrid fibers and fine aggregates that meet both hardened and fresh concrete characteristics. The study is conducted in amendment of w/b ratio, superplasticizer, proportion of fine aggregate to coarse aggregate, optimumal cement replacing by fly ash, dosage of low macro fibre and micro fibre. Mix-50c-X is the best mix design that was produced. The mix quantity for 1m3 concrete was 315 kg Class F fly ash, 315 kg OPC, 630 kg quarry dust, 508 kg river sand, 400 kg coarse aggregate, 0.7% superplasticizer,0.32% w/b, 0.10% macro fiber, and 0.01% micro fiber. This SCC mixture showed fresh characteristics as well as compressive strengths of more than 22 MPa and 62 MPa after 1 day and 28 days, respectively. The results of high-strength SCC demonstrated the enormous potential for the local construction, especially precast product.

Pengaruh Penggunaan Zeolit dan Serat Agave Sisalana Terhadap Kuat Tekan dengan Metode Self Compacting Concrete (SCC)

Self Compacting Concrete (SCC) is concrete innovation which does not require vibrations during installation and compaction. SCC concrete can flow freely with its weight and is capable of filling a mold well, ensuring perfect compaction without vibration. In 1988, in order to eliminate or reduce the need for vibration to achieve density and thereby reduce the labor required for concrete placement, SCC was developed in Japan. In this research, the production of SCC was investigated by replacing the fine aggregate in the SCC mixture by 3%, 7% and 11% of zeolite material and by adding 0.005% of agave sisalana fiber of cement weight. The 15/30 cm concrete cylinders were used in 16 samples for compressive strength. It is shown that the values of flowability, filling capacity, and permeability decrease with increasing use of zeolite content based on the results of the research conducted. The results of the compressive strength test show that the variation of 7% zeolite + 0.005% sisalana fiber has the highest value of compressive strength at FAS 0.43, with an average of 38.46 MPa, and the highest value of compressive strength at FAS 0.45, with an average of 37.07 MPa.

Investigation of self-compacting concrete utilizing different supplementary pozzolanic materials for cement replacement

This study enhances self-compacting concrete (SCC) properties by adjusting the mix design, reducing the water-to-cement ratio, and adding permeability-reducing admixtures (GGBS, fly ash, silica fume, bentonite). Different admixture proportions were tested to improve mechanical characteristics. Four SCC mixtures were formulated, varying GGBS and fly ash (0-70%) and silica fume and bentonite (0-20%). Auromix 300 plus (0.6% by weight of cement) was used as a chemical admixture. Strength properties (compressive, flexural, split tensile, elastic modulus) were evaluated on specimens cured normally for 28 days, then in NaCl for 56-112 days. Optimal mixtures were found: GGBS 30% for compressive strength, bentonite 10% for flexural and split tensile strength. Results indicate increased strength and reduced porosity by incorporating these materials.

Experimental investigation of mechanical and durability performances of self-compacting concrete blended with bagasse ash, metakaolin, and glass fiber

This study investigated the effects of using bagasse ash (BA) and metakaolin (MK) together as substitutes for cement in self-compacting concrete (SCC), together with the addition of glass fiber (GF), on the physical and mechanical characteristics of concrete. Eighteen SCC mixes were created, each containing different proportions of BA (0%, 10%, 15%, and 20%), MK (0%, 10%, 15%, and 20%), and BA and MK collectively (10% + 5% and 10% + 10%) as cement replacements with and without 0.1% GF. Using the results of the slump flow, T500 slump flow, V-funnel, and L-box tests, the performance of fresh SCC was determined. Furthermore, this study evaluated the strength, durability, and microstructural properties of the SCC samples. The SCC mix blended with 10% BA and 5% MK revealed better flowability as the slump flow increased from 692 mm to 715 mm. A strong linear correlation was discovered between the slump flow values (mm) and V-funnel duration (sec) and blocking ratio (H2/H1) with R2 = 0.8876 and R2 = 0.8467, respectively. Of all test mixes, the SCC mix blended with 10% BA, 5% MK, and 0.1% GF (SCC1B10M5) demonstrated the highest degree of strength. At 56 days, the 10% BA, 5% MK, and 0.1 GF mix had 12.8%, 25.7%, and 22.2% higher compressive, flexural, and splitting tensile strengths than the control mix, respectively. SCC, combined with BA, MK, and GF, outperformed the control mix. After immersion in a 3% H2SO4 solution, the SCC mix having 10% BA, 5% MK, and 0.1% GF experienced a minimum reduction in weight loss and ultrasonic pulse velocity of 1.01% and 3.1%, respectively. Additionally, there was a decrease of 29.4% in the percentage of charges passed. The ideal composition was achieved by incorporating 10% BA, 5% MK, and 0.1% GF into the SCC mixture, resulting in a dense structure without any visible pores or cracks during the microstructural analysis.

Mechanical performance of eco-friendly self-compacting concrete (SCC) mixtures and two-way slabs partially containing cement kiln dust as cement replacement and internally reinforced with waste plastic mesh

A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was investigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.

Experimental Study on Fracture Properties of Self-Compacting Concrete Containing Red Mud Waste and Different Steel Fiber Types

This study aims to investigate the effect of integrating red mud (RM) waste and different types of steel fibers on the fracture toughness characteristics of self-compacting concrete (SCC). A total of 24 specimens consisting of notched SCC beams with various steel fibers (measuring 100 × 100 × 500 mm) are subjected to a three-point bending test. This study examines five various fiber types characterized by varying shapes and aspect ratios. These fiber types include the hook-end fiber with lengths of 60 and 30 mm, the long straight fiber with lengths of 21 and 13 mm, and the flat-end fiber. Six concrete mixtures, each incorporating fibers with 1% of the volume percentage, are examined. RM is used at a replacement rate of 20% of the mass of cement. Another objective of the study is to analyze the mechanical and fresh characteristics of concrete. The findings indicate that the incorporation of steel fiber has an adverse effect on the fresh concrete characteristics of SCC. The presence of steel fiber results in enhanced mechanical properties, peak loads, and deflection at the point of failure, in addition to an increase in the crack mouth opening displacement. The fracture toughness of SCC mixtures is also influenced by the presence of steel fiber.

The Effect of Rice Husk Ash as Cement Substitution on the Compressive Strength of Self-Compacting Concrete

Self-Compacting Concrete (SCC) is an innovative solution in today's world of concrete technology. Unlike traditional concrete, it does not require a vibrator for compaction, which makes concrete work easier. One of the key features of SCC is its high workability, which is achieved through the use of chemical admixtures and mineral additives. Rice husk ash is one such additive that can be used as a pozzolanic material for concrete mixtures, which is important as rice husk waste can cause environmental problems. The objective of this study was to investigate the effect of rice husk ash on SCC concrete. The study involved using Rice Husk Ash (RHA) as a partial replacement for cement in SCC concrete at varying percentages (0%, 5%, 10%, and 15% of cement weight). The results of the slump flow test showed that the highest value of 775 mm was achieved at 15% RHA, meeting the specifications of SCC concrete. In terms of compressive strength, the results showed that the SCC mixture without rice husk ash (0% RHA) had the highest average compressive strength, which was 30.56 MPa at 14 days and 31.66 MPa at 28 days of concrete. On the other hand, the average compressive strength of SCC concrete with rice husk ash mixture was highest at 5% RHA, with 25.04 MPa at 14 days and 28.81 MPa at 28 days. Overall, the study found that the use of rice husk ash in SCC concrete had a significant effect on its compressive strength, with the highest compressive strength being achieved at 5% RHA.

Influence of Basalt Fiber on the Rheological and Mechanical Properties and Durability Behavior of Self-Compacting Concrete (SCC)

This experimental study presents the influence of basalt fiber on the rheological and mechanical properties and the durability behavior of self-compacting concrete (SCC). In this study, a total of five self-compacting concrete mixtures were prepared: one as a control mix and the other mixes with 0.05%, 0.1%, 0.15%, and 0.2% basalt fibers. Slump flow and V-funnel flow tests were employed to assess the influence of basalt fibers on the rheological properties of fresh self-compacting concrete (SCC). Additionally, mechanical properties, including compressive strength, splitting tensile strength, and flexural strength, were analyzed. Furthermore, the mechanical properties were assessed following exposure to elevated temperatures (400 °C and 600 °C) as well as 100 and 200 freeze-thaw (F/T) cycles. Additionally, water absorption and ultrasonic pulse velocity tests were conducted on the SCC mixes after 28 days of curing. The results revealed that the addition of fiber has a significant effect on the rheological properties of fresh SCC mixtures. As the volume of fibers increases, the reduction in rheological properties increases. Basalt fiber had no effect on the compressive strength, while the splitting and flexural strength were significantly enhanced by 33% using basalt fiber. As temperatures and freezing-thawing cycles escalated, the mechanical properties of SCC exhibited a decline. Experimental findings indicated that elevating the temperature to 600 °C resulted in a decrease of over 20% in both the tensile and compressive strengths of SCC. Moreover, the results demonstrated that the incorporation of basalt fibers substantially enhanced the mechanical properties of SCC when subjected to high temperatures and freezing-thawing cycles. In addition, water absorption increased slightly by the incorporation of basalt fiber.

The effect of chemical oxygen demand of domestic wastewater on workability, mechanical, and durability of self- compacting concrete

Due to worldwide water scarcity, especially in arid regions, and the substantial use of drinking water in concrete production, the consideration of gray water usage is growing. However, wastewater contamination adversely affects concrete's mechanical strength and durability, with Chemical Oxygen Demand(COD) as one of the indicator. In the present work, the effect of COD of different types of domestic wastewater on workability, mechanical, and durability properties of self-compacting concrete (SCC) with 400 kg/m3 and 440 kg/m3 of cement, and water-to-cement ratios of (w/c) 0.36 and 0.5 for 12 different SCC mixture designs were investigated. The results of the experiments indicated that increasing the COD of domestic wastewater negatively impacts the workability of fresh concrete. Additionally, as the COD of the wastewater increases, the compressive strength of SCC decreases at 7 and 28 days when using raw sewage, sewage sludge, and artificial wastewaters. However, by 90 days, the compressive strength showed no significant difference compared to SCC made with tap water. With increasing COD of wastewater, the 28-day tensile strengths of SCC decreased by 6–10 %. The COD of wastewater did not significantly affect the flexural strength. However, the fracture toughness, at a water-cement ratio (w/c) of 0.5, decreased with increasing COD, reaching a reduction of 36 % at a COD of 940 mg/L. As the COD concentration rises, water absorption increases. In SCC samples containing sludge water and raw sewage, capillary water absorption was at its maximum due to the presence of impurities, as well as organic and mineral materials.

Sustainable use of magnesite mine waste in self-compacting concrete and its study on strength, microstructure, cost and CO2 emission

Managing waste materials from mining is of universal interest owing to its massive volume, ecological impacts, health hazards, and disposal challenges despite high operational costs. Advancements advocate for recycling mine waste to sustainably support construction. As the construction sector heavily consumes resources, utilizing mine waste from magnesite mines (MMW) in concrete has gained attention. This experimental study assesses the viability of substituting MMW for natural fine and coarse aggregates in self-compacting concrete (SCC) at intervals of 10% up to 50% by weight. Evaluations were done on fresh (slump flow, T50 slump, V-funnel, J-ring, L-box) and hardened (compressive, splitting tensile, and flexural strength) properties, along with microstructural features, cost, and CO2 emissions. The findings unveil that nearly all mixtures exhibit commendable performance, where mine waste is replaced for fine and coarse aggregates showcasing superior fresh and hardened properties, respectively. Fresh property results reveal the SF1 flow category with VF1 and VF2 viscosity types for the SCC mixtures. Moreover, these SCC mixtures observed substantial strength enhancements of approximately 10% to 15% in compressive, splitting tensile and flexural test results at 28 and 90 days. Microstructural analysis corroborates the observed strength outcomes, indicating a denser concrete matrix. Significant environmental and economic benefits were observed, including a notable 20% reduction in CO2 emissions and 17% cost savings. These findings underscore the potential of integrating MMW into SCC mixtures as a sustainable approach towards construction materials, offering both performance and environmental advantages.

Performance Evaluation of Self-Compacting Glass Fiber Concrete Incorporating Silica Fume at Elevated Temperatures

In this work, the properties of self-compacting concrete (SCC) and SCC containing 0.5 and 1% glass fibers (with lengths of 6 and 13 mm) were experimentally investigated, as well as their performance at high temperatures. With a heating rate of 5 °C/min, high-temperature experiments were conducted at 200, 400, 600, and 800 °C to examine mass loss, spalling, and the remaining mechanical properties of SCC with and without glass fibers. According to the results of the flowability and passing ability tests, adding glass fibers does not affect how workable and self-compacting SCCs were. These findings also demonstrated that the mechanical properties of samples with and without glass fibers rose up to 200 °C but then decreased at 400 °C, whereas the mixture containing 0.5% glass fibers of a length of 13 mm displayed better mechanical properties. Both SCC samples with and without glass fibers remained intact at 200 °C. Some SCC samples displayed some corner and edge spalling when the temperature reached about 400 °C. Above 400 °C, a significant number of microcracks started to form. SCC samples quickly spalled and were completely destroyed between 600 and 800 °C. According to the results, glass fibers cannot stop SCC from spalling during a fire. Between 200 and 400 °C, there was no discernible mass loss. At 600 °C, mass loss starts to accelerate quickly, and it increased more than ten times beyond 200 °C. The ultrasonic pulse velocity (UPV) of SCC samples with glass fibers increased between room temperature and 200 °C, and the mixture containing 0.5% glass fibers of a length of 13 mm showed a somewhat higher UPV than other SCC mixtures until it started to decline at about 400 °C.

Sustainable self-Compacting concrete with marble slurry and fly ash: Statistical modeling, microstructural investigations, and rheological characterization

The escalating generation of marble waste and the substantial carbon footprint associated with cement production pose significant environmental challenges. Thus, by substituting fly ash for supplementary cementitious material and using leftover marble waste for fine aggregate in concrete can reduce cost and carbon emissions that may lead to sustainable development. The presented paper aims to study the effect of partial substitution of marble slurry with natural fine aggregates and fly ash as supplementary cementitious material (SCM) on Self-Compacting Concrete (SCC). Polycarboxylate Ether (PCE) based superplasticizer (SP) was added in the concrete mix, to decrease the demand of higher water to binder (w/b) ratio. After developing SCC, fresh state properties and compressive strength (CS) at the curing age of 7 and 28 days were evaluated. To maximize the utilization of marble slurry and fly ash, mixture optimization was performed using the Box-Behnken Design (BBD), a robust technique within the response surface methodology (RSM) framework. Rheological analysis was performed to analyse the fresh state behaviour of the SCC with the help of the Bingham and Modified Bingham (MB) models. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) studies were also carried out to study the behaviour of the marble slurry and fly ash in the concrete. Carbon emission and cost analysis of SCC was evaluated at different replacement level of the marble slurry and fly ash. It was inferred that marble slurry and fly ash can be used in the certain percentages without compromising any strengthen and flowability properties of the SCC. The rheological behaviour also confirmed that linear and nonlinear behaviour of SCC in the certain mix proportion may results in the formation of the stable SCC. The analysis of cost and carbon emission confirmed that sustainable SCC mixture achieved substantial reductions of 21.44 % in cost and a remarkable 47.71 % decrease in carbon dioxide (CO2) emissions compared to conventional concrete.

Experimental and predictive study of self-compacting concrete containing reclaimed asphalt pavement

This work focuses on the reuse of reclaimed asphalt pavement (RAP) in the production of self-compacting concrete (SCC) for usage in the construction of rigid pavements. The article first describes an experimental study where five SCC mixtures incorporating 0%, 20%, 40%, 60% and 100% volumetric substitutions of natural aggregates by RAP were formulated. Several characterisation tests in the fresh and hardened states were then performed. The results of all performed tests showed that RAP has a slight negative effect on SCC performance in the fresh state. The most significant reduction observed does not exceed 18% for slump-flow and 10% for L-shaped box values when total substitution is applied. Furthermore, the mechanical properties noticeably decrease with an increase in RAP content, with reductions of up to 37% in 28-d compressive strength and 23% in 28-d indirect tensile (IDT) strength observed in the case of full replacement. However, it is possible to formulate SCC mixtures even with 100% RAP substitutions and meet specifications for rigid pavement construction. In addition, modelling of the various mechanical characteristics made it possible to find out the reason behind the reduction in these properties with RAP content. In fact, the thin bitumen film around RAP particles weakens their surface adhesion with the hydrated cement paste. With the intrinsic RAP properties found, the hardened-state characteristics of any other SCC mixture incorporating RAP could be predicted.

Durability Performance and Mechanical Behavior of Pet Fiber Reinforced Recycled Fluid Concrete

Abstract Many environmental problems can be attributed to various sources, such as the demolition of old buildings, waste from bricks, glass waste, among others, which are generated worldwide. This waste is converted and recycled as natural aggregate. On the other hand, a significant issue with concrete incorporating Recycled Concrete Aggregate (RCA) is its inferior properties compared to natural aggregate concrete. The subpar properties of RCA concrete can be enhanced by the addition of Fibers. This research examines the effects of polyethylene terephthalate fiber (RPETF) and recycled fine concrete aggregates (RFCA) on the mechanical properties and durability of self-compacting concrete (SCC). Three concrete families were created: one using RPETF alone, one using RFCA alone, and a third utilizing both RPETF and RFCA combined. The natural fine aggregates (NFA) were replaced with RFCA in increments of 25% from 0% to 100%. The results showed that the split tensile strengths of the mix of 100% RFCA and 1.2 % RPETF have improved over time by 28% compared to the mix with 100% RFCA alone. However, the inclusion of RPETF in SCC mixtures with varying amounts of RFCA resulted in reduced durability of the composite.

Influence of calcined dam mud on the thermal conductivity of binary and ternary self-compacting concrete mixtures using the equivalent mortar method

Reducing energy consumption in concrete buildings requires cement-based structural materials that have low thermal conductivity. Moreover, low thermal conductivity is a crucial property of building materials used for thermal insulation to ensure the comfort of building occupants. The research evaluates the effect of using calcined mud (CM) and natural pozzolan (Pz) on the thermal conductivity of self-compacting concrete (SCC). To optimise SCC formulations, the equivalent concrete mortar method has been used. This communication mainly focuses on the equivalent self-compacting concrete mortars (ESCCMs). The current study consists of ten formulations: one control (based on Portland cement) and nine others containing binary and ternary systems of Portland cement, calcined mud, and natural pozzolan with 10%, 20%, and 30% replacement rates . The mixtures were prepared using tests of cement paste and equivalent mortar in a fresh state. Afterwards, they were assessed based on their compressive strength at 14, 28, 90, and 180 days and their thermal conductivity at 28 and 90 days in the hardened state. The self-compatibility, the thermal conductivity, and the mechanical performance results obtained by relevant tests on ESCCMs prove that the ternary systems (Portland cement, CM, and Pz) open up many techno-economic development avenues in SCC applications to be explored.