Aggregate Self-compacting Concrete Research Articles

Durability evaluation and lifetime prediction of recycled coarse aggregate self-compacting concrete after freeze-thaw and sulfate erosion coupling

This paper aims to study the durability of recycled coarse aggregate self-compacting concrete (RCASCC) after being subjected to freeze-thaw and sulfate coupling. The durability comprehensive evaluation index of RCASCC based on the entropy weight method was defined, and the variation law of the durability comprehensive evaluation index concerning RCA substitution rate, freeze-thaw environment, and coupling frequency was obtained. GM (1, 1) model based on grey system theory was used to evaluate the durability of RCASCC under the coupling effects of freeze-thaw and sulfate attack. The results show that there are some differences in the accuracy of the four GM (1, 1) models. It is recommended that the EGM model can be used to predict the durability of the RCASCC under the coupled effects of freeze-thaw and sulfate erosion. Moreover, the working life of RCASCC under the coupling effects in the outdoor environments of northeast, north, and northwest China was calculated, when the comprehensive evaluation index of durability decreases to 75% as the failure criterion. A multi-criteria analysis employing TOPSIS and VIKOR methods was conducted to evaluate the durability of RCASCC under these coupling effects. A multi criteria analysis was conducted on the durability of RCASCC under the coupling effects of freeze-thaw and sulfate erosion using TOPSIS and VIKOR methods. Under these two rankings, the splitting tensile strength is the index that changes the most after coupling effects, while the compressive strength changes relatively little. The importance of dynamic elastic modulus and weight is different due to different materials and evaluation methods. RC100-H typically exhibits the largest variation, while NC-H and RC50-NM typically exhibit smaller variations.

Prediction on compressive strength of recycled aggregate self-compacting concrete by machine learning method

The compressive strength is generally a crucial mechanical indicator for evaluating the quality of recycled aggregate self-compacting concrete (RASCC). To obtain a reliable prediction result of the compressive strength of RASCC, machine learning methods, including artificial neural network (ANN), random tree (RT), bagging, and random forest (RF), are utilized to predict the compressive strength of RASCC in this study. To build predictive models, 18 features and 289 data samples were collected from previous literature. The prediction effects of 4 artificial intelligence (AI) models on compressive strength of RASCC are compared. Four statistical parameters were used to evaluate the performance of the models, and a comparison was made between the model-predicted results and the experimental results. A good correlation between machine learning models and experimental results was obtained. Sensitivity investigation reveals that the cement content and the apparent density of natural coarse aggregate have the greatest influence on compressive strength. The study demonstrates the potential of ANN and RF models as useful tools that can support mortar design and/or optimization, with higher accuracy and good interpretability. According to this study, machine learning regression techniques hold great potential as instruments for forecasting RASCC's compressive strength.

Compressive Behaviour of Long Steel Tube Columns Filled with Recycled Large Aggregate Self-Compacting Concrete

One of the important directions for green development in the world today is to expand the application methods of recycled concrete, improve the utilization rate of waste aggregates, and slow down the consumption of natural resources. The column structure with a large length and slenderness ratio is the most widely used compression unit in practical engineering, which conforms to the principle of sustainable development. In this paper, we study the mechanical properties and failure modes of long columns fabricated from steel tubes filled with recycled large aggregate self-compacting concrete (RLASCC-ST-LC) under compression load. Moreover, we examine the influence of steel tube thickness, recycled large-aggregate particle size, the strength of self-compacting concrete, and the length-to-diameter ratio on the performance of the members through finite element modelling. The results indicated that RLASCC-ST-LCs exhibited different degrees of buckling damage, and the damage processes were basically the same as that of steel tube concrete. When the thickness of steel pipe increased from 4 mm to 5 mm, the ultimate bearing capacity of the component increased by 12.1%; when the strength of self-compacting concrete increased from 30 MPa to 40 MPa and 50 MPa, the ultimate loads of the component increased by 6.96% and 12.4%, respectively. However, the increase in the aspect ratio weakened the bearing capacity of the component, and the ultimate bearing capacities reduced by 4.78% and 10.51% when the aspect ratios were 8, 10, and 12. Finally, based on the existing design codes, the theoretical calculation formulas are proposed for the ultimate bearing capacities of RLASCC-ST-LCs. These findings have significant implications for the widespread application of RLASCC-ST-LCs.

Three-Dimensional Multi-Phase Microscopic Simulation of Service Life of Recycled Large Aggregate Self-Compacting Concrete

Three-Dimensional Multi-Phase Microscopic Simulation of Service Life of Recycled Large Aggregate Self-Compacting Concrete

Carbonation resistance of sustainable self-compacting concrete with recycled concrete aggregate and fly ash, slag, and silica fume

This study focused on the problem of recycling construction and demolition wastes as well as industrial waste by-products into sustainable concrete materials. By combining addition of three different industrial waste by-products, an environmentally friendly recycled aggregate self-compacting concrete (RA-SCC) mix was put forward. Carbonation resistance and microstructure of SCC incorporating high volumes of industry by-products and recycled aggregates were studied in this paper. A total of 9 RA-SCC with 50%, 75% supplementary cementitious materials (SCMs) and different SCM combinations were prepared, which consist of binary mix with fly ash (FA), ternary mix with FA and ground granulated blast-furnace slag (GGBS), and quaternary mix with FA, GGBS, and silica fume (SF). An exposure period of 3, 7, 14, and 28 days was adopted for accelerated carbonation tests. The test results indicate that, as RCAs content increased, RA-SCC carbonation depth increased. The carbonation depth of SCC with 100% RCAs increased by 49.35% compared to that of normal SCC. In addition, carbonation resistance of RA-SCC mixes with a given compressive strength decreased with increasing SCM content. However, the loss in carbonation resistance was greatly mitigated by the combined addition of different SCMs, on account of the substitution of cement with industrial by-products and natural aggregates with RCAs. The combined addition of different SCMs enhanced the carbonation resistance of RA-SCC mixes. The test results were validated through microstructural analysis using scanning electron microscopy (SEM), and X-ray diffraction (XRD). A comparison between predictions calculated using existing models and measured carbonation depth was implemented. By taking into account the effect of RCAs and SCMs, a modified carbonation model in conjunction with fib carbonation model was put forward.

Compression Performance of Steel Tube with Recycled Large Aggregate Self-compacting Concrete

Compression Performance of Steel Tube with Recycled Large Aggregate Self-compacting Concrete

Waste Plastic Induced in Self Compacting Concrete to Avoid Plastic Pollution

Abstract: In this present study the plastic aggregate obtained from E-waste is used as a partial replacement of coarse aggregate in self-compacting concrete. An experimental investigation on the fresh, hardened characteristics of concrete using M40 grade of Self compacting concrete are carried out by casting standard concrete with various volume fractions of plastic aggregate such as 0%, 10%, 20%, 30%, 40%, 50% to determine optimal dosage. The fresh properties of SCC reveal that the workability of concrete are improved by using plastic aggregate. Strength properties such as compressive strength shows that up to 30% substitution of coarse aggregate there is no major change in compressive strength as compared to normal concrete. Beyond that there is drop in compressive strength for 50% replacement of coarse aggregate by plastic aggregate. Split tensile strength, Flexural strength and Young modulus of concrete increases for 10% plastic aggregate. Beyond that strength decreases upto 50% replacement. Impact strength decreases for all replacement levels.

Mechanical Properties of Steel-Polyvinyl Alcohol Fiber Recycled Coarse Aggregate Self-Compacting Concrete: Orthogonal Testing

Mechanical Properties of Steel-Polyvinyl Alcohol Fiber Recycled Coarse Aggregate Self-Compacting Concrete: Orthogonal Testing

Study on Mechanical Properties and Erosion Resistance of Self-Compacting Concrete with Different Replacement Rates of Recycled Coarse Aggregates under Dry and Wet Cycles

Concrete that self-compacts is frequently utilized in engineering construction. Recycled coarse aggregate self-compacting concrete (RCASCC) is made by partially substituting recycled coarse aggregates (RCA) for natural coarse aggregates in order to conserve construction resources. This study examines the impact of linked sulfate erosion, dry and wet cycles, and RCA replacement rates of 0%, 25%, 50%, 75%, and 100% on the mechanical properties and durability of RCASCC. By using the mass loss rate, relative dynamic elastic modulus, corrosion resistance factor, X-ray diffraction (XRD), scanning electron microscope (SEM), and atomic force microscope (AFM) analyses, as well as other macroscopic and microscopic methods, it is possible to examine the deterioration patterns of RCASCC under dry and wet cycles. The results demonstrate that the addition of RCA has a notable impact on concrete’s resistance to sulfate attack during both dry and wet cycles. The erosion products steadily rise, the interfacial transition zone (ITZ) becomes rougher, and the sulfate resistance falls as the replacement rate of RCA rises. According to the findings of SiO2, AFt, and CaCO3, the examination of corrosion products from XRD and microstructure from SEM and EDS is carried out. The old mortar that has adhered to the surface of RCA, as shown by the AFM analysis of ITZ and the SEM analysis of RCA, can significantly affect the roughness of ITZ inside RCASCC.

Study on the bulk density and influencing factors of green ferronickel slag self-compacting concrete aggregates

The compactness of aggregates has a significant impact on the workability of self-compacting concrete. The bulk density of aggregates is an effective parameter for evaluating the compactness of aggregates, reflecting the degree of compactness of the aggregate system. This study aims to explore the theoretical calculation model and application of the bulk density of green ferronickel slag as aggregates in self-compacting concrete. The influence of different particle size distributions and ferronickel slag content on the bulk density of the aggregate system was analyzed. Based on the calculation method of the maximum bulk density of aggregates, the bulk density of the aggregate system was calculated for different particle size distributions and nickel-iron slag content, and the effect of nickel-iron slag content on the compactness of the aggregate system was analyzed.

Comparative analysis of quaternary blended self-compacting concrete (QBSCC) mixes incorporating induction furnace slag (IFS) and crushed stone aggregate: A performance study

This study explores using Induction Furnace Slag (IFS) as aggregate in Quaternary Blended Self-Compacting Concrete (QBSCC) mixes. The experimental work consists of two stages. Stage I focuses on determining the optimal QBSCC mixes, aiming to develop environmentally friendly Self-Compacting Concrete (SCC) by utilizing different types and ratios of cementitious materials. A total of 27 QBSCC mixes were prepared with a reference SCC mix consisting of 100% ordinary Portland cement (OPC), are prepared considering water binder (w/b) ratio of 0.4. The quaternary blended mixes are created by combining OPC, class F Fly Ash (FA), Silica Fume (SF) and Ground Granulated Blast Furnace Slag (GGBFS). The replacement ranges for SF are set between 2.5% and 7.5% in increments of 2.5%, for FA between 10% and 20% in increments of 5%, and GGBFS between 30% and 50% in increments of 10%. In stage II, the optimized QBSCC mixes are further enhanced by incorporating IFS, the properties in the fresh state such as slump flow, V-funnel, L-box, and J-ring tests are conducted for all SCC mixes, all of which comply with the EFNARC guidelines. The mechanical characteristics studied, includes compressive strength (cube and cylinder), split tensile strength (at 3, 7, 28, and 56 days), flexural strength (at 28 and 56 days), elastic modulus, shear strength and pull-out bond strength (at 56 days) are evaluated. It is noted that the hardened properties of SCC mixes containing IFS exhibit slightly higher values compared to crushed stone aggregate SCC mixes. Furthermore, an increase in Supplementary Cementitious Material (SCM) content in QBSCC mixes leads to a decrease in the hardened properties, irrespective of the kind of aggregate used. The QBSCC mixes identified as SCC57.5/42.5, SCC52.5/47.5, and SCC47.5/52.5 are determined to be the preferred blends for producing Self-Compacting Concrete (SCC). Remarkably, Induction Furnace Slag (IFS) can be utilized as both fine and coarse aggregate, completely replacing conventional aggregates, regardless of the content of supplementary cementitious materials (SCM). This finding highlights the notable effectiveness of IFS as a replacement material in SCC production.

Bone-china ceramic powder and granite industrial by-product waste in self-compacting concrete: A durability assessment with statistical validation

Due to continuous stockpiling of industrial by-products, waste management and disposal has become an underlying problem. Utilization of these industrial wastes as a substitution to concrete components can be a promising solution towards conservation of energy and curtailment of CO2 emission. The present study is an initiative to explore the durability behaviour of self-compacting concrete containing bone-china ceramic powder waste (BCPW) and granite cutting waste (GCW). The aim of this study is to investigate the use of bone-china ceramic powder waste (BCPW) and granite cutting waste (GCW) as substitutes for cement and natural fine aggregates in self-compacting concrete. The replacement ratios of BCPW were taken as 0%, 10%, 20%, and 30% for cement and of GCW were taken as 0%, 20%, 30%, and 40% for NFA to prepare the SCC mixes. The self-compacting concrete mixes were tested for acid attack, sulphate attack, sorptivity, and thermal gravimetric analysis (TGA). Statistical analysis was used to validate the findings. The results show that the use of BCPW and GCW as substitutes in self-compacting concrete improves its durability. The ceramic granite modified concrete shows less weight and compressive strength loss compared to conventional concrete, up to an optimum replacement level. This improvement is attributed to the pozzolanic property of BCPW and the better filling property of GCW. However, adverse impacts were observed beyond this limit. The study provides insight into the potential of using industrial by-products in self-compacting concrete, offering a sustainable solution to waste management, and contributing to the reduction of CO2 emissions. The statistical analysis used to validate the results adds rigor to the study and further supports the findings. The use of bone-china ceramic powder waste and granite cutting waste in self-compacting concrete is a novel approach, which can improve the durability and sustainability of concrete structures.

Study on Durability Characteristic Strength of Recycled Waste Concrete as Fine Aggregates in Self-Compacting Concrete

Abstract: In developing nations, with the raising overpopulation, both economy and pollution free environment in construction industry are of principal importance in order to meet the undeniable human needs of multifarious forms. Thus, use of waste aggregates in the manufacturing is of new type of concrete, which plays a critical role in the construction industry, for fulfilling the demand of aggregates. Most of the waste materials are arising from industrial waste and demolishing waste. Hence, recycling, reuse and exchange of this waste appears to be an effective solution and most appropriate decision. In the current research work desirable characteristics of recycled aggregate concrete were considered. These experiments were conducted for different ages of concrete such as 7 and 28 days to assess the split tensile strength. The workability properties of mix are evaluated by workability tests are flow test. It addresses experiment on different mixes of self- compacting concrete. One with fresh coarse and fine aggregates, while the others with restoration of 15%, 30%, 45%, 60%, 75%, 90% and 100% recycled fine aggregates. The design mix proportion in M25 with the proportionate of 1:1:2 for self-compacting concrete is taken.

Discrete element analysis of the effect of aggregate morphology on the flowability of self-compacting concrete

As the filling layer material of CRTS III slab ballastless track structure, self-compacting concrete (SCC) requires good fluidity. In this paper, the 3D laser scanning technology and digital image processing technology were used to characterize the aggregate morphology quantitatively, and an aggregate classification method considering the angularity of mesoscale was proposed. Meanwhile, aggregate particles with natural morphology were generated by Clump method, and the slump-flow test of SCC was simulated in 3D by the discrete element method (DEM) based on the adhesive rolling resistance linear model. On this basis, the effect of aggregate morphology on the flowability of self-compacting concrete was quantitatively studied, and the explanation was given from the perspectives of aggregate voidage and aggregate behavior. The results show that aggregate's macro-shape has twice the effect on self-compacting concrete flowability as aggregate's meso-angularity. For the sake of obtaining better flowability of self-compacting concrete, the priority order of aggregate is smooth spherical aggregate, multi-angular spherical aggregate, smooth elongated-flaky aggregate and multi-angular elongated-flaky aggregate. In addition, the flowability of self-compacting concrete is inversely proportional to the content of multi-angular elongated-flaky aggregate. The content of multi-angular elongated-flaky aggregate in self-compacting concrete for use as track filling layer should be kept below 10 %.

The Impact of castoff aggregate on the fresh and mechanical behaviour of high-range water reducer administered self-compacting concrete

Self-Compacting Concrete has excellent flowing properties and it can integrate under its self-weight. The construction-demolition waste produced with the crinkling of any building could be used as a partial substitute for coarse aggregate in self-compacting concrete. The present study involves the comparison of fresh and hardened properties of M35 grade SCC with 0%, 25%, 50%, 75%, and 100% substitution of recycled coarse aggregate. Fresh properties of recycled aggregate incorporated self-compacting concrete include the evaluation of slump, L-box and V-Funnel. Hardened properties are calculated by destructive and non-destructive methods. With the results, the optimum percentage of substitution of RCA is proposed from the study.

Mechanical Behaviour of Self-Compacting Concrete Using Ceramic Waste

The use of Self Compacting Concrete (SCC) which has high workability is the current choice to facilitate casting work so that it can pass through denser reinforcement areas without compaction. The rapidly increasing demand for concrete can cause damage to nature due to the overexploitation of minerals used for concrete such as crushed stone and lime. Construction waste can be an alternative to substitute the use of natural coarse and fine aggregate and an option to reduce gas emissions resulting from processing construction materials such as crushing work and cement production. Moreover, it can increase the efficiency of waste. In this study, ceramic waste is used as a substitute for coarse aggregate, which has the same characteristics as natural aggregate and is usually only dumped in landfill. This study aims to determine the mechanical behavior of SCC using ceramic waste as coarse aggregate substitution with a diameter of 9,52 mm. The mix design uses the Indonesian standard, SNI 7656-2012 with a maximum coarse aggregate size of 9.52 mm and Sika viscocrete 1003 as a superplasticizer. The concrete specimen is 15 cm in diameter and 30 cm in height cylinder of as many as 25 specimens. Design concrete strength is f’c = 25 MPa at 28 days old. The variation of the coarse aggregate substitution of ceramic waste is 0%, 25%, 50%, and 75%, and the 1.5% superplasticizer by the weight of cement. It is obtained that the maximum compressive strength of SCC is a variation of 50% ceramic waste, 25.98 MPa. It showed that the compressive strength did not experience a significant increase, which was only 0.06% increase from the design concrete strength. The stress value also showed a slight increase of 50% ceramic waste variation at 9.42 MPa with a 0.00254 strain value. The modulus of elasticity of concrete at maximum stress is 30,045.89 MPa. It can be concluded that ceramic waste can be used as a substitute for coarse aggregate in SCC. Although it cannot significantly increase the strength of the concrete as well as its stress and modulus of elasticity, ceramic waste substitution for natural aggregate in concrete can minimize the exploitation of minerals in nature and the strength also can exceed the design concrete strength.

Utility of Ultrasonic Pulse Velocity for Estimating the Overall Mechanical Behavior of Recycled Aggregate Self-Compacting Concrete

Ultrasonic pulse velocity (UPV) is a non-destructive measurement technique with which the quality of any concrete element can be evaluated. It provides information on concrete health and for assessing the need for repair in a straightforward manner. In this paper, the relationship is studied between UPV readings and the mechanical behavior of self-compacting concrete (SCC) containing coarse, fine, and/or powdery RA. To do so, correlations and simple- and multiple-regression relationships between compressive strength, modulus of elasticity, splitting tensile strength, flexural strength, and UPV readings of nine SCC mixes were assessed. The correlations showed that the relationship of UPV with any mechanical property was fundamentally monotonic. The inverse square-root model was therefore the best-fitting simple-regression model for all the mechanical properties, although for bending-tensile-behavior-related properties (splitting tensile strength and flexural strength) the estimation accuracy was much lower than for compressive-behavior-related properties (compressive strength and modulus of elasticity). Linear-combination multiple-regression models showed that the properties related to bending-tensile behavior had a minimal influence on the UPV value, and that their introduction resulted in a decreased estimation accuracy. Thus, the multiple-regression models with the best fits were those that linked the compressive-behavior-related properties to the UPV readings. This therefore enables the estimation of the modulus of elasticity when the UPV and compressive strength are known with a deviation of less than ±20% in 87% of the SCC mixes reported in other studies available in the literature.

Effect of rubber crumb and polyethylene terephthalate as coarse aggregate in self-compacting concrete

Effect of rubber crumb and polyethylene terephthalate as coarse aggregate in self-compacting concrete

Effect of Recycled Aggregate Concrete and Steel Fibers on the Fresh Properties of Self-Compacting Concrete

Globally, the amount of solid waste is constantly increasing, and its disposal is one of the critical issues in recent research studies. Concrete waste includes the rubble of demolished buildings, whether old buildings or those that have been subjected to earthquakes, etc. This research project aims to improve sustainability in the construction industry by recycling and reusing coarse aggregate that was previously used in concrete buildings. The objective is to utilize this recycled material to produce self-compacting concrete (SCC) and assess its performance in its fresh state. By finding new ways to repurpose materials that would otherwise go to waste, this research contributes to developing environmentally friendly practices and reducing the industry's carbon footprint. Furthermore, evaluating the performance of the recycled coarse aggregate in SCC will provide insights into its potential for future use in construction projects, which could ultimately lead to cost savings and improved efficiency in the industry. Recycled coarse aggregate (RCA) was used as a substitute for the natural coarse aggregate (NCA) with volume ratios of 0, 25, 50, 75, and 100%, and steel fibers (SF) were added to the concrete with different volumes ratios (0, 0.5, and 1 %). Workability tests such as slump flow, V-funnel, and L-box tests were carried out for the mixtures in their fresh state. In general, the results of the experimental work showed that the fresh properties indicated that almost all SCC mixtures were within the specified range, as stated in EFNARC requirements.

Fresh and hardened properties of recycled plastic fiber reinforced self-compacting concrete made with recycled concrete aggregate and fly ash, slag, silica fume

This study addressed the issue of recycling of waste plastic, industry by-products and waste concrete into sustainable concrete materials, which aims to produce a green and environmental-friendly self-compacting concrete (SCC). A novel and sustainable approach was proposed by combined inclusion of supplementary cementitious materials (SCMs) and recycled plastic fibers (RPFs), which was expected to improve the workability, mechanical properties and durability of recycled aggregate SCC (RA-SCC) simultaneously. This study firstly presents a deep insight into the benefits of the coupling effect of waste plastic fibers and SCMs on the fresh and hardened properties of recycled aggregate SCC mixes. Four series, 17 RPF reinforced RA-SCC (RPF-RA-SCC) were prepared by substantially substituting natural aggregates with recycled concrete aggregates and cement with SCMs, as well as reinforced with RPFs resulting from cutting waste plastic bottles. Fresh properties, including filling ability, cohesiveness, passing ability, segregation resistance and hardened properties, in terms of compressive, elastic modulus and flexural strength were measured. The effect of RCA content (50%, 100%), SCM content (50%, 75%) and different combination type, RPF content (0.5%, 1.0%, 1.5%) on the fresh and hardened properties of RA-SCC mixes was analyzed. The coupling effect of RPFs and SCMs was analyzed in detail. Microstructure analysis using scanning electron microscope (SEM) was conducted to study the microstructure characteristic. The test results indicated that the addition of RPFs impaired the workability. However, the inclusion of SCMs greatly improved the fresh properties and all RPF-RA-SCC mixes exhibited superior workability. The combined addition of RPFs and SCMs resulted in an excellent coupling effect and leaded to a notable improvement on the mechanical properties. The benefits of combined addition of SCMs and RPFs are higher than the sum of the benefits obtained through individual inclusion of SCMs and RPFs. • A sustainable approach was proposed by combined inclusion of SCMs and waste plastic fibers. • Fresh and hardened properties were simultaneously improved by combined addition of SCMs and waste plastic fibers. • The addition of SCMs increased the pull-out and bond strength of waste plastic fibers. • Combined addition of RPFs and SCMs result in excellent coupling effect. • Combined addition of RPFs and SCMs result in additional improvement in the net gain.