Study on the effect of carbonized recycled coarse aggregate admixture on the properties of self-compacting concrete

doi:10.21203/rs.3.rs-4741986/v1

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Study on the effect of carbonized recycled coarse aggregate admixture on the properties of self-compacting concrete

https://doi.org/10.21203/rs.3.rs-4741986/v1

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In order to analyze the effect of carbonated recycled coarse aggregate (RCA) on the mechanical and chloride ion penetration resistance of self-compacting concrete (SCC), recycled self-compacting concrete (RCASCC) was prepared with RCA treated with different admixtures (15%, 30%, and 50%) and different carbonation pressures (0, 75 kPa, and 150 kPa), and was tested for its compressive strength, flexural strength, electric flux, and its pore structure and micro-morphology were analyzed. The results show that RCA substitution rate and carbonation pressure have a significant effect on the compressive strength, flexural strength and electrical flux of RCASCC, with the increase of RCA dosage, the compressive strength of RCASCC firstly increases and then decreases, while its electrical flux firstly decreases and then increases; with the increase of RCA carbonation pressure, the compressive strength of RCASCC gradually decreases while its electrical flux gradually increases; the increase of RCA dosage and carbonation pressure both reduce the compressive strength of RCASCC, while its electrical flux firstly decreases, while the increase of RCA dosage and carbonation pressure gradually increases. Increasing the RCA doping and carbonization pressure both reduce the flexural strength of RCASCC; when the RCA doping is 30% and the carbonization pressure is 75 kPa, the 28d compressive strength and chlorine ion permeation resistance of RCASCC are improved by 10.3% and 20.9%, respectively, and the pore size of the pre-wetted RCASCC is refined, and the interfacial transition zone is structurally dense.

RCASCC

Carbonization

Mechanical properties

Resistance to chloride penetration

Pore structure

Within the dynamic construction landscape, the realization of towering and expansive modern reinforced concrete structures necessitates the utilization of dense reinforcement schemes and intricate geometric configurations. However, traditional concrete encounters difficulties in achieving adequate compaction within intricate molds while preserving its high-performance characteristics. Inadequate compaction frequently results in void formation, detrimentally affecting the mechanical integrity of the concrete. These challenges are adeptly addressed through the adoption of self-compacting concrete (SCC) [1], an innovative concrete variant renowned for its exceptional fluidity and resistance to segregation, empowering it to autonomously spread, fill molds, and encapsulate reinforcement without the need for mechanical consolidation [2, 3]. Furthermore, in stark contrast to conventionally vibrated concrete, SCC facilitates accelerated construction schedules for numerous reinforced concrete undertakings by alleviating concerns related to noise generation and compaction effectiveness [4]. The defining disparities between meticulously formulated SCC and conventional concrete reside in its reduced coarse aggregate content, heightened paste content, lowered water-to-binder ratio, and the strategic inclusion of high-performance superplasticizers [5]. To ensure a homogeneous and cohesive SCC blend, cement dosages commonly range from 450 to 600 kg/m³, surpassing those employed in traditional vibrated concrete [6]. Notably, a proportion of this cement can be substituted with mineral admixtures, including fly ash (FA), ground granulated blast-furnace slag (GGBFS), and silica fume (SF), further enhancing the overall performance and sustainability of the concrete mixture [7].

While SCC boasts numerous advantages, its reliance on substantial cement quantities escalates production costs and CO₂ emissions, adversely impacting the environment [8–11]. China, for instance, annually produces 15 billion tons of natural gravel and sand while generating 2.5 billion tons of construction waste. Additionally, greenhouse gas (GHG) emissions from concrete production often exceed 5% of global emissions. Thus, enhancing the sustainability of the concrete industry is imperative for preserving the natural environment, reducing waste concrete, and mitigating GHG emissions [12]. Substituting cement with supplementary cementitious materials (SCMs) like FA, GGBFS, and SF can mitigate environmental pollution and CO₂ emissions [13–15] .

Numerous SCC studies have explored the use of industrial by-products [16–20]. The rheological and mechanical attributes of High-Strength Self-Compacting Concrete (HSSCC) augmented with varying percentages of FA, GGBFS, or a blend of both, ranging from 0–60% of the total binder composition, were thoroughly analyzed by Mohammed et al. [21]. Their observations underscored the preponderance of FA in enhancing HSSCC's workability over alternative admixtures, albeit at the cost of a gradual decrement in its 28-day compressive strength. Furthermore, Kapoor et al. [22] conducted an in-depth study on the durability properties of SCC formulated using recycled coarse aggregate (RCA) as either partial or full substitutes for natural coarse aggregates (NCA), along with selected mineral admixtures as partial replacements for Portland cement. Their conclusions highlighted that a 50% substitution of NCA with RCA, coupled with the incorporation of SF or metakaolin (MK) in conjunction with Portland cement, effectively mitigated durability impairments, with MK demonstrating superior performance over SF. Nevertheless, the complete substitution of NCA with RCA, even with the inclusion of the aforementioned pozzolanic additives, exhibited limited capacity to compensate for durability degradation.

Although SCC contains fewer aggregates compared to conventional vibrated concrete, their inclusion still influences both fresh and hardened properties. It is advocated that coarse RCA, sourced from construction and demolition waste, be utilized as an alternative to NCA, thereby mitigating environmental impacts during the process of concrete construction [23–26]. Integrating recycled coarse aggregates into SCC to produce recycled self-compacting concrete (RCASCC) not only reduces material costs but also addresses environmental concerns associated with waste concrete, yielding substantial economic and social benefits [27]. However, RCA's high porosity, water absorption, and crushing value due to attached mortar and internal microcracks significantly impact RCASCC's mechanical and durability properties [22, 28, 29]. Therefore, pre-treatment methods like coating RCA with slurries, polymer immersion, mechanical removal of attached mortar, and CO₂ reinforcement are employed to enhance RCA quality and, consequently, RCASCC performance [30, 31]. Among these, carbonation treatment utilizes carbonation products to fill cracks and pores in RCA, refining its microstructure and bolstering its physical and mechanical properties [32, 33], all while being cost-effective and environmentally friendly.

To achieve sustainable development in SCC and foster the large-scale application of waste concrete, numerous researchers have conducted exhaustive investigations into the performance of SCC incorporated with recycled aggregates. Grdić et al. [34] endeavored to prepare SCC using RCA, reporting a marked reduction in SCC's fluidity as the RCA content increased. Panda and Bal [35] analyzed the impact of RCA substitution rates ranging from 0–40% on concrete's mechanical properties, observing a decline in compressive strength across various strength grades with higher RCA substitution rates. Omrane et al. [36] noted that incorporating 20% natural pozzolanic ash as a cement replacement enhanced the chloride ion penetration resistance and sulfate resistance of RCASCC with 100% RCA substitution. Boudali et al. [37] examined the durability of RCASCC under sulfate attack conditions, finding that RCASCC outperformed its reference SCC counterpart. Rajhans et al. [38] demonstrated that the sole addition of FA during mixing could produce concrete with superior properties and reduced creep. Asghar et al. [39] compared the water absorption and porosity of RCA after carbonation treatments at 0.5 MPa for 1 h and 0.1 MPa for 24 h, concluding that increased pressure enhanced carbonation rates.

To mitigate excessive CO₂ emissions from SCC production and alleviate the depletion of natural aggregate resources, this study investigates the incorporation of RCA subjected to various replacement levels (15%, 30%, 50%) and carbonation pressures (0, 75 kPa, 150 kPa) into SCC, supplemented with a certain amount of FA and slag to achieve a target strength of C50 for RCASCC. The chloride ion penetration resistance of RCASCC is explored through electrical flux and mercury intrusion porosimetry (MIP) tests. Microstructural insights are provided by scanning electron microscopy (SEM), elucidating the individual and combined effects of carbonation treatment and RCA content on RCASCC's mechanical properties and chloride ion penetration resistance. This research aims to provide a valuable reference for the application of RCA in SCC.

2.1 Materials

The materials employed consist of P·O 42.5 Ordinary Portland Cement (OPC) as the cementitious binder, Class II FA as a supplementary cementitious material, and S95 grade slag powder, characterized by a specific surface area of 456m²/kg. The coarse aggregate is comprised of continuously graded crushed stone, spanning a particle size range of 4.75-20mm, further categorized into NCA and RCA, whereas the fine aggregate utilizes natural river sand (NS) with a fineness modulus of 2.35. The gradation profiles of both coarse and fine aggregates are depicted in Fig. 1. As for the admixture, a commercially procured polycarboxylate superplasticizer (SP) serves as the water-reducing agent.

2.2 Mix design and specimens preparation

According to the "Technical Specifications for Application of Self-compacting Concrete" (JGJ/T 283–2012), a preliminary mix design is carried out to design SCC with a target strength of C50. The replacement rates of RCA are 15%, 30%, and 50%, and the carbonization pressures on the RCA are 0, 75 kPa, and 150 kPa, with 0 indicating no carbonization treatment. See Table 1 for the detailed mix design. RCASCC-A-B: A represents the replacement rate of RCA; B represents the carbonization pressure on RCA, with 1 representing 75 kPa and 2 representing 150 kPa.

Table 1

Mix proportions of concrete specimens
NO.	OPC	FA	Slag	NS	NCA	RCA	Water	SP
SCC	371	106	53	920	817.5	0	174.9	9
RCASCC-15-0	371	106	53	920	694.9	122.6	174.9	9
RCASCC-30-0	371	106	53	920	572.2	245.3	174.9	9
RCASCC-50-0	371	106	53	920	408.75	408.75	174.9	9
RCASCC-15-1	371	106	53	920	694.9	122.6	174.9	9
RCASCC-30-1	371	106	53	920	572.2	245.3	174.9	9
RCASCC-50-1	371	106	53	920	408.75	408.75	174.9	9
RCASCC-15-2	371	106	53	920	694.9	122.6	174.9	9
RCASCC-30-2	371	106	53	920	572.2	245.3	174.9	9
RCASCC-50-2	371	106	53	920	408.75	408.75	174.9	9

Measure the required amounts of various raw materials for the experiment. Pour the SP into water and stir for 120 seconds. Then, pour the natural aggregate, cement, and NS into the mixer in order from fine to coarse, dry mix for 80 seconds. Finally, pour in the mixture of the SP and water and continuously stir for 200 seconds. The mixture was poured and cast into test specimens for the required tests and then transferred to a standard curing room (temperature of 20°C and humidity ≥ 90%) to cure until the corresponding age.

2.3 Experimental Methods

2.3.1 Mechanical properties tests

The compressive and flexural strengths of RCASCC blends were evaluated in adherence to the standardized testing protocols outlined in GB/T 50081 − 2002 for assessing the mechanical properties of conventional concrete. Following curing durations of 7, 28, and 90 days, specimens measuring 150 mm×150 mm×150 mm in size were subjected to mechanical testing, utilizing a compression apparatus capable of applying a maximum force of 3000 kN. To ensure accuracy and reliability, the flexural strength was determined by averaging the results from three individual specimens, while the compressive strength was assessed through testing six fractured specimens.

2.3.2 Electrical flux test

In accordance with the Chinese standard GB/T 50082 − 2009, cylindrical RCASCC specimens measuring Φ100 mm × 50 mm were prepared for assessment after a curing period of 28 days. Prior to undergoing testing, the lateral surfaces of the specimens were coated with epoxy resin, with any voids in the coating subsequently filled. Subsequently, these specimens were subjected to vacuum saturation utilizing an automated machine of model BSJ-A. An intelligent concrete electrical flux tester, model DTL-6, was employed to conduct the electrical flux test, where a constant direct current voltage of 60V was applied across the specimen ends. The anode experimental cell was replenished with a 0.3 mol/L NaOH solution, whereas the cathode cell was filled with a 3.0% NaCl solution. The initial current reading was documented, and the duration of the test was maintained at 6 h.

2.3.3 Microstructure tests

Upon reaching the prescribed curing durations, the RCASCC specimens were meticulously sectioned into cubic samples, each measuring 10 mm × 10 mm × 10 mm (totaling three specimens). These specimens were subsequently immersed in anhydrous ethanol for a period of 48 hours to halt hydration processes, followed by dehydration in a vacuum drying chamber (model RSD-100E) at a temperature of 60 ℃ for 72 consecutive hours. The pore structure of the block samples was then analyzed utilizing an automated mercury porosimeter of the AutoPore Iv 9510 model. Additionally, Field Emission Scanning Electron Microscopy (FESEM) was employed to scrutinize the hydration products, microstructural characteristics, and the interface transition zone within the samples.

3.1 Compressive Strength

Detailed compressive strength data of SCC cubes at 7d, 28d, and 90d intervals for various RCA incorporation levels are presented in Fig. 2. It can be found that an initial increase in compressive strength is observed across all curing ages, which subsequently diminishes with an increasing proportion of RCA content. Similarly, under increasing carbonation pressures, a similar trend (initial rise then decline) is discernible, albeit with strengths not falling below those recorded at zero carbonation pressure. Specifically, when RCA is incorporated at 30%, the compressive strengths at 7d, 28d, and 90d without carbonation reach peaks of 45 MPa, 63.1 MPa, and 68.7 MPa, respectively. Notably, the greatest enhancement in compressive strength across all ages occurs at a carbonation pressure of 75 kPa, with strengths of 49MPa, 66.2 MPa, and 71.6 MPa at 7d, 28d, and 90d, respectively, for the 30% RCA mix. These values represent increases of 13.7%, 9.2%, and 10.1% over uncarbonated SCC strengths. However, as RCA content rises to 50%, compressive strengths decrease across all ages.

This varying trend can be attributed to the intricate interaction of two principal factors. Firstly, the heightened surface roughness of RCA, compared to that in conventional concrete's interfacial transition zone, leads to stronger bonding between RCA and fresh mortar. Secondly, the pores and cracks within RCA absorb moisture, resulting in higher water content at the recycled aggregate-fresh mortar interface, which fosters the formation of larger calcium hydroxide crystals that weaken the structure [40]. When RCA content is low, the enhanced bonding strength due to RCA's roughness outweighs the weakening effect, leading to a slight increase in compressive strength. Conversely, at 50% RCA content, the weakening effect dominates, leading to a notable decrease in compressive strength.

Furthermore, carbonation treatment of RCA significantly improves the compressive strength of SCC at all ages, with greater improvements observed in the low carbonation pressure group compared to the high carbonation pressure group. Specifically, when RCA is incorporated at 30%, the 75 kPa treatment group exhibits an increase ranging from 4.6–8.9%, while the 150 kPa treatment group shows an increase of 1.4–2.4%. This is because CO₂ diffuses through RCA pores, reacting with calcium hydroxide (CH) and hydrated calcium silicate (C-S-H) to form calcium carbonate precipitates, which gradually stabilize into calcite, filling pores and cracks within RCA and improving its microstructure [41, 42]. Macroscopically, this manifests as enhanced compressive strength. However, under high carbonation pressures, fragile RCA components are damaged, severely compromising its performance [43], resulting in decreased compressive strength of RCASCC.

3.2 Flexural Strength

Figure 3 shows the flexural strength of RCASCC under varying RCA incorporation ratios and carbonation pressures. Figure 3 reveals a gradual decline in flexural strength as the RCA content escalates from 0–50%. With the intensification of carbonation pressure, the flexural strength of RCASCC initially augments and subsequently diminishes, mirroring the trend observed in compressive strength. Specifically, at 0% RCA incorporation, the flexural strength is 6.9 MPa, whereas at 50% RCA incorporation, the flexural strength increases by 9.1% and 3.8% to 5.5 MPa and 5.3 MPa, respectively, under carbonation pressures of 75 kPa and 150 kPa compared to the uncarbonated counterpart. This reduction in flexural strength is primarily attributed to two factors: firstly, the proliferation of weaker and more intricate interfacial transition zones (ITZs) associated with increased RCA content [44] ; secondly, the inherently higher porosity and lower specific gravity of RCA, rendering it inferior in strength to natural aggregates [45, 46].

Furthermore, it is discernible that as the carbonation pressure escalates from 75 kPa to 150 kPa, the flexural strength diminishes, with decrements of 8.1%, 8.8%, and 8.3% at RCA replacement levels of 15%, 30%, and 50%, respectively. This phenomenon can be attributed to the microstructural degradation of RCA under heightened carbonation pressures, resulting in the deterioration of the ITZs, which are crucial for the mechanical performance of the composite material. [43] .

3.3 Electrical Flux

The electrical flux test data of 28d is shown in Fig. 4. It can be found that except for the RCASCC-50 group, which has an electrical flux exceeding 1000 C and is at a low chloride ion penetration level, the electrical flux of the other groups is below 1000 C, at a very low chloride ion penetration level. When the RCA dosage is small (≤ 30%), the electrical flux of SCC decreases. The RCA incorporation was 15%, and the electrical flux was 610C and 656C at the carbide pressure of 75 kPa and 150 kPa, which decreased by 10.8% and 4.1% compared with the uncarbonized group (684C). The diminished chloride ion penetration can primarily be attributed to the accumulation of the solid product, which is a consequence of the reaction, on the surface of RCA. This accumulation leads to the densification of the interfacial cementitious matrix, thereby enhancing the microstructure by effectively filling the pores present within the RCA. [44, 47, 48]. As the RCA dosage further increases to 50%, the electrical flux significantly increases, with an increase of 6.3%~24.4% compared to SCC. This observation underscores a substantial decrease in the chloride ion permeability of SCC, which can be attributed to the intrinsic higher porosity of RCA in comparison to natural aggregates, coupled with suboptimal bonding performance between RCA and the surrounding matrix. This suboptimal bonding, in turn, gives rise to an abundance of pores and cracks within the transition zone, thereby contributing to the observed reduction in chloride ion permeability. [22, 49]. It is further discernible that as the carbonation pressure escalates, the electrical flux of RCASCC undergoes a gradual augmentation, which serves as an indication of a diminished resistance against chloride ion penetration. This phenomenon is caused by the high-pressure carbonation damaging some of the aged mortar in RCA, resulting in a relatively loose interfacial structure [43] .

3.4 Porous Structure

The pore size distribution results of the self-compacting concrete samples within each experimental group are revealed in Fig. 5. Upon scrutiny, it is discerned that the peak of the most probable pore size for RCASCC-30-2 undergoes a leftward shift, signifying a refinement towards smaller pore diameters below 50 nm, as compared to SCC. Conversely, the peak for RCASCC-50-2 is observed to shift towards larger diameters. To facilitate a comprehensive analysis of the MIP test outcomes, the data were subsequently categorized into pore types—harmless, less harmful, harmful, and more harmful—and plotted as pore distribution content graphs, as depicted in Fig. 5. This analysis underscores that the introduction of RCA in RCASCC-30-2 leads to a passive reduction in the proportion of harmful and more harmful pores, in contrast to SCC, whereas in RCASCC-50-2, an increase in these detrimental pore types is evident. These findings passively demonstrate that an augmentation in RCA content significantly elevates the content of harmful pores in SCC, whereas carbonation exerts a mitigating effect by slightly diminishing their prevalence [50]. This phenomenon underscores the profound influence that RCA content and carbonation exert on the mechanical strength and permeability properties of self-compacting recycled concrete, thereby validating their crucial role.

Furthermore, Fig. 6 passively displays the variations in the content of diverse pore sizes across the SCC groups. A comparative analysis between RCASCC-50-2 and RCASCC-50-1 reveals that the latter experiences a passive increase in the proportion of harmless and less harmful pores, indicating a refinement in the capillary and larger pore structures. Consequently, from a pore structure perspective, the alterations in the strength and permeability behavior of RCASCC upon the incorporation of RCA under varying carbonation pressures can be logically and comprehensively explained.

3.5 Microscopic Morphology

The microstructures of SCC in various groups are presented in Fig. 7. It is observed that the interfacial transition zone between aggregates and mortar in SCC exhibits a relatively low porosity and overall compactness. From the perspective of hydration products, a high degree of hydration is observed, resulting in the formation of numerous C-S-H gels that fill the pores, contributing to an overall superior compactness. In comparison to SCC, the aggregate-mortar interfacial transition zone in RCASCC-30-2 appears more dense, with pores and cracks filled by a greater amount of hydration products and tighter interconnections among these products. This validates the effectiveness of carbonation in enhancing the microhardness of the ITZs in recycled aggregate concrete [47, 50]. However, with the increase in RCA content, RCASCC-50-2 exhibits significant cracks and pores in the ITZs, along with partially hydrated cement particles, a relatively low content of hydration products, and a porous overall structure. In contrast, RCASCC-50-1 demonstrates improved compactness in ITZs compared to RCASCC-50-2. Although cracks and pores are still observable, they are partially filled by hydration products, and there is a significant increase in the amount of hydration products generated by the hydration reaction, leading to a better filling effect and improved overall structural compactness. This further supports the notion that carbonation under low-pressure conditions is more effective in improving RCA.

In summary, it is observed that the mechanical properties and resistance to chloride ingress of RCASCC can be augmented through the judicious incorporation of RCA and the application of an optimal carbonation pressure. Conversely, the excessive utilization of either factor results in a marked deterioration of these properties, underscoring the criticality of striking a balance between the two parameters. Specifically, the addition of moderate RCA and application of an optimal carbonation pressure can improve the compressive strength and resistance to chloride ingress of RCASCC. Comprehensive consideration suggests that an optimal RCA content of 30% and a carbonation pressure of 75kPa yield superior RCASCC performance. Under these conditions, the maximum compressive strength ofRCASCC achieves 71.2MPa after 90 days, marking a 10.1% increase compared to uncarbonated specimens. Similarly, the flexural strength increases by 10.1% to 6.55MPa, while the electrical flux decreases by 15% to 680C. This enhancement can be attributed to the diffusion of CO₂ gas through RCA pores, reacting with CH and C-S-H to form calcium carbonate precipitates that stabilize into calcite, filling pores and cracks within RCA and thereby refining its microstructure [41, 42]. Consequently, the macroscopic manifestation is an improvement in compressive strength and chloride ion penetration resistance. Conversely, under high carbonation pressures, fragile components within RCA deteriorate, significantly compromising its performance [43], leading to reduced compressive strength and resistance to chloride ingress of RCASCC. Furthermore, RCA's inherent properties of high water absorption, porosity, and low strength exacerbate the issue when excessively incorporated [22, 49]. This results in poor bonding at the RCA-paste interface, creating numerous pores and cracks that further weaken the compressive strength and resistance to chloride ingress of RCASCC.

The incorporation of RCA into SCC initially enhances the compressive strength but subsequently leads to a decrease, while the flexural strength gradually diminishes. The RCA content should be limited to 50% or less. Under identical carbonation pressures, RCASCC with 30% RCA incorporation exhibits the highest compressive strength, and low carbonation pressures facilitate an improvement in compressive strength, ranging from approximately 4.2–10.7%.

RCASCC with 30% RCA incorporation achieves the lowest electrical flux, indicating a very low chloride ion permeability level. However, increasing the RCA content to 50% results in a significant decline in chloride ion permeability resistance, with a reduction of approximately 38%. Low carbonation pressures contribute to improved chloride ion permeability resistance in RCASCC.

After incorporating 30% RCA, the content of harmful and detrimental pores in SCC significantly decreases, and the pore size distribution is refined. Increasing the RCA content does not further improve the pore distribution. Pre-treating RCA under low carbonation pressure increases the content of non-harmful and slightly harmful pores, which aligns with the trends observed in strength and permeability resistance.

Compared to SCC, the ITZs in RCASCC with 30% RCA incorporation is densely filled with hydration products, and the interconnection between hydration products is tighter, resulting in an overall compact structure. However, with the increase in carbonation pressure, distinct cracks and loose interconnections between hydration products are observed in ITZs, along with a higher porosity.

Declaration of Competing Interest

The article is original, has not been published previously and has been written by the stated authors who are all aware of its content and approve its submission. It is not under consideration for publication elsewhere, no conflict of interest exists, and if accepted, the article will not be published elsewhere in the same form, in any language, without the written consent of the publisher.

Acknowledgements

The authors gratefully acknowledge the financial supports from the National Science Foundation of China (No. 52208286), Innovation Group Project of Hubei Province (No. 2024AFA033), Natural Science Foundation of Hubei Province (No. 2022CFB672), Knowledge Innovation Program of Wuhan-Shuguang Project (No. 2022020801020362), Guizhou Provincial Science and Technology Projects (No. 2023 − 207).

CRediT authorship contribution statement

Shukai Cheng: Conceptualization, Methodology, Resources, Formal analysis, Writing-review & editing. Qianyong Liang: Data curation, Formal analysis, Investigation, Validation, Writing-original draft, Testing and testing assistance. Guofu Chen: Conceptualization, Methodology, Formal analysis, Writing-review & editing. Kang Chen: Investigation, Testing and testing assistance, Writing-review & editing. Hongtao Wang: Conceptualization, Supervision, Writing-review & editing. Data Availability Statement: The data presented in this study are available on request from the corresponding author.

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Reviewers agreed at journal
08 Sep, 2024
Reviewers invited by journal
03 Sep, 2024
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15 Jul, 2024
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14 Jul, 2024

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Study on the effect of carbonized recycled coarse aggregate admixture on the properties of self-compacting concrete

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Abstract

Figures

1 Introduction

2 Experimental Investigations

2.1 Materials

2.2 Mix design and specimens preparation

2.3 Experimental Methods

2.3.1 Mechanical properties tests

2.3.2 Electrical flux test

2.3.3 Microstructure tests

3 Results and Discussion

3.1 Compressive Strength

3.2 Flexural Strength

3.3 Electrical Flux

3.4 Porous Structure

3.5 Microscopic Morphology

Discussion

Conclusion

Declarations

Declaration of Competing Interest

Acknowledgements

References

Status:

Version 1