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Oil-based drilling cutting pyrolysis residues-recycled fine powder sintered ceramsite: Basic properties, microsintering mechanism, lightweight concrete application and heavy metals solidification
... [8][9][10] Utilizing inorganic cementitious materials, such as cement, for the solidification/stabilization of toxic waste can form a strong cementitious matrix through chemical binding or physical adsorption by hydration products. [11][12][13][14][15][16] The physical binding involves encapsulating or adsorbing waste residue within the cementitious material, while the chemical binding solidifies through bonding resulting from ion exchange with the gel substance. [11][12][13][14] This alteration in the waste's fluidity, compressibility, and strength reduces the leaching of toxic components. ...
This work was designed to investigate the influence of arsenic dosage, variety on the mechanical properties, hydration, and solidification from the perspective of Portland cement (PC) performance evolution. The results demonstrate that using PC could solidify the arsenic wastes effectively, with arsenic leaching concentrations consistently below 5 mg/L. Arsenic wastes retard cement hydration, leading to a slower rate of hydrates formation, disrupting the calcium silicate hydrate (C–S–H) stacking structure, and thus detrimental to strength development especially at early age. The adverse effect is highly dependent on the arsenic variety. The insoluble calcium arsenate exhibits the least impact, while the arsenates show the largest challenging to immobilization due to the instability of hydrates. Molecular dynamic simulation indicates that arsenic can be chemically immobilized with Ca²⁺, and be physically adsorbed onto the positively charged C–S–H by forming As‐O···Ca···Si‐O units, accompanied by a significant reduction in adsorption energy by 46.5%. The arsenic solidification behavior provides a basis for the resource utilization of arsenic wastes in cementitious materials.
Engineered/Strain-Hardening Cementitious Composites (ECC/SHCC) are the most concerned high-performance fiber-reinforced cementitious composites in recent years. Well-known for their high/ultra-high deformation capacity (typically 3~10%) and distinguished crack width control ability under tension, ECC/SHCC demonstrate significant potential for use in resilient infrastructure applications. Incorporating industrial/agricultural/urban wastes/by-products into ECC production offers a compelling and sustainable approach to upcycle these materials, resulting in green and cheap ECC production. This study critically reviews the utilization of wastes/by-products as green and low-carbon matrix materials (including binders and aggregates) to enhance the overall sustainability of Portland cement-based ECC. The analysis encompasses their mechanical, durability, and environmental performances based on existing literature. Notably, sustainable binders are primarily prone to influence the fracture toughness of matrices and the fiber/matrix chemical/frictional bond, while sustainable aggregates tend to affect the fracture toughness of matrices, fiber orientation and distribution, fiber/matrix frictional bond, and aggregate/matrix interfacial bond. The findings underscore the practical applicability of ECC with sustainable matrices in infrastructure, supporting practitioners and policymakers in adopting materials that meet durability and environmental goals. This work concludes by presenting perspectives and recommendations for future studies, focusing on the use of low-carbon and sustainable matrices in ECC materials for greener and more resilient infrastructure.
Red mud, fly ash and waste sawdust are bulk solid wastes discharged from the alumina, power and wood processing industries respectively, and their increasing accumulation has brought serious hazards to the ecological environment and huge waste of secondary resources. A novel rapid roasting method was adopted to produce the ultra-lightweight ceramsites (ULC) using red mud, fly ash and waste sawdust in this work, and the various performances, microstructure and formation mechanism of ULC were investigated using FTIR, XRD, BET, SEM-EDS and Micro-CT. The fly ash significantly enhances the compressive strength of ULC by promoting the formation of small pores and FeAl 2 O 4 , and the increase in roasting temperature is beneficial for the expansion of ULC until they are over burning. As the mass ratios of red mud, fly ash, clay and waste sawdust are 46: 10: 36: 8, the ULC with a compressive strength of 2.25 MPa, a bulk density of 465 kg/m 3 and a water absorption of 8.8% are prepared when roasted at 1125 ºC for 5 min after preheating at 600 ºC for 5 min. The environmental assessment results indicates that the ULC are environmentally safe due to the effective solidification of hazardous elements. This study provides a promising way to produce ULC by utilizing industrial solid wastes.
Loose powder sintering was used to prepare porous ceramic from municipal solid waste incineration fly ash (MSWI FA) and waste glass (WG). Sintering experiments at various temperatures, holding times, Al2O3 and SiC were conducted to investigate their effect on the ceramic properties and volatile heavy metal removal efficiency. The results show that increasing temperature from 1100 °C to 1250 °C promoted the transition of the mixtures from loose powder to a densified sintered matrix, with a bulk density increase of 31.10% and an open porosity decrease of 70.41%. The bulk density of the ceramic increased to 2.44 g/cm3 with 3% Al2O3 addition. The removal rates of Pb, Zn, Cu and Cd were higher than 90% at 1200 °C for 90 min, and promoted by the increasing temperature and holding time. Notably, 3% Al2O3 addition inhibited the volatilisation of Zn, Cu and Cd, particularly for Zn, the removal rate of which reduced to 61.66% at 1200 °C. The bulk density of the ceramic decreased to a minimum value of 1.48 g/cm3 with 4% SiC. The ratio of MSWI FA:WG:Al2O3:borax of 28.3:56.7:10:5 was proposed to obtain ceramic with a bulk density of 1.54 g/cm3 and a water absorption rate of 8.59% at 1150 °C. The leaching concentration of the porous ceramic met the Chinese regulatory standard (GB 8978-1996). Preparation of MSWI FA-based porous ceramics using the powder sintering method is a promising route for the harmless utilisation of MSWI FA. The porous ceramic is potentially applicable as a thermal-insulation building material.
With the acceleration of urbanization, the production of waste concrete is getting higher and higher. A large amount of outdoor accumulations of waste concrete will leach heavy metals, not only causing harm to the soil, but also posing a risk to human health. Based on this, this paper systematically studies the basic physical properties and microstructure (XRF, XRD, and SEM–EDS) of outdoor natural accumulation waste concrete, and analyzes the heavy metals in waste concrete from the aspects of existing state, leaching mechanism, human health risk analysis, and summarized the direction of resource utilization of waste concrete, calculated the carbon emission reduction during recycling. The study found that heavy metals in waste concrete mainly exist in hydration products in the form of precipitation, adsorption, and replacement, summarized the leaching mechanism from the micro- and macro-aspects. The leaching mechanism of heavy metals can be assigned to chemical (mineral dissolution and effective amount of components) and physical (advection, surface erosion, and diffusion) processes from the macro-perspective. From the micro-analysis, it can be assigned to the following five processes: acid migrates from solution to liquid–solid surface, acid migration through leaching layer, rapid dissolution reaction controlled by diffusion at leaching boundary, heavy metal through leaching layer, and heavy metals through the solid/liquid surface to the solution. In addition, the concentration and the leaching rate of heavy metals in waste concrete were analyzed. It was found that the concentration of Cr was the highest reached to 4.7 mg/kg and the leaching rate of Cd was the highest, its leaching coefficient was calculated as a result of 1.713 × 10–6. However, there was no obvious regularity in the leaching of heavy metals in different accumulate particle sizes. Through the establishment of risk assessment system was found the concentration of heavy metals in waste concrete will not cause significant harm to human health. The effective limit of heavy metals after 3 months of accumulation of waste concrete was calculated as: Cr < 0.09 mg/kg, Cd < 0.00715 mg/kg, As < 0.392 mg/kg, and Pb < 0.732 mg/kg. And the carbon emission reduction of waste concrete recycling was calculated to be 28.764kgCO2/t. All the results of this study can promote the safe and environmentally friendly utilization of waste concrete.
With the increasing production of incineration fly ash (FA), its disposal has attracted more and more attention. Based on the transformation behavior of the FA/clay system during the sintering process, the feasibility of preparing high-strength ceramics from FA/clay was evaluated from the theoretical analysis and experimental verification perspective. The theoretical analysis showed that mixing FA and clay can reduce the liquid formation temperature, promoting the sintering process. Meanwhile, according to the CaO-SiO2-Al2O3 phase diagram, by controlling the addition of FA of 40 wt%, the potential balanced phases of the FA/clay system can be transformed into anorthite (CaAl2Si2O8), which is a typical ceramsite forming phase. The X-ray diffraction analysis confirmed that anorthite was the dominant phase in the sintered FA/clay sample. The experimental verification results presented that under the addition of 40 wt% FA, the sintering temperature of 1200 °C, and the holding time of 20 min, the obtained ceramsite with extremely excellent strength performance and heavy metal stability can meet the quality requirements of lightweight aggregates. This study can provide a reference for the resource utilization of FA and related hazardous wastes.
As a common lightweight aggregate concrete, the full lightweight ceramsite concrete has a very good engineering prospect, especially in the repair and reinforcement of existing concrete buildings. However, there were few studies on this aspect. The repair effect of repairing the structures of existing concrete (old concrete) with full lightweight ceramsite concrete (new concrete) was unknown. The influence of various factors on the tensile properties of this old and new concrete interface was unclear. In addition, the relevant calculation formula was also urgently needed to be investigated. This led to a lack of scientific reference in practical engineering. Therefore, ordinary concrete and full lightweight ceramsite concrete were used as the substrate material and the repair material, respectively. The tensile properties of interface between the full lightweight ceramsite concrete and ordinary concrete were systematically investigated by splitting tensile tests. As a result of this research, the repair effect of this restoration method was first obtained. Secondly, the relationship between three factors (the roughness of the interface, the interfacial agent and the difference in the curing age of the old and new concrete) and the tensile properties of the old and new concrete interface was revealed. Besides, the effects of these three factors on the tensile properties of the interface were quantified and ranked. Finally, a formula for calculating the tensile bearing capacity of the old and new concrete interface considering these three factors was established.
Heavy metal contaminated soils pose a serious threat to the environment, and preparing ceramsite using contaminated soils was proposed as an effective method to address this threat in this study. Specifically, two typical soils (i.e., contaminated clay and sandy soil) were mixed with different ratios and calcined at temperature 1000-1200 °C to prepare ceramsite. Special attentions were paid to evaluating the immobilization of heavy metals in ceramsite and identifying the corresponding immobilization mechanisms. Using the leachability of heavy metals from ceramsite as evaluation criteria, the optimum mixing ratio of clay/sandy soil and sintering temperature were determined as 0.6:0.4 and 1200 °C. Moreover, based on the spectroscopic characterizations and thermodynamic calculation, high sintering temperature well facilitated the liquid phases formation, promoting the reactions between heavy metals and aluminosilicates and the valence state conversion of heavy metals. Accordingly, heavy metals were well immobilized in ceramsite by forming thermodynamically stable minerals, being encapsulated in solid matrix, and transforming to valence states with low mobility. The leaching conditions including pH and temperature had minimal effect on the immobilization of heavy metals in ceramsite. In summary, ceramsite prepared by contaminated soils was environmentally friendly and had good potential in engineering application as building materials.
Recycled concrete powder (RCP) poses a considerable challenge with respect to effective utilisation of construction and demolition waste (CDW) resources due to its low activity, high water demand, and potential to cause dust pollution during storage. A suitable activation method is necessary for stimulating the potential activity of RCP and enhancing its utilisation. Therefore, the effect of mechanical, chemical, and thermal activation methods on the properties of RCP were investigated in this study. Mechanical and thermal activation were helpful for the activity of RCP due to the modification of particle size and distributions. RCP exhibits a higher content of SiO2 and a lower content of CaO as well as the main crystal phases of quartz, calcite, gismondine, and dolomite. After 400–800 °C thermal activation, dolomite is not observed while the RCP shows new active components (such as larnite, calcium silicate, and calcium oxide). The chemical activation test highlights that CaO (3%) is the most optimal, followed by CaSO4 (1%) and Na2SO4 (2%), while Ca(OH)2 (4%) has the least optimal activation effect on the strength activity index (SAI) of RCP mortar. For combined activation, Ca(OH)2 and CaSO4 with 1:1 ratio has the most optimal activation effect, and the SAI reaches 80.27%. Based on the mechanical performance, SAI, and micro-characteristics, the most feasible and effective activation method is thermal activation (800 °C), followed by chemical activation (Ca(OH)2+CaSO4), and mechanical activation (75 min). This study proposes a useful combined activation method for RCP that verifiably contributes to the application of CDW.
Large amounts of coal gangue and municipal sludge are generated from coal mining and municipal sewage. Some scholars have studied their use in ceramics, concrete, land reclamation and so on. However, in current study, heavy metals in coal gangue and municipal sludge in utilization have not been safely controlled, and there are potential risks to the ecological environment and human health. Therefore, this study systematically investigated the basic physical and chemical properties of coal gangue and municipal sludge samples, the ecological environment safety risk of heavy metals and other harmful substances (soluble phosphorus and fluorine). The results showed that the main compositions of coal gangue and municipal sludge samples were cristobalite, hematite and anorthite, which can be used as raw material for ceramsite preparation. The characteristic heavy metals in coal gangue and municipal sludge were As, Cd, Cu, Ni and Zn, which had certain environmental risks. When the optimum proportion of coal gangue: sludge = 70: 30, adding clay and blowing agent as auxiliary materials to make ceramsite, its properties, including bulk density, cylinder pressure strength and other physical properties, meet the Chinese standard “light aggregate and its test method” (GB/T 17431). The heavy metal environment and human health assessment model of the product was constructed, in which the risk assessment results are, that the content of characteristic heavy metals in ceramsite was significantly reduced, and this content conformed to the requirements of heavy metals in the Chinese standard “technical specification of cement kiln cooperative disposal of solid waste” (GB/T 30760), riskless to the human body and external environment. The compressive strength of the two kinds of ceramsite concrete can reach LC35, and the density grade was 1400–1650 N/m³, which meets the requirements of Chinese standard “technical specification for lightweight aggregate concrete” (JGJ 51). All the properties of this product meet the corresponding standards and there was no risk to the external environment, to provide theoretical guidance for the harmless and resource utilization of urban sludge and coal gangue.
This study aimed to assess the feasibility of manufacturing high-strength and low-density proppants from oil-based drilling cuttings pyrolysis residues (ODPR) and red mud (RM). The effects of ODPR and RM content on the performance of the proppants were studied, respectively. The optimum sintering condition was determined by response surface methodology (RSM), and the sintering mechanism was explored based on microstructural analysis of the proppants. The results showed that high-strength and low-density proppants with the breakage ratio of 8.6 % under 52 MPa closed pressure, bulk density of 1.45 g·cm⁻³, and apparent density of 2.96 g·cm⁻³ were obtained under the optimum preparation conditions (mass ratio of ODPR: RM: bauxite: MnO2 of 20: 8: 76: 4, sintering temperature of 1342 °C, sintering time of 1.0 h, sintering rate of 4.9 °C·min⁻¹). The performance of the product proppants could meet the requirements of the Chinese Petroleum and Gas Industry Standard “Measurement of properties of proppants used in hydraulic fracturing and gravel-packing operations” (SY/T 5108-2014). ODPR and RM in the raw materials provided the chemical components of Al2O3, SiO2, CaO, BaO, Na2O, and K2O, which were involved in the formation of crystalline phases and molten phases during the sintering process. The performance of high-strength was primarily provided by the framework structure containing the crystalline phases and the dense structure caused by the molten phases. In addition, the Fe2O3 of RM would promote the generation of closed pores and then enhance the lightweight performance of proppants; however, excessive RM incorporation would lead to the formation of connected pores, which had a negative effect on the breakage ratio of proppants. This study not only creates a new pathway for recycling ODPR and RM within the shale gas industry but also provides a novel approach for manufacturing high-strength and low-density proppants.
The potential harm to the environment and human body caused by heavy metal elements such as Cd, Cr, Pb in fly ash cannot be ignored. In this study, microscopic analysis and heavy metal hazard analysis were performed on fly ash samples from four regions in China. XRF, XRD, FTIR and SEM/EDS test results showed that the main components of fly ash are Si, Ca, Al, O and other elements, and the main mineral components are mullite, quartz and amorphous aluminosilicate. The results showed that six heavy metal elements of As, Hg, Cd, Cr, Pb and Ni from the EDS test charts of these four types of fly ash. Based on the detection of the six heavy metal contents in fly ash, the results of the pollution evaluation of these four types of fly ash were consistent according to the single factor index, potential ecological risk index, and index of geo-accumulation. This indicated that Cd/Hg in FA 1, FA 2 and FA 3 has a high risk of environmental pollution. In the meantime, Cr and As in fly ash need to be controlled, because the human health risk assessment showed that they will bring carcinogenic risk to the human body through oral intake. The study on the migration law of characteristic heavy metals by taking FA 4 as an example showed that the leaching rate of Cr, Hg and Cd decreased with the increase of grinding particle size. Among the three characteristic heavy metals, mercury had the highest leaching rate. From the XPS detection results of FA 4, it was found that the valence states of these three heavy metals in FA 4 are Cr³⁺, Cr⁶⁺, Cd²⁺, Hg²⁺ respectively. These harmful heavy metal ions gradually enter the deep soil and groundwater through osmosis. Finally, based on the control model constructed in this study, the contents of these three heavy metals in fly ash in different application scenarios were limited.
The accumulation of large amounts of sediment in Yellow River has posed a threat to the local ecological environment. In this study, Yellow River sediment was used as the main raw material to prepare lightweight ceramsite and masonry mortar. The effects of pulverized coal addition, calcination time, and calcination temperature on the microstructure of ceramsite were investigated. The effects of the amount of raw materials, concentration of glutinous rice slurry, and substitution amount of ceramsite (as opposed to standard sand) on the properties of masonry mortar were then studied. For a pulverized coal addition of 10%, the calcination temperature was 1,125 ℃, calcination time was 30 min, bulk density of the ceramsite was 879 kg.m⁻³, water absorption was 5.9%, and cylinder pressure strength was 9.1 MPa. When the mass ratio (hydrated lime: Yellow River sediment: standard sand) was 3:4:2, glutinous rice slurry with a concentration of 3% was added and then cured in a curing box at a temperature of 25 ± 2℃ and humidity of 95 ± 2% for 28 days. The surface hardness of the obtained masonry mortar was 97 HA, and the unconfined compressive strength was 1.1 MPa. After 28 days of curing with ceramsite instead of standard sand, the surface hardness of the masonry mortar was 94.5 HA and the unconfined compressive strength was 0.91 MPa; this indicated that the standard sand can be completely replaced by ceramsite, thereby effectively increasing the utilization rate of Yellow River sediment. This work provided a feasible method for efficient utilization of Yellow River sediment resources.
To find cementitious composites that can be suitable for superseding Portland cement and alleviate the demerits of it for the environment, this study develops newly cementless ternary geopolymer composites of red mud (RM)-reactive ultra-fine fly ash (RUFA)-recycled powder (RP) activated by sodium hydroxide and sodium silicate, and using different mixing ratios as well as curing conditions. Then, the microstructural properties, pore structures, mechanical properties and geopolymerization reactions of them were studied systematically. Herein, we successfully synthesize cementless ternary geopolymers with the excellent workabilities and mechanical properties, which could be comparable to traditional cement. Their compressive strength can reach up to 46 MPa and the strength enhancements were mainly attributed to gel products such as N-ASH, CSH and (N, C)-ASH being found in specimens, which were interwoven to form a dense microstructure. Besides, the disparities of RM and RP contents in matrix would result in the transformation of gel products: C-ASH and Fe-silicate gels were mainly presented in specimens with high RM, N-ASH gels in specimens with high RUFA, and (N, C)-ASH gels specimens in specimens with high RP. These gels facilitated to reduce of dry shrinkage by refining the pore size. All these results contribute to a better understanding of the chemical properties of alkali-activated materials and facilitate their applications.
This paper presents a discussion involving practical aspects of applying contamination indices and ecological risk factors derived from chemical elements in the environmental assessment of soils and sediments. The single and integrated indices: Geoaccumulation index (Igeo), Enrichment factor, Contamination factor (CF), Pollution Index (PI), Ecological risk factor (Eir), Pollution Load Index (PLI), Degree of contamination, Modified Contamination Factor (mCdeg), and potential ecological risk index (PERI) were discussed, and some applications were presented didactically. The analytical care needed to obtain reliable indices with the studied ecosystem is also evidenced. In addition, the advantages and limitations of the use of these indices are presented.
The residue derived from oil-based drilling cutting pyrolysis could be used as paving materials. Some petroleum hydrocarbons remain in the residue after pyrolysis and cause severe environmental pollution. This work took it as the primary research object and carried out soil column leaching experiments with different leaching amounts to explore the relationship between the characteristics of vertical migration of petroleum hydrocarbons in soil and the dynamic response mechanism of soil microbial ecological effects on petroleum hydrocarbons. The soil's pH value and water content did not differ significantly. And the vertical migration ability of each petroleum hydrocarbon component was different. In petroleum hydrocarbon contaminated soil, the relative abundance of Proteobacteria maintained a high level (23.6%-60.7%). At the genus level, the relative abundance of Massilia was high and got lower with the increase in leaching amount. According to PICRUSt, Monooxygenase [EC: 1.14.13.-] played a significant role in petroleum hydrocarbon degradation. While Long-chain-fatty-acid-CoA ligase [EC: 6.2.1.3] had the highest relative abundance. By studying the influence of shale gas oil-based drilling cuttings pyrolysis residue on soil physical and chemical properties and soil microorganisms, the resource application of pyrolysis residues provides scientific ecological assessment.
Foamed glass-ceramics were prepared at 1000 °C through the one-step sintering process by applying waste glass and slow-cooled high-titanium blast furnace slag as raw materials. This study investigated the effects of borax as the flux agent on the crystalline phases, microstructure, and properties of foamed glass-ceramics, respectively. It was found that the borax would decrease the system's softening temperature and viscosity, thus enhancing the foaming and crystallizing process. Besides, the XRD results showed that the main crystal types of foamed glass-ceramics presented no difference with different contents of borax addition, but their crystallinity and crystal morphology differed. With the increasing borax content, the porosity and water absorption increased, while the volume density, thermal conductivity, and compressive strength all decreased. In particular, the sample added with 6 wt% borax exhibited the optimal comprehensive properties. This study provided a practical guideline for effectively reusing solid industrial wastes to produce foamed glass-ceramics.
Oil-based drill cuttings (OBDC), as a by-product produced from the exploration and extraction of shale gas fields, have received increasing attention as both hazardousness and potential energy resources. In this study, the pyrolysis performance of OBDC was investigated using a thermogravimetric analyzer (TGA) and fixed-bed reactor. Results showed that the primary decomposition of OBDC occurred at 85–360 °C. The average activation energy calculated by model-free methods Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (OFW), Starink, and Friedman (FM) models were 53.11, 57.87, 53.38, and 64.23 kJ/mol, respectively. The reaction model depended on the degree of conversion. Moreover, high heating rates were conductive to predict the reaction mechanism. The analysis results of pyrolysis products showed that with the temperature increased from 450 °C to 600 °C, the oil yield presented a first increased and then decreased tendency, and reached the highest (14.94%) at 500 °C, then decreased to 12.10% at 600 °C. The oil was mainly composed of diesel fraction (C12-C22), which can be used as a fuel or raw material. Moreover, the lower heating value (LHV) of gaseous products was the highest (31.80 MJ/Nm³) at 600 °C. In addition, the oil content of char was far below 0.3%, and the heavy metal content in char was below the national standards (CJ/T 362–2011, China), suggesting that OBDC pyrolysis could achieve energy recovery and harmless treatment simultaneously. The results can provide a theoretical basis and data support for optimizing and developing OBDC pyrolysis reactors and processes.
With an increase in municipal solid waste incineration (MSWI) fly ash and its dangerous characteristics, the manner of its disposal has caused widespread concerns. In this study, ceramsite was prepared by using MSWI fly ash, civil sludge, and contaminated soil as the main raw materials; then, a certain proportion of clay was added as an additive. The optimum MSWI fly ash content and sintering conditions were investigated, and the immobilization mechanisms of heavy metals were explored. Based on the obtained results, the optimum preparation conditions were a preheating temperature of 400 °C, a preheating time of 10 min, a sintering temperature of 1150 °C, and a sintering time of 20 min. Moreover, the optimal raw material ratio of MSWI fly ash, civil sludge, contaminated soil, and flint clay was 30%:40%:15%:15%. Under these optimum preparation conditions, the obtained ceramsite showed the following excellent performance parameters: a 1-h water absorption of 0.97%, bulk density of 998.7 kg/m³, and cylindrical compressive strength of 37.84 MPa. Furthermore, the leaching of heavy metals was far less than the standard GB5085.3-2007. The immobilization of heavy metals in the ceramsite was mainly caused by the glass phase encapsulation and the formation of new crystal phase with the heavy metals. In addition, the generation of aluminosilicates played a positive role in the immobilization of heavy metals. Thus, the reuse of MSWI fly ash by preparing fly ash-based ceramsite is one of the effective methods for reducing solid wastes.
The preparation of construction and demolition (C&D) waste into a recycled concrete aggregate (RA) for use in concrete helps save natural resources and solve the problem of construction waste disposal. However, the defects of RA with the loose surface, cracks, and pores limit its resource utilization of building materials. In this study, RA was reinforced by wrapping using recycled fine concrete powders (RFP) cement paste. On the basis, the effect of RFP cement pasted synergistic carbonation on the performance of RA and strengthen the mechanism. The results shows RA's apparent density and crush value has been improved after RFP cement slurry treatment, but obviously, the water absorption has been increased. RA showed more significant results after the 20% RFP cement slurry synergistic carbonation treatment: the apparent density of RA increased by 5.6% and the crushing value decreased by 44.87%, while the water absorption increased by only 11.2%. In microscopic analysis, showed that treated RA with RFP cement slurry synergistic carbonation to generate a large amount of hydrated calcium silicate (C–S–H) gel and CaCO3 products, which filled the pores, microcracks, and interfacial transition zone (ITZ) of RA and also reinforced the loose particles on the RA surface.It showed that the pore reduction of RA was 25.1%, and the CaCO3 content increased from 11.1% (wrapped slurry only) to 20.75% (synergistic effect).Adding the right amount of RFP can save cement and reduce cost and improve the strengthening performance.