Fine Recycled Concrete Aggregates Research Articles

Fracture properties and acoustic emission characteristics of manufactured sand recycled fine aggregate concrete

To promote the application of recycled fine aggregates, fracture characteristics of concrete beams containing manufactured sand (MS) and recycled fine aggregate (RFA) were investigated. The fracture properties and acoustic emission (AE) characteristics of manufactured sand recycled fine aggregate concrete (MSRFAC) with 0 %, 25 %, 50 %, 75 % and 100 % RFA replacement rates were evaluated by three-point bending test of single-sided notched beams. The fracture mechanisms of MSRFAC beams were explored using AE and digital image correlation (DIC) techniques, and fracture process zone (FPZ) was qualitatively and quantitatively analyzed. The results indicated that the critical nominal stiffness, initial fracture toughness, fracture energy and characteristic length of MSRFAC decreased significantly with the increase of RFA replacement rate, up to 20.2 %, 37.7 %, 22.8 %, and 26.6 %, respectively, while the unstable fracture toughness was insensitive to the variation of RFA. Moreover, the AE activity, the tensile crack, large-scale crack, high amplitude, and high peak frequency in MSRFAC increased with increasing RFA replacement rate. According to the FPZ characteristics of MSRFAC, its FPZ length increased with the increase of RFA replacement rate, while the FPZ width decreased with the increase of RFA replacement rate. The critical FPZ lengths of MSRFAC with different RFA replacement rates were about 20.2–30.0 mm, and the maximum FPZ widths were about 26.0–36.7 mm. The RFA weakened the friction mechanism and interlocking effect between aggregates of MSRFAC, resulting in a faster FPZ propagation rate and smaller damage width of MSRFAC than normal manufactured sand concrete.

Behavior of the use of fine recycled concrete aggregates on rheological parameters and hardened mortar properties

The depletion of natural sand and the large amount of demolition waste that exists across the world are realizing the potential benefits of using this abundant waste to create recycled fine aggregates for use in the production of masonry mortars. This research aims to analyze the mechanical performance of mortar with recycled aggregates from old concrete, natural sand (NS) is partially substituted with fine recycled concrete aggregates (FRCA) and a quantity of superplasticizer has been added to keep the same spreading. The experimental study focused on different substitution rates by volume (0%, 25%, 50%, 75% and 100%) for recycled sand. Tests in the fresh state of the mortar such as spreading, yield stress and plastic viscosity will be carried out. In order to evaluate the mechanical performance of the recycled mortar, tests of compressive strength and flexural strength will be carried out. As well as the effect of the use of these aggregates on durability such as shrinkage and sorptivity. The results found show that recycled sand can be an alternative to natural sand, despite its detrimental effects on the durability properties of the mortar. These effects can be neglected given its contribution to the economic and environmental aspect. Adequate relationships have been established to predict rheological parameters, mechanical strengths and durability performances as a function of test parameters with high correlation coefficient and low root mean square error.

Durability analysis of metakaolin recycled concrete under sulphate dry and wet cycle

This study aims to enhance the durability, cost-effectiveness, and sustainability of recycled fine aggregate concrete (RFAC) subjected to the combined effects of wet-dry cycles and sulfate erosion. Dry–wet cycle tests were conducted in RFAC with different admixtures of biotite metakaolin (MK) and 15% fly ash (FA) mix (M) under 5% sulfate erosion environment. The effect of 0%, 30%, 60% and 90% recycled fine aggregate (RFA) replacement of natural fine aggregate on mass loss, cubic compressive strength, relative dynamic modulus test of RFAC, damage modeling and prediction of damage life of concrete were investigated. The results showed that the concrete cubic compressive strength and relative dynamic modulus were optimal for recycled concrete at 15% MK biotite dosing and 60% RFA substitution, and its maximum service life was accurately predicted to be about 578 cycles under 5% sulfate dry–wet cycling using Weibull function model. This study is pioneering in addressing the durability of RFAC under sulfate attack combined with wet-dry cycling, employing a novel approach of incorporating MK and FA into RFAC. The findings highlight the practical application potential for using MK and FA in RFAC to produce durable and sustainable construction materials, particularly in sulfate-exposed environments. This research addresses a critical challenge in the construction industry, providing valuable insights for developing more durable and eco-friendly construction materials and contributing to long-term sustainability goals.

Experimental Study of Mechanical Properties and Theoretical Models for Recycled Fine and Coarse Aggregate Concrete with Steel Fibers.

With diminishing natural aggregate resources and increasing environmental protection efforts, the use of recycled fine aggregate is a more sustainable approach, although challenges persist in achieving comparable mechanical properties. Exploration into the incorporation of steel fibers with recycled aggregate has led to the development of steel-fiber-reinforced recycled aggregate concrete. This study investigates the shrinkage performance and compressive constitutive relationship of steel fiber recycled concrete with different steel fibers and recycled aggregate dosages. Initially, based on different replacement rates of recycled coarse aggregate and different volume contents of steel fiber, experimental results demonstrate that as the replacement rate of recycled coarse aggregate increases, shrinkage also increases, while the addition of steel fiber can mitigate this effect. An empirical shrinkage model for steel fiber recycled concrete under natural curing conditions is also proposed. Subsequently, based on the uniaxial compression test, findings indicate that with an increasing replacement rate of recycled fine aggregate, the peak stress and elastic modulus of concrete decrease, accompanied by an increase in peak strain, and the addition of steel fiber limits concrete crack development and enhances its brittleness while the peak stress and strain of recycled fine aggregate concrete are enhanced. However, the steel fiber volume percentage has a negligible effect on the elastic modulus. A constitutive relationship for concrete considering the effects of recycled fine aggregate and steel fiber is also proposed. This finding provides foundational support for the influence patterns of steel fiber dosage and recycled aggregate ratio on the mechanical properties of steel fiber recycled concrete.

Environmental impacts and performance assessment of recycled fine aggregate concrete.

Natural disasters and human demolition create vast amounts of construction and demolition waste (CDW), with a substantial portion being concrete waste. Managing this concrete waste is a daunting challenge for developing countries with limited resources, aiming to mitigate its harmful environmental effects. Therefore, the proposed approach involves using recycled fine aggregates (RFA) instead of fresh fine aggregates (FFA) in concrete, which aligns closely with achieving sustainable environmental objectives. Extensive laboratory tests were conducted to assess the effects of adding RFA to concrete. The influence of 0 to 100% RFA replacement and different curing times was investigated on compressive strength, tensile strength, resistance against chloride ion penetration and chemicals exposure, and quality of aggregates. So, around 30%, 35%, 20%, and 79% reductions in compression strength, tensile strength, modulus of elasticity, and workability were estimated when 100% RFA was used in recycled aggregate concrete (RAC). However, according to results analyses, the performance of RAC is reliable up to 50% of RFA in proposed conditions and mix design. In addition, major environmental impacts such as global warming potential, aquatic eutrophication, and aquatic acidification were reduced by 47%, 40%, and 18%, respectively, for concrete having 50% RFA than concrete having 100% FFA.

Possibilities of replacing natural sand in concrete

This study explores the potential of using fine recycled aggregate (FRA) to replace natural sand in concrete production. The research was divided into two parts. In the first part, natural aggregate’s complete fine fraction (0‑4 mm) was replaced with FRA in conventional concrete for two strength classes. In the second part, individual fine components of high-performance concrete (HPC) were substituted with a similar fraction of fine recycled HPC and concrete aggregate. The physical and mechanical properties of these mixtures with recycled aggregate were evaluated against reference mixtures that contained only natural aggregate, following European standards. Results showed that while most of the concrete and HPC mixtures with recycled aggregate showed slight decreases in properties compared to the reference mixes, the most significant reduction in mechanical properties was observed in the flexural tensile strength of the concrete mixture with FRA, which decreased by over 50 %. The absorption by immersion increased by up to 85 %. The deterioration in properties must be considered during the design stage and only used in applications where it will not affect the functionality of the structures.

Carbonation resistance of recycled fine aggregate concrete reinforced by calcium sulfate whiskers

This study investigates mechanical and carbonation resistance tests conducted on Recycled Fine Aggregate Concrete (RFAC) with three different Recycled Fine Aggregate (RFA) replacement rates and four calcium sulfate whisker (CSW) contents, and investigates the effects of RFA replacement rate and CSW content on the mechanical properties of RFAC and the carbonation resistance of RFAC with calcium sulfate whiskers at different ages of carbonation. The microstructure of CSW-modified RFAC was observed and analyzed by SEM electron microscopy to explore further enhancement and toughening mechanisms of CSW in RFAC, as well as the optimal content of CSW in RFAC. In addition, the carbonation depth of recycled concrete with calcium sulfate beard is modeled based on a quadratic fitting formulation. The test results show that the mechanical properties and carbonation resistance of RFAC would decrease with the increase of the RFA replacement rate. Incorporating CSW can effectively improve the mechanical properties and carbonation resistance of RFAC. At 60 % RFA substitution, CSW at 2 % content has the most significant effect on the mechanical properties and carbonation resistance of RFAC. Microscopic analysis shows that CSW has a bridging effect at the micro-cracks in the concrete matrix, preventing the creation and expansion of micro-cracks in the concrete matrix, thus improving RFAC mechanical properties of RFAC and resistance to carbonation. The predicted results of the carbonation depth model which are constructed from the test data coincide with the results. We can use them to predict and analyze the carbonation depth of the carbonation resistance of recycled concrete.

Analysis of water migration in an earthen landfill cover with recycled construction waste

In this study, numerical analysis was conducted to investigate the effects of particle sizes on water migration in a three-layer landfill cover system using recycled concrete aggregates (RCAs). This cover system consists of a top fine recycled concrete (FRC) aggregate layer and a middle coarse recycled concrete aggregate layer overlying a bottom silty refuse soil layer. Numerical simulations were performed to back analyse a flume model test data and further evaluate the particle size effects of RCAs on the effectiveness of the cover system. With the increase in rainfall duration, surface runoff reduced, while the lateral diversion increased pronouncedly. Nonetheless, no significant percolation is observed through the cover system using RCAs during 100-year extreme rainfall with different durations. Based on the results, the d10 of FRC is recommended to be from 0.2 to 0.5 mm.

A Meta-Analysis of the Effect of Moisture Content of Recycled Concrete Aggregate on the Compressive Strength of Concrete

To reduce the environmental impact of concrete, recycled aggregates are of significant interest. Recycled concrete aggregate (RCA) presents a significant resource opportunity, although its performance as an aggregate in concrete is variable. This study presents a meta-analysis of the published literature to refine the understanding of how the moisture content of RCA, as well as other parameters, affects the compressive strength of concrete. Seven machine learning models were used to predict the compressive strength of concrete with RCA, including linear regression, support vector regression (SVR), and k-nearest neighbors (KNN) as single models, and decision tree, random forest, XGBoost, and LightGBM as ensemble models. The results of this study demonstrate that ensemble models, particularly the LightGBM model, exhibited superior prediction accuracy compared to single models. The LightGBM model yielded the highest prediction accuracy with R2 = 0.94, RMSE = 4.16 MPa, MAE = 3.03 MPa, and Delta RMSE = 1.4 MPa, making it the selected final model. The study, employing feature importance with LightGBM as the final model, identified age, water/cement ratio, and fine RCA aggregate content as key factors influencing compressive strength in concrete with RCA. In an interaction plot analysis using the final model, lowering the water–cement ratio consistently improved compressive strength, especially between 0.3 and 0.4, while increasing the fine RCA ratio decreased compressive strength, particularly in the range of 0.4 to 0.6. Additionally, it was found that maintaining moisture conditions of RCA typically between 0.0 and 0.8 was crucial for maximizing strength, whereas extreme moisture conditions, like fully saturated surface dry (SSD) state, negatively impacted strength.

Compressive Behaviors of High-Strength Geopolymeric Concretes: The Role of Recycled Fine Aggregate

In this study, natural fine aggregates (NFAs) in high-strength fly ash (FA)/ground granulated blast furnace slag (GGBFS)-based geopolymer concretes were both partially and completely replaced by RFAs to prepare geopolymer recycled fine aggregate concrete (GRFC). Herein, the impacts of RFA content (0%, 25%, 50%, 75%, and 100%) on the fresh and hardened performance and microstructural characteristics of a GRFC were investigated. The results indicated that with increasing RFA substitution ratio, the setting time of the GRFC decreases. In addition, the compressive strength and elastic modulus decrease. However, owing to the enhanced adhesion of the geopolymer matrix and recycled aggregate, RFA has a relatively small impact on the compressive strength, with a maximum strength loss of 9.7% at a replacement level of 75%. When the RFA content is less than 75%, the internal structure of the concrete remains relatively compact. The incorporation of RFA in concrete has been found to adversely affect its compressive strength and elastic modulus, while simultaneously increasing its brittleness. The increase in dosage of RFA leads to a reduction in the compressive strength and elastic modulus of concrete, while partial failure occurs when the GRFC constitutes 100% of the RFA. The existing stress–strain model for conventional concrete is recalibrated for the GRFC. Observed by SEM, with increasing RFA, the damage is mainly concentrated at the interface associated with the attached cement. Although the recalibrated model predicts the stress–strain responses of the GRFC reasonably well, an acceptable range of deviation is present when predicting the residual stress due to the relatively high strength and brittle behavior of the GRFC during compression. Through this research, the applicability of RFA is expanded, making it feasible to apply large quantities of this material.

Influence of Recycling Processes on Properties of Fine Recycled Concrete Aggregates (FRCA): An Overview

Concrete waste recycling processes involve multiple stages, equipment, and procedures which produce Fine Recycled Concrete Aggregates (FRCA) for use in construction. This research aims at performing a comprehensive overview of the recycling technologies, recycling processes, and normative requirements to produce high-quality FRCA and to investigate the influence of these processes on their physical properties. The properties investigated were the particle size distribution (PSD), water absorption, oven-dry density, and adhered paste. The correlations between these properties were also investigated. The results indicate that the recycling processes with the highest potential for producing high-quality aggregates demand jaw crusher and impact crusher combinations. These processes are better suited for achieving FRCA with the desired particle size distribution and oven-dry density. However, water absorption and adhered paste, which are critical factors for obtaining high-quality FRCA, seem to be more dependent on the original material than on the recycling process.

Effects of elevated temperature exposure on the mechanical properties of recycled fine aggregate concrete

ABSTRACT In this work, a compound waste material was made up of raw construction waste concrete, waste tiles, and waste bricks was mixed at a weight ratio of 6:3:1. They were ground into recycled fine aggregates (RFA). RFA substituted the local river sand in proportions of 0%, 30%, 50%, 70%, and 100% for preparing recycled fine aggregate concrete (RFAC) with varied water-to-cement ratios. It intended to explore concrete’s mechanical properties and ultrasonic pulse velocity changes before and after high temperatures (300–800°C). The loss on ignition (LOI) of concrete was simultaneously determined to compare the performance in resisting elevated temperature. Test results presented that the higher the replacement ratio of RFA, the gradually higher the reduction in the concrete splitting tensile, compressive, and residual compressive strengths and ultrasonic pulse velocity after elevated temperature exposure. A rapid reduction was especially found at the heated temperature of exceeding 440°C. Furthermore, the old cement paste adhered to the surface of the raw construction waste had a relatively higher LOI. This led to the consequence that the RFAC had an increased LOI with the increment of the RFA replacement ratio, while the LOI of RFAC dropped with the increment of the originally heated temperature.

Impact of Recycled Concrete and Brick Aggregates on the Flexural and Bond Performance of Reinforced Concrete

The construction industry strongly relies on concrete and clay bricks for various applications. The escalating demand for these materials, driven by rapid population growth, has led to resource depletion and increased construction and demolition waste (CDW). Recycling CDW into construction materials, particularly in the form of recycled concrete aggregates (RCAs) and recycled brick aggregates (RBAs), has emerged as a promising solution. This study deals with the structural performance of concrete incorporating RCAs and RBAs. The experimental program encompasses material characterization, concrete mix design, and several tests to assess density, compressive strength, bond behavior, and flexural properties. The results indicate that the replacement of fine natural aggregate (NA) with fine RCAs or RBAs has a negligible impact on density, while the partial replacement of coarse NAs with RAs yields modest reductions in compressive strength. Notably, the bond strength between steel rebar and concrete is influenced by the type and content of RA, with specimens containing RCAs exhibiting a higher bond strength than those with RBAs. Empirical models used to predict bond strength generally align with experimental results, with conservative predictions by some models, such as ACI 318, and overestimation by others, such as models proposed by AS-3600 and CEB-FIB. The flexural tests of beams highlight the variation in stiffness and load-bearing capacity with the proportion of NAs replaced by RAs. While beams with 50% NA replacement demonstrate comparable performance to control beams, those with 100% RA replacement exhibit lower cracking and yielding stiffness. Cracking patterns in beams with RAs differ from control beams, with RA-containing beams showing more cracks and an altered crack distribution. The findings underscore the feasibility of using recycled aggregates in construction, with partial NA replacement offering a balance between sustainable material usage and desired structural properties.

Kinetics and structure analysis of CO2 mineralization for recycled concrete aggregate (RCA)

CO2 mineralization of solid waste in the construction industry for green concrete production is a promising approach for economically storing CO2 and recycling solid waste. Recent investigations have underscored the significance of CO2 sequestration and the augmentation of RCA performance engendered by the holistic reaction processes. While there is a pronounced interest in the optimization of macroscopic reaction conditions (e.g., temperature, pressure, etc.), the exploration and enhancement of the reaction kinetics stage often remains under explored. This study employed a reaction kinetics model to quantify the reaction rate unveiled two distinct reaction stages within the mineralization reaction. Early evaporation and pore formation established the groundwork for the diffusion mechanism of gas product layers in the middle and later stages, emphasizing the crucial role of water in connecting solid ion leaching and gas dissolution-diffusion in the reaction. The water content of the reaction has an optimal value (4%–6%), smaller particle size correlates with a higher optimal water content. Pre-soaking with a calcium hydroxide (CH) solution or suspension was employed to improve mineralization reaction kinetics, resulting in RCA with improved pore characteristics and strength. The crushing index decreased by 28.8% and 21.8%, the water absorption rate decreased by 11.1% for both coarse and fine RCA, and the cumulative total porosity of fine RCA decreased by 17.6%. This research aims to broaden the applications of waste concrete in the CO2 capture, utilization and storage (CCUS) industry and produce low-cost, extensively processed, and high-strength RCA products while contributing to sustainable CO2 management.

Effect of Coarse and Fine Recycled Concrete Aggregates on the Performance of Geopolymer Concrete

Effect of Coarse and Fine Recycled Concrete Aggregates on the Performance of Geopolymer Concrete

Study on fracture characteristics and fracture mechanism of fully recycled aggregate concrete using AE and DIC techniques

Fracture behaviors of manufactured sand-recycled coarse aggregate concrete (MSRCAC), recycled fine aggregate concrete (RFAC), and fully recycled aggregate concrete (FRAC) were investigated by performing three-point bending tests on single-edge notched beams using acoustic emission (AE) and digital image correlation (DIC) techniques. The effects of recycled fine aggregate (RFA), recycled coarse aggregate (RCA), and their interaction on fracture parameters, AE characteristics and fracture process zone (FPZ) of concrete were comparatively analyzed. The results indicated that it was mainly transgranular failure and intergranular failure for RFAC, while transgranular failure for MSRCAC and FRAC. The RFA and RCA reduced the initial fracture toughness, unstable fracture toughness and fracture energy of concrete, and their interaction resulted in poor fracture properties of FRAC. In addition, the RFA and RCA significantly increased the AE activities, the proportion of tensile cracks, and the high-frequency amplitude and peak frequency of concrete. The toughening effect of FPZ was weakened by the RFA and RCA, resulting in an obvious increase in FPZ length and damage propagation of FRAC. Meanwhile, the width of FPZ was reduced, the maximum FPZ width of concrete with different combinations of recycled aggregates was approximately 1.8–3.1 times the maximum aggregate size, which could be explained as the RFA and RCA reduced the aggregate interlocking effect of concrete, while the RCA had a greater effect on the damage mechanism and FPZ of concrete than the RFA.

Optimization in recipe design of interlocking compressed earth blocks by incorporating fine recycled concrete aggregate

Interlocking Compressed Earth Blocks (ICEBs) have recently surfaced as a valuable and innovative inclusion among earthen building materials. They offer workable answers to the common problems with burned bricks and cement blocks. Researchers frequently used river sand in their studies to address and reduce the finer content in soil. This study explored recipes to make ICEBs from construction and demolition wastes. Fine recycled concrete aggregate (FRCA) was used as a soil modification within the ICEBs as a part of this investigation to support eco-friendly, low-carbon product development driven by global climate concerns and the need for improved construction waste management to combat pollution. ICEBs, made by mixing construction and demolition trash, regulate environmental impact and address the scarcity of building materials. Due to the inherent diversity of soil and the lack of a standardized mix design for the manufacturing of ICEB, 40 different mix ratios were generated using the proportionated blends of sand and FRCA. Based on the compressive strength results, the best recipes representing conventional river sand and the FRCA were selected. The prepared samples of ICEBs using the optimized mix recipes of river sand and FRCA were further analyzed for mechanical, thermal, and durability performance alongside the required forensic endorsements, and the test results were enhanced for both ICEBs compared to first-class burnt clay bricks. Sand-incorporated ICEBs achieved 13.72 MPa compressive strength, while FRCA-incorporated ICEBs reached 13.38 MPa. Both ICEBs showed a noticeable improvement in compressive strength compared to various studies. The durability of ICEBs, in terms of water absorption, improved around 70% compared to fired bricks commonly used in the construction industry. The test findings reveal that FRCA incorporated ICEBs showed 14.3% lower thermal conductivity than ICEBs with sand incorporation. Therefore, the use of ICEBs specially designed with FRCA provides the most sustainable alternative to conventional fired bricks used by the construction sector in the developing countries.

Advancements in Concrete Performance by Using Waste materials in the Mixture

There have been serious research advancements in concrete materials to make construction more sustainable. Specifically, this is true with regard to alternative ingredients used for self-compacting concrete (SCC) production. To improve its sustainability, this study is aimed at adding Fine Recycled Concrete Aggregate (FRCA) and Recycled Concrete Aggregate (RCA) into SCC. Crushed and reclaimed asphalt (RCA), on the other hand, has many benefits including lower environmental impact and cost-effectiveness. Nevertheless, there are several issues associated with contractors’ knowledge among others being variations in their properties. It’s also known that FRCA can imbibe water faster; hence, mineral admixtures may be introduced to further enhance mechanical behaviour of the concrete. Fly ash and geopolymer synthesis are examples of waste products from industry as well as by-products of coal combustion which are useful in making green concretes. The best results would be achieved if fly ash, a popular Supplementary Cementitious Material (SCM) that reduces Ordinary Portland Cement’s (OPC’s) need is divided according to its oxide content. In order for geopolymers to become an alternative for cement making materials such as aluminosilicate source or alkali reactants are applied. Engineered Cementitious Composite (ECC) enhances performance of concrete even more with strain-hardening properties, especially in terms of durability and tensile capacity. On the whole, manufacturing concrete from recycled and industrial waste products is cost effective and environmentally beneficial. These materials can be maximized if prope performance-driven design strategies and contemporary waste management systems are put into place. This paper emphasizes how essential and crucial it is to incorporate sustainable methods in the production of concrete to create a more environment friendly construction industry.

Assessing the potential of recycled fine aggregate from freeze-thawed parent concrete for structural concrete

Recycled fine aggregate (RFA) generated from waste concrete, especially in harsh environment, can be considered as an alternative to natural sand. The yield rate, gradation and properties of RFA from natural aggregate concrete with the target strength of C40 as parent concrete (PC) every 200 freeze–thaw (FT) cycles are investigated. To more accurately evaluate the application potential of RFA, the mechanical properties and durability of recycled fine aggregate concrete (RFAC) is further studied. The results showed that as the FT cycles of PC increased, the yield rate of RFA decreases and the grading curve of RFA meets the requirements of Class II aggregate. The limit FT cycles of PC in Class II and III RFA are 148 and 450, respectively. For the compressive strength of RFAC that meets the design requirements, the FT cycles of PC are no more than 530. Based on 50 years of RFAC in Class D and Class E environments, the limit FT cycles of PC are 663 and 200, respectively. The limit FT cycles of PC are 221 based on 50 years of RFAC service in cold regions. Through the FT cycles of PC, the Class of RFA and the mechanical and durability of RFAC can be directly predicted. This provides a theoretical and data support for improving the utilization rate of waste concrete in FT environment.

Experimental Study on Flexural Fatigue Resistance of Recycled Fine Aggregate Concrete Incorporating Calcium Sulfate Whiskers

In order to study the flexural fatigue resistance of calcium sulfate whisker-modified recycled fine aggregate concrete (RFAC), flexural fatigue cyclic loading tests at different stress levels (0.6, 0.7, and 0.9) considering a calcium sulfate whisker (CSW) admixture as the main influencing factor were designed. Furthermore, the fatigue life was analyzed, and fatigue equations were established using the three-parameter Weibull distribution function theory. In addition, the micro-morphology of CSW-modified recycled fine aggregate concrete was observed and analyzed through Scanning Electron Microscopy (SEM), and the strengthening and toughening mechanisms of CSW on recycled fine aggregate concrete were further explored. The test results demonstrate that the inclusion of recycled fine aggregate reduces the fatigue life of concrete, while the incorporation of CSW can effectively improve the fatigue life of the recycled fine aggregate concrete, where 1% of CSW modification can extend the fatigue life of recycled fine aggregate concrete by 56.5%. Furthermore, the fatigue life of concrete under cyclic loading decreases rapidly as the maximum stress level increases. Fatigue life equations were established with double logarithmic curves, and P-S-N curves considering different survival probabilities (p = 0.5, 0.95) were derived. Microscopic analyses demonstrate that the CSW has a “bridging” effect at micro-seams in the concrete matrix, delaying the generation and enlargement of micro-cracks in the concrete matrix, thus resulting in improved mechanical properties and flexural fatigue resistance of the recycled fine aggregate concrete.