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.

Effect of Salt Solution Erosion on Mechanical Properties and Micropore Structure of Recycled Fine Aggregate ECC.

This study examined the impact of sulfate and sulfate-chloride dry-wet cyclic erosion on the mechanical properties and microscopic pore structure of engineered cementitious composite (ECC) with recycled fine aggregate (RA). Uniaxial tensile tests and four-point bending tests were conducted to evaluate the mechanical properties of RAECC, while the resonance frequency ratio was used to assess the integrity of the specimens. Finally, X-ray computed tomography (X-CT) reconstruction was employed to analyze the erosion effects on the microscopic pore structure. The results showed that the uniaxial tensile strength and flexural strength of the RAECC specimens in corrosive solution first increased and then decreased, and the 5% Na2SO4 solution caused the most serious erosion of the specimens. The resonance frequency ratio of the specimens reached the peak value when they were subjected to dry-wet cycles 15 times in the 5% Na2SO4 solution. During the erosion process, the pore space of the specimen first decreased and then increased, and the number of pores increased. The erosion process is the result of the erosion products continuously filling and eventually destroying the pores, and the erosion damage produces a large number of new pores and poor sphericity, leading to a decline in mechanical properties.

Study on Long Term Property of Soft Soil Solidified with Industrial Waste Residue and Regenerated Fine Aggregate.

The long-term properties of solidified soft soil, including an immersion test, the dry-wet cycle and the freeze-thaw cycle, were systematically studied. Firstly, the immersion stability of solidified soft soil was confirmed. The appearance of soft soil solidified by a solidified agent and raw fine aggregate did not change significantly, and it was still intact without damage when the soaking time increased up to 28 d. Secondly, the mass and compressive strength loss of solidified soft soil were determined. When the number of dry-wet cycles was one, three, five and seven, the accumulated-mass loss rate was 1.4%, 3.0%, 4.5% and 6.0%, respectively, and the compressive-strength loss rate was -10.3%, 13.9%, 41.2% and 53.6%, respectively. Compared with solidified soft soil under standard curing environments, solidified soft soil after seven dry-wet cycles showed small cracks, and the structural compactness began to decline. Finally, the influence of the freeze-thaw cycle on the mass, compressive strength and microstructure of solidified soft soil was confirmed. When the number of freeze-thaw cycles was 5, 10, 15 and 20, the accumulated-mass loss rate was 12.6%, 16.7%, 17.9% and 18.8%, respectively. The microstructure of the solidified soft soil was damaged, and the increase in porosity was the main reason for its strength reduction or even failure. Nevertheless, soft soil with a solidified agent and recycled fine aggregate had no obvious damage to the microstructure, and the freeze-thaw resistance was relatively superior.

A green ultra-high performance geopolymer concrete containing recycled fine aggregate: Mechanical properties, freeze-thaw resistance and microstructure.

The shortage of natural aggregate poses challenges and offers new opportunities for the construction industry. Under this background, the emergence of recycled aggregates sheds new lights on building aggregate. In this study, a green ultra-high performance geopolymer concrete (UHPGC) containing recycled fine aggregate (RFA) was prepared. To assess the feasibility of RFA and reveal the reaction mechanism of UHPGC, the reaction process, mechanical properties, freeze-thaw resistance and microstructure were systematically studied. The heat evolution results indicate that the control of reaction process could be achieved by adjusting the precursor component. A compact microstructure with extremely low porosity could be formed in the UHPGC specimens, which contributes to their good mechanical properties and freeze-thaw resistance. Good compatibility in the interface transition zone between fiber, paste and RFA could be observed, indicating great potential in the manufacture of UHPGC by alkali-activation technology. A considerable environmental benefit could be obtained in UHPGC when compared to ordinary ultra-high performance concrete (UHPC). This study is expected to offer more insights into the application of recycled aggregate and the manufacture of green UHPC.

Study on the Performance of Recycled Coarse and Fine Aggregates as Microbial Carriers Applied to Self-Healing Concrete.

The contradiction between the scarcity of natural resources and the demand for construction materials has given rise to the application of recycled aggregates. Microbial self-healing concrete (SHC) is a clean and smart material, and its carrier has a great influence on repair performance. In this paper, recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) were used as carriers, and their different repair effects over time were intensively investigated. The results showed that the RCA carrier had a better repair effect compared with that of RFA, and the maximum healing width could reach 0.27 mm by 28 day. The microbial repair efficiency was significantly influenced by the distribution of old mortar, with the RFA specimen having a small volume and wide distribution of repair products, while the RCA repair showed a centralized tendency. In addition, SEM, MIP and XRD characterization were used to analyze the repair mechanism. The time-dependent repair model was developed, and the applicability of the model for concrete enhancement under microbial repair was verified through experimental results. The research results could promote industrial applications by giving intelligent and green properties to recycled aggregates.

Development of Sustainable Engineered Cementitious Composites by Incorporating Local Recycled Fine Aggregate.

In this study, sustainable engineered cementitious composites (ECC) exhibiting high tensile strength as well as high tensile strain capacity were successfully developed by incorporating polyethylene (PE) fiber, local recycled fine aggregate (RFA), and limestone calcined clay cement (LC3). The improvement in tensile strength and tensile ductility was attributed to the self-cementing properties of RFA as well as the pozzolanic reaction between calcined clay and cement. Carbonate aluminates were also generated owing to the reaction between calcium carbonate in limestone and the aluminates in both calcined clay and cement. The bond strength between fiber and matrix was also enhanced. At the age of 150 days, the tensile stress-strain curves of ECC containing LC3 and RFA shifted from a bilinear model to a trilinear model, and the hydrophobic PE fiber exhibited hydrophilic bonding performance when embedded in RFA-LC3-ECC matrix, which could be explained by the densified cementitious matrix as well as the refined pore structure of ECC. Moreover, the substitution of ordinary Portland cement (OPC) by LC3 resulted in energy consumption and equivalent CO2 emission reduction ratios of 13.61% and 30.34%, respectively, when the replacement ratio of LC3 is 35%. Therefore, PE fiber-reinforced RFA-LC3-ECC demonstrates excellent mechanical performance as well as considerable environmental benefits.

Study on the Effect of Recycled Fine Aggregate Qualities on Fly Ash/GGBS-Based Geopolymer Mortar.

The rapid expansion of construction, fueled by industry and economic and population growth, has exacerbated the challenge of managing construction waste, especially concrete waste. One promising solution lies in the utilization of recycled fine aggregate (RFA), especially in combination with the emerging geopolymer technology, an innovative alternative to traditional cement. This study systematically explores the effects of incorporating varying qualities and quantities of RFA into geopolymer mortars. By using GGBS and FA as raw materials and replacing natural aggregates (NA) with RFA at different rates (25%, 50%, 75%, and 100%), the research investigates the fresh properties, mechanical characteristics, and drying shrinkage of geopolymer mortar. Key findings reveal that RFA significantly influences the flowability of geopolymer mortar: when RFA content is above 75%, preprocessed RFA (with particles below 0.15 mm removed) has substantially improved flowability, increasing it more than 20%. The critical impact of RFA preprocessing on enhancing mechanical properties and the higher the inclusion level (above 75%), the more pronounced is the advantage in enhancing the compressive strength compared to unprocessed RFA. Additionally, RFA was found to contribute to a denser interfacial transition zone (ITZ) than natural aggregate, which helps maintain the compressive strength at increased RFA dosages. Contrary to findings in cement mortar, a positive correlation exists between pore volume and compressive strength in geopolymer mortar incorporating RFA. This study underscores the potential of refined RFA preprocessing methods in advancing sustainable construction, highlighting avenues for the broader application of RFA in geopolymer mortar.

Influence of Recycled Fine Aggregate Content on Properties of Soft Soil Solidified by Industrial Waste Residue.

The influence of recycled fine aggregate content on the properties of soft soil solidified by industrial waste residue was systematically studied. First, the addition of recycled fine aggregate may provide skeleton support, which was conducive to improving the solidification properties. Comparing the addition of recycled fine aggregate content and a composite solidification agent separately, the compressive strength increased 48.01 times and 1.32 times, respectively. Second, the composition and quantity of the hydration products were analyzed by X-ray diffraction (XRD) and thermal gravity analysis (TG/DTG). In addition to silicon dioxide and aluminum oxide, a number of new minerals, including hydrated calcium silicate, calcium hydroxide and ettringite, were produced under different recycled fine aggregate contents. The diffraction peak of hydrated calcium hydroxide was weak, which indicated that the crystallinity and relative content was low. The main reason for this was that it was consumed as the activator of the secondary hydration reaction of blast furnace slag. With the increase in recycled fine aggregate content, the total weight loss (hydration products, crystal water, impurities) increased significantly, at rates of 6.9%, 7.0%, 7.2%, 8.8% and 9.7%. The addition of recycled fine aggregate does not change the composition and quantity of the hydration products, and the increased weight loss in this part might be caused by the cement paste attached to the surface of the recycled fine aggregate. Finally, their microstructure was analyzed by scanning electron microscopy (SEM). Larger and more pores appeared in the solidification system with the increase in recycled fine aggregate, and a large amount of ettringite was prepared. An excess in recycled fine aggregate caused more pores, and the negative impact of too many pores exceeded the lifting effect of the aggregate, resulting in the decline of its mechanical properties. Therefore, there was a suitable range for the use of recycled fine aggregate, which was not more than 40%. In conclusion, recycled fine aggregate not only acts as a skeleton to improve solidification strength, but could also realize the comprehensive utilization of waste, which provided a new scheme for solid waste utilization and soft soil solidification.

Shear Behavior of Recycled Fine Aggregate Reinforced by Nano-MgO Modified Cement.

In order to study the mechanical modification effect of nano-MgO on cement-reinforced recycled fine aggregate (CRA), direct shear tests and triaxial shear tests were carried out. In the test of recycled fine aggregate reinforced by nano-MgO modified cement (MCRA), the cement content was fixed at 2%, and the nano-MgO content varied between 0%, 0.5%, 1.0%, 1.5% and 2.0%. The test results showed that adding nano-MgO can greatly increase both the direct shear strength and triaxial shear strength of MCRA. This increase in direct shear strength was mainly attributed to the increase in cohesion. However, this increase in triaxial shear strength was attributed to the simultaneous increase in the cohesion and friction angle.

The Effect of Cementitious Materials on the Engineering Properties and Pore Structure of Concrete with Recycled Fine Aggregate.

With the rapid development of urbanization, the construction industry consumes a lot of cement and produces a large amount of construction waste. To overcome this situation, the rational use of recycled aggregate produced from waste concrete is one of solutions. In some countries, the building industry has approved the use of recycled coarse aggregates in concrete, with some limits. However, practically all existing standards and regulations prohibit the use of recycled fine aggregate (RFA) in concrete. Therefore, study on improving the performance of RFA concrete is vital. In this study, the effects of fly ash and GGBS on concrete with RFA were investigated. Compressive strength, pore structure, drying shrinkage and accelerated carbonation were tested. The correlation between the pore structure and properties of concrete was analyzed. The results show that adding fly ash and GGBS to RFA concrete increased its compressive strength, modified pore structure, reduced drying shrinkage, and even achieved higher compressive strength and lower drying shrinkage than normal concrete. The compressive strength was mainly affected by the capillary pores, and the carbonation was mainly affected by the gel pores.

An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste.

For complete utilization of construction and demolition (C&D) waste, an investigation of all size fractions of C&D waste generated during the recycling process should be conducted. In this work, the effects of three recycled concrete materials with different sizes (recycled coarse aggregate (RCA) with a size of 4.75-25 mm, recycled fine aggregate (RFA) of 0.15-4.75 mm, and recycled powder (RP) smaller than 0.15 mm) produced from concrete waste on the fresh and hardened mechanical properties of concrete were evaluated. The replacement ratios of natural coarse and fine aggregates by RCA and RFA were 30, 60, and 100%, and those of ordinary Portland cement for RP were 10, 20, and 30%. The results showed that the concrete properties deteriorated with increasing replacement ratio regardless of the type of recycled materials. The properties were reduced in the order of the use of RFA, RCA, and the simultaneous use of RCA and RFA. In addition, concrete with 30% RP showed lower mechanical strength than concrete with 100% RCA and 100% RFA. However, all concretes could be applicable for structural purposes under different environmental exposure conditions. In particular, concretes with 10% RP and 20% RP showed better cost-benefits compared to natural aggregate concrete with 100% ordinary Portland cement. These promising findings provide valuable initiatives for the effective and complete recycling of C&D waste.

The Durability of Recycled Fine Aggregate Concrete: A Review.

With the rapid development of urbanization, many new buildings are erected, and old ones are demolished and/or recycled. Thus, the reuse of building materials and improvements in reuse efficiency have become hot research topics. In recent years, scholars around the world have worked on improving recycle aggregates in concrete and broadening the scope of applications of recycled concrete. This paper reviews the findings of research on the effects of recycled fine aggregates (RFAs) on the permeability, drying shrinkage, carbonation, chloride ion penetration, acid resistance, and freeze-thaw resistance of concrete. The results show that the content of old mortar and the quality of recycled concrete are closely related to the durability of prepared RFA concrete. For example, the drying shrinkage value with a 100% RFA replacement rate is twice that of normal concrete, and the depth of carbonation increases by approximately 110%. Moreover, the durability of RFA concrete decreases as the RFA replacement rate and the water-cement ratio improve. Fortunately, the use of zeolite materials such as fly ash, silica fume, and meta kaolin as surface coatings for RFAs or as external admixtures for RFA concrete had a positive effect on durability. Furthermore, the proper mixing methods and/or recycled aggregates with optimized moisture content can further improve the durability of RFA concrete.

Time-Dependent Shrinkage Model for Recycled Fine Aggregate Thermal Insulation Concrete.

In this study, the shrinkage performance of recycled aggregate thermal insulation concrete (RATIC) with added glazed hollow beads (GHB) was investigated and a time-dependent shrinkage model was proposed. Two types of recycled fine aggregate (RFA) were used to replace natural fine aggregate in RATIC: RFA from waste concrete (RFA1) and waste clay brick (RFA2). Besides, the mechanical properties and thermal insulation performance of RATIC were also studied. Results showed that the pozzolanic reaction caused by RFA2 effectively improved the mechanical properties of RATIC; 75% was the optimal replacement ratio of RATIC prepared by RFA2. Added RFA decreased the thermal conductivity of thermal insulation concrete (TIC). The total shrinkage strain of RATIC increased with the increase of the replacement ratio of RFA. The 150d total shrinkage of RATIC prepared by RFA1 was 1.46 times that of TIC and the 150d total shrinkage of RATIC prepared by RFA2 was 1.23 times. The addition of GHBs led to the increase of early total shrinkage strain of concrete. Under the combined action of the higher elastic modulus of RFA2 and the pozzolanic components contained in RFA2, the total shrinkage strain of RATIC prepared by RFA2 with the same replacement ratio was smaller than that of RATIC prepared by RFA1. For example, the final total shrinkage strain of RATIC prepared by RFA2 at 100% replacement ratio was about 18.6% less than that of RATIC prepared by RFA1. A time-dependent shrinkage model considering the influence of the elastic modulus of RFA and the addition of GHB on the total shrinkage of RATIC was proposed and validated by the experimental results.

Effect of Pre-Wetting Recycled Mortar Aggregate on the Mechanical Properties of Masonry Mortar.

In this research we evaluated the use of recycled fine mortar aggregate (RFMA) as a fine aggregate for new masonry mortar creation. The pre-wetting effect on the aggregate before creating the mixture was analyzed as a method to reduce its absorption potential. A control mixture of conventional mortar and two groups of recycled mortars were designed with a partial replacement of natural sand by RFMA (pre-wetted and not pre-wetted) performed in different proportions. The results established that the pre-wetting process allows a reduction in the amount of water required during the creation of new mixtures, regulating the water/cement (W/C) ratio and improving the properties of recycled mortars such as air content, fresh and hardened densities, and compressive and adhesive strength for all substitution levels. Mortar made with a 20% substitution and pre-wetted until it was at 67% of its absorption capacity displayed adhesive values higher than the ones shown by the reference mortar. The pre-wetting process proves to be an easy performance technique; it is inexpensive, environmentally friendly, and the most valuable fact is that specialized equipment is not necessarily needed. This process is the most profitable option for improving RFMA exploitation and reuse.

Effect of Fiber Content on the Mechanical Properties of Engineered Cementitious Composites with Recycled Fine Aggregate from Clay Brick.

In this study, recycled fine aggregate (RFA), also known as recycled brick micro-powder (RBM), was used to completely replace quartz sand for the preparation of green, low-cost ecological engineered cementitious composites (ECO-ECC). RFA was used to replace ultrafine silica sand in the range of 0-100%. Firstly, the optimal replacement rate of RFA was determined, and the test results showed that the ECO-ECC prepared by fully replacing quartz sand with RFA as fine aggregate had strain hardening and multiple cracks, and the tensile strain of the specimens could reach 3%. Then the effects of fiber volume fraction and size effect on the mechanical properties of ECO-ECC were systematically investigated. The results showed that the fiber volume fraction has some influence on the mechanical properties of ECO-ECC. With the increase of fiber volume fraction, the ultimate deflection of the material keeps increasing up to 44.87 mm and the ultimate strain up to 3.46%, with good ductility and toughness. In addition, the compressive strength of the material has a good size effect, and there is a good linear relationship between different specimen sizes and standard sizes. It provides a good basis for engineering applications. Microscopic experimental results also showed that fibers play an important bridging role in the material, and the fiber pull-out and pull-break damage effects are significant.

Experimental Study of Utilizing Recycled Fine Aggregate for the Preparation of High Ductility Cementitious Composites.

Waste concrete was recycled and crushed into fine aggregate to prepare a high ductility cementitious composite (HDCC) in this study, for helping dispose the massive amount of construction waste and for reserving natural resources. Firstly, the features of recycled fine aggregate (RFA) were analyzed in detail and compared with natural fine aggregate (NFA). After that, the mechanical properties, including compression, flexure, bending and tension, and the microstructure of high ductility cementitious composite (HDCC) prepared with RFA were systematically investigated and compared with that of HDCC prepared with NFA. The results show that, since RFA has a higher water absorption rate and contains 4.86 times as much crush dust as NFA, HDCC with RFA forms a denser matrix and a higher bond between fiber and matrix than HDCC with NFA. Thus, HDCC with RFA has higher compressive, flexural, bending and tensile strength. Meanwhile, the higher bond between the fiber and matrix of HDCC with RFA and the finer particle sizes of RFA can greatly promote the development of multiple cracking. As a result, HDCC with RFA exhibits more remarkable stain hardening, and presents 182.73% higher peak deflection in bending and 183.33% higher peak strain in tension than HDCC with NFA. Finally, with the consideration of fiber volume fraction, the prediction models for the peak strengths of HDCC with RFA were proposed. The prediction results show a good agreement with the test results.

Concrete Mix Design for Completely Recycled Fine Aggregate by Modified Packing Density Method.

The undesirable properties of conventional recycled fine aggregate (RFA) often limit its application in the construction industry. To overcome this challenge, a method for preparing completely recycled fine aggregate (CRFA), which crushes all concrete waste only into fine aggregate, was proposed. The obtained CRFA had high apparent density, and its water absorption was lower than that of the conventional RFA. To take advantage of the CRFA, this paper introduced the modified packing density method for the CRFA concrete mix design. The modified packing density method took account of the powder with a particle size of smaller than 75 µm in the CRFA and balanced both the void ratio and the specific surface area of the aggregate system. Concrete (grade C55) was prepared using the CRFA to validate the feasibility of the proposed method. The unit price of the prepared CRFA concrete was around 12.7% lower than that of the natural aggregate concrete. Additionally, the proposed procedure for the concrete mixture design could recycle all concrete waste into the new concrete and replace all the natural fine aggregate in the concrete mixture.

Mechanical Behavior of Masonry Mortars Made with Recycled Mortar Aggregate.

Recycling is an important habit to avoid waste. This paper evaluates the performance of masonry mortar, elaborated by replacing natural sand with recycled fine aggregate (RFA) obtained from mortar. Five families of mixtures were prepared with different replacement proportions: 20%, 40%, 60%, and 100%. A 1:4 volumetric cement-to-aggregate ratio was used for all mixtures by experimentally adjusting the amount of water to achieve the same consistency of 175 ± 5 mm. The effects of the following procedures were analyzed: (1) the use of a deconstruction technique to collect the RFA, (2) pre-wetting of the aggregates, and (3) the use of a commercial plasticizer. Experimental results show that it is possible to use this type of recycled fine aggregate as a substitute for natural sand by up to 60% in the manufacture of masonry mortar without significantly affecting its properties.

Sulfur Dioxide Degradation by Composite Photocatalysts Prepared by Recycled Fine Aggregates and Nanoscale Titanium Dioxide.

To alleviate the heavy burden on landfilling, construction and demolition wastes (C&DWs) are recycled and reused as aggregates in cementitious materials. However, the inherent characteristics of recycled fine aggregates (RFA), such as the high crushing index and high-water absorption, magnify the reusing difficulty. Nevertheless, attributing to the high porosity and high level of calcium hydroxides existing in the old mortar, RFA is featured with a high specific surface area and a high alkalinity. These features are useful to augment the total photo-degradation of SO2 by nano-TiO2 (NT) intermixed mortar, leading RFA to be an excellent potential carrier to load nano-TiO2 and prepare the composite photocatalyst. Hence, this study proposed to load NT onto the surface of RFAs and river sands (RSs) (the control) by the soaking method, preparing composite photocatalysts denoted as NT@RFA and NT@RS, respectively. The prepared composite photocatalysts were then utilized as sands in photocatalytic mortar to evaluate for SO2 degradation. Experiments identified a 50% higher amount of NT was loaded onto the surface of FRA relative to the control. This higher loading amount plus higher alkalinity ultimately translated into a higher photocatalytic activity. In addition, the mortar containing NT@RFA exhibited 46.3% higher physiochemical absorption and 23.9% higher photocatalytic activity than that containing NT@RS. In addition, the durability, embodied by the reuse and anti-abrasive properties, of NT@RFA exceeded that of NT@RS. The overall findings reveal that the NT@RFA not only garners beneficial effect from the high porosity but also generates positive effect from the high alkalinity. Though a number of studies deal with building materials with NT, this study is the first to load NT onto RFA and prepare composite photocatalysts which were then used as fine aggregates in building materials. Consequently, this study proves the potential high-added-value reusability of RFA in green construction materials and provides a low-cost, high-efficiency approach to degrade atmospheric SO2.

Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.