Recycled Brick Research Articles

Shear Behavior of Solid and Hollow Cylindrical Concrete Beams Made with Recycled Brick

Shear Behavior of Solid and Hollow Cylindrical Concrete Beams Made with Recycled Brick

Particle crushing mechanism of recycled aggregate with different component categories: applied to pervious concrete base

This paper focuses on the particle crushing mechanism of construction solid waste recycled aggregate (CWRA), particularly recycled concrete (RC) and recycled bricks (RB), using natural gravel (NG) as a control group. Compression tests, combined with the Weibull distribution, fractal dimension theory, and relative crushing rate, were conducted to investigate the crushing behavior of these materials under different loads. Results indicate that, under the same load, the crushing degree ranks from highest to lowest as RB, RC, and NG. The Weibull distribution effectively describes the crushing state, with “fragmentation” being the primary mode for most materials, while RC also exhibits “grinding.” As the load increases, the relative crushing rate rises for all materials but slows beyond a certain load threshold, indicating greater difficulty in further crushing. The study identifies a load threshold of 400 kN, beyond which changes in void fraction and relative crushing rates become less significant, particularly in stronger aggregates. Highlights Identified that mortar attached to the RC surface is the primary cause of the increased particle crushing below 0.6 mm. Introduced Weibull distribution parameters a and b to accurately characterize the crushing state of RA particles. Revealed the errors between fractal dimension-based evaluations and the actual crushing state of RC particles. Proposed a two-stage crushing mode for RC. Determined the critical threshold value for the variation of crushing degree with load level.

Bond behavior between geopolymer recycled brick aggregate concrete and steel bars after exposure to high temperatures

The use of recycled brick aggregate (RBA) as the replacement for natural coarse aggregate in geopolymer concrete is an effective method for waste recycling. When the formed geopolymer recycled brick aggregate concrete (GRBC) is employed in structures, it may encounter the risk of fire. Whether the steel bars and GRBC can work together after a fire is the basis for structural safety and analysis. However, previous research on the bond behavior between GRBC and steel bars after exposure to high temperatures is still lacking. In this paper, pull-out tests on 50 GRBC and 50 ordinary recycled brick aggregate concrete (ORBC) were conducted to investigate the effects of temperature (20 °C, 200 °C, 400 °C, 600 °C, and 800 °C), and RBA replacement ratio (0 %, 25 %, 50 %, 75 %, and 100 %). The test results show that the failure pattern of GRBC specimens changes from splitting-pull-out failure to pull-out failure as the heating temperature increases. The bond strength decreases with the increase of temperature or RBA replacement ratio. When the temperature rises from 200 °C to 800 °C, the bond strength of GRBC pull-out specimens decreases by 11.54 %–72.33 % compared with the specimens at room temperature, and the decrease rate is lower than that of ORBC. The bond strength of GRBC specimens with a 100 % replacement ratio decreases by 46.34 %–53.74 % compared with those without replacement. The peak slip of GRBC specimens generally increases with increasing temperature or decreasing RBA replacement ratio. Based on the post-temperature test results and the room temperature model, suitable models for the bond strength and peak slip of GRBC after high temperatures were established. The predicted results of bond stress−relative slip curves were in good agreement with the test results. The findings of this study can provide a foundation for the application of GRBC, and provide a basis for its structural analysis after high temperatures.

Recycling of Brick and Road Demolition Waste in the Production of Concrete

Construction and public works sites generate a significant amount of waste that is often costly to dispose of. To reduce the environmental impact and promote sustainability, recycling and recovering this waste is increasingly being recognized as a viable solution. This paper presents the findings of an experimental program investigating the feasibility of using brick and road demolition waste as concrete components. By substituting a portion of sand and cement with recycled materials, this study compares the properties of the reference concrete with concrete containing varying amounts of brick waste and road demolition debris. The obtained results demonstrate that the produced concrete with up to 40 % recycled content achieved a compressive strength exceeding 20 MPa after 28 days. This study suggests that recycled brick and road demolition waste could be a sustainable and economical substitute for conventional aggregates. Incorporating these materials into concrete reduces the cement content while maintaining or even improving the fresh and hardened properties of the concrete. However, it is crucial to limit the use of road demolition sand to 10 %, crushed brick fines to 20%, and brick sand (CBS) to 30% to ensure optimal performance.

Feasibility of foam concrete using recycled brick and roof tile fine aggregates

Brick (BR) and roof tile (RT) fine aggregate fractions derived from construction and demolition wastes have a low recycling rate in new construction and building materials. This article assesses their suitability for replacing the limestone aggregate in foam concrete, which helps valorise such fractions and conserve natural limestone resources. Two concrete categories containing or not silica fume (SF) were investigated, while the BR and RT aggregate replacement rates were 10%, 20% and 40%. Tested properties include flow, density, water absorption, porosity, thermal conductivity, mechanical strengths, microscopy, drying shrinkage, resistance to freeze/thaw cycles and elevated temperature. Results showed that the concrete mechanical properties improved when the limestone aggregate was replaced by 10% BR or RT but gradually curtailed at higher addition rates. Such results concorded with the density, water absorption and porosity measurements. Foamed concrete containing BR is more resistant (compared to RT) to drying shrinkage, freeze/thaw cycle, and heat exposure, which was ascribed to the relatively lower BR porosity that improves the concrete mechanical properties and durability.

Strength and microstructure of geopolymer recycled brick aggregate concrete after high temperatures

Geopolymer recycled brick aggregate concrete (GRBC), as a new environmentally friendly material, exhibits excellent mechanical performance at ambient temperature, but its properties after exposure to high temperatures are not clear. In this paper, the strength and microstructure of GRBC after high temperatures were investigated and compared with ordinary recycled brick aggregate Portland cement concrete (ORBC) through compressive strength, splitting tensile strength, and microscopic tests. The main parameters varied in the strength tests were temperature (20 °C, 200 °C, 400 °C, 600 °C, and 800 °C) and recycled brick aggregate (RBA) replacement ratio (0 %, 25 %, 50 %, 75 %, and 100 %). The results indicated that the strength of GRBC decreased less than that of ORBC after high temperatures. The compressive strength retention rate of GRBC after exposure to 800 °C was 0.359−0.456, and the tensile strength retention rate was 0.415−0.442. The strength of GRBC with 50 % RBA replacement ratio was about 0.70 that of the case without RBAs. The microscopic test results showed that the structure of GRBC was denser than that of ORBC, and the interfacial transition zone (ITZ) between matrix and RBAs was less affected by the temperature. The first weak zone after high temperatures was RBA itself for GRBC, but ITZ between matrix and RBAs for ORBC. The X-ray diffraction analysis indicated that the phase composition of GRBC and ORBC after high temperatures was basically similar to that at ambient temperature. The strength of GRBC was mainly provided by the N-A-S-H and C-A-S-H gels, while the strength of ORBC was mainly relied on the C-S-H gel.

Optimisation of the performance of alkali-activated mortars using CDW binders from different sources

This study investigates the fresh-state properties and the hardened-state physical and mechanical properties of a total of 64 alkali-activated mortars incorporating different wastes as binders, such as fly ash (FA), recycled concrete (RC), recycled brick (RB), and recycled tile (RT). These waste materials were activated using sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). Linear regression analysis was employed to evaluate the impact and significance of Na2O concentration (9 % or 15 %), modulus of silica (0.5 or 1), curing time in the oven (24 or 48 h), and temperature (50 °C or 70 °C) on the properties of the mortars. The results, analysed using ANOVA, indicate that all properties were affected by these parameters, except for the initial curing time in the oven for mortars made with construction and demolition waste (CDW), which showed no significant differences between periods of 24 and 48 h. Compared to mortars produced with RC, the contribution of these parameters to mechanical properties was more prominent in the mixes with RT and RB. The highest compressive strength at 28 days, for the mortars with CDW binders, was obtained by incorporating RT with 12 % of Na2O, modulus of silica of 1 and 70 °C for 48 h of initial curing, reaching 12.5 MPa. This value is 2.1 times higher than the strength obtained in mixes with RB or RC. The results also show that the performance of the mortars is highly related to the reactivity of the waste material (mortars with RT performed better) and prove that each raw material has its own optimum criterion.

Quantifying the influence of single particle shape on crushing characteristics of recycled aggregates: Experimental and numerical insights

Exploring the interplay between shapes and crushing characteristics of recycled aggregates (RA) is pivotal for understanding their macro-mechanical behavior in bulk materials. This investigation quantitatively characterizes the shapes of recycled bricks (RB), recycled concrete (RC), and recycled mortar (RM) particles, and assesses their single-particle crushing characteristic. Key focus areas include the analysis of crushing modes, fractal attributes, strength, and energy, supplemented by a comparative study using discrete element method (DEM) simulations to predict outcomes for particles of specific sphericity. Findings reveal that the shapes of RA particles are mainly disk, block, blade and bar, with particle size showing negligible influence on these forms. Crushing behaviors are categorized into penetrating fracture, corner rupture, and overall fragmentation, closely linked to particle sphericity. Notably, an increase in sphericity leads to a reduction in fractal characteristics of RA, refining the gradation distribution from broad to narrow spectrums. An exponential relationship is identified between the crushing strength of RA and particle sphericity, a pattern also mirrored in the correlation between crushing energy and sphericity, thereby underscoring the significant influence of particle shape. These relationships facilitate predictions regarding the crushing strength and energy based on sphericity. While numerical simulations broadly align with experimental data, discrepancies in the crushing energy of highly spheric particles necessitate adjustments, resulting in a modified predictive equation for crushing energy. This work enriches the understanding of RA crushing behavior, offering invaluable insights for predicting the single-particle strength and deformation characteristics across different sphericities, thus advancing material engineering and recycling practices.

Fabrication and characterization of recycled construction waste bricks modified with sisal fibers

The study presents an investigation into the preparation and characterization of modified hemp fiber reinforced recycled construction waste bricks for ground and road applications. By incorporating 1 % hemp fiber and a 70/30 ratio of recycled concrete aggregate to recycled brick aggregate, the optimal combination was identified, resulting in a maximum compressive strength of 36.2 MPa, a 38.7 % improvement over the control bricks. The addition of 2 % hemp fiber increased the flexural strength by 85.7 %, while the thermal conductivity decreased by 41.5 % with the inclusion of 2 % hemp fiber and 100 % recycled brick aggregate. Scanning electron microscopy and X-ray diffraction analysis confirmed the compatibility of hemp fibers with the cement matrix and their role in enhancing the microstructure of the bricks and hydration process. These findings highlight the potential of hemp fiber-reinforced recycled waste bricks as environmentally friendly high-performance materials for sustainable ground and road construction.

Enhancing compressive strength and sustainability: a machine learning approach to recycled brick and tile concrete mix design

Optimizing concrete mix designs, especially for recycled brick and tile (RBT) concrete, is critical in construction materials. The optimization of RBT concrete mix designs was investigated using machine learning (ML) methods and metaheuristic algorithms. Hyperparameter tuning of the XGBoost (XGB) model was conducted using SFO, HGS, and HBA algorithms. Critical hyperparameters, including population size and iterations, were identified to ensure model convergence and performance. The model's predictive accuracy for compressive strength (CS) was evaluated using the coefficient of determination (R2) metric, revealing its superiority in mitigating overfitting. SHAP analysis highlighted testing age, cement content, and total coarse aggregate as influential input variables. A practical approach to RBT concrete mix design optimization was introduced, enabling the achievement of specific CS targets while maximizing RBT usage. Pareto solutions provided actionable insights for engineers to create tailored high-performance concrete mixes. This research contributes significantly to sustainable concrete mix design by offering practical ML tools.

Assessing particle crushing mechanism and optimizing design for recycled aggregates in road bases via a novel particle crushing DEM method

This study introduced an innovative and effective algorithm that aims to provide a comprehensive simulation of particle crushing behavior in complex granular materials. Based on the Griffith's strength theory, the algorithm was formulated and implemented using the discrete element method (DEM). This algorithm accurately simulates the crushing behavior of real particles under arbitrary three-dimensional stress states. The robustness of the proposed method and the distribution pattern of the resulting child particles were verified through a series of single- and multi-particle crush tests. The findings demonstrate that the proposed approach exhibits exceptional generalizability, effectively describes the particle crushing behavior of granular materials, and features high efficiency and cost-effectiveness. The particle crushing simulations were conducted accordingly via DEM on a combination of natural gravel (NG), recycled mortar (RM), and recycled brick (RB) aggregates for use in road bases. The results revealed the particle crushing mechanisms in single-, binary-, and ternary-type recycled aggregate mixtures. Additionally, this study revealed the influence of recycled aggregate types on particle crushing within these different mixtures. The ternary design charts and tables were developed to determine the maximum contents of recycled aggregates in accordance with the particle crushing value requirements for different highway classes and aggregate base types. This study not only holds significant theoretical importance in developing efficient particle-crushing algorithms, but also offers valuable insights and scientific references for improving the resourceful utilization of recycled aggregates derived from construction and demolition wastes in road bases.

Bond behavior of deformed rebar in concrete containing recycled brick aggregate and waste rubber

The reuse of aggregates and crumb rubber (CR) in concrete is gaining interest globally for reducing the adverse effects on the environment and maintaining construction sustainability. The bond strength of reinforcing rebars in such concrete is one of the key issues to be addressed before their practical application, particularly in structural elements. Pull-out tests were performed on 80 specimens to assess the bond performance of deformed rebars in rubberized recycled brick aggregate concrete (RRBAC). After investigating the strength properties of RRBAC, pull-out tests were performed on two sizes of cylindrical specimens. RBA%, CR%, rebar diameter (d), embedment length (le), and concrete cover-to-rebar diameter ratio (c/d) were among the test variables in this bond behavior investigation. Bond stress-slip relationships were obtained, examined, and average bond strengths were compared with the available codes. Concrete split failure was observed in 79% of the tested specimens, whereas rebar fracture was not seen in any of the tests. The bond strength was found to be decreased with the inclusion of RBAs and CRs though relative improvement was observed for higher percentage RBAs. Additionally, regression analysis was performed on the experimental data to produce a closed-form equation for forecasting the bond strength for RRBAC. With a strong coefficient of determination (R2 = 0.97) and low values of error terms, the predicted bond strengths were seen to be a good agreement with the test results.

Study on Mechanical Properties and Microscopic Mechanism of PVA-Modified Recycled Brick Aggregate Concrete

This paper addresses a range of environmental issues stemming from the improper disposal of construction waste and its low recycling rate by examining the effects and mechanisms of polyvinyl alcohol (PVA) solution in modifying recycled aggregates. Basic physical properties, energy-dispersive spectroscopy (EDS), X-Ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to study these effects and mechanisms. Tests on basic mechanical properties were performed to assess the impact of aggregate modification and the brick-concrete ratio on recycled brick-aggregate concrete’s mechanical characteristics. Nuclear magnetic resonance and microhardness tests were performed to analyze the influence exerted by PVA modification on the interfacial transition zone (ITZ), microstructure, and pore structure, thus exploring the connection between modified recycled-brick-aggregate concrete’s microstructure and its icromechanical properties. The findings show that the water absorption and crushing index of recycled aggregates (RA) immersed in a 10% PVA solution for 24 h decrease significantly, while the apparent density increases most notably. This phenomenon can be ascribed to the development of a PVA coating on the exterior of the reused aggregates. The optimal mechanical properties for recycled brick aggregate concrete (RAC) occur when the replacement rate is 30% and the brick-concrete ratio is 1:1. The compressive strength is 44.2 MPa, the bending strength is 15.6 MPa, and the splitting tensile strength is 3.85 MPa. Additionally, the modification with PVA results in a higher percentage of transition pores, while simultaneously reducing the percentage of macropores. There is an uptick in the frequency of harmless and less harmful pores, and a declining proportion of harmful and more harmful pores. The ITZ’s structural morphology in the RAC is effectively improved by the coating structure formed through the bonding of the polymer with cement hydration products, and PVA modification reduces the thickness of this zone.

Study on the mechanical properties and microstructure of recycled brick aggregate concrete with waste fiber

Abstract Recycled concrete technology can promote the sustainable development of the construction industry, but the insufficient mechanical properties of recycled concrete have become a key constraint on its development. By adding waste fibers, the mechanical properties of recycled concrete can be improved, and the problem of disposing of waste polypropylene fibers can be solved. In this article, the effects of recycled brick aggregate content and waste fiber content on the mechanical properties and microstructures of recycled brick aggregate concrete through macroscopic mechanical experiments and microstructure experiments are investigated. The results show that the addition of recycled brick aggregate reduces the mechanical properties of concrete; when the content of recycled brick aggregate is 100%, the compressive strength and splitting tensile strength decrease by 22.04 and 20.00%, respectively. The addition of waste fibers can improve the mechanical properties of recycled brick aggregate concrete, but it is necessary to control the contents of waste fibers in a certain range. When the content of waste fibers is 0.08%, the best improvement effect on the mechanical properties of concrete is achieved; the compressive strength of concrete with a 50% (100%) recycled aggregate replacement rate increases by 6.06% (8.90%), while the splitting tensile strength of concrete with a 50% (100%) recycled aggregate replacement rate increases by 2.30% (6.16%). Through microstructural analysis, the mechanism by which waste fiber improves the mechanical properties of recycled brick aggregate concrete is revealed. The addition of waste fibers has the effect of strengthening the framework inside the recycled brick aggregate concrete, forming a good structural stress system and allowing the recycled brick aggregate concrete to continue to bear loads after cracking. In this study, waste brick aggregate and waste fiber are effectively utilized, which can not only reduce pollution to the environment but also realize the sustainable utilization of resources.

Study on Resourceful Treatment and Carbon Reduction Intensity of Metro Shield Slag: An Example of a Tunnel Interval of Shenzhen Line 13

At present, the scale of subway construction in Chinese cities has reached a new height, and the shield slag produced by it has also surged year by year. Untreated subway shield slag not only occupies the space resources of the country, but also carries CO2, which causes negative impacts on the environment and which, as a result, is not conducive to the realization of the goal of the national “double-carbon” strategy. Therefore, how to effectively manage the shield slag produced by subway construction has become a scientific problem that needs to be solved urgently. In order to scientifically dispose of metro shield slag and quantify the carbon reduction intensity of its disposal, based on the new shield slag integrated recycling technology, and taking a tunnel interval of Shenzhen Line 13 as an example, this study systematically sorted out the shield slag disposal process, clarified the management path of the on-site resource utilization of slag, and quantitatively compared the carbon emissions before and after the treatment as well as carbon reduction intensity. The results show that the on-site disposal process is basically feasible, and that, it is possible to achieve a shield structure slag reduction of resource products and mud cake water content of less than 40% of the target, in the case of 160,000 m3 of shield structure slag resource utilization after a total carbon reduction of about 4240.13 t CO2, of which each preparation of 1 m3 of recycled bricks can bring about a benefit of carbon reduction of 240.09 kg CO2. Compared with the conventional mud head truck slag disposal, shield structure slag resource utilization can save a utilization cost of about 10.4 million yuan, meaning that, in terms of economic and social levels, this method can achieve good benefits. This case verifies the feasibility of the new technology, and the results of the study can provide experience for other metro projects’ shield slag resource utilization, and provide stakeholders with a shield slag recycling management strategy for government departments to scientifically formulate metro shield slag management policy to provide data support.

Experimental Torsional Capacity of Plain Concrete Beams Made from Crushed Clay Brick and Recycled Brick Concrete as Coarse Aggregate

Concrete was made with four different types of coarse aggregate, i.e., natural stone aggregate concrete (NSAC), crushed virgin clay brick aggregate concrete (VBAC), crushed recycled brick concrete aggregate concrete (RBAC), and crushed recycled stone concrete aggregate concrete (RSAC). Beam specimens prepared from these four types of concrete were subjected to pure torsional moment up to failure. From this experimental procedure, ultimate torque at failure along with twisting angle were observed. From the torque vs. twisting angle curves, torsional stiffness and torsional toughness were also evaluated for these four types of concrete. It was observed that ultimate torque of VBAC and RBAC was 95% and 90% of that of NSAC, respectively. The torsional toughness of VBAC was found to be 68%–72% of that of NSAC. In addition, experimental torques were compared with predictions of torsional strength as per five commonly used models. For VBAC, the ultimate torque prediction made by skew bending theory was found to be the closest to the experimental findings.

Mechanical properties and frost resistance of recycled brick aggregate concrete modified by nano-SiO2

Abstract In this work, brick aggregates were immersed in nano-SiO2 solution for 2 days, and the effects of nano-SiO2 on the brick aggregate properties, mechanical properties (compressive strength, flexural strength, and splitting tensile strength), frost resistance (apparent phenomenon, mass loss, relative dynamic modulus of elasticity, and compressive strength) of recycled brick aggregate concrete and the microstructure of recycled brick aggregate concrete were investigated. The results show that nano-SiO2 can effectively improve the performance of recycled brick aggregate and the mechanical properties of recycled brick aggregate concrete, mainly by reducing the water absorption and crushing index and improving the compressive strength, flexural strength, and splitting tensile strength. With increasing nano-SiO2 solution concentration, the compressive strength, flexural strength, and splitting tensile strength of recycled brick aggregate concrete first increase and then decrease. The frost resistance of recycled brick aggregate concrete is superior to that of ordinary aggregate concrete, while the frost resistance of nano-SiO2-modified recycled brick aggregate concrete is inferior to that of recycled brick aggregate concrete. In addition, the freeze‒thaw damage mechanism of recycled brick aggregate concrete is analyzed, and a freeze‒thaw damage life prediction model of nano-SiO2-modified recycled brick aggregate concrete based on the Weibull distribution is proposed.

Characterization of Recycled Aggregates of Concrete and Bricks in the Central Region of Burkina Faso

Aggregates used in the construction of civil engineering works have an impact on the properties of concrete. For several years the central region is famous because of the effects of extraction of natural aggregates on the environment. We conducted laboratory tests on several recycled aggregates of concrete and bricks to determine their mechanical properties. This choice was guided by a concern to identify and analyze the characteristics of natural and recycled aggregates of concretes that impact the properties of concrete on the one hand and to show the importance of increased use of recycled aggregates in concrete production to better preserve the environment and move towards sustainable development moreover. To better understand the qualities of these aggregates, it is necessary for us to carry out experimental tests in the laboratory.
 The objective also guided the choice of the different types of recycled aggregates selected for the measurement of mechanical properties in the central region: Crushed Natural Gravel, Rolled Natural Gravel, Crushed Recycled Gravel, Recycled Spinning Gravel, Alluvionary Natural Sands, Recycled Brick Sands.
 The results show that recycled aggregates of concrete and bricks in the central region can be used for high-quality concretes on the one hand and reduce the impact of artisanal extraction of non-recycled aggregates on the environment on the other hand.
 In short, we retain that the characteristics of recycled aggregates are a function of the rate of mortar gangues glued to the mother aggregates.

Using recycled bricks to improve the compressive strength of concrete and produce lightweight concrete

This research presents the aim of using sustainable materials like crushed bricks from the demolition of old buildings as additives to preserve the environment, reduce energy consumption, reduce the cost of concrete, improve the properties of concrete, and obtain lightweight concrete for high buildings with more fluidity for narrow places. Also, it discusses the best replacement ratios because the knowledge about them is still lake. Three mixes of concrete were used and tested. Mix-1was the standard, where the replacement of coarse aggregate with crushed brick aggregate has been used in mix-2, the mix-3 was to study the replacement of fine aggregate by powder brick. In this analysis, only two factors were taken into account: the percentage of coarse aggregate replaced by brick aggregate (from 0 to 50%) and the percentage of fine aggregate replaced by brick aggregate (from 0 to 75%). Compressive strength was tested after curing at ages (7, and 28) days. The results showed that concrete with crushed brick aggregate reduces unit weight and increases of compressive strength of concrete. Using mix-2 increased the compressive strength by about 9.7%, and 7% at ages (7, 28) days respectively, and reduced the weight by 11%. Also, using mix-3 increased the compressive strength with high percentages of about 59%, and 61% at ages (7, and 28) days respectively, with a little percentage of reducing the weight by 2%.

Recycling of waste magnesia refractory brick powder in preparing magnesium phosphate cement mortar: Hydration activity, mechanical properties and long-term performance

Waste magnesia refractory bricks (MRBs) that remain from industrial production are landfilled in large quantities or recovered to prepare recycled bricks with low added value. In consideration of the significant level of magnesia in waste bricks, this work proposes to extract and recover magnesia from spent bricks for manufacturing magnesium phosphate cement mortar (MPCM). The essential attributes of recycled magnesia (RM) and its influence on the workability, hydration temperature rise, mechanical properties, phase evolution, long-term performance and microstructure of MPCM were analyzed. The results reveal that RM significantly prolongs the setting time and reduces the overall hydration heat release, which is beneficial to the application in large-scale engineering. The compressive strength of MPCM prepared by RM (MPCMRM) initially grew and then decrease with the increase of magnesia to phosphate ratio (M/P ratio). The optimal performance was observed at M/P = 4, and the compressive strength cured for 3 h and 28 d were 39.1 MPa and 68.5 MPa respectively. While the mechanical properties of MPCMRM were marginally inferior to those of dead-burned magnesia (DM), it was found to satisfy the early and long-term strength requirements of engineering repair materials. In addition, MPCMRM did not generate new mineral phases, and the crystal morphology of hydration products (struvite) was worse than that of mortar prepared by DM. MPCMRM also exhibits excellent water resistance and volume stability due to the crystal characteristics of low-activity RM. It seems that RM can completely replace DM to prepare MPCM and achieve satisfactory performance, which not only reduces the cost of repair materials, but also provides a fresh approach for the recycling of waste MRBs.