Residual Bond Strength Research Articles

Corrosion failure analysis of interfacial bond performance in circular seawater sea-sand concrete encased weathering steel structures

This paper investigated the bond-slip behavior of circular seawater sea-sand concrete encased weathering steel (CSSCEWS) structures after chloride-induced corrosion. Electrochemical corrosion tests and push-out tests were conducted on fifteen designed CSSCEWS specimens. The results revealed that the corrosion ratio and steel section type distinctly influenced the interfacial bond performance. Both the ultimate and residual bond strengths decreased with the increase of the corrosion ratio, and the decline rate slowed down gradually. Compared to the uncorroded specimens, the average damage ratio of the ultimate strength of the specimens with a corrosion ratio of 8% is 25.9%, while the average damage ratio of the residual strength is 49.1%. The bond toughness continuously decreased with prolonged corrosion, while the bond stiffness and energy dissipation index first increased and then decreased. Additionally, formulas for calculating the corroded bond strengths of CSSCEWS specimens were proposed. Considering the strength damage due to corrosion and the stiffness damage due to slip, a three-stage bond-slip constitutive model was proposed. Finally, this model was applied to the nonlinear spring elements in finite element modeling to effectively simulate the interfacial bond behavior during the loading of corroded CSSCEWS specimens.

Re-anchoring of failed in-situ grouted post-tension anchor rods with high rod to duct area ratios

An experimental program was conducted that simulated an internal rod failure to review re-anchoring ability, transfer length, and residual bond strength of grouted post-tension anchors with high rod to duct area ratios under in-situ conditions. Additionally, a theoretical model founded on interference fit, initial assumptions, and debris wedging was expanded to include a concrete to pipe interface. The experimental program included three full scale concrete specimens, whose length, annulus space for grout, and anchor diameter were nearly identical to existing anchors within dams in California. The specimens were instrumented along the anchor and concrete to capture strains in the longitudinal and transverse directions, the values of which, were compared against the theoretical model and found to be in good agreement along with the measured transfer length values. The debris wedging ratio found was consistent across the specimens and closely resembles the ratio captured in a similar study by the authors.

Bond Behavior and Failure Mechanisms of the Interface between Engineered Cementitious Composites and Shaped Steel

Due to their excellent ductility and crack-control ability, engineered cementitious composites (ECCs) combined with shaped steel can produce steel-reinforced engineering cementitious composite (SRECC) structures which exhibit significant advantages in prefabricated buildings. The interface bond behavior is the base for the cooperative working performance of the shaped steel and ECC. This study included push-out tests of one ordinary concrete control specimen and ten ECC specimens. The various parameters were the ECC compressive strength, fiber volume content, cover thickness, and the embedded length of shaped steel. The bond stress–slip curves at the loading and free end were obtained, and the effects of various parameters on the characteristic points of curves were analyzed. The results indicated that the ordinary concrete specimen failed in brittle splitting, with the cracks completely penetrating the surface of the specimen. Due to the fiber-bridging effect in ECCs effectively preventing the development and extension of cracks, the shaped steel at the free end was obviously pushed out, and the surrounding matrix maintained good integrity after testing finished. For ECC specimens, bond or splitting-bond failure occurred, exhibiting outstanding ductility. Compared with the ordinary concrete specimen, the standard ultimate and residual bond strength of ECC specimens improved by 37.9% and 27.4%, respectively. Besides the increase in ECC compressive strength, the fiber volume content and cover thickness had a significant positive influence on the ultimate and residual bond strength, whereas the effect of the embedded length was the opposite. Finally, the calculation equations of characteristic bond strength were proposed, and the calculated values matched well with the experimental values.

Bond behavior between highly ductile fiber-reinforced concrete (HDC) and deformed rebar under repeated and post-repeated monotonic loading

This paper tested nine groups of six specimens each to investigate the bond behavior between deformed steel reinforcing bars and highly ductile fiber-reinforced concrete (HDC) under repeated and post-repeated monotonic loading considering different compressive strengths, flexural toughnesses, fiber volume contents and cover thicknesses. The results indicate that fiber bridging of cracks allowed the bonds in the HDC specimens to exhibit more ductile failure mode and greater energy dissipation capacity than those in conventional concrete. Furthermore, an increase in compressive strength or cover thickness improved the bond strength, whereas excessive flexural toughness was detrimental to further improvement in the bond strength and energy dissipation capacity. Finally, the residual bond strength increased by 95.03 % as the fiber volume content increased from 1 % to 2 %. Specimens with insufficient flexural toughness and cover thickness exhibited the deterioration in their bond strength and residual bond strength, with the former degrading more than the latter. After repeated loading, the stiffness of the primary ascending branch of the monotonic bond stress–slip curve significantly increased, whereas that of descending branch generally decreased. These results were applied to derive an equation for the bond strength between deformed bars and the HDC in which they are embedded under post-repeated monotonic loading.

Bond properties of deformed steel bars coated with quartz sand modified enamel in concrete under both monotonic and reversed cyclic loading

Reinforced concrete structures located in seismic zones require significant ductility, which is affected by the bond properties between steel and concrete. The bond may be negatively impacted by anti-corrosion coatings. Quartz sand modified enamel (QSME) enhances the bond ductility for steel rebars in concrete under monotonic loading. This study investigates the bond properties of QSME-coated deformed steel rebars under monotonic and cyclic loading. For comparison, uncoated, fusion-bonded epoxy (FBE)-coated, and unmodified enamel-coated steel rebars are also studied. In addition to the coating type, the effects of steel rebar diameter, anchorage length, and concrete strength are considered. Acoustic emission (AE) technique was utilized to capture the AE energy released during the pull-out tests. Results showed that the bond stiffness and strength properties of QSME-coated steel rebars increase when concrete strength increases, while they decrease with rebar diameter under monotonic loading. The energy dissipation capacity of QSME-coated deformed rebar specimens is in average 1.43, 2.11, and 1.56 times greater than that of uncoated, FBE- and enamel-coated specimens, respectively. Among all coating types, the QSME-coated steel rebars exhibit the highest degradation index for the residual bond strength and the most AE activity, attributed to their improved chemical bonding and interfacial friction.

Bond performance of marine concrete with nano-particles to steel bars under the action of both Cl− erosion and freeze-thaw cycles

Offshore structures serve in harsh environment here the combined effects of freeze-thaw cycles and Cl− erosion severely degrade the bond performance between steel bars and concrete, significantly reducing the structures' service life. This paper investigates the bond performance of marine concrete with nano-particles to steel bars under the simultaneous influence of Cl− erosion and freeze-thaw cycles. The bond-slip (τ-s) curves are derived from pull-out tests, in order to reveal the mechanism of nano-particles to improve the bond performance of reinforced concrete under the action of both Cl− erosion and freeze-thaw cycles, the microstructure of the bond interface between steel bar and concrete is examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and mercury impression test (MIP). The test results show that adding nano-SiO2 and nano-TiO2 enhance the cracking bond strength (τs), ultimate bond strength (τu), ultimate slip value (Su), and residual bond strength (τr) of reinforced concrete. The optimal content for both nano-SiO2 and nano-TiO2 are 2 %, with nano-SiO2 showing superior effect. When Cl− erosion and the number of freeze-thaw cycles are certain (N = 100), the τu values of NSC20 and NTC20 are increased by 26.25 % and 16.68 %, and the Su values are increased by 25.30 % and 22.89 %, respectively, compared with PC. The results of the SEM and EDS analyses indicate that nano-particles promote C–S–H gel formation, reduce porosity and optimize concrete's pore structure, enhance shear strength at the bonding surface, reduce Cl− content at the interface, slow down the corrosion of the steel bars. Thus, the addition of nano-particles significantly improves the bond performance of reinforced concrete under the action of both Cl− erosion and freeze-thaw cycles, which is vital for enhancing the load-bearing capacity and seismic performance of engineering structures.

Degradation of flexural bond of CFRP bar in UHPFRC after exposure to elevated temperature

This paper investigated degradation of flexural bond of a ribbed carbon fiber reinforced polymer (CFRP) bar in ultra-high-performance fiber reinforced concrete (UHPFRC) after exposure to elevated temperatures. For this purpose, the mechanical properties of UHPFRC and thermal properties of CFRP bars after exposure to elevated temperatures were investigated, and a total of 16 groups of hinged beams were fabricated with variables of embedment length (4db, 10db, 20db, and 40db), bar type and exposed to elevated temperatures (200 °C, 300 °C, 400 °C, 600 °C). The mechanical properties of UHPFRC increased until elevated temperatures reached 400 °C and it was shown that the reduction of the ultimate tensile strength of CFRP bars were not notable after exposure to elevated temperatures of up to 300 °C. The ultimate moment of ribbed CFRP bars after exposure to elevated temperatures at 200 and 300 °C was similar. After exposure to an elevated temperature of 400 °C, it decreased by about 29–63 % compared to non-heated specimens, with bar rupture. Although similar decomposition temperatures of ribbed and sand coated CFRP bars occurred, the residual flexural bond strength of the ribbed CFRP bar was larger than that of the sand coated CFRP bar after exposure to elevated temperature at 400 °C. In addition, a relatively lower reduction of bond strength occurred in RC-40ED-400 compared to RC-10ED-400 and RC-20ED-400. Based on the test results, development length with consideration of degradation of developed tensile and normalized bond strength of CFRP bars were proposed, and it was found that the required development length of ribbed CFRP bars after exposure to elevated temperatures at 400 °C increased by 294 % compared to ambient temperature.

Seismic Performance of Steel-Reinforced High Strength Concrete Joints Considering Bond Slip Effect

This study presents a solution for push-out failure for the staged bond-slip constitutive relationship between the structural steel and high strength concrete, taking into account the concrete strength grade, anchoring length, and stirrup ratio. The critical point coordinates for different stages are determined by the tests of 14 steel-reinforced high strength concrete (SRHSC) specimens. It is observed that with the increase in the concrete strength grade and anchorage length, the ultimate load of the specimens increased significantly, but the influence on the residual bond strength was not significant. The effect of the stirring ratio was mainly manifested in a slight increase in the initial bond strength. The formula for calculating SRHSC characteristic bond strength and characteristic slip value is established, and the bond-slip constitutive relation of SRHSC is proposed based on the tests. The material constitutive model considering the effect of bond-slip is implanted into the software in the case of the ABAQUS finite element platform. The material is applied to the numerical simulation analysis of the SRHSC exterior joints. The rationality and accuracy of the new material are verified by comparing the simulation results with the test results.

Experimental Study on the Bonding Performance between Shaped Steel and High-Strength Concrete

The integration of steel fibers into high-strength concrete (HSC) offers a solution to address the brittleness and limited ductility typically associated with conventional HSC structures. To investigate the bonding properties between shaped steel and high-strength concrete with steel fiber (SFRC), thirteen tests of the shaped steel/SFRC specimens are conducted to explore the effects of various factors such as steel fiber volume ratio, concrete strength grade, reinforcement ratio, steel embedment depth, and cover thickness on bond–slip behavior. Three distinct failure modes, such as pushout failure, bond splitting, and yielding failure of steel, are identified during the pushout tests. Three different types of bond strength, such as the initial bond strength, the ultimate bond strength, and the residual bond strength, are observed from the load–slip curves between the shaped steel and concrete. By incorporating nonlinear spring elements, a numerical model for accurately simulating the bond performance between the shaped steel and SFRC specimens is developed. The bond strength between the shaped steel and concrete increase as the concrete strength, cover thickness, steel fiber volume ratio, and stirrup ratio increase, while it decreases as the steel embedment depth increases. A model for the bond strength between shaped steel and SFRC is developed, and it agrees well with the test data.

Experimental study on bond performance of staggered lap rebars in ultra-high performance concrete (UHPC)

Ultra-high performance concrete (UHPC) has received extensive attention worldwide due to its ultra-high mechanical properties and durability. The bond performance between steel bars and UHPC is crucial for the design of Reinforced-UHPC structures. To study the bond performance of overlapping steel bars in UHPC, a total of 13 groups of 39 pull-out tests were conducted with overlapping lengths, cover thickness, steel bar diameter, and clear spacing of steel bars as influencing variables in this study. According to the results, when the lap length increased from 4 times the bar diameter (4db) to 5db and 6db, the maximum bond strength decreased by 10% and 20%, respectively. Moreover, with an increase in the cover thickness from 25 mm to 35 mm and 45 mm, the maximum bond strength increased by 6% and 14%, while the residual bond strength increased by 15% and 48%, respectively. When the diameter of the reinforcing bars increased from 16 mm to 20 mm and 25 mm, the ultimate load capacity increased by 50% and 70%, respectively, while the bond stress decreased by 16% and 27%. Additionally, the bond strength showed less sensitivity to the clear spacing of steel bars, with a decrease of 3% and 10% in bond strength when the clear spacing increased from 1.5db to 2db and 3db, respectively. The ductility of the specimen decreases when the bar diameter or the clear distance between bars is too large. A theoretical calculation formula for splitting bond strength was established, which yielded accurate results. Furthermore, a bond-slip model was fitted based on the test results, providing reference for finite element analysis of steel bar-UHPC structures.

Bond performance of freeze-thaw damaged concrete and reinforcing bars subjected to high-cycle fatigue loading

Concrete bridges are susceptible to the detrimental effects of freeze-thaw cycles (FTCs) and dynamic vehicle loading in cold regions, compromising the bond between reinforcing bars and concrete. After high-cycle fatigue loading using eccentric pull-out tests, an experiment on the bond performance of freeze-thaw damage specimens was carried out. The investigation focused on the impact of FTCs, fatigue load cycles (FLCs), and concrete strengths on the bond behaviour. The test results showed that eccentric pull-out specimens of reinforced concrete with freeze-thaw damage under high-cycle fatigue loading were more susceptible to experiencing splitting failure. As the number of FTCs increased, the peak and the residual bond strength decreased continuously. Fatigue loading had a slight improvement effect on the peak bond strength, but it significantly reduced the residual bond strength when the specimens suffered from higher fatigue damage. The peak slip initially increased and subsequently decreased with FTCs, showing minimal sensitivity to the number of FLCs. Considering the stiffness degradation of the ascending section, a bond-slip model for freeze-thaw damaged concrete and reinforcing bars under high-cycle fatigue loading was established, and verified through experimental results.

Influence of seawater immersion on acrylic adhesive properties and bond strength on wet composites

This paper describes a study on an acrylic based adhesive developed for marine repair applications. The adhesive alone was aged for over 12 months and tensile samples were tested periodically to characterize the influence of seawater aging at 40 °C. The adhesive alone plasticizes in seawater, losing around 40 % of both modulus and strength after 12 months, but these are largely recovered after drying. In parallel, adhesively bonded glass and carbon fibre composite assemblies were tested after similar aging times. Both retain over 80 % of unaged apparent shear strength after 12 months in natural seawater at 40 °C. Adhesive bonding of wet composite substrates, which had been immersed in seawater for up to 12 months before bonding, was also evaluated to determine residual bond strength. The break strengths of assemblies of wet glass fibre composites were not affected by substrate immersion for up to 12 months before bonding, while strengths of carbon fibre composite assemblies dropped to around 50 % after prolonged substrate immersion. Reasons for this difference are discussed. The results suggest that this adhesive shows good durability and should be considered for marine repair applications.

A simple direct current model for residual bond strength assessment of embedded rebars in thermally damaged concrete

Fire events are highly fatal to human lives and properties, and should be considered at structural design phases. Concrete structures are essentially fire resistant up to certain level, beyond that structural components would degrade away from their design values. Residual capacities of fire exposed structures should be properly assessed before strengthening tasks can be carried out. Among those, the residual bond strengths between reinforcing bars and concrete are of particular importance because they determine the mechanical performance of all reinforced concrete components. This study focused on proposing novel nondestructive approaches to assess the residual bond strengths after thermal exposures. Specifically, a simple direct current (DC) model was implemented to yield electrical resistivity indices that can closely reflect the bond strength degradations up to 400 ℃. DC polarization measurements were split into three phases through which each index induced the degradations differently. Capability and efficiency of the DC indices to assess residual bond strengths of thermally damaged concrete were analyzed and discussed. Results presented have suggested that the proposed DC approach performed better than using residual compressive strengths to assess residual bond strengths, and was more advantageous for its nondestructive features.

Evaluation of residual bond behaviour between rebar and recycled aggregate concrete after high-temperature exposure followed by water spray cooling

This paper presents an evaluation of the residual bond behaviour between rebar and recycled aggregate concrete (RAC) using granite natural coarse aggregates and different recycled coarse aggregate (RCA) replacement levels (δ = 0%, 30%, 50%, and 100%) for both pull-out and cubic specimens. After high-temperature exposure (T = 200, 400, and 600 ℃) followed by water spray cooling, the results revealed a consistent decline in bond strength and compression strength with increasing temperature. Compared to ambient conditions, bond strength and compression strength decreased by 65.2% ∼ 77.8% and 53.2% ∼ 58.4%, respectively, after exposure to 600 ℃. The reduction rate of residual bond strength changed significantly at about 400 ℃. There was a linear relationship between RAC compression strength and rebar–RAC bond strength after high temperature exposure followed by water spray cooling. With increasing RCA replacement levels, the relative bond strength gradually improved at the same temperature. Based on the regression analysis, empirical formula for the rebar–RAC bond strength and bond–slip relationship models were proposed, all taking into account RCA replacement levels and temperature.

Behavior of high strength reinforcing steel rebars after high temperature exposure: Tensile properties and bond behavior using pull-out and end beam tests

High strength reinforcing steel (HSRS) is increasingly being adopted in the construction industry in North America due to its high load-carrying capacity, yet their behavior relative to normal grade rebars under external hazard events such as fire exposure still need further research. In current work, the first goal is to investigate the residual tensile properties of different types of HSRS and normal rebars including ASTM A706, A615, A1035CS, and A1035CM with grades of 420, 550, and 690 before and after high temperatures (350 °C and 700 °C), that simulates residual capacity after different levels of fire exposure. The second goal is to explore the residual bond strength of these rebars using both pull-out and end-beam tests after heat exposure, facilitating a comparison among test methods and evaluating their reliability under fire hazard conditions. The tensile test results indicated insignificant changes in the mechanical properties of all rebars after 350 ℃ heat exposure. However, there was a significant reduction of more than 30% in both yield and ultimate strength after 700 ℃ heat exposure for high grades like grade 690 of ASTM A1035. Among all rebar types and grades, only grade 420 of ASTM A706 retained most of its ductility and strength, making it the most reliable rebar among those tested against fire hazards. In the bond tests, splitting failure was observed at both ambient and after 500 °C heat exposure. Heat exposure resulted in a 73% reduction in bond strength across all rebars for the pull-out tests, with no significant variations between rebar types. On the other hand, end-beam tests indicated a 12.6% average reduction in bond strength with a 9% improvement in bond behavior for ASTM A706 grade 420. However, for ASTM A1035 CS grade 690 and ASTM A706 grade 550 there were slight reductions in bond behavior, with decreases of 9% and 14%, respectively. Compared to the end-beam test, the pull-out test results in a significant reduction in bond strength due to its high dependency on excessive compressive strength reduction resulting in brittle splitting failure. Based on comparison with empirical models, it is recommended not to use models derived from pull-out tests to estimate bond strength, as they tend to overestimate it. Instead, empirical models based on end-beam tests are recommended, since they show consistency with test results. It should be noted that although the bond strength based on splitting failure is primarily dependent on concrete properties, changes were observed in the bond behavior among different rebars, which can be attributed to changes in friction at the interface due to morphological changes in the rebar surface after heat exposure, as well as potential variations in thermal expansion properties, which need further research.

Applying Microbial-Induced Calcium Carbonate Precipitation Technology to Improve the Bond Strength of Lightweight Aggregate Concrete after High-Temperature Damage

High temperatures and external force can easily lead to a decline in the bond strength of reinforced concrete components. Microbial-induced calcium carbonate precipitation (MICP) technology has considerable potential for repairing concrete. Given this, this study utilized MICP technology to improve the bond strength of heat- and pull-damaged lightweight aggregate concrete (LWAC). The specimens of a control group (Group A) and two experimental groups (Group B and Group C) were prepared. The experimental group was prepared using lightweight aggregates (LWAs) that had been immersed in a nutrient solution and a bacterial solution. The control group was prepared using LWAs that were not immersed in a nutrient solution or bacterial solution. These specimens healed themselves in different ways after exposure to high temperatures (300 °C and 500 °C) and pull-out damage. Groups A and B adopted the same self-healing method; that is, their specimens were placed in a computer-controlled incubator at 40 °C. Group C used different self-healing methods. The specimens in this group were soaked in a mixed solution of urea and calcium acetate at 40 °C for two days and then taken out and placed in an incubator at 40 °C for two days. A cycle took four days until the expected self-healing age was reached. After being exposed to 300 °C and self-healed for 90 days, the residual bond strengths of the secondary pull-out tests in Groups A, B, and C were 20.63, 22.13, and 25.69 MPa, respectively. Moreover, compared with Group A, the relative bond strength ratios of the secondary pull-out tests in Groups B and C increased by 5.8% and 20.3%, respectively. This demonstrates that MICP technology could effectively improve the bond strength of LWAC after high-temperature and pull-out damage.

Fiber Synergy of Polyvinyl Alcohol and Steel Fibers on the Bond Behavior of a Hybrid Fiber-Reinforced Cementitious Composite.

Based on multi-scale characteristics inherent in the cracking process of cementitious composites, fibers with different geometric dimensions are simultaneously used to restrain the formation and development of cracks at different scales. Accordingly, hybrid fiber-reinforced cementitious composites (HyFRCCs) exhibit excellent bond behavior and deformation capacity in terms of tension and compression, accompanied by higher damage tolerance. Using these benefits of the mechanical properties of HyFRCCs, the structural performance of HyFRCC structures under complex loading conditions can be improved. To objectively evaluate the contributions of all fibers to the mechanical properties of HyFRCCs, steel macro-fibers, and polyvinyl alcohol (PVA) micro-fibers were used to design several reinforced cementitious composites. Four of the specimens were mono-fibrous cementitious composites, three specimens were cementitious composites reinforced with hybrid fibers, and one was a non-fibrous cementitious composite. The synergy effect of the steel and PVA fibers was analyzed using various fiber combinations. The results indicated a significant enhancement of the bonding properties of HyFRCCs through the incorporation of PVA and steel fibers. Specifically, the peak bond strength, peak slip displacement, and residual bond strength exhibited increments ranging from 31.0% to 41.7%, 60.6% to 118.4%, and 34.6% to 391.3%, respectively, in comparison to the reference test block. Notably, the combined presence of the PVA and steel fibers consistently demonstrated a positive confounding effect on the residual bond strength. However, negative confounding effects were observed in terms of the peak bond strength and peak slip displacement, particularly with 1.0% steel fiber content and 0.5% PVA fiber content.

Numerical and Experimental Investigation of Residual Stress and Bond Strength in Friction Surface Cladding Process

Numerical and Experimental Investigation of Residual Stress and Bond Strength in Friction Surface Cladding Process

Deterioration of bond performance between BFRP bars and coral aggregate concrete incorporating slag-based geopolymers under seawater corrosion environments

The utilization of durable geopolymers instead of ordinary Portland cement (OPC) for developing geopolymer-based seawater coral aggregated concrete (GPCAC) in coastal constructions contributed to the improved marine resource utilization and the reduced CO2 emissions and construction costs. Thus, this study investigated the durability of GPCAC and its bond performance with basalt fiber-reinforced polymer (BFRP) bars under seawater drying-wetting cycles, and cement-based CAC was also selected as a comparison. The bond characteristics and degradation mechanisms of slag-based GPCAC and cement-based CAC specimens were compared and analyzed under different seawater exposure condition. Experimental results revealed that both GPCAC and CAC specimens demonstrated various degrees of degradation in bond strength, whereas their initial bond stiffness exhibited a slight increase owing to the hygroscopic expansion of the superficial epoxy resin of BFRP bars, after being exposed to seawater environmental attacks. This degraded bond strength was primarily attributed to the existence of corrosive ions (i.e., SO42-, Mg2+, and Cl-) in seawater and free OH- in concrete capillary pores. These compounds chemically reacted with the slurry hydration products and the resin matrix, which resulted in the decreasing of concrete strength, the hydrolysis of the resin matrix, the deterioration of fibers, and fiber-resin interface debonding. Compared with CAC specimens, GPCAC specimens achieved better resistance to seawater attacks owing to the more dense and stable reaction products formed by geopolymers compared to OPC. After being subjected to 60 °C seawater attacks for 12 months, approximately 4.9% and 12.0% reductions in the bond strength were reported for GPCAC and CAC specimens, respectively. Finally, the residual bond strength of both GPCAC and CAC specimens was predicted after being served in seawater erosion conditions for 50 years.

Bond characteristics of quartz sand modified enamel coated steel bars with concrete

Porcelain enamel, as a coating material, has a glassy and smooth surface that reduces the bond action with surrounding concrete when applied to steel rebar. In this work, quartz sand modified enamel (QSME) coatings are proposed for the first time to improve the bond action with concrete. The bond characteristics of QSME-coated steel bars in concrete are experimentally investigated by pull-out tests, and the effects of the size and content of quartz sand are considered. The microstructure of the steel bar/concrete interface is characterized by using a scanning electron microscope, and the surface profile is analyzed with a 3D scanner. Results show that QSME coating significantly increases the bond strength, bond stiffness, bond ductility, bond toughness, and residual bond strength of plain steel bars, which increase with an increase in the quartz sand content. The bond strength of QSME-coated deformed steel bars decreases compared with that of uncoated rebars due to the reduced rib height. However, QSME coating improves the bond stiffness, bond ductility, bond toughness, and residual bond strength of deformed steel bars. For QSME-coated steel bars, the bond strength linearly increases with an increase in the surface roughness.