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To investigate the interfacial bonding performance between high-early-strength high-ductility concrete (HES-HDC) and existing concrete, 108 bonding specimens were used to study the effects of concrete substrate roughness, the content of silica fume, hydroxypropyl methylcellulose (HPMC), and polyethylene (PE) fiber in HES-HDC, as well as curing age and testing methods on the interface failure mode, load-slip curve, and interfacial bonding strength between HES-HDC and concrete. The results show that the interfacial bonding strength at 2 h of all bonding specimens exceeded 1.2 MPa, with the interfacial bonding strength at 1 day reaching 60% of that at 28 days, demonstrating significant high-early-strength properties, meeting the requirements for rapid repairs. The concrete substrate roughness significantly influenced the interface failure mode and the characteristics of the shear load-slip curve. The interfacial shear strength increases with increasing concrete substrate roughness, HPMC content, fiber content, and curing age. HES-HDC with 6% silica fume exhibits higher interfacial shear strength with existing concrete. Based on the experimental results, a formula for the interfacial bonding strength between HES-HDC and concrete was proposed, considering interface properties and material strength, which could be applicable for predicting bonding strength using different interface testing methods.

This study aims to address the issues posed by frost damage to concrete structures in cold regions, focusing on reinforcement and repair methods to increase the service life of existing structures instead of costly reconstruction solutions. Due to the limitations of conventional concrete in terms of durability and strength, this research focused on ultra-high-performance concrete (UHPC) by replacing part of the cement with recycled brick powder (RBP) to strengthen ordinary C50 concrete, obtaining UHPC-NC specimens. Mechanical tests investigated the bonding performance of UHPC-NC specimens under various conditions, including interface agents, surface roughness treatments, and freeze–thaw after 0, 50, 100, and 150 cycles with a 30% replacement rate of RBP. Additionally, a multi-factor calculation formula for interface bonding strength was established according to the test data, and the bonding mechanism and model were analyzed through an SEM test. The results indicate that the interface bonding of UHPC-NC specimens decreased during salt freezing compared to hydro-freezing, causing more severe damage. However, the relative index of splitting tensile strength for cement paste specimens showed increases of 14.01% and 14.97%, respectively, compared to specimens without an interface agent. Using an interface agent improved bonding strength and cohesiveness. The UHPC-NC bonding model without an interfacial agent can be characterized using a three-zone model. After applying an interfacial agent, the model can be characterized by a three-zone, three-layer bonding model. Overall, the RBP-UHPC-reinforced C50 for damaged concrete showed excellent interfacial bonding and frost resistance performance.

This study addresses the challenges of overlaying old concrete pavement with asphalt by introducing a new trackless tack coat material containing polymer. The aim is to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement. It contributes to the development of improved construction techniques for pavement rehabilitation and highlights the need for reliable adhesion performance evaluation based on different spray amounts and surface conditions. Additionally, to evaluate the effect of the adhesion performance based on the spraying amount, a tensile adhesion test was conducted by applying spray amounts of 0.30, 0.45, and 0.60 l/m2 on different surface conditions. The basic and adhesion performances of the polymer-modified tack coat material are evaluated through direct tensile and shear bond strength tests. The test outcomes demonstrated that the newly developed polymer-modified tack coat material had considerably greater adhesion strength compared to the traditional rapid-setting products. Its adhesive strength was 1.68 times higher on concrete and 1.78 times higher on asphalt. The new trackless tack coat material exhibited an adhesion performance of 1.05 MPa in direct tensile strength at 0.45 l/m2, which was 1.21 times higher than the rapid-setting tack coat. Results also confirmed that the new tack coat material exhibits values 1.90 times greater than the conventional rapid-setting tack coat material in shear bond strength, respectively. By simulating the process of separation and re-adhesion of pavement layers caused, the new tack coat material shows a tensile adhesion strength of 63% of the original state, which is advantageous for securing the durability of the pavement. Overall, the newly developed polymer-modified trackless tack coat has been shown to effectively enhance the adhesion performance between pavement layers without process delay, highlighting the potential of the new tack coat material to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement.

In this paper, the copper-based welding wire was used to complete the double-layer billet assembling, and bimetal Ti/steel clad plates were successfully prepared by hot rolling. The transverse bonding strength distribution was studied through microstructure characterization and the finite element method (FEM). The influence factors of oxidation, temperature, and stress were discussed. The results showed that the bond strength exhibited a transverse heterogeneity, which was 294 MPa at the width center and gradually decreased to 101 MPa at the width edge. Correspondingly, the interface at the center was well bonded while it contained cracks and voids at the edge. The oxidation occurred only at the edge for cracking in the weld during rolling, which deteriorated the bonding strength. The temperature along the width direction had little effect on the bonding strength for its small drop. Compared with these, the decreased normal stress from center to edge caused by the width resistance and metal flow characteristics was the main reason for the transverse heterogeneity of bonding strength. Based on this, a transverse bonding strength prediction equation considering the distribution of stress and bonding strength was proposed, and the relative error of it was 8 ~ 15%.

In the current study, we proposed a method of differential temperature rolling with electromagnetic induction heating to prepare Ti/Al composite plates in a protective atmosphere to realize the homogeneous deformation of Ti/Al bonding rolling and improve the interfacial bonding strength of the composite plates. The temperature field required for homogeneous deformation rolling of titanium and aluminum was constructed using finite element simulation by adjusting the parameters of electromagnetic induction heating, which made a temperature difference of about 632 °C between titanium and aluminum, and the temperature of each plate was relatively uniform. The induction heating experiment was designed based on the finite element simulation, and the experiment verified the accuracy of the simulation results. The effects of rolling temperature and reduction rate of homogeneous deformation and bonding strength of Ti/Al composite plates were evaluated by rolling experiments. With the increase of rolling temperature and reduction rate of titanium, when the heating temperature of the Ti plate is 750–850 °C, and the reduction rate is 30%–48%, the reduction rate of Ti plate and Al plate gradually tend to be the same. When the titanium plate and aluminum plate temperature is 850 °C and 188 °C, respectively, with a rolling reduction rate of 48%, the deformation rate of Ti plate and Al plate is 46.8% and 48.6%, respectively. Moreover, the bonding strength of the composite plate reaches 77MPa.

Surface preparation is an important step in adhesive technology. A variety of abrasive, chemical, or concentrated energy source treatments are used. The effects of these treatments vary due to the variety of factors affecting the final strength of bonded joints. This paper presents the results of an experimental study conducted to determine the feasibility of using fiber laser surface treatments in place of technologically and environmentally cumbersome methods. The effect of surface modification was studied on three materials: aluminum EN AW-1050A and aluminum alloys EN AW-2024 and EN AW-5083. For comparison purposes, joints were made with sandblasted and laser-textured surfaces and those rolled as reference samples for the selected overlap variant, glued with epoxy adhesive. The joints were made with an overlap of 8, 10, 12.5, 14, and 16 mm, and these tests made it possible to demonstrate laser processing as a useful technique to reduce the size of the overlap and achieve even higher load-bearing capacity of the joint compared to sandblasting. A comparative analysis was also carried out for the failure force of the adhesive bond and the failure energy. The results show the efficiency and desirability of using lasers in bonding, allowing us to reduce harmful technologies and reduce the weight of the bonded structure.

To enhance the quality stability of 3D printing concrete, this study introduces a novel machine learning (ML) model based on a stacking strategy for the first time. The model aims to predict the interlayer bonding strength (IBS) of 3D printing concrete. The base models incorporate SVR, KNN, and GPR, and subsequently, these models are stacked to create a robust stacking model. Results from 10-fold cross-validation and statistical performance evaluations reveal that, compared to the base models, the stacking model exhibits superior performance in predicting the IBS of 3D printing concrete, with the R2 value increasing from 0.91 to 0.96. This underscores the efficacy of the developed stacking model in significantly improving prediction accuracy, thereby facilitating the advancement of scaled-up production in 3D printing concrete.

Well integrity is of high importance during the entire well life span especially when renewable energy resources such as geothermal are designed to cover the increasing world energy demand. Many studies have documented the importance of the casing–cement interfacial bonding to ensure critical well integrity achievements; however, laboratory experiments and field data are not always aligned. Furthermore, Finite Element Analysis shows relatively high discrepancies compared with the results of various scholarly published works. The limitations in the FEA are most probably generated by the casing–cement interaction modeling parameters. Typically, the contact between casing and cement is modeled using the so-called CZM method, which includes the shear debonding process into the FEA. Several setups have been used in the past to determine the interfacial casing–cement bonding shear strength. Some of these setups are briefly summarized herein. The novelty of this paper consists in the combination of a relatively simple experimental setup with the finite element modeling of the experiment itself to demonstrate that it is important to acquire accurate laboratory data for debonding simulations and, thus, to improve the well integrity prediction. The aim of this paper is to better understand the limitations of the finite element method when modeling shear bonding of the cement and, in the same, to verify that the proposed experimental setup can be modelled using numerical approaches. The successful numerical simulation can later be used for upscaled models. The results confirm the experimental push down setup and aid engineers to further understand and validate CZM models and optimize the well design to achieve maximum well integrity potential. Our results are within 1% error from the average field data.

Material extrusion additive manufacturing, also known as fused filament fabrication (FFF), is currently one of the most widely used technologies. Although promising, the technology is prone to several defects including poor surface quality, low dimensional accuracy, and inadequate mechanical performance caused by weak bonds between successively deposited layers. Studies have shown that bonding between filaments forms above the material’s glass transition temperature which makes it essential to study the thermal history of the printing process. Since interlayer bonding is thermally driven, this study has focused on the development of a regression model to predict the average interlayer bonding strength of a part using the thermal history of the printed layers and the process parameter settings. The process parameters studied are deposition temperature, print speed, and layer thickness. This study relies on using finite element analysis (FEA) to obtain the part’s thermal history and scanning electron microscopy (SEM) to evaluate the bond quality by performing microstructure analysis. The average interlayer bond strength was assessed by measuring the interlayer bond widths and average weld times of all layers in a printed part. The weld time is the time that the temperature of an extruded filament stays above the glass transition temperature when reheated by an adjacent layer. This study includes experimental validation of the developed predictive models to estimate the average weld time and average bond strength of thin wall samples. Results show that the average bond strength is most significantly influenced by two key variables—the average weld time and layer thickness.

Diamond-copper/steel matrix abrasive composites were prepared by the roll-bonding technique. Firstly, the effects of the roll-bonding technical parameters (including sintering parameters, rolling parameters, and the component content) on the interfacial bonding strength in the composites were researched. Then, the surface macroscopic characteristics of the composites and the microstructures of the bonding interfaces were observed. The static compressive strength of the diamonds in the composites and the grinding performance of the composites were measured. Finally, the mechanisms for the effects of the roll-bonding technical parameters on the interfacial bonding strength were explored. The results showed that with increasing those parameters, the interfacial bonding strength between diamonds and the matrices displayed an initial increase and then a significant decrease. Furthermore, the optimal interfacial bonding strength (11.4 kN/m) and an excellent grinding performance (abrasive ratio of 23.2) were obtained from the diamond-steel matrix composites containing 10 vol% binder and 25% concentration of diamonds, when sintered at the temperature of 900 °C for holding time of 30 min and cold rolled at the reduction rate of 70%. The composites prepared with the optimum technical parameters had acceptable surface smoothness. In addition, the diamonds could be dispersed homogeneously in the matrices and firmly adhered to the substrates. When the diamond concentration was 25% in cold-rolling, the diamond-steel matrix composites showed better grinding performance. By improving the pressure condition of metallurgical bonding between diamonds and metal matrices from static pressure to rolling dynamic pressure, the sintering condition of temperature and holding time can be reduced and shortened, and the sintering condition effect on the interfacial bonding can be weaken. Thus, the application of the roll-bonding technique to the preparation of diamond-metal matrix composites could effectively avoid the thermal damage of diamonds caused by sintering process.