Fundamental Mechanical Properties Research Articles

Experimental Study on Basic Mechanical Properties of Core-Column Non-mortar Aerated Concrete Block Masonry

Autoclaved aerated concrete (AAC) block masonry has been widely used for bearing walls of multi-story buildings or non-bearing walls of high-rise buildings because of its unique advantages, such as lightweight, low pollution output, and excellent thermal insulation performance. However, traditional AAC block masonry has the disadvantages of high water absorption, poor adhesion to mortar, and low construction efficiency. In order to improve the performance of traditional AAC masonry, this paper proposed a new kind of mortar-free AAC block masonry with concrete core-columns. Fundamental mechanical properties of compression and shear were studied. We divided a total of 16 compression specimens into four groups according to different hollow ratios and strength grades of the block, and eight shear specimens into two groups based on different hollow ratios. Each specimen consists of three-layer blocks with two core columns at the point of quadri-section. The diameters of columns were, respectively, 100 mm and 80 mm. The specimens were loaded at a constant speed to evaluate their bearing capacity, displacement response, crack development, and damage state. The formula of the average values and design values of the compressive and shear strength of masonry were obtained statistically. The stress–strain constitutive relation of masonry expressed by a three-stage curve was presented. Furthermore, the result of numerical analysis using the ABAQUS finite element program aligned well with the experimental results. The compressive strength and shear strength of the new type of masonry are no less than traditional AAC masonry, and new masonry has higher construction efficiency and more stable strength.

Influence of basalt micro-fibres on the abrasion resistance of concrete in hydraulic structures

In hydraulic structures, abrasion resistance can be a significant driver in concrete specification. Basalt micro-fibres represent a potentially sustainable construction product and have been shown to provide various benefits in concrete, however the implications for hydrodynamic abrasion resistance are to date unclear. This paper is the first investigation of its kind to examine the abrasion resistance of basalt fibre-reinforced (BFR) concretes using the ASTM C1138 underwater test method. Towards this, concretes incorporating fibre dosages of 0.5, 1, 1.5 and 3 kg/m3 were tested. The relationships between concrete abrasion and its fundamental mechanical properties are evaluated. For the particular concretes examined, it is found that based on the Shapiro-Wilks tests at 95% confidence, abrasion loss in BFR concretes followed a normal distribution; the use of basalt fibre in contents of up to 3 kg/m3 did not have a significant effect on abrasion resistance, compressive and tensile splitting strengths, as well as modulus of elasticity. It can be concluded that basalt micro-fibre can be used for their other attributes such as controlling bleeding, shrinkage and plastic cracking in concrete hydraulic structures without deleterious effects on abrasion resistance. The regression models proposed to predict concrete abrasion loss from its mechanical properties were found to be only significant at 48 h for compressive strength and 24 h for both tensile splitting strength and modulus of elasticity.

Mechanical characterization of fish oil microcapsules by a micromanipulation technique

This paper aims to study the mechanical properties of fish oil microcapsules made of different food-grade formulations and processing conditions, which is crucial to maintaining their mechanical integrity in further compaction for developing the final dosage form of tablet. The combination of gelatin and gum Arabic or maltodextrin were use as wall materials. Spray drying, complex coacervation, and double encapsulation (coacervation followed by spray coating) were used to prepare different fish oil microcapsules. Both fundamental physical properties and mechanical properties of microcapsules were investigated. The mechanical characterization results were obtained using a micromanipulation technique and revealed that the mean rupture forces of individual microcapsules ranged from 0.44 ± 0.11 to 1.73 ± 0.27 mN and tended to increase with increasing particle size. The Young's modulus of microcapsules was determined by fitting the experimental force versus displacement data with the Hertz model. The microcapsules prepared by coacervation of gelatin and gum Arabic followed by spray coating with a mixture of gelation and maltodextrin were the strongest and stiffest based on the calculated nominal rupture stress and Young's modulus respectively. These findings can provide guidance on choosing the most desirable formulation and processing conditions to produce strong microcapsules with desirable barrier properties for industrial applications.

Low-Temperature 2D/2D Ohmic Contacts in WSe2 Field-Effect Transistors as a Platform for the 2D Metal-Insulator Transition.

We report the fabrication of hexagonal-boron-nitride (hBN) encapsulated multiterminal WSe2 Hall bars with 2D/2D low-temperature Ohmic contacts as a platform for investigating the two-dimensional (2D) metal-insulator transition. We demonstrate that the WSe2 devices exhibit Ohmic behavior down to 0.25 K and at low enough excitation voltages to avoid current-heating effects. Additionally, the high-quality hBN-encapsulated WSe2 devices in ideal Hall-bar geometry enable us to accurately determine the carrier density. Measurements of the temperature (T) and density (ns) dependence of the conductivity σ(T, ns) demonstrate scaling behavior consistent with a metal-insulator quantum phase transition driven by electron-electron interactions but where disorder-induced local magnetic moments are also present. Our findings pave the way for further studies of the fundamental quantum mechanical properties of 2D transition metal dichalcogenides using the same contact engineering.

Thermal distribution in cement-treated base: Effect of curing methods and temperature estimation using Artificial Neural Networks

Due to the effect of curing temperature and heat absorption on the performance of cement-treated bases (CTB), thermal shrinkage cracks can happen in CTB during the early-age curing period. However, there have been non-existent studies on the relationship between temperature distribution in CTB versus various curing methods. In this paper, a field experiment was conducted to monitor temperature at different depths and to investigate fundamental mechanical properties of CTB. An Artificial Neural Network (ANN) model was also developed to estimate temperature distribution in CTB segments exposed to three different curing methods (wet burlap, wet geotextile, and asphalt emulsion). The results indicated that wet burlap and wet geotextile curing methods exhibited better quality cures than asphalt emulsion, expressed by higher 14-day compressive and splitting tensile strengths, due to less temperature absorbed into CTB structure. Shrinkage cracks were also observed on CTB surface cured with asphalt emulsion due to more heat absorption. The ANN-based model proposed using four input parameters: air temperature, measurement depths, curing methods, and times of day showed a high accuracy with R-value ≥0.96 and average MSE ≈ 0.0038. A sensitivity analysis using Connection Weight Approach has proven the importance of curing methods which contributed to the highest dominance of 30.1%, whereas air temperature, times of day, and measurement depths accounted for 26.4%, 26.6%, and 16.9%, respectively. Thus, the ANN-based model has accurately estimated temperature distribution in CTB while curing.

Elastic Properties of Steel-Cord Rubber Conveyor Belt

Reinforced with steel-cord rubber conveyor belt (SCB), i.e. a unidirectional composite material (CM) with some of the fundamental mechanical properties values of its reinforcement and matrix differing by a factor of ten thousand, is a key infrastructure component of overland minerals transportation industry. Critically, to date no investigative work has been performed on the mechanical behaviour of SCBs subjected to the extreme dynamic-loading conditions of tropical cyclones, hurricanes, and tornados. Determination of a full suite of elastic characteristics of the belt will enable the study of the mechanical behaviour of SCB subjected to these natural hazardous wind events. We investigate tensile and shear moduli of a commercial SCB with the use of modified standard practices and innovative approaches, including tensile testing and methods of torsion of long straight bar and of square plate. We propose a novel design of mechanical tensometer which allows tensile testing of significantly shorter test specimens as compared with the test specimen dimensions per current standards. Analytically, tensile modulus is determined using the rule of mixtures and shear moduli are calculated based on the variational principles. We find that the tensile modulus of SCB can be determined analytically with high confidence. However, analytically derived in-plane shear moduli values can only be considered as a first approximation and need to be verified experimentally. The results of our work improve understanding of stress-strain state and thus can help predict the mechanical behavior of the SCBs under the irregular and extreme dynamic loading conditions of natural hazardous wind events.

Production of Sustainable concrete brick units using Nano-silica

Concrete bricks or blocks are the most commonly used as construction materials over the world. They are used extensively in buildings due to the raw materials availability and the main binder of concrete is Portland cement which is well known manufactured. Cement is a major contributor to climate change; cement manufacturing is a significant source of CO2 emissions, the primary greenhouse gas of concern. So, the use of a locally available solid waste materials or industrial by-products depends on availability of the local materials such as glass powder and steel slag as partial replacements of cement in concrete which are considered as a viable strategy for reducing the cement proportion use. This research aims to produce sustainable and economic bricks using glass powder and steel slag powder as replacements of cement and study the effect of the added Nano-silica to concrete brick mixes to improve the properties of bricks. Two different curing methods were included to investigate the effect of curing regime on some fundamental mechanical and physical properties (compressive strength and flexural strength, ultrasonic pulse velocity and drying shrinkage) of concrete bricks. The first curing method was the normal curing method at 23 ± 2°C and the second curing method was the boiling water method at 100°C. Different six mixes were cast and cured under different curing conditions before testing. From the test results, it has been found that the use of 2.5 % or 3.5 % of Nano-silica in concrete brick mixes can significantly increase the compressive and flexural strengths at early and late ages. Also these strengths of bricks exhibited better performance due to boiling curing compared with normal curing. However, the results of drying shrinkage with boiling curing's specimens at all ages showed that the values of drying shrinkage were slightly higher than these of specimens shrinkage at normal curing method.

3D Printed Shape Memory Polymers Produced via Direct Pellet Extrusion.

Shape memory polymers (SMPs) are materials capable of changing their structural configuration from a fixed shape to a temporary shape, and vice versa when subjected to a thermal stimulus. The present work has investigated the 3D printing process of a shape memory polymer (SMP)-based polyurethane using a material extrusion technology. Here, SMP pellets were fed into a printing unit, and actuating coupons were manufactured. In contrast to the conventional film-casting manufacturing processes of SMPs, the use of 3D printing allows the production of complex parts for smart electronics and morphing structures. In the present work, the memory performance of the actuating structure was investigated, and their fundamental recovery and mechanical properties were characterized. The preliminary results show that the assembled structures were able to recover their original conformation following a thermal input. The printed parts were also stamped with a QR code on the surface to include an unclonable pattern for addressing counterfeit features. The stamped coupons were subjected to a deformation-recovery shape process, and it was observed that the QR code was recognized after the parts returned to their original shape. The combination of shape memory effect with authentication features allows for a new dimension of counterfeit thwarting. The 3D-printed SMP parts in this work were also combined with shape memory alloys to create a smart actuator to act as a two-way switch to control data collection of a microcontroller.

Effect of hybrid basalt fibre length and content on properties of cementitious composites

Nowadays, basalt fibre is gaining popularity in the field of construction materials due to its low production cost and enhanced mechanical properties. However, research is still needed into the use of a single type of fibre with different lengths in composite materials. Therefore, in this paper the hybridisation of basalt fibre of various lengths and contents is studied in order to take full advantage of multi-scale characteristic(s) with a single type of fibre, while the fundamental mechanical properties of single-length basalt-fibre-reinforced cementitious composites and hybridisation of different-length basalt-fibre-reinforced composites are investigated. Additionally, a hybrid fibre coefficient is developed to evaluate the effect of hybrid fibre in cementitious materials. A total of 17 mix proportions were made containing either a single length or a combination of four different lengths of basalt fibre (3, 6, 12 and 20 mm) with various total volume contents. The paper shows that the hybridisation of four different lengths of fibres in cementitious composites generally improved mechanical properties in comparison to plain and single-length fibre-reinforced mortar. The hybrid fibre coefficient also showed good consistency with the results of mechanical properties. Scanning electron microscopy demonstrated the proper bonding of basalt fibre with cementitious composites.

Durability evaluation of circulating fluidized bed fly ash-based geopolymer

To make full use of the circulating fluidized bed fly (CFB-FA), rich-water carbide slag was used as alkali-activator to promote the hydration of CFB-FA and prepare circulating fluidized bed fly-based geopolymer (CFB-FAG). The fundamental properties, mechanical properties, and acid alkali-resistance of CFB-FAG were investigated. The optimum content of CFB-FA is 25%. it indicates that CFB-FA can prepare the excellent properties of geopolymer without high-temperature heat treatment. The alkali resistance of CFB-FAG is better than that of acid resistance. Furthermore, the fatigue lifetime of CFB-FAG decreases by 20% after acid treatment. The achievement can help us make full use of the solid waste and achieve the goal of peak carbon dioxide emissions and carbon neutral.

Widths of imbricate thrust blocks and the strength of the front of accretionary wedges and fold-and-thrust belts

Besides the large-scale wedge shape itself, the most prominent structural feature of accretionary wedges and fold-and-thrust belts is the common pattern of imbricate thrust faults. This study illuminates the fundamental mechanical processes and material properties controlling the width of the crustal blocks bounded by major thrusts using analytical solutions of stress as well as two-dimensional finite-difference models. The numerical models predict that the initial width w0 of a thrust block is set when that block first forms at the very front of the wedge. The width is found to subsequently decreases approximately in proportion to the mean horizontal strain needed for an ideally triangular-shaped Coulomb wedge with a critical taper. Block width is proportional to the thickness H of the incoming, accreting sediment. A key quantity that influences the normalized initial block width w0/H is the distance L forward of the frontal thrust needed for the net horizontal force from shear on the base of the incoming sediment to balance the net force on the frontal thrust. It is within this distance where stress in the incoming sediment is substantially elevated and thus where the new frontal thrust forms. Results show that L/H and, correspondingly, w0/H increase with increasing sediment friction angle ϕ, cohesive strength C0 and pore-fluid pressure ratio λ, and decrease with increasing basal friction angle ϕb and basal dip β. Normalized width is sensitive to ϕ and relatively insensitive to ϕb and λ. Results for submarine and subaerial wedges follow the same scaling law. The scaling law relates the observables, w0/H and β, to the material properties, ϕ, ϕb, λ, and therefore provides a theoretical relation that can be used independent of, or together with critical Coulomb wedge theory (CWT) to constrain these properties.

Dynamic Deformation Behaviour of Chiral Auxetic Lattices at Low and High Strain-Rates

The mechanical behaviour of three different auxetic cellular structures, hexa-chiral 2D, tetra-chiral 2D and tetra-chiral 3D, was experimentally investigated in this study. The structures were produced with the powder bed fusion method (PBF) from an austenitic stainless steel alloy. The fundamental material mechanical properties of the sample structures were determined with classic quasi-static compressive tests, where the deformation process was captured by a high-resolution digital camera. The Split Hopkinson Pressure Bar (SHPB) apparatus was used for dynamic impact testing at two impact velocities to study the strain-rate dependency of the structures. Two synchronised high-speed cameras were used to observe the impact tests. The captured images from both quasi-static and dynamic experiments were processed using a custom digital image correlation (DIC) algorithm to evaluate the displacement/strain fields and the Poisson’s ratio. Predominant auxetic behaviour was observed in all three structures throughout most of the deformation process both under quasi-static and impact loading regimes. The tetra-chiral 2D structure showed the most significant auxetic behaviour. Significant stress enhancement in all tested structures was observed in dynamic testing. The Poisson’s ratio strain-rate dependency was confirmed for all three auxetic structures.

The modification of surface of barrels by gas nitriding

Steels which are used for manufacturing of highly stressed parts of military equipments such as barrels of small arms weapons must be modified by heat treatment due to achieve required mechanical properties. Moreover, other important properties of functional parts, especially a friction coefficient and surface pa-rameters of bore of barrels, must be optimized due to obtain the best accuracy in target and to increase the life time of barrel [1, 2]. The technology chromium plating, very widespread in the past, has been gradually replacing by more ecological nethods. This article is devoted to find a technology as a replacement of tradi-tional chromium plating. Experiments are focused on using of optimized gas nitriding processes for surface treatment. As a result, a higher surface hardness with low influence on the dimensional accuracy is expected. Gas nitriding process was applied to steels 42CrMo4 and 32CrMoV12-10 used for barrel manufacturing. The most important parts of barrel were evaluated, especially surface parameters as a morphology than chemical composition and naturaly a microstructure of the material. The analysis of surface morphology were performed by scanning electron microscopy; chemical composition was evaluated by GDOES method and mechanical properties by using microhardness methods. The measurements of depth of diffusion layer were performed by destructive and non-destructive methods. The measurements showed the influences of chemical composition of alloying elements in core of material after chemical-heat treatment process on depth of diffusion and influence of technology on development of porosity. All fundamental mechanical prop-erties significant for requiring function of barrel were documented [1, 2]. Nevertheless, the main task was the description of the porosity development in compound layer after gas nitriding and the increasing of sur-face hardness and the depth of diffusion layer according to chemical composition. Nitriding process was ap-plied for increasing of surface hardness of material in depth and improving of mechanical properties. Me-chanical properties of tested material were significantly increased.

Experimental study on the mechanical properties of internally cured concrete with super absorbent polymer under monotonic and cyclic loads

Four-point bending tests were carried out on super absorbent polymer concrete (SAPC) specimens under monotonic and cyclic loads to investigate the mechanical behavior of internally cured concrete with SAP agent. Firstly, the failure mode of SAPC under static four-points bending load was presented. Secondly, the load–displacement curves, as well as the tensile stress–strain curves of the concrete specimens, were obtained. The variation laws of critical parameters were fitted and analyzed by examining the characteristic values of stress–strain curves under monotonic loadings. The mathematical models were proposed based on the experimental results. Thirdly, the relationships between the plastic strain, unloading strain, and reloading strain, together with the damage index of concrete, were studied extensively, referencing the results of cyclic loadings. The stress–strain models of SAPC during cyclic loading were established, incorporating the damage index under different SAP contents. A comparison of the proposed model with the test data demonstrated satisfactory agreement. In conclusion, the results reveal basic characteristics of SAPC after the full curing period and present fundamental mechanical properties of SAPC under monotonic and cyclic loadings. The study provides valuable references for improving the application of SAPC in engineering practices.

Systematic Enumeration of Low‐Energy Graphyne Allotropes Based on a Coordination‐Constrained Searching Strategy

Based on a coordination‐constrained searching strategy, 48 new graphyne allotropes are discovered and systematically optimized by first‐principles calculations. Among these newly discovered 2D carbons, 127‐E20Y16‐0, 191‐E24Y24‐0, 191‐E18Y18‐0, and 191‐E24Y36‐0 with energies lower than those of the experimentally synthesized γ‐graphdiyne, β‐graphdiyne, and carbon ene‐yne are further confirmed to be dynamically, mechanically, and also thermally stable phases. Their fundamental electronic and mechanical properties are systematically studied and compared with those of γ‐graphdiyne and γ‐graphyne. The Heyd−Scuseria−Ernzerhof (HSE06)‐based electronic band structures reveal that 127‐E20Y16‐0, 191‐E24Y24‐0, 191‐E18Y18‐0, and 191‐E24Y36‐0 are semiconductors with bandgaps of 0.489, 0.994, 0.012, and 0.167 eV, respectively. Their narrow or tiny bandgap features suggest that they are potential materials for photodetecting in the ultra‐infrared region. The calculated mechanical properties of the hexagonal 191‐E24Y24‐0, 191‐E18Y18‐0, and 191‐E24Y36‐0 are just slightly dependent on the crystalline direction, and are similar to those of γ‐graphdiyne and γ‐graphyne. However, the tetragonal 127‐E20Y16‐0 shows obvious anisotropic features in both Young's modulus and Poisson's ratio. The results presented herein further enrich the structures of the family of graphyne allotropes. In view of their remarkable stability and potential applications in photoelectronics and nanomechanics, the newly discovered 127‐E20Y16‐0, 191‐E24Y24‐0, 191‐E18Y18‐0, and 191‐E24Y36‐0 are expectable targets for future experiments.

A Tissue Engineering Approach to Metastatic Colon Cancer.

SummaryColon cancer remains the third most common cause of cancer in the US, and the third most common cause of cancer death. Worldwide, colon cancer is the second most common cause of cancer and cancer deaths. At least 25% of patients still present with metastatic disease, and at least 25-30% will develop metastatic colon cancer in the course of their disease. While chemotherapy and surgery remain the mainstay of treatment, understanding the fundamental cellular niche and mechanical properties that result in metastases would facilitate both prevention and cure. Advances in biomaterials, novel 3D primary human cells, modelling using microfluidics and the ability to alter the physical environment, now offers a unique opportunity to develop and test impactful treatment.

Effect of 3d transition metal additions on the phase constituent, mechanical properties, and shape memory effect of near–eutectoid Ti–4Au biomedical alloys

Shape memory alloys (SMA) are important topics among the urgently demanded biomaterial and medical application issues. A series of promising near–eutectoid Ti–4 at.% Au–5 at.% X (X = 3d transition metals: V, Cr, Mn, Fe, Co, Ni, and Cu) alloys was systematically studied in this study. Specimens were prepared by physical metallurgy method and were analyzed by XRD, bending test, Vickers hardness, and tensile test. The additional third elements of Cr and Mn clearly showed shape memory effect. On the other hand, when the additional third elements were V, Cr, Mn, and Mo, the ternary alloys performed slight pseudoelasticity or limited superelasticity while there was no superelasticity observed as the third elements were Fe and Co. According to the investigation of fundamental mechanical properties, the additional third elements of Cr and Mn, which are classified as the optimized group, are superior to other alloys based on the evaluations of their strength, ductility, shape memory effect, and superelastic effect. This study systematically screened the influences of the 3d transition metals on the near–eutectoid Ti–4 at.% Au–5 at.% X alloys. The results can be a database and a guideline for the further specimen preparations and investigations for the future research.

CSAI analysis of non-crimp fabric cross-ply laminate manufactured through wet compression molding process

The main purpose of the present work is to demonstrate mechanical performance of a wet-compression-molding (WCM) composite product through conventional compressive-strength-after-impact (CSAI) analysis. Biaxial non-crimp fabric (NCF) is utilized to manufacture laminated composite panels. Specimens are cut from the panels and tested to characterize fundamental mechanical properties of the NCF composite. The volume fractions of fibers and voids are also measured to evaluate the quality of the WCM product. Impact tests are carried out to examine impact resistance of the composite structure. Numerous impact characteristics at various energy levels are quantitatively measured. Internal failure patterns and damage extent are revealed via X-ray CT. Compression tests on the impacted plates are followed to evaluate structural integrity and damage tolerance (SIDT). 3D DIC technique is employed and distinct buckling responses dependent on impact energy levels are successfully visualized. Experimental results are showing a promising potential of the WCM process as one of the alternatives to the conventional autoclave-based fabrication method.

Consistent apparent Young\u2019s modulus of human embryonic stem cells and derived cell types stabilized by substrate stiffness regulation promotes lineage specificity maintenance

BackgroundApparent Young’s modulus (AYM), which reflects the fundamental mechanical property of live cells measured by atomic force microscopy and is determined by substrate stiffness regulated cytoskeletal organization, has been investigated as potential indicators of cell fate in specific cell types. However, applying biophysical cues, such as modulating the substrate stiffness, to regulate AYM and thereby reflect and/or control stem cell lineage specificity for downstream applications, remains a primary challenge during in vitro stem cell expansion. Moreover, substrate stiffness could modulate cell heterogeneity in the single-cell stage and contribute to cell fate regulation, yet the indicative link between AYM and cell fate determination during in vitro dynamic cell expansion (from single-cell stage to multi-cell stage) has not been established.ResultsHere, we show that the AYM of cells changed dynamically during passaging and proliferation on substrates with different stiffness. Moreover, the same change in substrate stiffness caused different patterns of AYM change in epithelial and mesenchymal cell types. Embryonic stem cells and their derived progenitor cells exhibited distinguishing AYM changes in response to different substrate stiffness that had significant effects on their maintenance of pluripotency and/or lineage-specific characteristics. On substrates that were too rigid or too soft, fluctuations in AYM occurred during cell passaging and proliferation that led to a loss in lineage specificity. On a substrate with ‘optimal’ stiffness (i.e., 3.5 kPa), the AYM was maintained at a constant level that was consistent with the parental cells during passaging and proliferation and led to preservation of lineage specificity. The effects of substrate stiffness on AYM and downstream cell fate were correlated with intracellular cytoskeletal organization and nuclear/cytoplasmic localization of YAP.ConclusionsIn summary, this study suggests that optimal substrate stiffness regulated consistent AYM during passaging and proliferation reflects and contributes to hESCs and their derived progenitor cells lineage specificity maintenance, through the underlying mechanistic pathways of stiffness-induced cytoskeletal organization and the downstream YAP signaling. These findings highlighted the potential of AYM as an indicator to select suitable substrate stiffness for stem cell specificity maintenance during in vitro expansion for regenerative applications.

Experimental Investigation on the Mechanical Properties and Microstructure of Basalt Fiber Reinforced Engineered Cementitious Composite.

This study investigated fundamental mechanical properties of a basalt fiber reinforced engineered cementitious composite (BF-ECC) with different volume fractions of basalt fiber (BF), water–binder ratio (W/B) and fly ash (FA) content. The compressive strength, splitting tensile strength, flexural strength and static modulus of BF-ECC were studied at 3, 28 and 56 days, respectively, to explore their development along the ages. Furthermore, the scanning electron microscopy (SEM) analysis was conducted to evaluate the microstructure of BF-ECC. Experiment results demonstrated that bond quality between the BF and the matrix is good, which leads to a significant increase in the flexural strength and splitting tensile strength. The pozzolanic effect of FA obviously improved the splitting tensile and flexural strength of BF-ECC after 56 days of curing, and the appropriate content of the FA content in the BF-ECC ranges from 50% to 60%.