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The purpose of this study is to investigate the effect on flexural strength of fire-damaged concrete repaired with high-strength mortar (HSM).

Reinforced concrete beams with dimension of 100 mm × 100 mm × 500 mm were used in this study. Beams were then heated to 400°C and overlaid with either HSM or high-strength fiber reinforced mortar (HSFM) to measure the effectiveness of repair material. Repaired beams of different material were then tested for flexural strength. Another group of beams was also repaired and tested by the same procedure but was heated at higher temperature of 600°C.

Repair of 400°C fire-damaged samples using HSM regained 72 per cent of its original flexural strength, 100.8 per cent of its original toughness and 56.9 per cent of its original elastic stiffness. Repair of 400°C fire-damaged samples using HSFM regained 113.5 per cent of its original flexural strength, 113 per cent of its original toughness and 85.1 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSM regained 18.7 per cent of its original flexural strength, 25.9 per cent of its original peak load capacity, 26.1 per cent of its original toughness and 22 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSFM regained 68.4 per cent of its original flexural strength, 96.5 per cent of its original peak load capacity, 71.2 per cent of its original toughness and 52.2 per cent of its original elastic stiffness.

This research is limited to the size of the furnace. The beam specimen is limited to 500 mm of length and overall dimensions. This dimension is not practical in actual structure, hence it may cause exaggeration of deteriorating effect of heating on reinforced concrete beam.

This study may promote more investigation of using HSM as repair material for fire-damaged concrete. This will lead to real-world application and practical solution for fire-damaged structure.

The aim of this research in using HSM mostly due to the material’s high workability which will ease its application and promote quality in repair of damaged structure.

There is a dearth of research on using HSM as repair material for fire-damaged concrete. Some research has been carried out using mortar but at lower strength compared to this research.

This paper aims to investigate the flexural properties i.e. the flexural strength and the flexural modulus under the influence of selected input variables, namely; fiber type, fiber loading and fiber size in fabricated natural fiber polymeric composites through using Taguchi’s design of experiment methodology.

The Taguchi’s design of experiment approach has been used to scheme a suitable combination to fabricate the polymeric composites. Pure polypropylene (PP) has been chosen as a matrix material, whereas two types of fibers, namely; wood powder (WP) i.e. sawdust and rice husk powder (RHP), have been used as a reinforcement in the matrix. Microstructure analysis of fabricated and tested samples has also been evaluated and analyzed using a scanning electron microscope. This analysis has divulged that at moderate fiber size and higher fiber loading, no gap or cavities presented between the fillers and matrix particles, which illustrates the good interfacial bonding between the materials.

The flexural strength of the wood powder pure polypropylene (WPPP) composite decreases if the fiber content gets increased beyond 20 Wt.%. In addition, the flexural strength of hybrid composite (WPRHPPP) has been revealed to get improved more in comparison to composites with single fiber as reinforcement. Furthermore, the flexural modulus of WPPP composite has also increased with the increase in fiber loading. It has been concluded that reinforcement size plays an imperative role in influencing the flexural modulus. The optimum parametric setting for the flexural strength and the flexural modulus has been devised as; fiber type – WPRHP, fiber loading – 10 Wt.% and fiber size – 600 µm; and fiber type – WP, fiber loading – 30 Wt.% and fiber size – 1,180 µm, respectively. The microstructure images clearly revealed that during conducted flexural tests, some particles get disturbed from their bonded position that mainly represents the plastic deformation.

The fabricated polymer materials proposed in the research work are green and environmentally friendly.

The natural fiber-based composites are possessing wide-spread requirements in today’s competitive structure of manufacturing and industrial applications. The fabrication of the natural fiber-based composites has also been planned through the designed experiments (namely; Taguchi Methodology- L₉ orthogonal array matrix), which, further, makes the analysis more fruitful and qualitative too. The fabricated polymer materials proposed in the research work are green and environmentally friendly. Shisham WP has been rarely used in the past researches; therefore, this factor has been included for the present work. The injection molding process is used to fabricate the three different polymer composite by varying the fiber weight percentage and fiber size.

The purpose of the paper is to explore the structural feasibility of substituting traditional thick joint mortars with earth slurry mortars modified with varying amounts of sand. Thin jointing of earth blocks would reduce the cost of sustainable earth construction.

Compressive strength of earth‐block cubes was determined. Flexural strength was measured using the BRE electronic bond wrench, which enables block couplets to be tested quickly and accurately. Three samples of earth block, one from southwest England and two from East Anglia, together with nine examples of earth slurry mortar jointing were studied, including the effect of reinforcing the joint and or the block using hessian.

The 28‐day cube characteristic compressive strengths were determined for Appley soil, Norfolk lump and Beeston soil, the last with 0 per cent sand, 25 per cent sand and with 25 per cent sand with hessian. The flexural strengths of Appley and Beeston earth slurries were determined, along with Thermalite thin jointed cement and cement mortar for comparison. The Beeston soil flexural strength increased with increasing sand content. Earth slurry with 40 per cent sand and hessian present in the joint gave the greatest strength. It is important to use blocks and slurry mortars of the same soil. Extruded and compressed earth blocks are best suited to slurry jointing.

This work successfully demonstrates the structural feasibility of carefully reducing the thickness of earth mortars when constructing sustainable earth block walling. Characteristic flexural strengths are suggested where the test results were sufficiently consistent, and of a magnitude likely to be useful in design.

The infill masonry walls in recent worldwide earthquakes have shown that it is necessary to conduct further studies to characterize the behavior of existing buildings and, in particular, of infill masonry walls under seismic activity. The lack of characterization studies of infill walls made by concrete blocks justifies the investigation reported herein, which includes experimental tests on sample sets to evaluate the mechanical properties of masonry components (units and mortar) and assemblages (wallets) made with masonry units from Faial. For the later, normal compressive, diagonal tensile/shear and out-of-plane flexural strengths were obtained according to standard procedures, the results of which are presented in the manuscript. The paper aims to discuss these issues.

One experimental campaign was conducted with the aim to mechanically characterize concrete blocks masonry samples. Several experimental tests were carried out in full-scale masonry concrete wallets according to the constructive methodology used.

Based on the data obtained from the mechanical characterization tests of the concrete masonry blocks, it can be seen that under simple compression, the masonry specimens’ average resistance is about 6 times superior than the average resistance to diagonal shear/tension, while the stiffness is almost doubled. In simple compression tests, it was observed that the masonry specimens cracked in areas of higher drilling of the blocks. In the tensile tests by diagonal compression, it was found that the test specimens were mainly fissured by the block/mortar joint interfaces, following the delineation of settlement and top joints.

There are no experimental results available in the literature for this type of bricks that can contribute to the development of numerical studies.

Seeks to examine the bond strength of a large range of structural polypropylene fibres, as used in concrete, to determine the most effective fibre capable of transmitting load (N/mm²) between fibre and cement within the concrete matrix.

Following fibre selection characterised by the highest bond strength, determined from a series of pull out tests, BS flexural tests were carried out using high bond strength fibres (40 mm × 0.9 mm diameter used at 6 kg/m³) to determine whether or not structural polypropylene fibres had any effect on the ultimate flexural strength of fibre‐reinforced concrete, when compared with the plain control sample. Fibre orientation, type of rupture failure mode and post‐crack performance were examined.

Even structural fibre dispersion was found to be best achieved with the use of monofilament polypropylene fibres (19 mm × 22 micron used at 0.9 × kg/m³) in addition to the 6 kg/m³ structural fibre dose. Structural polypropylene fibres were found not to provide additional flexural strength however, they did provide post‐crack control, limiting the crack width with subsequent enhanced durability that in turn will provide lower life cycle costs.

In addition to increased durability the use of fibre reinforcement negates the need to place steel reinforcement bars.

Investigates the ambiguity in literature between claims made by different investigators regarding the effects of polypropylene fibres on compressive and flexural strengths.

In the recent years, the industries show interest in natural and synthetic fibre-reinforced hybrid composites due to weight reduction and environmental reasons. The purpose of this experimental study is to investigate the properties of the hybrid composites fabricated by using carbon, untreated and alkaline-treated hemp fibres.

The composites were tested for strengths under tensile, flexural, impact and shear loadings, and the water absorption characteristics were also observed. The finite element analysis (FEA) was carried out to analyse the elastic behaviour of the composites and predict the strength by using ANSYS 15.0.

From the experimental results, it is observed that the hybrid composites can withstand the maximum tensile strength of 61.4 MPa, flexural strength of 122.4 MPa, impact strength of 4.2 J/mm² and shear strength of 25.5 MPa. From the FEA results, it is found that the maximum stress during tensile, flexural and impact loading is 47.5, 2.1 and 1.03 MPa, respectively.

The results of the untreated and alkaline-treated hemp-carbon fibre composites were compared and found that the alkaline-treated composites perform better in terms of mechanical properties. Then, the ANSYS-predicted values were compared with the experimental results, and it was found that there is a high correlation occurs between the untreated and alkali-treated hemp-carbon fibre composites. The internal structure of the broken surfaces of the composite samples was analysed using a scanning electron microscopy (SEM) analysis.

The purpose of this paper is to investigate the effect of thermal‐oxidative aging at 150°C on the mechanical properties of carbon fibre reinforced bismaleimide composites.

Composites specimens after thermo‐oxidative aging at 150°C for various times (up to 1,000 h) were investigated by scanning electron microscopy (SEM) for fracture morphology, Fourier transform infrared (FTIR) spectroscopy for chemical structures, and flexural strength test and inter‐laminar shear strength (ILSS) test for mechanical properties.

The results indicated that the mechanical properties of carbon fibre/BMI composites were affected significantly by testing temperature rather than by aging time. SEM results showed that the good adhesion of fibre and matrix resulted in the better mechanical properties. The composites showed lower flexural strength and ILSS at 150°C due to the viscoelastic behaviour of matrix resin. The FTIR spectra confirmed the decomposition of crosslinked maleimide occurred just on the surface of composites during various aging times.

Results indicated that carbon fibre/BMI composites had excellent heat resistance and aging resistance.

Due to their excellent thermal and mechanical properties, the carbon fibre/BMI composites show greater potential for their applications in some extreme fields such as aerospace and machine.

The paper investigates the relationships of the fracture morphologies of composites and chemical structures of matrix resin to the mechanical properties after thermo‐oxidative aging.

3D printing of composites has a high degree of design freedom, which allows for the manufacture of complex shapes that cannot be achieved with conventional manufacturing processes. This paper aims to assess the design variables that might affect the mechanical properties of 3D-printed fibre-reinforced composites.

Markforged Mark-Two printers were used to manufacture samples using nylon 6 and carbon fibres. The effect of fibre volume fraction, fibre layer location and fibre orientation has been studied using three-point flexural testing.

The flexural strength and stiffness of the 3D-printed composites increased with increasing the fibre volume fraction. The flexural properties were altered by the position of the fibre layers. The highest strength and stiffness were observed with the reinforcement evenly distributed about the neutral axis of the sample. Moreover, unidirectional fibres provided the best flexural performance compared to the other orientations. 3D printed composites also showed various failure modes under bending loads.

Despite multiple studies available on 3D-printed composites, there does not seem to be a clear understanding and consensus on how the location of the fibre layers can affect the mechanical properties and printing versatility. Therefore, this study covered this design parameter and evaluated different locations in terms of mechanical properties and printing characteristics. This is to draw final conclusions on how 3D printing may be used to manufacture cost-effective, high-quality parts with excellent mechanical performance.

The purpose of this study is to evaluate and compare the mechanical performance of FFF parts when subjected to post processing thermal treatment. Therefore, a study of the annealing treatment influence on the mechanical properties was performed. For this, two different types of Nylon (PA12) were used, FX256 and CF15, being the second a short fibre reinforcement version of the first one.

In this study, tensile and flexural properties of specimens produced via FFF were determined after being annealed at temperatures of 135°C, 150°C or 165°C during 3, 6, 12 or 18 h and compared with the non-treated conditions. Differential scanning calorimetry (DSC) was performed to determine the degree of crystallinity. To evaluate the annealing parameters’ influence on the mechanical properties, a full factorial design of experiments was developed, followed by an analysis of variance, as well as post hoc comparisons, to determine the most significative intervening factors and their effect on the results.

The results indicate that CF15 increased its tensile modulus, strength, flexural modulus and flexural strength around 11%, while FX256 presented similar values for tensile properties, doubling for flexural results. Flexural strain presented an improvement, indicating an increased interlayer behaviour. Concerning to the DSC analysis, an increase in the degree of crystallinity for all the annealed parts.

Overall, the annealing treatment process cause a significant improvement in the mechanical performance of the material, with the exception of 165°C annealed specimens, in which a decrease of the mechanical properties was observed, resultant of material degradation.

The purpose of this paper is to characterize mechanical properties (tensile, compressive and flexural) for the three-dimensional printing (3DP) process, using various common recommended infiltrate materials and post-processing conditions.

A literature review is conducted to assess the information available related to the mechanical properties, as well as the experimental methodologies which have been used when investigating the 3D printing process characteristics. Test samples are designed, and a methodology to measure infiltrate depths is presented. A full factorial experiment is conducted to collect the tensile, compressive and bending forces for a set of infiltrates and build orientations. The impact of the infiltrate type and depth with respect to the observed strength characteristics is evaluated.

For most brittle materials, the ultimate compression strength is much larger than the ultimate tensile strength, which is shown in this work. Unique stress–strain curves are generated from the infiltrate and build orientation conditions; however, the compressive strength trends are more consistent in behavior compared to the tensile and flexural results. This comprehensive study shows that infiltrates can significantly improve the mechanical characteristics, but performance degradation can also occur, which occurred with the Epsom salts infiltrates.

More experimental research needs to be performed to develop predictive models for design and fabrication optimization. The material-infiltrate performance characteristics vary per build orientation; hence, experimental testing should be performed on intermediate angles, and a double angle experiment set should also be conducted. By conducting multiple test scenarios, it is now understood that this base material-infiltrate combination does not react similar to other materials, and any performance characteristics cannot be easily predicted from just one study.

These results provide a foundation for a process design and post-processing configuration database, and downstream design and optimization models. This research illustrates that there is no “best” solution when considering material costs, processing options, safety issues and strength considerations. This research also shows that specific testing is required for new machine–material–infiltrate combinations to calibrate a performance model.

There is limited published data with respect to the strength characteristics that can be achieved using the 3DP process. No published data with respect to stress–strain curves are available. This research presents tensile, compressive and flexural strength and strain behaviors for a wide variety of infiltrates, and post-processing conditions. A simple, unique process is presented to measure infiltrate depths. The observed behaviors are non-linear and unpredictable.