Increasing Fiber Content Research Articles

Mesoscale modeling of flexural fracture behavior in steel fiber reinforced concrete

This paper presents a computational study on the flexural fracture behaviors of steel fiber reinforced concrete (SFRC). The focus is on investigating the impacts of various factors on SFRC, utilizing a discrete-continuum coupled finite element method. This method explicitly models each material phase, including coarse aggregates, mortar paste, steel fibers and interfacial transition zones (ITZs), allowing precise tracking of mesoscale cracking during bending. The simulation method is developed, calibrated and validated before conducting a parametric investigation. Critical factors considered include the spatial positioning of coarse aggregates and steel fibers, fiber content, length and diameter, and the bonding property of fiber-mortar ITZs. Results indicate that steel fibers modify crack development in notched beams, causing greater distortion in the primary crack. Increasing fiber content from 0 to 2% enhances flexural tensile strength but introduces more variability. Longer fibers initially increase strength, then decrease, while thicker fibers consistently reduce strength. Improving the bond between fibers and mortar does not substantially increase the load-bearing capacity of the beam. In conclusion, this study shows how the established approach enhances understanding of the mechanical responses of SFRC under flexural-fracture loading.

Wastepaper fiber‐reinforced concrete containing metakaolin: Effect on fracture behavior

AbstractPlasterboard, a commonly utilized construction material, comprises a gypsum core nestled between two paper layers. Gypsum after demolition of plasterboards is a recyclable waste that has been reused into new plasterboard or other purposes such as agricultural products. However, there is a lack of understanding on the potential for recycling the paper layers. This study investigates the use of wastepaper fibers, obtained from the paper layers, as a reinforcing material and metakaolin as a partial cement replacement material in concrete. This study demonstrates the ability of the paper from waste plasterboard for reinforcing concrete. Wastepaper fibers were used at different concentrations ranging from 0 to 2.5% by weight of binder. Bending test was conducted for assessing fracture behavior of concretes, including load bearing capacity, modulus of rupture, crack mouth opening displacement (CMOD) at the load bearing capacity, fracture toughness, and fracture energy. Slump, axial compression, and scanning electron microscopy (SEM) were also conducted on the concretes. It is found that incorporating wastepaper fiber by up to an optimum content of 1.5% results in an increase in the compressive strength (57%), flexural load bearing capacity and modulus of rupture (31%), CMOD displacement at load capacity (14%), fracture toughness (37%), and fracture energy (73%) of the metakaolin‐based concrete. However, further increase in the wastepaper fiber content results in decreased mechanical properties of the concrete, which is due to the fiber agglomeration and non‐uniform distribution within the concrete matrix. Based on the results, the concrete with 20% metakaolin and 1.5% wastepaper fiber experiences similar mechanical properties to the conventional concrete. The results of this study underscore the substantial potential of leveraging waste materials such as wastepaper and by‐products like metakaolin to diminish reliance on conventional cement. This approach not only enhances the mechanical properties of concrete but also fosters sustainable building practices by promoting the recycling of waste materials, reducing carbon footprint, and mitigating the environmental impacts inherent in traditional concrete production.

Incorporation of hemp flour to obtain gluten-free noodles of higher nutritional quality

One of the most important challenges in the production of gluten-free foods is the need to improve their nutritional quality. This work attempts to produce gluten-free noodles by substituting three different percentages of corn flour with hemp and to evaluate their technological and nutritional quality. This study used corn flour with 10.33 % protein and 1.57 % fiber and commercial hemp flour with 23.57 % protein and 28.75 % fiber. The pastas were made by extrusion by adding pregelatinized starch, ovalbumin and salt to obtain the control, then substitutions were made with 5 %, 10 % and 15 % hemp flour. The addition of hemp flour did not significantly affect the most important quality indicators, such as optimum cooking time and cooking residue, and even increased the firmness of the cooked pasta. Protein and fiber content increased significantly. It can be concluded that the addition of these percentages of hemp flour does not produce a deterioration of the technological quality of gluten-free pasta and allows for an increase in fiber and protein content, generating a significant improvement of nutritional quality.

Experimental Study of the Physical and Mechanical Properties of Cement‐Based Composite Reinforced With Macro‐/Microfibers: Case of Rhecktophyllum camerunense and Triumfetta pentandra

Plant fibers have the ability to bridge crack propagation on a microscopic scale for microfibers and on a macroscopic scale for macrofibers. Therefore, the use of two or more fiber types in an appropriate combination can potentially improve the overall properties of the cement composite as well as promote green construction. The hybrid composite was cast using random orientation with two fibers: Rhecktophyllum camerunense as macrofiber and Triumfetta pentandra as microfiber. Cement mortar matrices were reinforced with a constant microfiber length of 1 mm and three different macrofiber lengths of 1.5, 3, and 6 mm at varying fiber contents of 1%, 1.5%, and 2.5% wt. The physical characteristics of the composite were assessed by porosity, density, and water absorption. Mechanically, three‐point bending tests and single‐edge notch bending (SENB) tests were performed after 7 and 14 days of curing. Mode I fracture behavior (KIC) and modulus of rupture (MOR) were calculated as per formulation. Physical experimental results reveal that there is a correlation between the rate of water absorption, porosity, density, and that of the fiber loading and length in the composite. Mechanically, the developed material presented a multiple cracking behavior under bending. There was a decrease in MOR and fracture toughness values with a decrease in macrofiber content in the hybrid composite. They both presented an increase in value with an increase in fiber content and fiber length. The composites reinforced with both fibers presented higher values of MOR than the unreinforced due to the powerful interfacial bond between the fibers and the cement matrix. The unreinforced composites had the least MOR and fracture toughness values of 0.442 MPa and 694,000 N.m1.5, respectively, showing that they are very reactive to faults at low stress levels.

Characteristics of metakaolin-based geopolymers using bemban fiber additives

<p>The aim of this study was to investigate the chemical composition and thermal properties of kaolin, the physical properties of metakaolin, and the mechanical properties of metakaolin-based geopolymers using bemban fiber. Kaolin was calcinated to become metakaolin at 600 ℃ for 2 h for optimum conditions. The chemical composition of kaolin mostly consisted of 59.30% SiO<sub>2</sub>, 34.30% Al<sub>2</sub>O<sub>3</sub>, and 3.06% Fe<sub>2</sub>O<sub>3</sub>. The transformation of kaolin into metakaolin with temperature was determined through thermal stability tests and analyzed using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Regarding the thermal properties of kaolin, predehydroxylation occurred at 31.07–92.69 ℃, dihydroxylation occurred at 400–600 ℃, and the endothermic peak in the DTA curve was recorded at 505.63 ℃. This research also analyzed the physical and mechanical characteristics of metakaolin-based geopolymers, with the additional variation percentages of bemban fiber alloys resulting from a 3% NaOH alkalization treatment for 2 h. The test results indicate that the bemban fiber improves the physical and mechanical characteristics of geopolymers. This improvement is related to the enhanced geopolymer characteristics, including a water absorption capacity of 1.10%, porosity of 2.32%, compressive strength of 35.33 MPa, and splitting tensile strength of 11.29 MPa with the addition of 1.5% bemban fiber. Although the split tensile strength increases as the fiber content increases, adding 1.5% of bemban fiber is optimum because a higher content decreases the workability of mixtures.</p>

Wind turbine blades with hybrid fiber composite: Tensile properties and numerical verification

Wind turbine blades are the main component of wind turbines to capture effective wind energy, and require good quality and reliable performance. Therefore, the manufacturing cost of wind turbine blades is much higher than that of other components of wind turbines. The blade is a slender elastomer prone to vibration. The wind turbine vibration always arises in the blade instability. At the same time, the blade is also a typical aerodynamic component. In the process of rotation, it will not only produce mechanical vibration but also bear aerodynamic force. In this paper, the mechanical properties and modal numerical simulation analysis of composite blades with different hybrid ratios of carbon fiber and glass fiber are analyzed, it is found that with the increase of carbon fiber content, the mechanical properties of the blade gradually increase, and the torsional vibration resistance of the blade become stronger. Therefore, the wind turbine blades of hybrid fiber composites have a longer service life, which can reduce material wastage and help protect the environment.

Impact of solid-state fermentation utilizing Saccharomyces boulardii on the chemical composition and bioactive constituents of rice husk

The objective of this study was to evaluate the effect of solid-state fermentation, utilizing Saccharomyces boulardii on brown rice husk, black rice husk, and smoked rice husk substrates in terms of the availability of different compounds. The fermentation process was carried out at 37 °C for a maximum of 12 h, using yeast (2.5 % w/w) and water (25 %). During fermentation, black rice husks (BLRH) exhibited an increase in vitamins, protein, and fiber content, whereas brown rice husks (BRRH) showed an increase in carbohydrate and fiber, and smoked rice husks (SRH) decreased lipid and fiber content. The solid-state fermentation process also enhanced the availability and accessibility of minerals, except for smoked rice husk. The levels of phenolic compounds in fermented black, brown, and smoked rice husks were 1165, 1108, and 1051 μg per gram of sample, respectively. Importantly, black rice husk fermented for 8 h demonstrated the most favorable results in terms of nutrient and bioactive compound availability. Principal Component Analysis (PCA) revealed correlations among the variables, which could be manipulated to improve the accessibility of diverse compounds.

Bacteria Pseudomonas taiwanensis as a decomposing agent of peat fiber

Efforts are needed to accelerate the decomposition of peat fiber to reduce the fiber content through bioaugmentation using Pseudomonas taiwanensis bacteria so that it can reduce the high-water content of peat fiber. The research aimed to determine the effect of adding Pseudomonas taiwanensis bacteria on the decomposition of peat fiber. This research is a laboratory experimental research. The research sampling location was in Bereng Bengkel Village, Palangkaraya. The parameters observed included fiber content, fiber size distribution, and peat fiber decomposition speed following the Peat Testing Manual. The research instrument was an observation sheet for fiber content, size distribution, and peat fiber decomposition speed. Research data was analyzed using descriptive statistical analysis. The results showed that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days in fibrous peat resulted in the highest reduction in fiber content, from the initial condition of 61.14% to 12.33%. This variation also shows a decrease in coarse and medium fiber content and a significant increase in fine fiber content. The decomposition rate for this variation shows good consistency. The conclusion was that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days showed optimal results in accelerating the decomposition of peat fiber through the bioaugmentation method.

Peningkatan Kadar Serat Brownies Kukus dengan Penggunaan Tepung Kacang Merah (Phaseolus vulgaris L.)


 
 
 Brownies are a type of dark brown cake with a soft texture, a distinctive chocolate aroma and a sweet taste. Generally, flour-based brownies have a low fiber content. Therefore, red bean flour is expected to be used to increase fiber content. The purpose of this study was to determine the effect of using red bean flour on the fiber content of steamed brownies and produce steamed brownies with high fiber content and the best characteristics. This study used a completely randomized design (CRD) with the treatment ratio of wheat flour and red bean flour, namely: 100:0, 90:10, 80:20, 70:30, and 60:40 repeated 3 times to obtain 15 experimental units. The data obtained were analyzed by Analysis of Variance (ANOVA), followed by the Duncan Multiple Range Test (DMRT). The results showed that the use of red bean flour had a significant effect (P<0.05) on crude fiber content, moisture content, ash content, protein content, fat content, carbohydrate content, and sensory properties of steamed brownies, but had no significant effect (P > 0.05) on the sensory properties of the color of steamed brownies. Treatment of 70 percent wheat flour and 30 percent red bean flour was the best treatment with 5.08 percent crude fiber content, 23.66 percent moisture content, 2.20 percent ash content, 8.84 percent protein content, 33.81 percent fat content, carbohydrate content of 31.46 percent with color, aroma, texture, taste and overall acceptance favored by the panelists.
 
 

Dough rheology and internal structure of bread produced with wheat flour partially substituted by buckwheat flour: A step towards enhancing nutritional value

Buckwheat flour is a pseudocereal that can be used to improve the nutritional value of staple food, such as bread. However, substituting wheat flour can be challenging due to potential loss of the final product's technological quality. Therefore, understanding the influence of buckwheat inclusion level on dough rheology and bread quality is essential. This study evaluated the effect of wheat flour substituted by buckwheat flour on dough rheology and bread quality over the staling process. Wheat flour was replaced by 0%, 10%, 20% and 30% of buckwheat flour and the resulting dough mixing properties, viscosity profile, gel texture, rheology behaviour and extensibility properties were analysed. Internal bread structure (C-Cell and confocal microscopy), specific volume, density and crumb texture profile were also assessed. The increase in buckwheat level gradually decreased flour water absorption (p < 0.05), dough stability and development time, with increased gluten weakening as evidenced by decreased C2 values (protein strength) of Mixolab. As a result, the dough was less resistant to extension, with decreased extensibility. The highest viscosity profile of the starch paste was observed with 30% buckwheat inclusion level, which may lead to faster bread staling process. A solid-like and elastic behaviour was observed in the rheology evaluation, suggesting an interaction between fibre and starch from buckwheat with gluten proteins. Although changes in dough rheology occurred, the bread quality remained unchanged at levels of up to 20% buckwheat level (p > 0.05), with similar specific volume, density, internal structure and texture profile compared to the control bread (0% buckwheat). In conclusion, buckwheat was found to be a viable wheat flour substitute with only minimal changes in dough behaviour and maintenance of bread technological quality, while enhancing the nutritional profile by increasing fibre content and total essential amino acid.

Effect of Roasting on the Proximate Composition, Antioxidant Activity, and Functional Properties of Afrostyrax lepidophyllus (Country Onion) Seeds

Afrostyrax lepidophyllus seed is a nontimber forest product which has a strongly ferocious smell of garlic or onion. It is widely used in central and west Africa in traditional medicine and as spices. The seeds used as spices are generally roasted in order to improve their flavor or aroma. However, roasting conditions vary and also affect the quality of the final product. In order to define the best roasting conditions, A. lepidophyllus seeds were roasted using microwave (200, 300, and 450 W for 10 min), oven (10 and 20 min at 180°C), and pot (5, 10 and 15 min) and blended into flour. The proximate composition, physical, functional, and antioxidant activities of (control) and roasted flours were analyzed. Irrespective of the roasting method, there was a significant increase in fiber content (oven (0.5–1.20%), pot (0.47–1.27%), and microwave (0.50–0.93%)) with increase in time and temperature. The carbohydrate content increased (77.74–81.50%), while protein content dropped with roasting. A significant increase in ash, total phenolic contents (TPC), antioxidant activity (AOA), and functional properties compared to the control was recorded. Roasting A. lepidophyllus seeds in the pot at 250 ± 5°C, 15 min was found to be a good method which maintained or increased its functional and physicochemical properties. With the good TPC and AOA, A. lepidophyllus roasted flour can be a potential ingredient for nutraceutical food development.

Flours from fermented lentil and quinoa grains as ingredients with new techno-functional properties

The need to provide novel, nutritious plant-based products requires seeking high-value, sustainable protein sources, like quinoa and lentils, having an increased digestibility and lacking antinutrients. Fungal fermentation has evidenced enhanced nutritional value of flours obtained from these grains. However, research into techno-functional properties, essential to the new product development, is lacking. This study investigated the techno-functional properties of flours made from lentil and quinoa after fermenting them with Pleurotus ostreatus and subjecting them to two drying techniques (lyophilisation and hot air drying). In both cases, the fermentation led to noteworthy improvements in swelling and water holding capacity, especially in those lyophilised than those dried. In contrast, the emulsifying, foaming, thickening, and gelling capacities decreased significantly. The loss of abilities was more severe for dried grains than for lyophilized ones. The thermomechanical analysis of the fermented flours showed lower thickening and gelling potential compared to untreated flours. Microscopy images revealed that the state and structure of starch granules were affected by both fermentation and drying processes. Starch granules in lentils were partly pre-gelatinised and trapped in the cotyledon cell, resulting in limited thickening and gelling abilities. In contrast, in quinoa, starch underwent pre-gelatinisation and retrogradation during the fermentation process, promoting the production of resistant starch and increasing fibre content. This study presents the potential of treated flours as ingredients possessing unique attributes compared to protein and fibre-rich conventional products.

Study on Mechanical Properties of Cement–Jute Fiber Modified Weak Expansive Soil

Sixteen groups of comprehensive tests were undertaken to examine the modifications in the mechanical characteristics of weak expansive soil resulting from the inclusion of a composite material comprising cement and jute fibers. The aim of the tests was to analyze the unconfined compressive strength and shear strength. The results reveal that (1) as the modified material content increased, the stress–strain curve of the modified soil progressively became steeper, with a more pronounced peak value. Under the same strain condition, the stress variation increased accordingly. After the stress reached its maximum, a sudden phenomenon of brittle axial compression failure occurred. (2) With the increase in cement content, the unconfined compressive strength and shear strength of the modified expansive soil gradually increased, reaching the highest shear strength when the cement content was 8%. With the increase in jute fiber content, the unconfined compressive strength and shear strength of modified expansive soil increased first and then decreased, reaching the highest value when the content was 0.5%. (3) The cohesion of modified expansive soil increased with the increase in cement content. When the cement content was 8%, the cohesion of the soil sample was as high as 298.29 kPa. The cohesion of modified expansive soil increased first and then decreased with the increase in fiber content. When the jute fiber content was 0.5%, the cohesion reached the maximum value. (4) The internal friction angle of the modified expansive soil increased with the increase in cement content. When the cement content was 8%, the internal friction angle of the soil sample increased by 2.64°. The cohesion of modified expansive soil increased first and then decreased with the increase in fiber content. When the jute fiber content was 0.5%, the internal friction angle reached the maximum value.

Quality Production of Sainfoin Swards Challenged by Global Change in Mountain Areas in the Western Mediterranean

Legume-based livestock forage systems are widespread and socially relevant agroecosystems that are essential for delivering high-quality forage. Therefore, it is critical to determine how climate change and management might affect the functioning of forage agroecosystems. The objective of this study was to explore the potential of sainfoin swards under different management regimes by combining results from an experiment on species diversity effects on yield developed under extreme climatic conditions and a survey of sainfoin (Onobrychis viciifolia Scop.) swards and nutritive value in mountain regions in Catalonia, Western Mediterranean. Our results show that 12–59% of the variability in forage nutritive value parameters was accounted for by management. Young cattle-grazed swards showed higher nutrition quality that decreased faster than sheep-grazed or only mown swards. Mixing sainfoin with orchardgrass increased fiber content (e.g., +22% neutral detergent fiber) and decreased protein (−26%) and lignin (−11%) compared to sainfoin monocultures. However, under the extreme climatic conditions of the last three years, the only diversity effect found on yield was the identity of the species present. We propose that a combination of different sainfoin management regimes might be beneficial regionally for both quality forage production and overall biodiversity conservation, whereas traditional systems may be vulnerable to changing climatic conditions.

Pfaffia glomerata by‐product: drying, characterisation and utilisation in cereal bars

SummaryThis study aimed to evaluate the convective drying of a by‐product obtained by hydrodistillation of Pfaffia glomerata roots (PGB) and investigate the utilisation of the resulting powder in the preparation of cereal bars. Drying at 80 °C for 120 min was the selected condition for PGB due to the higher levels of phenolic acids (gallic, coumaric and ferulic) catechin and higher antioxidant activity than drying at 60 °C for 180 min, and, better technological properties and higher β‐ecdysone content than drying at 100 °C for 100 min. There was an increase in fibre content (110%), antioxidant compounds (97%) and compressive strength (377%) and a decrease in lipid content (31%) when the PGB content of cereal bars was increased from 0% to 9%. Colour parameters, purchase intention and most sensory parameters were similar among cereal bar formulations, indicating that PGB is a promising ingredient for the nutritional enrichment of cereal bars.

Study on early dynamic compressive strength of alkali-activated slag high performance concrete

The effects of different flyash content, steel fibre content and water-binder ratio on the dynamic compressive strength of alkali-activated slag high performance concrete (ASHPC) were studied. When flyash and water-binder ratio rose, the dynamic compressive strength of ASHPC fell by 27.3% and 23.5%, respectively, and increased by 81.6% when steel fibre content increased. The dynamic elastic modulus rises by 35.0% with an increase in steel fibre content and falls by 48.0% and 65.6%, respectively, with an increase in flyash content and water-binder ratio. The toughness conversion ratio and pre-peak toughness ratio dropped by 34.1% and 9.5%, respectively, whereas the post-peak toughness ratio rose by 36.4% with an increase in flyash content. The test block’s pre-peak toughness ratio and toughness conversion ratio increased by 12.7% and 60.0%, respectively, with an increase in steel fibre , whereas the post-peak toughness ratio declined by 31.0%. With the increase of water-binder ratio, the pre-peak toughness ratio and toughness conversion rate of the test block increased by 31.0 % and 132 %, respectively, and the post-peak toughness ratio decreased by 42.8 %. The energy absorption and reflection rise while the energy transmission falls as flyash concentration and the water-binder ratio rise. The transmission energy rises as the amount of steel fibre grows, while the energy absorption and reflection fall.

Effects of fiber properties on flexural and fracture characteristics of manufactured sand concrete based on acoustic emission

Fiber-reinforced concrete (FRC) with natural sand (NS) as fine aggregate has been regarded as an favorable cementitious composites in engineering application due to its superior mechanical and fracture properties, etc. As a promising substitution for NS in conventional concrete, manufactured sand (MS) presents great potential in minimizing environmental impacts and increasing economic benefits. This paper presents the effects of fiber type (steel fiber, basalt fiber, glass fiber), fiber content (0 %, 1 %, 2 %) and fiber length (6 mm, 13 mm, 20 mm) on mechanical and fracture characteristics of manufactured sand concretes (MSCs) with 100 % replacement ratio of NS with MS. The entire fracture processes of MSCs were monitored using acoustic emissions (AE) in real time. The results showed that flexural strength of MSC increases with the addition of three different fibers, and steel fiber exhibits the best reinforcement effect. MSC with 1 % steel fiber content exhibits the highest flexural strength. Meanwhile, the longer the fiber length is, the smaller the flexural strength presents. The effects of fiber properties on AE parameters (count, b-value, information entropy) revealed that the addition of fibers reduces the fluctuation of counts and information entropy. The MSC with 2 % steel fiber content exhibits more dramatic fluctuations of b-value and information entropy after post-peak, which reveals greater internal damage in specimen. The longer the steel fiber is, the more dramatic the AE signal fluctuations and the more severe the damage inside the specimen emerge. Parametric analysis of rise angle (RA) and average frequency (AF) for classifying fracture modes (tensile and shear cracks) show that the incorporation of fibers can reduce the tensile cracks of MSC specimen under four-point bending. With the increase of fiber content, the tensile cracks first decrease and then increase. The longer fiber length is, the more tensile cracks generate during the fracture process.

Degradation of SMA-13 low-temperature performance under coupled dry and wet-salt corrosion

To investigate the low-temperature performance of polyester fiber-modified asphalt mixtures under the influence of dry-wet-salt corrosion coupling, six different polyester fiber content levels (0%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5% by weight of the mixture) were chosen for preparing SMA-13 asphalt mixture specimens. The Ultrasonic non-destructive testing, semi-circular bending tests, and scanning electron microscopy (SEM) were employed to evaluate the low-temperature performance of these mixtures under dry-wet-salt corrosion conditions with varying cycle numbers (0, 2, 4, 6, 8 cycles). The results of ultrasonic non-destructive testing showed that the wave velocity exhibited a trend of initial increase followed by a subsequent decrease with the increase in polyester fiber content. It reached a maximum value of 4.06 cm/us at a fiber content of 0.4%. The semi-circular bending tests (SCB) revealed that the fracture toughness of the polyester fiber asphalt mixture decreased as the number of dry-wet cycles increased. The impact of salt-dry-wet coupling > water-dry-wet coupling. Notably, after undergoing 4 cycles of water-dry-wet exposure, the overall fluctuation in specimen fracture toughness was minimal, indicating that results after four cycles could be suitable for evaluating the long-term degradation performance of asphalt mixtures under extended water-dry-wet cycling. SEM test results demonstrated that a polyester fiber content of 0.4% led to the formation of a strong fibrous network structure within the asphalt mixture. This significantly reduced moisture and salt intrusion during the dry-wet cycling process, enhancing the low-temperature crack resistance of the specimens.

Mechanical Properties and Microstructure of Polypropylene-Glass-Fiber-Reinforced Desert Sand Concrete.

In order to improve the performance of desert sand concrete, polypropylene fiber (PF) and glass fiber (GF) were used to prepare desert sand concrete (DSC) with different fiber and volume content, and the basic mechanical properties, such as cube compressive, tensile and flexural strengths, were tested and studied. Based on the mercury injection method (MIP) and scanning electron microscopy (SEM), the evolution of pore structure and interface structure was analyzed. The mechanism of fiber toughening was revealed at the microscopic level. The results show that the slump of DSC decreases with the increase in fiber content. The slump of glass-fiber-reinforced DSC (GFRDSC) is smaller than that of polypropylene-fiber-reinforced DSC (PFRDSC). The strength enhancement of DSC by fibers is in the order of flexural strength > split tensile strength > compressive strength. The flexural strength of hybrid-fiber-reinforced DSC (HyFRDSC) (0.1% PF + 0.1% GF) is increased by 40.7%. Meanwhile, fibers can improve the toughness of DSC. The MIP results show that the porosity of HyFRDSC decreased by 50.01%, and the addition of fiber can effectively refine the large pore size. The SEM results show that the incorporation of PF and GF causes the formation of a uniform and dense structure between the fibers, cement and aggregate. The two can give full play to the crack-resisting and toughening effect in different loading stages, thus improving the macromechanical properties of DSC.

Effect of steamed purple sweet potato addition on chemico-physical properties of sandwich bread

Purple sweet potato (PSP) has the potential to be used to prepare functional foods due to its attractive color and high anthocyanin content. With completely randomized design experiments used, the study investigated the effect of the percentage of steamed PSP (25, 29, 33 and 37% of total batch weight) on the overall quality of sandwich bread. The results showed that the added PSP significantly affected the color (L*, a* and b*) and anthocyanin content of bread. The sandwich bread with 33% PSP had the most intense purple color, and a soft structure was found with a measured hardness of 92.12 and 25.11 g force in the bread crust and the centre of the bread, respectively. The expansion ratio was 5.86 times compared with the control sample (5.47 times), and the moisture and anthocyanin content were 38.23% and 55.14 mg%, respectively. The findings of this study also suggested that the preparation of sandwiches with the addition of PSP, in addition to providing a beautiful color, also has the potential to improve overall product quality, increase fiber content (2.4%) and DPPH free radical scavenging activity (28.80%) compared to the control sample.