Dynamic mechanical properties of hybrid fiber reinforced concrete

In this study, the dynamic mechanical properties of hybrid fiber reinforced concrete (HFRC) are analyzed with respect to failure mode, dynamic increase factor (DIF), and peak strain by means of a SHPB testing apparatus. The factors that influence the dynamic mechanical properties include fiber type and fiber content. It is concluded that the best dynamic mechanical properties of fibers are CS-PHFRC at medium and low strain rates and AS-PHFRC at a high strain rate. Within a certain range, the higher the fiber content is, the larger the DIF of the corresponding HFRC and the more obvious the increase in dynamic compressive strength. AS-CSHFRC improves the dynamic compressive deformability of the HFRC. The polypropylene fiber causes plasticity, as shown in the failure mode of concrete. The Ottosen nonlinear elastic model, modified by introducing the damage factor, can better describe the dynamic mechanical properties of HFRC.

Effect of Rice Straw on Tensile Properties of Tailings Cemented Paste Backfill

It is important and difficult to improve the tensile strength of backfill material to ensure the stability of goafs. In this study, rice straw (RS) in fiber form is used to improve the tensile properties of cemented paste backfill (CPB). An orthogonal experiment was designed, Brazilian indirect tensile strength tests were conducted to test the tensile performance of RS fiber-reinforced cemented paste backfill (RSCPB) under different fiber content (1, 2, 3 kg/m3) and fiber length (0.8~1, 1~3, 3~5 cm), and the microstructure of RSCPB was analyzed with scanning electron microscopy (SEM). The results showed that, compared with the conventional cemented paste backfill (CCPB), the increase in tensile strength of RSCPB ranged from 115.38% to 300.00% at 3 days curing age, 40.91% to 346.15% at 7 days, and −38.10% to 28.00% at 28 days., and the strain was slightly reduced during the curing period. The tensile strength, strain, and percentage increase of the RSCPB compared to the CCBP did not show a monotonic pattern of variation with the RS fiber content and length during the curing period. The RSCPB samples fractured under peak stress, showing obvious brittle failure. In addition, sulfate generated from S2− in the tailings inhibits the hydration reaction, and generates swelling products that form weak structural surfaces, which, in turn, lead to a 28-day tensile strength and strain of RSCPB lower than those at 7 days.

Effect of Particle Size on Physico-Chemical and Antioxidant Activity of Insoluble Dietary Fiber Powder from Corncob (Zea mays L.)

Effects of particles size of dietary fiber powder on the physico-chemical properties and antioxidant activity of corncob were investigated. Corncob was grounded in a regularly mill and grinding characteristics and the particles size were evaluated by particle size analyzer (PSA) using laser diffraction method and Fourier transform infrared (FTIR). The results showed that the insoluble dietary fiber (IDF) powder from corncob had the highest crude fiber content (32.31%) and carbohydrates (55.07%). Spectral analysis shows that the IDF matrix structure does not change after grinding and has three characteristics of absorption spectra at 3433-3425 cm-1 (O-H); 2920 cm-1 (C-H) and 1635 cm-1 (aromatic) in presence of the special structures of polysaccharide and lignin compounds. Particle size analyzer (PSA) results showed that the size of IDF 200 mesh and 80 mesh powder were 63.13 and 260.89 μm, respectively. The insoluble dietary fiber (IDF) significantly shows a decrease in dietary fiber content in line with the reduction in particle size. The IDF powder with a particle size of 63.13 μm showed that highest total phenolic content accompanied with the best antioxidant activity through all antioxidant assays (p < 0.05). This study concluded that the IDF micro-powder particle size exerted influence on physico-chemical properties, dietary fiber, total phenolic and antioxidant activity.

Consistent Organochlorinated Pesticides (OPC) Residues Contamination in Beans Consumed in Gombe Metropolis Nigeria

Most of the locally consumed beans in our vicinity contain excess chemicals of pesticides residues which are harmful to humans and environmental hazards to ecosystem. Investigation of this study revealed contamination level of organochlorine pesticides residues in dried beans originating from Nigeria with a view to controlling them, it also studies crude fiber of beans showed that B4 has the highest fiber content, 27.85% and the order of decreasing value as B4, B5 , B1, B3 and B2. The least percentage of crude fiber was shown by B2 in all the beans samples analyzed. This study also investigated the pesticides residue components of the organochlorinated pesticides test. The presence of pesticide residues in all 14 types of organochlorine pesticides in beans is lower than a previously reported level. Despite this, the amount of organochlorine pesticides tested is more than the permitted levels of 0.01 to 0.2 mg/kg, indicating that the beans consumed in the Gombe metropolis included pesticide residues beyond the permissible limit.

Behavior of Fibrous Reinforced Concrete Splices

Background: The tangent of the relationship between bond stress and displacement (slip) is called the modulus of displacement and gives the basis for the theory. This theory is used to determine the stress distribution along the spliced reinforcement bars. Objective: This research presents a modification on the theory of the modulus of displacement to determine the stress distribution along the spliced reinforcement bond for fibrous reinforced concrete. Methods: 1- General differential equations are derived for concrete stress, stress in reinforcement bars and bond stress between reinforcement bars and surrounding concrete. 2-The general solutions of these D.E. are determined and Excel data sheets are prepared to apply these solutions and determine the concrete, steel and bond stresses. Results: Excel data sheets are prepared to determine the concrete, steel and bond stresses. The stresses are determined along the bar splice length considering the effect of steel fiber content. Conclusion: The maximum concrete stress is obtained at center x=0 and minimum at . Maximum bond stress obtained at and minimum at the center. The maximum steel stress at and minimum at . The value of (σcmax) increased linearly with increasing of (ρ). The concrete stress increased nonlinearly with (ρ%) and linearly with ( fy) and (fc’). Also increasing of (k) and bar diameter have small effects. The value of bond stress decreased linearly with (Qf) and (ρ%).

Proximate Analysis of Merang Mushrooms (Volvariella volvacea) Cultivated on Corncob and Rice Bran Media

Merang Mushroom (Volvariella volvaceae) is one of the edible mushrooms. The nutritional content of merang mushrooms makes this mushroom has potential as a medicine and food supplement. Merang mushrooms are known to function as antioxidants, antidiabetic, antiviral, and can lower cholesterol. The purpose of the research is to find out the nutritional content of merang mushrooms that are cultivated in corncob media with the addition of rice bran. The analysis used was proximate analysis to determine moisture, ash, and fiber content using the AOAC method, fat content analysis using the Soxhlet method, protein content analysis using the Kjeldahl method, and carbohydrate Analysis (By difference). The results of the analysis were 2.17% ash content, 85.14% water content, 3.65% crude fiber content, 1.99% fat content, 2.7% crude protein content, and 8.0% carbohydrate content. Based on research, it can be said that mushroom has a good nutritional content that can provide health benefits.