Dahan Institute of Technology

About: Dahan Institute of Technology is a based out in . It is known for research contribution in the topics: Dielectric & Compressive strength. The organization has 93 authors who have published 175 publications receiving 4022 citations. The organization is also known as: DAHAN.

Mechanical properties of high-strength steel fiber-reinforced concrete

Abstract: The marked brittleness with low tensile strength and strain capacities of high-strength concrete (HSC) can be overcome by the addition of steel fibers. This paper investigated the mechanical properties of high-strength steel fiber-reinforced concrete. The properties included compressive and splitting tensile strengths, modulus of rupture, and toughness index. The steel fibers were added at the volume fractions of 0.5%, 1.0%, 1.5%, and 2.0%. The compressive strength of the fiber-reinforced concrete reached a maximum at 1.5% volume fraction, being a 15.3% improvement over the HSC. The splitting tensile strength and modulus of rupture of the fiber-reinforced concrete improved with increasing the volume fraction, achieving 98.3% and 126.6% improvements, respectively, at 2.0% volume fraction. The toughness index of the fiber-reinforced concrete improved with increasing the fraction. The indexes I 5 , I 10 , and I 30 registered values of 6.5, 11.8, and 20.6, respectively, at 2.0% fraction. Strength models were established to predict the compressive and splitting tensile strengths and modulus of rupture of the fiber-reinforced concrete. The models give predictions matching the measurements.

Strength properties of nylon- and polypropylene-fiber-reinforced concretes

Abstract: The strength potential of nylon-fiber-reinforced concrete was investigated versus that of the polypropylene-fiber-reinforced concrete, at a fiber content of 0.6 kg/m 3 . The compressive and splitting tensile strengths and modulus of rupture (MOR) of the nylon fiber concrete improved by 6.3%, 6.7%, and 4.3%, respectively, over those of the polypropylene fiber concrete. On the impact resistance, the first-crack and failure strengths and the percentage increase in the postfirst-crack blows improved more for the nylon fiber concrete than for its polypropylene counterpart. In addition, the shrinkage crack reduction potential also improved more for the nylon-fiber-reinforced mortar. The above-listed improvements stemmed from the nylon fibers registering a higher tensile strength and possibly due to its better distribution in concrete.

Mechanical properties of polypropylene hybrid fiber-reinforced concrete

Abstract: This paper investigates the mechanical properties of polypropylene hybrid fiber-reinforced concrete. There are two forms of polypropylene fibers including coarse monofilament, and staple fibers. The content of the former is at 3 kg/m3, 6 kg/m3, and 9 kg/m3, and the content of the latter is at 0.6 kg/m3. The experimental results show that the compressive strength, splitting tensile strength, and flexural properties of the polypropylene hybrid fiber-reinforced concrete are better than the properties of single fiber-reinforced concrete. These two forms of fibers work complementarily. The staple fibers have good fineness and dispersion so they can restrain the cracks in primary stage. The monofilament fibers have high elastic modulus and stiffness. When the monofilament fiber content is high enough, it is similar to the function of steel fiber. Therefore, they can take more stress during destruction. In addition, hybrid fibers disperse throughout concrete, and they are bond with mixture well, so the polypropylene hybrid fiber-reinforced concrete can effectively decrease drying shrinkage strain.

Mix proportions and mechanical properties of concrete containing very high-volume of Class F fly ash

Abstract: Two types of Class F fly ash with 4.6% and 7.8% loss on ignition were used for an experimental investigation dealing with concrete incorporating very high volumes of Class F fly ash (HVFA). A rational mix design method was developed for concrete with 20–80% fly ash replacement for cement. Tests were performed for fresh and hardened concrete properties. Test results indicated that the setting times and the air content of fly-ash concrete increased as the fly ash replacement level increased. The compressive and flexural strength of the HVFA concrete mixtures demonstrated continuous and significant improvement at late ages of 91 and 365 days. Relation was formulated for flexural and compressive strength for all grades of HVFA concrete. The concrete mixture containing low-LOI fly ash exhibited superior mechanical properties than those of the corresponding mixture containing high-LOI fly ash. These results confirm the feasibility that up to 80% of Class F fly ash can be suitably used as cement replacement in concrete by using a rational mixture proportions.

Synthesis and characterization of zinc titanate nano-crystal powders by sol–gel technique

Abstract: A sol–gel technique including the Pechini process has been employed for the preparation of nano-sized zinc titanate (ZnTiO 3 ) powders. The yielding powders were heated at temperature from 500°C to 1000°C for various times. The ZnTiO 3 phase was formed at the beginning of 500°C. The shape of crystalline will be changed from granular to fiber as the calcination temperature increasing from 800°C to 1000°C. The activation energy of crystallization of ZnTiO 3 is 172.74 kJ/mol calculated from Kissinger's equation. The activation energy of grain growth is 20.83 kJ/mol experimented by Arrhenius equation.