Osman Çelik

In this paper, abrasion of high volume fly ash (HVFA) concretes made with 50% and 70% of cement replacement with fly ash was assessed in terms of its relation to flexural tensile strength. Comparisons were made between normal Portland cement (NPC) concrete and fly ash concrete. Comparisons were also made between fly ash concretes. Investigation results have shown that the abrasion resistance increased as flexural tensile strength increased. Analysis of the results showed that, for concrete with tensile strength of greater than 4–5 MPa, the abrasion resistance of HVFA concrete with 70% replacement with cement was found to be higher than that of counterpart control NPC concrete and concrete made with 50% fly ash. The comparison between the relation of abrasion to compressive strength and abrasion to flexural tensile strength made in terms of R2 of the linear regression showed that a stronger relation existed between abrasion and flexural tensile strength than that of abrasion to compressive strength of the concrete studied. L'étude a pour but d'estimer la relation entre la résistance à l'usure avec la résistance à la traction en flexion des bétons contenant de 50% et 70% de cendres volantes. On a comparé le béton pur au béton contenant des cendres volantes. Des comparaisons ont été faites également entre les différents bétons contenant des cendres volantes. Les resultats de la recherche ont montré que la résistance à l'usure augmente à mesure que la résistance à la traction en flexion de 4∼5 MPa ont une résistance à l'usure plus grande s'ils contienneint 70% de cendres volantes que s'ils étaient purs ou contenaient 50% de cendres volantes. La comparaison entre les relation de la résistance à l'usure en compression et de la résistance à l'usure en traction a été établie en termes de R2 de la régression linéaire. On a prouvé qu'une relation plus forte a été obtenue entre la résistance à l'usure et la résistance à la traction en flexion par rapport à la résistance à l'usure en compression du béton étudié.

Badly compacted mixtures will develop undesirable properties of low stiffness, bad fatigue resistance, bad durability, etc. that is not expected from a good pavement. This paper is to evaluate the compactibility of hot asphalt mixtures (HAM) made with crump rubber ...

In this study the effects of mechanical milling on the structural and morphological characteristics of MgH2 were investigated and it was found a strong correlation with the hydrogen desorption temperature of MgH2. The MgH2 powder was mechanically milled for a duration ranging from 0.5 to 20h. X-ray diffraction (XRD), scanning electron microscope (SEM), and optical microscope (OM) techniques were used

A surface modification process was used to modify the surface properties of a steel material by using the TIG method on AISI 8620 steel with a 135-A constant energy input and the addition of 0.5g of constant SiC particle and variable C content. SEM and optical microscopy were used to characterize the microstructure of the materials tested. To evaluate the

The present study evaluates the tribological properties of boride layers on the surface of AISI 4140 steel, formed using the pack-boriding method. Commercial EKabor®2 was used as the boronizing agent and the treatment was carried out at 900, 950, 1000, and 1050 °C for 2, 4, and 6 h, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness tests were used to characterize the phase composition, microstructure, and local hardness, respectively, of the borided steel samples. Block-on-disc tests were used to investigate tribological properties. Abrasive wear tests were carried out using emery paper at a fixed sliding speed and three different loads. Adhesive wear tests were executed against AISI 52100 steel at a fixed load and distance. The coefficient of friction values (COF) of the samples were determined simultaneously during the tests. The weight loss and COF of the borided samples were compared with untreated samples and the results suggest that both wear resistance and friction properties of the AISI 4140 steel improve with boriding.