https://hdl.handle.net/20.500.12619/49643 2026-04-13T17:48:23Z 2026-04-13T17:48:23Z Sevinç, Vahdettin https://hdl.handle.net/20.500.12619/49651 2020-02-26T08:39:37Z 2001-01-01T00:00:00Z

Effects of colemanite waste, cool bottom ash, and fly ash on the properties of cement Sevinç, Vahdettin In this study, the physical and chemical properties of colemanite ore waste from concentrator, coal bottom ash, fly ash, cement+ash mixtures, cement+colemanite ore waste, and their effects on the mechanical properties of concrete were investigated. These materials with different proportion were substituted with Portland cement. Physical properties such as setting time, volume expansion, and compressive strength were determined and compared to reference mixture and Turkish standards (TS). The results showed that cement replacement materials had clear effects on the mechanical properties. The use of fly ash and bottom ash even at the concentration of 25% showed either comparable or better result compared to reference mixture. Although replacement of Portland cement by 9 wt.% of colemanite ore waste causes reduction in the compressive strength, the values obtained are within the limit of TS. As a result, colemanite ore waste, fly ash, and bottom ash may be used as cementitious materials. (C) 2001 Elsevier Science Ltd. All rights reserved.

2001-01-01T00:00:00Z Sevinç, Vahdettin https://hdl.handle.net/20.500.12619/49655 2020-02-26T08:39:37Z 2003-01-01T00:00:00Z

Influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement Sevinç, Vahdettin This study has examined the effect of natural pozzolan (NP), colemanite ore waste (CW), coal fly ash (FA), and coal bottom ash (BA) on the properties of cement and concrete. The parameters studied included compressive strength, bending strength, volume expansion, and setting time. A number of cements were prepared (in the presence of fixed quantity of 10% FA, 10% BA, and 4% CW) by the replacement of Portland cement (PC) with NP in range of 5 - 30%. The results showed that the final setting time of cement pastes were generally accelerated when the NP replaced part of the cement. However, NP exhibited a significant retarding effect when used in combination with CW. The results also showed that the inclusion of NP at replacement levels of 5% resulted in an increase in compressive strength of the specimens compared with that of the control concrete. The replacement of PC by 10 - 15% of NP in the presence of fixed quantity of CW improves the bending strength of the specimens compared with control specimens after 60 days of curing age. (C) 2003 Elsevier Science Ltd. All rights reserved.

2003-01-01T00:00:00Z Sevinç, Vahdettin https://hdl.handle.net/20.500.12619/49653 2020-02-26T08:39:37Z 2002-01-01T00:00:00Z

An investigation on the use of tincal ore waste, fly ash, and coal bottom ash as Portland cement replacement materials Sevinç, Vahdettin The possibility of using tineal ore waste (TW), coal bottom ash (BA), and fly ash (FA) as partial replacement in concrete was examined through a number of tests. The properties examined include setting time, compressive strength, mortar expansion, water consistency of mortar, and microstructure. The results showed that compressive strength of all specimens containing I wt.% of TW was higher than that of the control at the 28th day of curing. At 90 days, the contribution to strength by BA + TW and FA + TW was higher than in the concrete-prepared equivalent TW beyond 3 wt.% of Portland cement (PC) replacement. With the replacement of 3-5 wt.% of PC by TW, the compressive strength of the concrete decreased compared to control concrete. However, the values obtained are within the limit of Turkish Standards (TS). Adding BA or FA with TW improved the performance relative to TW replacement only. Increasing replacement of TW gives rise to a higher setting time. As a result. TW, BA, and FA samples may be used as cementitious materials. (C) 2002 Elsevier Science Ltd. All rights reserved.

2002-01-01T00:00:00Z Sevinç, Vahdettin Yalçın, Nevin https://hdl.handle.net/20.500.12619/49652 2020-02-26T08:39:37Z 2001-01-01T00:00:00Z

Heavy metal contents of Lake Sapanca Sevinç, Vahdettin; Yalçın, Nevin The heavy metal pollution of Lake Sapanca located in the Marmara region (Turkey), was investigated over time. The lake is the drinking water source of the city of Adapazari and its environs. The D-80 (TEM) motorway passes about 5 km along the lake's zero point in the Sapanca district. The motorway's wastewater drainages have been connected to the lake without having been subjected to any wastewater treatment. The motorway was opened to service in October 1990. Analyses were performed in 1991 and were repeated in 1999 in order to observe changes in Pb, Fe and Zn contents. Samples were collected from the ends of the drainage channels opening into the lake and metals were determined using flame atomic absorbtion spectrophotometry (FAAS). According to the results obtained, Zn levels were found to be lower than the limits. However, Pb and Fe concentrations increased significantly at all points and exceeded the limit values. The concentrations of Pb and Fe may be rising in the lake, and hence there is a need for continued monitoring of the levels of toxic heavy metals in the lake.

2001-01-01T00:00:00Z