Gökhan Görhan

Production of fired construction brick from high sulfate-containing fly ash with boric acid addition.

The increase of power plant capacity has led to the production of an increasing amount of fly ash that causes high environmental impact in Turkey. Some of the fly ash is utilized within the fired brick industry but high sulfate-containing fly ash creates severe problems during sintering of the fired brick. This study attempted to investigate the potential for converting high sulfate-containing fly ash into useful material for the construction industry by the addition of boric acid. The chemical and mineralogical composition of fly ash and clay were investigated. Boric acid (H3BO3) was added to fly ash—clay mixtures with up to 5 wt.%. Six different series of test samples were produced by uniaxial pressing. The samples were fired at the industrial clay-brick firing temperatures of 800, 900 and 1000 °C. The microstructures of the fired samples were investigated by scanning electron microscopy and some physical and mechanical properties were measured. It was concluded that the firing at conventional brick firing temperature of high sulfate fly ash without any addition of boric acid resulted in very weak strength bricks. The addition of boric acid and clay simultaneously to the high sulfate- containing fly ash brick dramatically increased the compressive strength of the samples at a firing temperature of 1000 °C by modifying the sintering behaviour of high sulfate fly ash.

The Investigation of Heat Performance and Thermal Conductivity of Different Wall Materials at High Temperatures

The current study investigated heat transfers at high temperatures and compressive strength after exposure to high temperatures of gas concrete, clay brick, rice husk bricks used as wall materials, and gypsum plaster and common plaster used as coating materials. Tests measuring apparent porosity, water absorption, bulk density and compressive strength were performed on the samples prepared in 100 mm x 100 mm x 100 mm size. In the high-temperature experiment, the samples with K-type NiCr-Ni thermocouple were placed in a specially designed laboratory furnace. The internal temperature of the furnace was set at 800 o C. The researchers found that out of the samples exposed to high temperatures compressive strength and thermal conductivity of the gypsum plaster mortar were better than those of the common plaster mortar. Furthermore, the gas concrete, a wall material, was found to have a low thermal conductivity. As a result, the gas concrete and common plaster mortar, which were exposed to high temperature, were found to be more durable than other materials and, therefore, more advantageous when used in construction.

The Effect of Amount of Alkaline Solution on Fly ash and Metakaolin based Geopolymer Mortar Properties

This study investigated the effect of four different amounts of alkaline solution (240, 270, 390 and 435 ml) used in the production of metakaolin and fly ash-based geopolymer mortar on sample properties. In the preparation of geopolymer mortars, metakaolin obtained by the sintering at 1000 °C of kaolin clay and fly ash obtained from Kutahya Seyit Omer (Turkey) thermal power plant was used. Geopolymer mortars were cast into 40x40x160 mm molds and cured for 5 h at 80 o C in a laboratory-type oven. The curing process of the samples was completed, and they were subjected to physical and mechanical tests at the end of the 7th day following their production. Consequently, it was determined that the ideal amount of alkali solution in the preparation of the geopolymer mortar samples was 270 ml. In addition, the flexural and compressive strength values of the geopolymer mortars produced using 270 ml alkaline solution were 4.9 MPa and 21.8 MPa, respectively.