Gokhan Baykal

Utilization of fly ash by pelletization process; theory, application areas and research results

Abstract Although pelletization process is a world wide known technique in the production of artificial aggregates, it has not been widely used in construction sector. The 1985 figures show that overall pellet production for use as metallurgical product was 435 million tons and with respect to statistical figures that belong to 1989 the agglomerated product use in construction sector as lightweight aggregate was only 1.2 million tons. The reasons of low utilization of coal combustion by-products as lightweight aggregates in the construction sector are: — the availability of natural resource products and relatively higher costs of agglomeration process due to initial investments and — energy requiring curing procedures to obtain adequate strength for construction applications (e.g. steam curing and sintering). However, depending on the agglomerated materials’ properties and process efficiency, artificial aggregates with adequate engineering performance may be produced by moisture treatment under atmospheric conditions. In this study, the engineering performance of moist cured fly ash pellets including the effect of lime and cement additions both for geotechnical application and concrete production purposes were investigated and the results obtained are quite satisfactory for the related design requirements.

Influence of different processing techniques on the mechanical properties of used tires in embankment construction

Use of the processed used tires in embankment construction is becoming an accepted way of beneficially recycling scrap tires due to shortages of natural mineral resources and increasing waste disposal costs. Using these used tires in construction requires an awareness of the properties and the limitations associated with their use. The main objective of this paper is to assess the different processing techniques on the mechanical properties of used tires-sand mixtures to improve the engineering properties of the available soil. In the first part, a literature study on the mechanical properties of the processed used tires such as tire shreds, tire chips, tire buffings and their mixtures with sand are summarized. In the second part, large-scale direct shear tests are performed to evaluate shear strength of tire crumb-sand mixtures where information is not readily available in the literature. The test results with tire crumb were compared with the other processed used tire-sand mixtures. Sand-used tire mixtures have higher shear strength than that of the sand alone and the shear strength parameters depend on the processing conditions of used tires. Three factors are found to significantly affect the mechanical properties: normal stress, processing techniques, and the used tire content.

Neuro-fuzzy based constitutive modeling of undrained response of Leighton Buzzard Sand mixtures

This study aims to develop neuro-fuzzy (NF) based constitutive model for Leighton Buzzard Sand fraction B and Leighton Buzzard Sand fraction E mixtures using experimental data. The experimental database used for NF modeling is based on a laboratory study of saturated mixtures with various mix ratios under a 100kPa effective stress. Emphasis was placed on assessing the role of fines content in mixture and strain level on the deviatoric stress and pore water pressure generation in a 100mm diameter triaxial testing apparatus. The input variables in the developed rule based NF models are the Leighton Buzzard Sand fraction E content, and strain, and the outputs are deviatoric stress, pore water pressure generation and undrained Youngs modulus. Experimental results show that Leighton Buzzard Sand fraction B and Leighton Buzzard Sand fraction E mixtures exhibits clay-like behavior due to particle-particle effects with the increase in Leighton Buzzard Sand fraction E content. It is also shown that the performance of capacities of proposed NF models are quite satisfactory.

Analyzing the Crushing of Granular Materials by Sound Analysis Technique

Signal processing techniques have been introduced in the past two decades into engineering applications to analyze particle-scale microstructure. In this paper, a different approach of signal processing techniques for the geotechnical engineering application is introduced. The crushing of granular particles was analyzed by using the sound analysis technique during the shear process of granular materials. Sound analysis setup was implemented to direct shear box to analyze the crushing of granular materials under shear loading. The microphone signal by using an Electret Microphone is processed and the signal coming from the microphone was analyzed by using the Fourier Transform method. Although the analysis is very complex, it is believed the information obtained will help in understanding when the crushing process begins and the extent of crushing which will lead to better understanding of granular materials subjected to shear.

SEISMIC BEHAVIOR OF GEOGRID REINFORCED SLAG WALL

Flexible retaining structures are known with their high performance under earthquake loads. In geogrid reinforced walls the performance of the fill material and the interface of the fill and geogrid controls the performance. Geosynthetic reinforced walls in seismic regions must be safe against not only static forces but also seismic forces. The objective of this study is to determine the behavior of a geogrid reinforced slag wall during earthquake by using shaking table experiments. This study is composed of three stages. In the first stage the physical properties of the material to be used were determined. In the second part, a case history involving the use of slag from steel industry in the construction of geogrid reinforced wall is presented. In the third stage, the results of shaking table tests conducted using model geogrid wall with slag are given. From the results, it is seen that slag can be used as fill material for geogrid reinforced walls subjected to earthquake loads.

Introducing sound analysis technique into simulation of crushing of granular materials

Signal processing techniques have been introduced in last two decades into geotechnical applications to analyze particle-scale microstructure. In this paper, a different approach for geotechnical application of signal processing techniques will be introduced. The crushing of granular particles was analyzed by using sound analysis technique during the shear process of granular materials. Sound analysis setup is implemented to direct shear box to analyze the crushing of granular materials under shear loading. The microphone signal by using Electret Microphone is processed and the signal coming from microphone was analyzed by using Fourier Transform method. Although the analysis is very complex, it is believed the information obtained will help in understanding when the crushing process begins and the extent of crushing which will lead to better understanding of granular materials subjected to shear.