J Pak Mater Soc 2008; 2 (1) 33 Phase and Microstructure of Brick-Clay Soil and Fired Clay-Bricks From Some Areas in Peshawar Pakistan Safeer Ahmad 1 , Yaseen Iqbal 2 , Fazal Ghani 3 1. Department of Physics, Islamia College University, Peshawar Pakistan 2. Department of Physics, University of Peshawar, Pakistan 3. Department of Prosthodontics, Khyber College of Dentistry, Peshawar (Pakistan). Corresponding Author: Safeer Ahmad, Lecturer, Department of Physics, Islamia College University, Peshawar (Pakistan). Tel: 0092 – (091) 9216513 Cell: 0092 0 (0333) 9119526 Email: safeer_ahmad13@yahoo.com ABSTRACT Objectives: Bricks being the most frequently used product in the local construction industry. However, there has been very little or no relevant information about the manufacturing standards and quality of locally-made bricks as compared to that in developed countries. It is the aim of this study to provide some information about the local raw brick-materials as well as of the bricks manufactured from these. Materials and Methods: Samples of soil and bricks were collected from two representative kilns of district Peshawar (Pakistan). Fine powders of both of these were obtained by manual triturating in a pestle and mortar system. XRD was performed for phase analysis using powder X Ray Diffractometry (JEOL, JDX 3500) system. SEM studies for micro-structural analysis of brick samples (4x4x4 mm 3 ) were also carried out using a JSM-5910 JEOL SEM. For SEM, samples were fine polished with a twin prep 3 TM grinding polishing machine. The smooth polished surfaces were chemically etched with 5% HF solution for one minute. Finally, the samples were mounted onto stubs with silver paint and gold coated in order to avoid charging in the SEM. Results: X-ray diffraction revealed that raw brick soils in use by the local brick-industry comprised predominantly of quartz, albite and chlorite along-with illite, melilite, calcite and orthoclase. In the processed brick-samples, mullite and cristobalite were not observed in SEM indicating the use of a low- firing temperature (~1000 o C) and absence of kaolinite in raw materials. Consequently, the local brick specimens were expected to be more porous and mechanically weak as compared to those from advanced countries. The direct naked eye examination of the sample brick had non-uniform colour and the presence of pebbles a further indication of non-professional processing of initial raw ingredients. Cracks seen in the fired brick samples were seen as further indication of improper heat-treatment and processing. SEM EDS of brick-samples showing the presence of iron was seen as the cause of red colour in the brick. Conclusions: The use of low-temperature firing cycle, rapid cooling, and absence of kaolinite in raw materials were seen as the main factors leading to bricks with compromised quality. INTRODUCTION Brick is a ceramic material mainly used in construction industry. Its production process involves forming of clay into rectangular blocks of standard size, followed by firing to temperatures ranging from 900 to 1200°C 1 . It is made of clay or shale and when given desired shape is dried and fired into a durable ceramic product. Brick is one of the most important building material. Energy consumption and pollution are the two important environmental and cost concerns related to brick industry. A report, in 1993, showed some more than 3000 brick kilns in operation in the country with an annual growth of 3 percent 2 . Old rubber, low- quality coal, wood and used-oil were reported as fuel in most brick kilns. Consumption of these fuels, combined with inefficient combustion process produces large quantity of hazardous gases that threaten the environment as well as those working in brick kilns. Since long, in fact, the brick-industry in the country has remained mostly traditional with no importance to enhancement or standardization of physical properties of the final product at all. Among the problems faced by the industry, the first and probably the most important is the supply of reasonably priced fuel in the form of fuel wood as well as coal. A second major problem is that the industry is not well organized and technically ill-prepared with very little know-how about it and few engineers and scientists having taken interest in this industry 2 . The history of brick industry is very old and can be traced back to about 5000 years old Safeer Ahmad, Yaseen Iqbal, Fazal Ghani: Phase and Microstructure of Brick-Clay Soil…….