Remerciez-le!

Remerciez @Admin pour avoir partagé cet document gratuitement, de la manière la plus simple, en partageant sur les réseaux sociaux.

technical guide Part CLAY BRICK MANUFACTURE BRICK MANUFACTURE Bricks made by shaping a plastic mass of clay and water which is then hardened by drying and ?ring are among the oldest and most enduring of mankind ? s building materials Until comparatively r

Part CLAY BRICK MANUFACTURE BRICK MANUFACTURE Bricks made by shaping a plastic mass of clay and water which is then hardened by drying and ?ring are among the oldest and most enduring of mankind ? s building materials Until comparatively recent times the clay was dug the bricks were made and the kilns set or drawn by manual labour with help from animal power About years ago the ?rst e ?ective machines for brick production appeared and the trend towards mechanisation of clay winning making and handling operations has continued at an increasing pace to the present day Brick is the simplest and most ancient of all building materials Few other fabricated building units have enjoyed such widespread and continuous popularity This enduring public acceptance is based on the unique combination of the properties o ?ered by brick to the owner and builder This single material can be used to enclose a structure with a decorative load- bearing wall which is exceptionally durable and if properly constructed in the ?rst place requires practically no maintenance Because of the versatility of the raw material which can readily be moulded into a great range of shapes and sizes and the exibility that this gives to design and construction building in brick has remained cost-e ?ective Secondary clay materials are compounds of alumina silica with minor amounts of lime magnesia soda or potash Iron compounds usually the oxides hydroxides or carbonates are nearly always present as impurities in brick clays and they account for most of the wide range of colours found in the ?nished product Clays containing up to of iron oxide give white to cream or bu ? colours which change to pinks and reds as the iron oxide content rises to between and By adding manganese dioxide in proportions from to a range of grey and brown colours can be produced More important than their chemical composition are the facts that ? when mixed with water the clay minerals give a plastic mass that can be shaped by pressure to form a brick ? at economically practical temperatures ranging between ? to ?C the clay particles can be fused into a cohesive mass of great compressive strength ? controlled evaporation of the free water surrounding the particles in plastic clay minimises excessive shrinkage and defects in the structure of the brick Modern brick manufacture involves high speed processing at extrusion rates of up to bricks per hour Solid bricks of the size traditional in South Africa x x mm weigh kg to kg Therefore ?nished bricks weigh approximately tonnes In the wet state before ?ring the clay is heavier For every bricks at least tonnes of material must be dried ?red to a temperature of ? to ?C depending on the clay used and cooled down C THE MANUFACTURING PROCESS Winning Heavy earth-moving equipment such as bulldozers scrapers and mechanical shovels are used to extract the clay and shales Crushing and blending After being transported from the pit by truck