Building and Construction Materials
- Created by: Maria5
- Created on: 11-05-17 12:59
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- Types of building and construction materials
- Building Stone e.g. limestone, granite and marble. Uses: building, kerb stones, floors and kitchen surfaces
- Competent with high load bearing strength
- Well Jointed so blocks are easily extracted or soft enough to be sawn into blocks
- Attractive in appearence
- Occur in thick, uniform units with dew structures or weakness to ensure a good quality product
- Impermeable and resistant to mechanical weathering
- Aggregate - has many purposes
- Natural aggregate is sand and gravely mainly extracted from recent deposits. Beds should be thick, without lateral or vertical variation, to give a consistent product. The sand and gravel must be clean with no impurities such as clay.
- Sand is used for mortar, concrete, ballast and as an abrasive.
- Pure quartz sand is used for glass making
- Hard rocks crushed for aggregate include many igneous rocks, gneiss, limestone and greywacke, along with industrial waste such as furnace ****.
- Gravel used to make concrete must contain rounded pebbles so they can slide over each other when it is poured
- Roadstone is crushed aggregate mixed with bitumen
- Must be strong with a high impact and crushing strength to withstand the weight of traffic
- Resistant to abrasion and mechanical weathering so the surface does not break up
- Impermeable and resistant to chemical corrosion e.g. salting of roads in winter
- Skid resistant - each chipping must be made of more than one mineral with different hardness, so they wear down at different rates and do not polish
- Bond well to bitumen
- Rocks such as basalt and dolerite are best. Granite is not a good choice as it suffers polishing
- Brick Clay
- Bricks are made from clay, mudstone or shale. Different compositions produce different types and colours of bricks.
- Thick beds with a constant composition are required.
- The clay is moulded into the required shape and fired at high temperatures in a kiln
- About 40% of British bricks are made from the Jurassic Oxford Clay. this has a high carbon content, which acts as an internal fuel when the bricks are fired, making the process more uniform and reducing energy costs
- Manufacture of cement and concrete
- Cement is made from a mixture of crushed limestone or chalk mixed with some clay or shale
- The limestone provides calcium carbonate and the clay provides silica and alumina
- The mixture is roasted in a rotary kiln at about 1500C and 5% of gypsum is added to prevent the cement setting too quickly
- Concrete is made by mixing cement with sand and gravel or crushed rock
- The mixture is roasted in a rotary kiln at about 1500C and 5% of gypsum is added to prevent the cement setting too quickly
- The limestone provides calcium carbonate and the clay provides silica and alumina
- The mixture is roasted in a rotary kiln at about 1500C and 5% of gypsum is added to prevent the cement setting too quickly
- Concrete is made by mixing cement with sand and gravel or crushed rock
- Cement is made from a mixture of crushed limestone or chalk mixed with some clay or shale
- Building Stone e.g. limestone, granite and marble. Uses: building, kerb stones, floors and kitchen surfaces
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