1. Rocks and Building 1.5 Cement and concrete

2. Learning objectives Understand how cement and concrete are produced Understand how cement and concrete are produced Be able to list some uses of cement and conctrete Be able to list some uses of cement and conctrete

3. Cement Lime mortar – doesn’t always set quick enough Lime mortar – doesn’t always set quick enough Not at all if wet Not at all if wet Romans – discovered adding volcanic ash to mortar made it set even when wet Romans – discovered adding volcanic ash to mortar made it set even when wet Used until the 18 th Century Used until the 18 th Century Heating limestone with clay produced Portland Cement Heating limestone with clay produced Portland Cement Ground into a fine powder Ground into a fine powder Sets when mixed with water and left Sets when mixed with water and left

4. Concrete Adding crushed stone or rocks to cement produces concrete Adding crushed stone or rocks to cement produces concrete Hardens the material Hardens the material Resists destructive forces Resists destructive forces Can be reinforced by pouring around steel girders Can be reinforced by pouring around steel girders

5. Making concrete Investigate which mix produces the strongest concrete Investigate which mix produces the strongest concrete Sand, cement, gravel Sand, cement, gravel

6. Key Points Cement is made by heating limestone with clay in a kiln Cement is made by heating limestone with clay in a kiln Concrete is made by mixing cement, crushed rocks and sand with water Concrete is made by mixing cement, crushed rocks and sand with water