Concrete is an integral part of modern society. From roads and bridges to the buildings in which we live and work, everywhere around are structures and infrastructures comprising concrete; whereas concrete is used for vital parts of our lives daily, knowing the science behind the cement that makes it so strong and reliable is a must.
Composition of concrete
Concrete is made from more than one type of material, which means it is a composite material. The composite is formed with a filling material, which is an aggregate used to make concrete texture, and a binder or paste used to “glue” or unite the filling. Cement and water are the binder. The mixture of aggregates, cement and water creates the useful compound known as concrete.
Cement is made of clay, sand, iron ore and limestone, burnt together at extremely high temperatures. Limestone must be removed and ground into small pieces. A mixer combines the small pieces of limestone, iron ore, sand and clay to form a powder of the four components. A rotary kiln placed into a cylinder, burn this material composition for a maximum of two hours.
When water is mixed with cement, a paste which binds all components it is formed. The hydration process is a chemical reaction between water and concrete components that causes the concrete to harden. You must use pure water to ensure that the chemicals react properly and create strong cement. The relationship between cement and water is crucial for the production of the useful cement. Too little or too much water can cause the cement to be too weak or unviable. Useful cement requires the perfect balance between the cement and water.
Aggregates are another component used in making concrete. They are materials such as sand or rocks that are added to the mixture of cement and water. Since cement is the most expensive part of manufacturing of concrete, adding the cheapest concrete aggregates gives you more for less. The final product is approximately 70% to 80% of the aggregates. Choosing a type of aggregate concrete depends on the type you want to produce. You can create dense and strong concrete using dense aggregates. Similarly, the use of soft and porous aggregates like sand creates weaker concrete with less wear resistance. Like water, the good aggregates must be pure. Any impurities in the aggregate could interfere with the chemical reaction needed to make concrete, or cause to be weakened.