In partial fulfilment of the requirements for
CHM031: Chemistry for Engineers
Dean William Tejada
August 07, 2019
In the building foundation, columns, beams, slabs, and other load-bearing elements concrete is used. A building material composed of fine aggregates(sand), cement for binding and mixed with water which hardens with time. Records of concrete making and using trace way back 6500BC form the regions of Syria and Jordan by the Nabataea traders, they use it to create concrete floors, housing structures and cisterns underground.
Other significant races and people that develope concrete are the Egyptians uses lime gypsum and Chinese by using dried bricks from mixing mud and straw. The Ancient Romans builds connecting roads from country to country by using a concrete mix composed of volcanic ash, lime, and seawater. In 1830 Lime and hydraulic cement are produced for the first time in Canada. Joseph Monier invented Reinforce concrete in 1849.
The concrete start at the cement. And cement start at the rock quarry, rock and boulder are crushed to rough gravel.
Then in the cement plant, it mixed with a small amount of calcium, silicon, aluminium, and iron called the raw mill. The raw mill is heated to a cylindrical furnace stretch one hundred yards long called a kiln, as the kiln rotates it heated the mill to partially molten. under the intense heat individual molecules tear apart to form new marble size component called clinker. Once the clinker is cold it is mixed with Gipson and ground to a super fine powder called Portland cement. Cement is now mixed with water to create a paste that coats the final ingredients sand and hardcore stone called aggregates. This process is called hydration which is a chemical process that changes its properties. From a plastic liquid state to a hardened state. And that process by combining sand, stone and cement form hardened concrete.
The self-healing concrete or bio-concrete was discovered by researcher and microbiologist Hendrik “Henk” Marius Jonkers. It began on being a research assistant at the Max Planck Institute for Marine Microbiology in Bremen on experimenting with limestone-producing bacteria. By adding bacteria (Bacillus pseudo?rmus and B. cohnii) to more commonly known ingredients to produce concrete. As of its name bio concrete its self-healing concrete through filling the cracks with limestone. By these characteristics, it is better than traditional it lessens the cost of repairing and maintenance expenses for bridges, tunnels and retaining walls, and buildings.
The bio concrete is made by replacing stone aggregates with aggregates sphere. This sphere contains the bacteria and its food calcium lactate. When stress create cracks water finds it ways into the concrete and corrode reinforcements, now this where the bio concrete comes in, having bacteria produces calcium carbonate(limestone) it has now had the ability to seal up the cracks being forms. When the bacteria eat or react to calcium lactate occurs only the water sit in the cracks and not during the mixing of the components of the aggregate sphere. the reaction produces calcium carbonate that fills the gaps and cracks caused by the stress.
Few years after its discovery bio concrete was subjected through under various external conditions and endurance test. This year Henk Jonkers has plans to launching self-repairing material, this invention has the great potential to lessen more repair due to its liquid form for buildings with bio concrete components for easy application. Other future application for these materials would have a huge impact on constructions and maintenance.
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