1.- Concrete is a material used in building construction, consisting of a hard, chemically inert particulate substance, known as an aggregate (usually made from different types of sand and gravel), that is bonded together by cement and water.
2.- The Assyrians and Babylonians used clay as the bonding substance or cement. The Egyptians used lime and gypsum cement. In 1756, British engineer, John Smeaton made the first modern concrete (hydraulic cement) by adding pebbles as a coarse aggregate and mixing powered brick into the cement.
3.- In 1824, English inventor, Joseph Aspdin invented Portland Cement, which has remained the dominant cement used in concrete production. Joseph Aspdin created the first true artificial cement by burning ground limestone and clay together. The burning process changed the chemical properties of the materials and Joseph Aspdin created a stronger cement than what using plain crushed limestone would produce.
4.- What's the difference between "cement," "concrete" and "mortar?" The terms refer to substances that have three distinct purposes:
Cement: The binding element in both concrete and mortar.
Concrete: A product composed of cement, sand and gravel or other coarse aggregate. When water is mixed in with this product, it activates the cement, which is the element responsible for binding the mix together to form one solid object.
Mortar: A product composed of cement and sand. When water is mixed in with this product, the cement is activated. Whereas concrete can stand alone, mortar is used to hold together bricks, stones or other such components.
5.- How dense is wet concrete? Concrete and mortar both have a density of about 2 to 2.1 tonnes per cubic meter. This figure applies both to wet and cured material. There are special lightweight concretes as low as 1.4 t/cu m.
6.Protect Your Head Wear a hard hat for head protection! Working on a construction site presents a variety of items to avoid that can cause serious head injury. Both construction equipment and tools are frequent potential hazards to concrete contractors and do-it-your-selfers.
7. Protect Your Back Be careful how you move heavy materials. Working with the normal materials that are required to make and pour concrete such as portland cement, aggregate, sand, and water can be very strenuous to the average person's back. Most of these materials are heavy even in small quantities.
8. Protect Your Back Take care to lift properly keeping your back straight and your legs bent to avoid serious back strain.
Carry these materials, if you have to, keeping them waist high and centered between your legs to lessen the chance for injury.
9. Proctect Your Back Use mechanical or manual equipment whenever possible to move materials as close to its final placement area. Use a cement mixer's chute, a concrete pump, or just a wheelbarrow to get the concrete placed.
Push the concrete to its final position with a shovel or similar tool. Do not lift the concrete mix.
10. Protect Your Skin Protect yourself from skin irritation and chemical burns when working with fresh concrete. Severe burns can result with on-going contact between fresh concrete and skin surfaces, eyes, and clothing.
Get minor burns treated by a physician, if they persist. Seek immediate medical help if burns affect a large area of your skin or appear to be deep.
11. Protect Your Skin Avoid direct skin contact with sand and aggregate since they are very abrasive to your skin.
Don't handle wet cement directly since it is basic so it will be injurious to your skin.
12. Protect Your Skin Don't handle portland cement without protection since it will draw moisture from your skin.
Wear protective clothing, such as waterproof gloves, long-sleeved shirts, and long pants to keep the concrete from making contact with your skin.
13. Protect Your Skin Ensure the protective clothing stays dry so it does not transfer the alkaline or hygroscopic effects to the skin.
Wear rubber boots if you must stand in the fresh concrete while it is being placed, screeded, or floated to prevent concrete from flowing into them and making contact with your lower legs, ankles and feet.
14. Protect Your Skin Use waterproof pads to protect your skin, knees, elbows, or hands from contact with fresh concrete during finishing.
Flush eyes and skin that come in contact with fresh concrete immediately with clean water.
15. Protect Your Skin Rinse clothing saturated from contact with fresh concrete quickly with fresh water.
Wear clean, dry, clothing each work day or for your project.
Take a bath or shower at the end of the work day or the conclusion of your do-it-yourself project.
16. Protect Your Eyes Wear proper eye protection when working with cement or concrete. Splattering concrete and blowing dust can easily enter your eyes during a concrete placement.
Wear full cover goggles or safety glasses with side shields, depending on the conditions at your project.
17. In almost 30 years, the U.S. Patent and Trademark Office has granted 5,564 patents for various masonry inventions.