What is cement ? :
In the most general sense of the word, a cement is a binder , a substance that sets and hardens independently and can bind itself to other materials also .
In terms of construction cement is anhydrous powder substance used to bind the aggregate materials of concrete .
Types of cement :
Hydraulic : a cement that hardens under water . eg-portland cement
Non hydraulic : cannot be hardened when exposed to water for eg - gypsum plaster
. What is cement ?
What is concrete ? :
Concrete is a mixture of cement (usually Portland cement) and stone aggregate. When mixed with a small amount of water, the cement hydrates form microscopic crystal lattices and locking the aggregate into a rigid structure .
Concrete is a composite construction material that is composed of cement (commonly Portland cement) and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks such as limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures.
Concrete solidifies and hardens after mixing with water due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material.
Concrete is used to make pavements, pipe, architectural structures, foundations, motorways/roads, bridges/overpasses, parking structures, brick/block walls and footings for gates, fences and poles. What is concrete ?
Reinforced concrete cement :
Reinforced concrete cement is concrete in which reinforcement bars ("rebars"), grids, plates or fibers have been incorporated to strengthen the concrete in the tension .
Concrete is strong in compression, but weak in tension, thus reinforcement increases the strength in tension. For a strong, ductile and durable construction the reinforcement shall have the following properties:
High strength
High tensile strain
Good bond to the concrete
Thermal compatibility
Durability in the concrete environment Reinforced concrete cement
Key characteristcs : :
Three physical characteristics give reinforced concrete its special properties :
First, the coefficient of thermal expansion of concrete is similar to that of steel, eliminating large internal stresses due to differences in thermal expansion or contraction.
Second, when the cement paste within the concrete hardens this conforms to the surface details of the steel, permitting any stress to be transmitted efficiently between the different materials.
Third, the alkaline chemical environment provided by the alkali reserve (KOH, NaOH) and the portlandite (calcium hydroxide) contained in the hardened cement paste causes a passivating film to form on the surface of the steel, making it much more resistant to corrosion than it would be in neutral or acidic conditions. Key characteristcs :