Cement, concrete and mortar are polymer or cement-based binders, compounds or aggregate mixtures for joining components and forming structures. Although the words concrete and cement are often used interchangeably, cement is actually an ingredient of concrete. Cement is typically made by heating limestone until it nearly fuses. The material is then ground into a fine powder. When this powder is mixed with water, the cement undergoes a chemical reaction and hardens into a mass that is resistant to water. If concrete is mixed with water and other aggregates - such as sand, stone, or gravel - the mixture is called concrete. Although it accounts for only 10 to 15% of the concrete’s total mass, cement is the essential binding agent for concrete. Mortar, a mixture of a binder or clinker and a fine aggregate, is used to bond together brick or other components in structural applications.
There are many different types of cement, concrete and mortar products. Grouts and fillers are sealants used to fill in gaps between tiles, bricks and other components. Thinset mortar, dryset mortar, and drybond mortar are cement-based coatings that are applied in thinner layers than liners and lining systems, which can prefabricated on-site by pouring, pumping, or gunning techniques. Product categories also include fabricated and custom shapes such as bricks and blocks. Investments consist of a refractory powder with a plaster or phosphate binder that is cast around a lost wax pattern. Permanent molds, refractories, powders, and aggregates are also available. Refractory aggregates are also used to build up a shell in the investment casting process.
Setting or curing technology is an important consideration when selecting cement, concrete and mortar. Hydraulic setting products use the hydration reaction of a salt to form a bond. Air setting or film drying materials form a bond or “harden” through the evaporation of water or an organic solvent. Some binders or adhesives use a chemical setting process. Cement, concrete and mortar that use heat setting or thermoset, hot melt, and two-component or multi-component bonds are also available. Hot melt bonds can be repeatedly softened by heat and hardened or set by cooling, which allows removal or repositioning during assembly. Multi-component systems react and cure into a polymerized bond or compound.
Processing specifications for cement, concrete and mortar include set or cure time, set or cure temperature, and shrinkage. Thermal and mechanical parameters cover maximum use temperature, modulus of rupture (MOR), and compressive strength. Maximum use temperature is the highest temperature to which cement, concrete and mortar can be exposed temporarily, without the degradation of structural or other required end-use properties. MOR, cross-break strength, or flexural strength indicates the maximum flexural strength to which cement, concrete and mortar can be subjected before failure or fracture occurs. Compressive strength or crushing strength is the maximum compressive load per unit cross-section.