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Andrew Sherratt's model of a secondary products revolution involved a widespread and broadly contemporaneous set of innovations in Old World farming.The use of domestic animals for primary carcass products was broadened from the 4th–3rd millennia BCE (c. Middle Chalcolithic) to include exploitation for renewable 'secondary' products: milk, wool, traction (the use of animals to drag ploughs ...
The Pantheon in Rome is an example of Roman concrete construction. Caesarea harbour: an example of underwater Roman concrete technology on a large scale. Roman concrete, also called opus caementicium, was used in construction in ancient Rome. Like its modern equivalent, Roman concrete was based on a hydraulic-setting cement added to an aggregate.
Concrete is a composite building material made from the combination of aggregate and a binder such as cement. The most common form of concrete is Portland cement concrete, which consists of mineral aggregate (generally gravel and sand), portland cement and water. After mixing, the cement hydrates and eventually hardens into a stone-like ...
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
A fairly well-defined reaction front can often be observed in thin sections; ahead of the front the concrete is normal, or near normal. Behind the reaction front, the composition and the microstructure of concrete are modified. These changes may vary in type or severity but commonly include: Extensive cracking; Expansion
Self-healing concrete is characterized as the capability of concrete to fix its cracks on its own autogenously or autonomously. It not only seals the cracks but also partially or entirely recovers the mechanical properties of the structural elements.
Foam concrete, also known as lightweight cellular concrete or foamed cement, is a cement-based material that incorporates stable air bubbles to create a lightweight and highly insulating product. Unlike air-entrained concrete, which introduces tiny air bubbles through an admixture during mixing, foam concrete replaces coarse aggregates with ...
Plants are capable of producing and synthesizing diverse groups of organic compounds and are divided into two major groups: primary and secondary metabolites. [9] Secondary metabolites are metabolic intermediates or products which are not essential to growth and life of the producing plants but rather required for interaction of plants with their environment and produced in response to stress.