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Concrete tests can measure the "plastic" (unhydrated) properties of concrete prior to, and during placement. As these properties affect the hardened compressive strength and durability of concrete (resistance to freeze-thaw), the properties of workability (slump/flow), temperature, density and age are monitored to ensure the production and ...
Greater chemical and thermal resistance, and better mechanical properties, are said to be achieved for geopolymer concrete at both atmospheric and extreme conditions. Similar concretes have not only been used in Ancient Rome (see Roman concrete ), but also in the former Soviet Union in the 1950s and 1960s.
Carbon fiber has many advantages in terms of mechanical and electrical properties (e.g., higher strength) and self-monitoring behavior due to the high tensile strength and high electrical conductivity. [64] Carbon products have been added to make concrete electrically conductive, for deicing purposes. [65]
Concrete has very favourable properties in fire – it is not adversely affected by fire until it reaches very high temperatures. It also has very high mass, so it is good for providing sound insulation and heat retention (leading to lower energy requirements for the heating of concrete buildings).
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. This kind of concrete is also known as self-repairing concrete.
As per Indian codes, compressive strength of concrete is defined as: Field cured concrete in cubic steel molds (Greece) The compressive strength of concrete is given in terms of the characteristic compressive strength of 150 mm size cubes tested after 28 days (fck). In field, compressive strength tests are also conducted at interim duration i.e ...
Concrete spalling from the ceiling of an office unit (interior) in Singapore, possibly due to rebar corrosion. Reinforced concrete can fail due to inadequate strength, leading to mechanical failure, or due to a reduction in its durability. Corrosion and freeze/thaw cycles may damage poorly designed or constructed reinforced concrete.
Fibers are added for long term durability of concrete. Glass [14] and polyester [15] decompose in alkaline condition of concrete and various additives and surface treatment of concrete. The High Speed 1 tunnel linings incorporated concrete containing 1 kg/m 3 or more of polypropylene fibers, of diameter 18 & 32 μm, giving the benefits noted ...