One more limitation of usual concrete is its low heat insulation value. That is why concrete walls are occasionally of a non-load bearing, sandwich type, being composed of a layer of insulating material cast between two concrete slabs. In this application, concrete is to a serious degree threatened by other types of curtain walls, including various types of sandwiches. Alternative way to give concrete protecting properties is to make it with relatively light weight aggregates – such as vermiculite, expanded clay, and so forth.
In this form, it not any more has sufficient quality of being physically strong to be used for load bearing purposes, although it has been very well utilised in long-span roof building. Prestressed concrete has gotten great significance as a building material. The basic characteristic of prestressed concrete is that, by compressing concrete and keeping it under compression, the tensile stresses caused by loads are neutralized (CEMENT). The compression is accomplished by casting the concrete around stretched rods or cables, the tension on which is released as the concrete sets.
A prestressed beam needs only one-fourth the weight of the steel and one-half the weight of concrete which is needed to support the same load by a usual reinforced concrete member. Although it was patented by a San Francisco engineer in 1886, prestressed concrete did not emerge as an accepted and effective building material until a half-century later. Since then it had been intensively used in Europe for structural purposes. Up to the present moment, prestressed concrete’s applications have been limited mostly to pipes, tanks, runways, and from time to time highway bridges.
As engineers and constructors gain experience and manage to reduce the manufacturing expenses, prestressing may become competitive with steel and with reinforced concrete building. After weighing up all the factors, the trend is more toward a substitution of concrete for other building materials than of other building materials for concrete. The use of portland cement which is made by heating a slurry of clay and crushed chalk should more than double in the next decades, may presumably triple, and at its lowest is expected to become greater by at least one-third.
Conclusion In today’s global industrial age, both wood and various forms of concrete are widely used construction materials. Without today’s improved methods of concrete and wood construction, a lot of modern methods of construction would be incapable of being accomplished. Concrete made possible the economical building and maintenance of a great number of concrete highways in England. Concrete runways support heavy planes for commercial and military use, and wood buildings and homes are found in every city and village.
Wood spectacular uses are found on every farm in silos, fences, walks, pools, and household supplementary parts and objects. Concrete’s hydraulic quality – the ability to harden under water – has made this building material the basic substance in building bridges, dams, reservoirs, hydroelectric power works, and docks. In addition, concrete is used not only for practical purposes but is utilised in structures of architectural beauty such as churches and temples. Royal National Theatre by Denys Lasdun
London Bridge. Was originally made from wood. Then it was replaced by the present concrete bridge in 1973. Museum of Natural History by Alfred Waterhouse The London Hilton on Park Lane by William B. Tabler Alexandra Road Housing by Neave Brown Victorian concrete house in south London Boston City Hall by Gerhard M. Kallmann, Noel M. McKinnell, and Edward F. Knowles Robarts Library by Toronto architects Mathers and Haldenby University of Massachusetts Dartmouth Campus Center by Paul Rudolph
Examples of buildings with timber frame Globe Theater, by unknown, at Southwark, London, England, UK, 1599 to 1614 London Terraced House by Vernacular Saint Paul’s Cathedral by Sir Christopher Wren Westminster Hall by unknown Some of the many oak timber frame buildings across the UK
Collins, P, Changing Ideals in Modern Architecture, 1750-1950, 2nd ed. Montreal: McGill-Queens University Press, 1998. Concrete (Material). Classic Encyclopaedia. Available from: http://www.cement.org/sitefinity/status?ReturnUrl=http:%2F%2Fwww.cement.org%2Fbasics%2Fconcreteproducts_prestressed.asp