2.1.3.2. Concrete classification:
Lightweight concrete can be classified according to:
2.1.3.2.1. The production methods:
There are three methods of producing lightweight concrete. First, lightweight aggregate has a specific gravity of 2.6 mm. That type of concrete is generally known by the name of lightweight aggregate. The second method of producing lightweight concrete relies on introducing large voids within the concrete. These voids are clearly distinguished from the extremely fine voids produced by air entraining. This type of concrete is variously known as aerated, cellular, foamed or gas concrete. The third method of obtaining lightweight concrete is by eliminating the fine aggregate from the mix so the coarse aggregate of ordinary weight is generally used. This concrete is known as no fines concrete (Neville and Brooks, 2010; Slaby, Aziz and Hadeed, 2008). Figure (2.2) shows these types of lightweight concrete.
Figure (2.2): Basic shapes of lightweight concrete. (Newman and Choo, 2003)
2.1.3.2.1.1 Lightweight aggregate concrete:
Lightweight aggregates are used to produce lightweight concrete when the weight of aggregates is lower than 1120 kg/m3 (Mehta and Monteiro, 2006). Lightweight aggregates have many sources: a)
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Aerated concrete is also commonly known as a cellular concrete (Neville and Brooks, 2010). It can be divided into two main types according to the method of production. They are foamed concrete (non-autoclaved aerated concrete (NAAC)) and autoclaved aerated concrete (AAC). Foamed concrete is produced by injecting preformed stable foam or by adding a special air-entraining admixture known as a foaming agent into a base mix of cement paste or mortar (cement+water or cement+sand+water). The AAC is produced by adding a predetermined amount of aluminum powder and other additives into slurry of ground high silica sand, cement or lime and water. (Yen, 2006; Li,
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(Emanuel and Fuchs, 2005). References Emanuel, E. & Fuchs, V. (2005). Solved! Washington Monthly, Vol.
The surface at which the concrete is supposed to be placed should be properly damped so that excess water is removed. Use of fibers or silica fumes can also help to reduce the crack formation. 5. Plastic Shrinkage in Shape of
Introduction In today’s world, most developing countries are in a race to build up the necessary infrastructure to scale up there operations and become the next global superpower. In this process, a lot of energy is consumed – be it for transportation, manufacturing or construction. This rapid growth of energy use seen over the past two decades have raised concerns for governments and energy-related organizations alike. Questions with regard to the supply, sustainability and exhaustion of energy sources abound, and while most developed countries have taken active steps to reduce consumption of scarce resources, the position of developing countries in this regard is still lacking.
( Bigelow,1994;Onosko and Jorgensen ,1998;Lewis and Batts
Eco friendly building material is those provide the appropriate service and lifetime, with the minimal maintenance, while minimizing the decimation the raw of material, the pollution from, and also energy consumption by production and use, and that have the maximum potential for the reuse. The use of the Eco friendly building materials and products are represents one important strategy in the design of a building. In addition, the Eco friendly building materials have benefits to the building users such as improved health and the productivity, in order to change the spatial configurations of the lower costs associated, reduced maintenance costs over the life of the building and so forth.
An introduction to highway building: Although there are many methods to constructing a road, all are based on the principle that geographical objects are removed and replaced with harder and more wear-resistant materials. The pre-existing rock and earth is removed by digging or explosions. Tunnels, embankments and bridge are then added when necessary. The material that the road is being constructed from is then laid by various pieces of equipment, which will be looked at in greater detail in this assignment. The construction management of roads has become increasingly more difficult as larger structures are constantly being required in increasingly short amounts of time.