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The Natural Aggregates, Pumice And Scoria For Example Can Be Used To Make ...


The natural aggregates, Pumice and Scoria for example can be used to make concrete weighing at about 25 to 30 pounds per cubic foot and extended as high as 65 pounds per cubic foot as argued by Glenn A. Black (2004). Furthermore, the use of coal cinders and expanded shale, clay and slate aggregates produced using rotary kiln method can deliver weights in a varying range from 75 to 120 pounds per cubic foot.
Another popular production method for this range of aggregates includes the sintering where the weights are delivered typically ranging from 90 to 120 pounds per cubic foot.
The high end applications of aggregate concrete include the production of aggregates capable of delivering weights up to 150 pounds per cubic foot using the air-cooled slag aggregates and the hard-rock aggregates such as sand and gravel and crushed stone, which produce conventional concretes as mentioned by Glenn A. Black (2004).
From the above it is clear that the aggregates that lie in the lower end of the weight that have lower compressive strength are used primarily for insulation purposes whilst those in the middle spectrum are used for insulation and filling. The high end of the lightweight aggregate concrete spectrum are used in a wide range of structural applications that demand high compressive strengths as well as efficient management of weight as argued by Glenn A. Black. The concrete spectrum for the lightweight aggregate concrete is presented in the figure below

Fig 1: Lightweight Aggregate Concrete Spectrum
(Source: Glenn A. Black (2004), Lightweight Concrete history, Applications and Economics, Indiana University)
2.3: Economics surrounding lightweight Aggregate Concrete
The key aspects of Lightweight Aggregate Concrete that attribute to the economical and structural benefits derived through the structural applications using LAC include the following
2.3.1: Fire resistance Resistance to fire is one of the critical elements that is expected in concrete to ensure that the fire resistance and the structural stability of the civil structure is maintained through the use of aggregate concrete as argued by John P. Ries and Thomas A. Holm (2006). The fire resistance of lightweight aggregate is higher compared to the typical concrete aggregate mainly because of the fact that the aggregate materials composing the lightweight aggregate have lower thermal conductivity, lower coefficient of thermal expansion as argued by John P. Ries and Thomas A. Holm (2006).


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