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Showing posts from May, 2017

Lightweight Aggregate Concrete: Types, Properties And Factors Affecting Mix Design

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LWAC is the popular type of light weight concrete, in which lightweight aggregates are used. The lightweight aggregates are relatively new materials. These have a unit weight up to 12kN/m3. The LWA can be either natural or artificial or manufactured. The natural aggregates include volcanic cinder, dolomite or pumice. The artificial aggregates can be blast furnace slag, sintered fly ash or bloated clay.

Vacuum Concrete: Techniques, Equipments, Advantages and Disadvantages

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One solution to the problem of converting a sufficiently high workability to a mix with a minimum desired water-cement ratio is attained by Vaccum- Dewatering of Freshly Placed Concrete. Concreting thin sections of slabs and walls will demand a mix of water cement ratio of 0.50 to 0.60. This is to facilitate proper placing and compaction. This mix will have less strength and abrasion resistance.
A treatment method that involves the removal of excess water and air by using suction is called as the vacuum treatment of concrete.


MINIMUM DIMENSIONS OF STRUCTURAL ELEMENTS

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There exist minimum dimension of structural elements in civil engineering structures that have to be followed while designing and in implementation. It is irrespective of the codes and provisions. Minimum dimension is the value that has to be implemented how lower be the load conditions exist in that particular area.

CHARACTERISTIC MEAN STRENGTH AND TARGET MEAN STRENGTH OF CONCRETE

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Characteristic Compressive strength The compressive strength of the concrete is given in terms of characteristic compressive strength of 150mm sized cubes that is tested at 28 days ( fck). The characteristic compressive strength is defined as the strength of the concrete below which not more than 5% of the test results are expected to fall. The compressive strength of the cube samples although exhibit variations, when plotted on a histogram are found to follow the shape of a bell shape curve, as shown below.