How to work the volume of concrete in a retaining wall

This construction video will provide some useful tips on computing the volume of concrete for retaining wall.

Retaining wall is defined as a rigid wall that is designed and constructed to withstand lateral pressure of liquid, earth filling, sand or other coarse materials which it is holding back.

Suppose, a retaining wall is segregated into two sections, section A is taken as base slab and section B is taken as the stem of retaining wall.

Therefore, the volume of retaining wall is determined with the following formula :-

Volume of retaining wall = Volume of base slab + Volume of Stem

Volume of base slab = length x breadth x height

= 10 x 3 x 0.2 (after converting 200 mm to meter) = 6m³

As the stem is a trapezoid, the following formula is used to calculate it’s volume :-

Volume of stem = [{a+b)/2} x h] x l

After putting the values, we get :-

= [{(0.5 + 0.2)/2} x 3] x 10 = 21m³

Therefore, total volume of retaining wall = 6 + 21 = 27m³

Therefore, the volume of concrete for the retaining wall = 27m³

If the retaining wall is segregated into three parts like part A, part B and part C. Part A is taken as the base slab, part B is taken as the stem and part C is taken as the counterfort of the retaining wall.

Therefore, the volume of retaining wall = Volume of base slab + volume of stem + volume of counterfort

= Volume of A + Volume of B + Volume of C

To learn the remaining calculation process, go through the following video tutorial.

Video Source: Nice engineering

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Published By
Rajib Dey
www.constructioncost.co
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Benefits of concrete covers blocks in RCC work

This construction video tutorial will guide you to make concrete cover block or rebar spacer at a reasonable cost.

A rebar spacer belongs to a object that fastens the reinforcing steel or "rebar" in reinforced concrete structures since the rebar is amassed in place before the pouring of final concrete. The spacers are remained in place for the pour to set the reinforcing in place, and turn into a permanent part of the structure.

When RCC work is going on, implanting steel in concrete (called as cover) is a vital process for resisting rebar from decaying as well as arranging fire protection to the rebar. If the proposed cover is not arranged, the rebar will start to decay in due course of time and will lead to collapsing of the structure beforehand. So, cover blocks can extend the life of the structure considerably without incurring so much expenses.

The exact amount of cover is set by the application and the environment (e.g., is the RCC under water, etc.)

In India, following are considered as the standard size for the covers :

Slab : 20 mm
Beam : 25 mm
Column : 40 mm
Foundation : 50 mm

Concrete covers ensure the accurate position of steel, thus allowing in the practical application of the theoretical specifications of concrete construction. The cover of the steel concerning a specific construction component (for instance in a concrete slab or a beam) should be usually constant inside the element.

The application of covers can be beneficial to the areas where high earthquake activity along with corrosive environment (like proximity to salt water of sea) occurs.

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Published By
Rajib Dey
www.constructioncost.co

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Characteristics of Mass Concrete

Mass concrete is made with solid structures (> 80 cm). These structures frequently contain a greater volume. It signifies that large volumes of concrete should be set up in a short time. It needs highly well-organized planning and competent methods.

Mass concrete is applied for:

 Foundations for large loads
 Foundations for buoyancy control
 Solid walls (e.g. radiation protection)
 Infill concrete

The following major issues are formed with these enormous structures:

 Extreme internal and external temperature discrepancies throughout setting and hardening
 Excessive maximum temperatures
 High internal and external temperature deviations and as a result forced shrinkage
 Secondary consolidation (settling) of the concrete and as a result cracking occurs over the top reinforcement layers and also settlement under the reinforcement bars

Riska: All of these issues can lead to cracks and cement matrix defects assumed to be “skin or surface cracks” which may happen if the external/internal temperature variation is more than 15 °C or the outer layers can contract because of their initial drying out. Usually, the depth of skin cracks is few centimeters and can close again later.

Proper Measurement:

 Utilize cements with low heat development
 Low water content (curtailment in w/c ratio)
 Biggest possible maximum particle size (e.g. 0–50 rather than 0–32)
 If required, chill the aggregates to have a low initial fresh concrete temperature
 Set the concrete in layers (layer thickness < 80 cm)
 Restrain the bottom layers to make sure that the entire section is recompacted as soon as the top layer is set
 Start curing by applying thermal insulation methods
 Make sure the proper design and circulation of joints and concreting sections, so that heat can be dissipated and the temperature developments and deviations can be adjusted

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Published By
Rajib Dey
www.constructioncost.co
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