PLAIN AND CIVIL: EXAMPLE 3.5.2. ESTIMATING A CONCRETE RETAINING WALL

List the materials required using class A concrete for the 50m retaining wall as shown.

$Vol_{ftg}=0.50m\left ( 1.50m \right )\left ( 50m \right )=37.50m^{3}$

$Vol_{retwall}=\frac{4.0m}{2}\left ( 0.30+0.60m \right )\left ( 50m \right )=90m^{3}$

$Vol_{total}=37.50m^{3}+90m^{3}=127.50m^{3}$

With class A mixture:

MIXTURE	PROPORTION	40kg	50kg	SAND	GRAVEL
		CEMENT	CEMENT

AA	1:1.5:3	12.0	9.5	0.50	1.0
A	1:2:4	9.0	7.0	0.50	1.0
B	1:2.5:5	7.5	6.0	0.50	1.0
C	1:3:6	6.0	5.0	0.50	1.0

$Cement=127.50m^{3}\left ( 9.0 \right )=1147.5\simeq {\color{Red} \mathbf{1148bags\left ( 40kg \right )}}$

$Sand=127.50m^{3}\left ( 0.50 \right )\left ( 1.25_{bulking} \right )=79.6875\simeq {\color{Red} \mathbf{80m^{3}}}$

$Volume_{gravel}=127.50m^{3}+\left [ 0.05m\left ( 1.50m \right )50m \right ]_{gravelbed}=131.25m^{3}$

$Gravel=131.25m^{3}\left ( 1.0 \right )=131.25\simeq {\color{Red} \mathbf{131.50m^{3}}}$

Weep holes:

$Pipe_{weephole}=\frac{50.0m}{2m}=25pcs$

25 pcs at 0.60m
25 pcs at 0.50m
25 pcs at 0.40m

Gravel filter:

$Volume_{gravelfilter}=3layers\left [0.30m\left ( 0.30m \right )\left ( 50m \right ) \right ]=13.50m^{3}$

Backfill material of 0.60m width: Include 20% for compaction.

$Volume_{backfill}=1.20\left [0.60m\left ( 4.0m \right )\left ( 50m \right ) \right ]=144m^{3}$

Summary of materials:

1148 bags 40-kg cement
80cu.m. sand
165cu.m. gravel
7 pcs 3" PVC pipe x 6.00m
144 cu.m. Backfill materials

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PLAIN AND CIVIL

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Tuesday 23 July 2019

EXAMPLE 3.5.2. ESTIMATING A CONCRETE RETAINING WALL

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