Concrete

ConcretePlain Concrete artificial stone as a result of mixing cement, fine aggregates and water. Reinforced Concrete- concrete with reinforcement properly embedded in a manner that two materials act together in resisting forces. Plain and Reinforced Concrete

The Ordinary Portland CementRapid Hardening Portland Cement which is preferred when high early strength concrete is desired. Blast Furnace or Sulfate Cement designed to resist chemical attack. Low Heat Portland Cement massive sections designed to reduce heat of hydration.Portland Pozzolan low hardening characteristicsHigh Alumina Cement

Different Types of Concrete Used in Construction:Coarse Aggregates crushed stone, crushed gravel or natural gravel with particles retained on a 5mm sieve. (The max. nominal size varies from 40, 20, 14 or 10 mm diameter.)Fine Aggregates crushed stone, crushed gravel or natural gravel with particles passing on a 5mm sieve.

AggregatesWorkabilityStrengthDurabilityEconomyThe Principle of Concrete MixingDesigned Mixture contractor is responsible in establishing the mixture proportionPrescribed Mixture the designing engineer specify the mixture proportion. The contractors responsibility is only to provide a properly mixed concrete containing the right proportions as prescribed in the plan. Concrete mixture may be classified as either: Concrete mix designs are often given by a ratio:

Usually the ratio is in terms of weight of the componentsProportioning Concrete

Cement

SandCrushed RockConcrete mix designs are often given by the following ratio:1:2:2Coarse Aggregates- crushed rockFine Aggregates- sandCementConcrete ProportionMixture ClassProportionCement in BagSandGravel40 kg50 kgcu.mcu.mAA1 :1 1/2: 312.09.50.501.0A 1 :2 : 49.07.00.501.0B1 :2 1/2: 57.56.00.501.0C1 :3 : 66.05.00.501.0AA proposed concrete pavement has a general dimension of 10cm thick, 3m wide and 5m long. Determine the quantity of cement in bags, sand and gravel in cubic meters, required using class C mixture.

Example:Determine the volume of the proposed concrete pavement.

Volume = Thickness x Width x LengthVolume = 0.10 x 3.0 x 5.0Volume 1.5 m3 B. Using the cement class mixture C, multiply the volume by the corresponding values:

Cement: 1.5 x 5.49 = 8.2 or 9 BagsSand: 1.5 x 0.44 = 0.66 m3Gravel : 1.5 x 0.89 = 1.34 m3Determine the volume of the proposed concrete pavement.

Volume = Thickness x Width x LengthVolume = 0.10 x 3.0 x 5.0Volume 1.5 m3 Volume Method Linear MethodSquare Concrete Column:

A reinforced concrete square column is 5m long with a cross sectional dimensions of 16 inches. Determine the quantity of cement, sand, and gravel using class A concrete.Example: Convert all measurements from inches to meters. (0.40 meters)

Solve for the cross sectional area of the column

Area = 0.40m x 0.40mArea = 0.16 m2A. By Volume MethodFind the volume of the column

Volume = 0.16m2 x 5mVolume = 0.80 m3

Cement Class A

Cement : 0.80 x 7.85 = 6.28 or 7 BagsSand: 0.80 x 0.42 = 0.34 m2Gravel : 0.80 x 0.84 = 0.67 m2

B. Linear MethodPopularly known as CHBLoad bearing and non bearing blocksLoad bearing 15 to 20 cm Non bearing 7 to 10 cmConcrete Hollow BlocksEstimating Masonry Work using CHB could be done by :Fundamental MethodArea Methods

A concrete hollow block wall has a general dimension of 3m high by 4m long. Determine the number of CHB to construct the wall.

Example

Divide the height by the height of one block1 block = 0.20m height

Divide the length of the fence by the length of one block. ( 0.40)A. Fundamental Method

Multiply 1 and 2

Pieces = 15 x 10 Pieces = 150