Concrete Grading and Mix Ratio for your building or structures.

The materials used in reinforced/unreinforced concrete are commonly weighed and mixed in large concrete mixers or small batches that are mixed by hand or in a portable mixer.

British standard 5328: specify concrete, including ready-mixed concrete, gives a range of mixes, prescribed mixes of cement, fine and coarse aggregates by volume or weight as they are measured with accurate method of measuring the proportion of cement to aggregates but allowing for close control of the water content.

Prescribed mixes are designed by the letters and numbers i.e. C7.5P, C10P, C15P, C20P, C25P, C30P, etc.

· The letter C stands for compressive

· The letter P for prescribed and

· The number indicates the 28-day characteristics cube crushing strength in Newton’s per-square millimeter (N/mm²⁾ that the concrete is expected to attain.

By Weight and By Volume:

By weight – for designed mix or for jobs of relative importance

By volume – The concrete is specify as a ratio of cement to fine aggregate to coarse aggregate.

Typically, i.e. 1:2:4 or 1:1 ½: 3.

Concrete should be specified using characteristics strength Fck.

Example:-

Strength classification of concrete;

	*CLASS-* *DESIGNATION*	*MIX RATIO*	*(Fck)* *CHARACTERISTIC STRENGTH* *(N/mm²)*	*GROUP* *(as per* *IS: 456-2000)*	*NORMAL LOWEST CLASS FOR USE AS SPECIFIED*
1.	Grade 5 (C₅)	1:5:10	5	Lean Mix
2.	Grade 7.5 (C_7.5)	1:4:8	7.5	Lean Mix
3.	Grade 10 (C₁₀)	1:3:6	10	Ordinary concrete
4.	Grade 15 (C₁₅)	1:2:4	15		Light weight concrete
5.	Grade 20 (C₂₀)	1:1½:3	20		Plain concrete
6.	Grade 25 (C₂₅)	1:1:2	25	STANDARD CONCRETE	Reinforced concrete
7.	Grade 30 (C₃₀)	DESIGNED	30		Reinforced concrete in foundation
8.	Grade 35 (C₃₅)		35
9.	Grade 40 (C₄₀)		40
10.	Grade 45 (C₄₅)		45
11.	Grade 50 (C₅₀)		50
12.	Grade 55 (C₅₅)		55
13.	Grade 60 (C₆₀)		60	Very High Quality Concrete

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Construction Procedure of Surface Road Side Drainage-PART 1 (with picture)

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Construction Procedure of Surface Road Side Drainage-PART 2 (with picture)

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Setting out of a building

A building is set out in order to accurately define the outline and width of the excavation and to determine the center line of the proposed building walls, so that construction according to the building professionals drawing (the architectural plan) plan can be transfer into the ground, this building process is called setting out of building. The center line method of setting out is generally preferred and adopted Setting out can be a very complex engineering process but with need experience its quite easy. Experienced engineer and surveyors are those involved in setting out of structures, in large projects, services of land surveyors are required for more accurate transfer of levels and angles in setting out with the aid of a Theodolite to decided point around the building area But we are going to concern ourselves with the most common setting out method · Setting out using pegging · Setting out using blocks. But here, we will be discussing

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