Concrete mix

For you in Civil Engineering must know about concrete. here I only share my little knowledge of it....

Concrete is one of material that used to made a building besides metal and wood.
concrete has special characteristic that made some people love it.
it can be made in any shape as long doesn't pass the first time setting.
time setting is a duration from cement where mix with water to the time where the cement can't react more with the water and should not disturb the bounding.

concrete made from 4 main element which is

1. Cement
2. Sand
3. Gravel and
4. Water

to made concrete with specific strength it should be design in laboratory called mix design.

but for simple design that don't need specific case it often to use volume comparison. note that this comparison only can be use for concrete with strength characteristic under 17,5 MPa (Mega Pascal)

this simple comparison is 1:2:3 for 1 part cement : 2 part Sand : 3 Part Gravel.
For the water use water cement (w/c) ratio 0,5-0,65 to obtain good result

the strength of concrete is decreased if you add more water than the w/c.

and remember to pour the concrete as soon the mix it ready, don't wait to long that will made the mix hard and can't shape anymore because it has become rock.

this 1:2:3 comparison will made concrete with strength 22,5 MPa or called K-225.
the other comparison id 1:3:5 that will made concrete strength 17.5 MPa (K-175)

to maintain the strength you should control the clean of it material (sand and gravel) make sure it doesn't have lot of mud in it.
and the water should clean from oil and other material.
remember the comparison and you will gain the strength you plan.