After reading this articles you’ll understand better the terms like 1.54 in concrete and 1.30 in mortar.
Definition of 1.54 in concrete
While water is included in dry mixture (cement+sand+aggregate) as well as wet concrete mixture is arranged in shuttering, the particles reorganize themselves into pores and voids which decreased the volume of wet mixture.
Void percentage compressibility :
Aggregate : 33 to 34% (voids are filled up and particles are reduced)
Sand : 20% (voids are filled up particles are reduced)
Cement : Inconsiderable (because of fine particles)
By summing up the percentage of aggregate and sand, we get 34% + 24% = 54%
Dry Volume is greater than 54% of wet volume
= 100/100 + 54/100 = 1 + .54 = 1.54
Because of that, Dry Volume = 1.54 x wet volume
Definition of 1.30 in mortar
Mortar is formed with cement and sand.
Void percentage compressibility :-
Sand : 20%
Cement : Inconsiderable (because of fine particles)
= 20%
Dry volume is greater than 20% of wet volume
= 100/100 + 20/100 = 1 + .20
As engineers select additional 5% to 10% for wastages and weak workmanship so that the quantities of cement and sand are not reduced, the mortar ratio is taken as follow :-
= 1.20+ .1 = 1.30
Because of that, dry volume = 1.30 x wet volume
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