How 1.54 in concrete and 1.30 in mortar are derived

This construction video tutorial briefly explains 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
Therefore, 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
Therefore, dry volume = 1.30 x wet volume

To get more clear ideas, go through the following construction video tutorial.

Video Source TECH@7K