Concrete is estimated in terms of the cubic yard. The price will vary somewhat according to the mixture and the amount of form work required. Mixtures are designated as " rich " - 1 part cement, 2 parts sand, 4 parts crushed rock, by volume; " medium " - 1:2:5; " ordinary " 1:3:6, and "lean," 1:4:8. The rich mixture is used for cellar floors on high grade work. Cisterns and tanks make use of a special mixture of 1:2:3, the stone or gravel being passed thru a " screen. Cement topping for cellar floors is a mortar composed of 1 part cement and 2 parts sharp sand. Sometimes a 1:1 mixture is used. Cellar floors and sidewalks are often priced by the foot surface measure, standard specifications for depth and construction being understood.

Table For Estimating Quantities For Concrete

(Proportion of materials in one cubic foot of concrete.)

MIXTURE

Rich (1:2:4)

Medium (1:2:5)

Ordinary (1:3:6)

Cement.............

.0.058 bbl.

0.048 bbl.

0.041 bbl.

Sand................

.0.0163 cu. yd.

0.0170 cu. yd.

0.0174 cu. yd.

Stone or gravel.......

.0.0326 cu. yd.

0.0341 cu. yd.

0.0348 cu. yd.

Example - Estimate quantities of various materials needed for a wall 10"X7'X

48', using a 1:2:5 mixture.

Solution -10X7X48/12=cu. ft..

Cement = 280X0.048 bbl. =13.44 bbl. Sand =280X0.017 cu. yd. = 4.76 cu. yd. Stone =280X0.0341 cu. yd. = 9.548 cu. yd.

Knowing the cost of cement per bbl. and of sand and stone per cu. yd., the cost of materials for the wall may be easily determined.

Table For Estimating Quantities For Cement Mortar

(Proportion of materials in one cubic foot of cement mortar)

MIXTURE

1:1

1:2

1:2

Cement..............

0.1481 bbl.

0.1239 bbl.

0.1052 bbl.

Sand.................

0.0311 cu. yd.

0.0344 cu. yd.

0.0370 cu. yd.

Example - Estimate quantities of material for 1:2 cement mortar for topping of cellar floor 1"X24'X40'.

Solution - 24X40/12=80 cu. ft..

Cement = 80XO. 1239 bbl. =9.912 bbl. Sand = 80X0.0344 cu. yd. = 2.752 cu. yd.

Analysis Of Labor Cost Factors Per Cubic Yard

1 mason, 2 hours @...........................................

2 laborers, 2 hours each @......................................

Total.....................................................$

Where forms are required add

1 carpenter, 2 hours @.......................................

Cellar floor construction costs approximately the same as wall work having forms. The expense of form work in ordinary basement wall construction is offset by labor and additional cement cost of topping of cellar floor.