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 " - 1:2½:5; " 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 ¼" 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 (1:2½:5) 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 1:2½:5 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 1:1½ 1:2 1:2½ 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.....................................................\$