Each 80-pound bag of QUIKRETE® Concrete Mix yields 0.6 cubic feet of mixed concrete.
Easiest answer is to use the Quikrete calculator at: https://www.quikrete.com/calculator/main.asp#concrete The answer is: 67 bags at 80lbs each.
Each 80-pound bag of QUIKRETE® Concrete Mix yields 0.6 cubic feet, therefore each cubic yard of concrete will require 45 bags (of 80-lb each). Yields will vary with waste, uneven subgrade, etc.
27 bags of 80 lb concrete mix you need 48.00 * 0.33 = 16.00 cubic feet of concrete an 80 lb bag of concrete mix is .6 cubic feet you need 16.00 / .6 = 26.67 -> 27 bags of 80 lb concrete mix
Considering a 75” equilateral triangle, the cross sectional area ([(side^2)sqr3/4]) is approximately 16.9 square feet. At 3-1/2” thickness, this volume will require approximately 4.9 cubic feet of concrete. Each 80-pound bag of QUIKRETE® Concrete Mix will yield approximately 0.6 cubic feet of mixed concrete, so you will need9 80-pound bags. Yields will vary with waste, uneven subgrade, etc. If the triangle is not equilateral with 75” sides, please contact our customer service representatives at 800-282-5828 or online via LiveChat at www.quikrete.com for calculation assistance.
95 bags @ 80# for a 4" slab 142 bags @ 80# for a 6" slab
QUIKRETE® Concrete Mix will begin to stiffen after approximately 60 minutes, and will be thumbprint hard in approximately 6 hours. Setting times will vary greatly with temperature, mixing water used, and relative humidity. Full curing will continue for the next month.
Naturally it depends on how thick you want the slab. 4" is the most common thickness. To achieve that over 124.4 sqft you would need: 139 forty pound bags or 111 fifty pound bags or 93 sixty pound bags or 70 eighty pound bags You can find Quikrete's calculator here: https://www.quikrete.com/calculator/main.asp#concrete