Concrete

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Formula

  • To make 1 yard - To make 1 cubic yard of concrete, you'd need seven 94-pound bags of cement, about 1/2 cubic yard of sand and just over 3/4 cubic yard of gravel. The amount of water you use depends on how wet the sand is.Oct 1, 2009 [1]
  • 10% cement, 75% aggregate, 15% water [2]
  • 150 kg/m3 of cement - with concrete at 4000 lb/cu yd [3] - was sufficient to get about 6000 psi concrete strength [4]. Does this mean abouut 8% of cement?
  • 500 lb per yard of cement in concrete is recommended - read a thesis on it - [5]
  • Lean or rich: 7-15% cement by volume -

Rich.gif

  • Lean concrete per california codes is 300 lb cement per yard of concrete, and is 700 PSI at 7 days. [6]
  • Lean is used below foundations - and is 700 psi or 1100 psi [7]

Slab Requirements

  • 2500 PSI concrete minimum for slab on grade in Oregon - [8] and Georgia [9]

Concrete Slump Testu

Measures inches of collapse, from 0-12", of a wad of concrete in a cone. 12" means it's complete water. 4" is very stiff.

Basics

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