Concrete

What is the Water Cement Ratio (W/C)?

Gallons of Water per One Bag of Cement (94lb)

W/C for Lab?

2 ½ - 3 gallons

W/C on Site?

4 - 8 gallons

Water-Reducing Admixture

Reduces amount of water needed for a mix, making concrete stronger

Retarder Admixture

Delays Setting Time - Good for hot areas where moisture needs to be retained or for larger structures

Accelerator Admixture

Speeds Setting - For colder areas or to reuse forms

Damp-Proofing Agent Admixture

Minimizes excess water absorption of the mix

Fly Ash Admixture

Reduces amount of cement needed

Silica Fume Admixture

Protects reinforcing steel (like rebars) from corrosion

Freeze Protection Admixture

Allows concrete to cure at temps as low as 20F

What is the Design of Mix?

Proportion of Cement:Sand:Gravel

Cement Factor

Cement Bags per Cubic Yard of Concrete

When should Water be added to a Concrete Mixer?

Before ¼ mixing time has passed

Max Time before Concrete should be Poured?

1 ½ hours

Type of Concrete Placement that can use a DROP CHUTE?

Direct Placement

Type of Concrete Placement that uses Pipes?

Pumping

Type of Concrete Placement also known as SHOTCRETE?

Pneumatic

Built-In Joint

Rubber/Elastic Strip cast into the slab with concrete poured over

Filled Joint

Wood placed in place, then “Formed in Place” Sealant poured in that Space

False Joint

Area is cast at a smaller depth so cracks form at that area (controls where cracks go)

What is the Best Temperature for Concrete to Cure?

60 to 80