Concrete Facts and Volume Calculator for Our Sydney Clients

Municipal Ready-Mix Ltd. has built a wealth of concrete knowledge while serving the industrial Cape Breton area over the last 63 years. From the ingredients used to mix concrete to safe handling precautions, we'd like to share some basic concrete information and tips. We've also included a concrete volume calculator to help you quickly determine how much concrete you need. Please click one of the links below for more information.

What is Concrete Made of?
Simple Facts about Concrete
Mix Applications
Concrete Precautions

What Is Concrete Made of?

Portland Cement
This grey powder, when mixed with water, forms the glue to bind together the other ingredients. The most commonly used cement is Type 10 Portland Cement.

Fine Aggregate (Sand)
Sand acts as a fill material, filling the voids between the larger particles. It can be either natural sand or crushed rock fines. In general, the finer the sand, the greater the water demand in the mix.

Coarse Aggregate
The coarse aggregate or stone content provides much of the bulk of concrete. It is important to use a strong, well-graded aggregate. Aggregates are most commonly crushed rock or naturally occurring gravel.

Water
Water is essential to react with the cement, hardening to form a solid matrix, binding the aggregate and sand together. The water content should not be too high, as the strength will decrease.

Simple Facts about Concrete

• Concrete is the most widely used construction material in the world.
• All concrete has a tendency to crack. As concrete hardens the cement and water begin to shrink, the stresses created by this shrinking cause the concrete to crack.
• There is a difference between cement and concrete. Cement is an ingredient in concrete, much like flour is an ingredient in cake mix. Dry, powdered (Portland) cement is blended with sand, stone and water to produce concrete.
• 1 Megapascal (MPA) = 145 Pound per Square Inch (PSI). This is a measure of strength.
• Concrete slump is a measure of the concrete's workability or viscosity when concrete is being placed.
• Once concrete is batched at the batch plant, it starts to hydrate or harden. Generally in the first 3 to 5 hours, concrete must be placed and finished. These conditions vary depending on the time of year and admixture dosages in the mix.

Mix Applications

Concrete Strengths Available

• 15 MPa (2200 psi)
• 20 MPa (2900 psi)
• 25 MPa (3600 psi)
• 30 Mpa (4400 psi)
• 35 MPa (5100 psi)
• 40 MPa (5800 psi)

Slumps
Mixes are designed to have slumps in multiples of 10mm.
Most common 20, 50, 80, 100 mm
10mm = (0.4 in.)
i.e. 80mm = (3.2 in.)

The following should be specified when ordering concrete:

A. Basement walls, footing and floors

• Strength MPa: 20; Slump mm: 100; Air content Percent: 2-5

• Strength MPa: 28; Slump mm: 80; Air content Percent: 5-8

• Strength MPa: 35; Slump mm: 80; Air content Percent: 5-8

Concrete Precautions

• Wet concrete contains calcium hydroxide, a corrosive chemical. Dust from dried concrete may contain hazardous materials.
• Avoid contact with skin and eyes.
• Wear protective clothing and goggles. Wear proper respirator when cutting dried concrete.
• If you must stand in wet concrete, use waterproof boots that are tight at the tops and high enough to stop the concrete from flowing into them.
• Wash wet concrete, mortar, cement, or cement mixtures from your skin with fresh, clean water immediately after contact.
• In case of eye contact, flush immediately with plenty of fresh water for up to 15 minutes. Consult a physician in cases of severe exposure.

Please contact Municipal Ready-Mix Ltd. to schedule your concrete delivery.