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FAQs

, Frequently Asked Questions, Independent Cement & Lime Group

Information on materials

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What is cement?
Cement is the binding element in both concrete or mortar. Concrete contains about 10-15% cement while mortar mixes contain different amounts of cement depending on the type of mortal mix.
What is concrete?
Concrete is a mixture of aggregates (sand and gravel/crushed stone) and cement paste. Approximately 10-15% cement is used in concrete. Cement and water go through a hydration process and get hardened binding aggregates components.

You can purchase ready-made Australian builders concrete mixes in bags that combine cement, sand and gravel, so that all you need to do is add water. This product is useful for small projects.

What is mortar?
Mortar is another building material composed of cement. Mortar composed of cement, sand and hydrated lime. Australian Builders mortar is sold in bags, in a dry pre-mixed form that you combine with water.
What are Supplementary Cementitious Materials (SCM)?
There are three main types of SCM’s used in Australia. Black-coal flyash, Ground granulated blast furnace slag and amorphous silica. SCM’s can be blended with cement as part of concrete mix. Concrete containing supplementary materials have better performance against several durability issues.
What is Hydrated Lime?
Hydrated lime is produced by calcining limestone, and then slaking with water to convert less caustic alkaline product. Hydrated lime can be used in mortar/render mixes to improve workability, plasticity and durability.
What is the difference between general purpose cement and general blended cement?
General Purpose cement (GP cement) is 100% cement. GP cement is produced from clinker, gypsum and limestone. General blended (GB) cement produced blending more than 7.5% (as per AS 3972) supplementary cementitious materials. Australian builders GB contains 50% ground granulated blast furnace slag and 50% general purpose cement. GB based concrete or mortar has lower early age strength development and longer setting. However, GB based products have higher longer term strength development and higher durability.
Does Australian Builders cement, concrete, or mortar have a use by date?
Yes, Australian Builders cement, concrete or mortar should be used within 6 months from the date of purchase.

Application – Concrete

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How many bags of 20kg pre-mix concrete needed to cover 1 cubic meter volume concrete?
Approximately 100 concrete bags (20kg) are needed to cover 1 cubic meter volume
What is the best way to cure your concrete?

Curing is keeping the surface of concrete continuously moist after placement to avoid faster water evaporation. Proper curing during early days of curing improves the strength and durability performance of concrete. Commonly used curing methods.

  • Applying curing compounds to the surface by sprayer
  • Placing and securing polythene sheeting over the surface
  • Spraying the surface with water.
  • Cover the concrete with sand or wet hessian
What is the compressive strength of Australian Builders concrete?
Properly compacted and cured Australian builders concrete achieved 25MPa compressive strength in 28days
How much water should you add for 20kg pre-mixed concrete?

Maximum of 2.4 litre clean water should be added to 20kg pre-mixed concrete. 

Does water help to improve the properties of concrete?

No, additional water in concrete affects the properties of concrete negatively. Excessive water reduces the strength and durability of concrete significantly. 

What is the setting time of Australian builders quick-set concrete?

Quick-set concrete achieve initial setting within 15 minutes. In warm temperature (specially in summer), quick-set achieve initial setting time within 5-10 minutes.

How long can you wait before concrete loses its workability?

It is recommended to use wet concrete as soon as possible to avoid any compaction issues.  

Application – Mortar

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How many bags of mortar (20kg) are required to cover 1 cubic meter volume
Approximately 100 bags of 20kg mortar are enough to produce 1m3 mortar mix.
How many bricks will a bag of mortar lay?
1 x 20kg bag will approximately lay 20-25 standard bricks within a 10mm joint.
How much water should you add for 20kg pre-mixed mortar?
Maximum 3.3 litre of clean water should be added to 20kg pre-mixed mortar.
How long can you wait before mortar loses its workability?
Wet mortar mix should be used within one hour.