1. What type of cement should be used for pizza oven, fireplace or high temperatures (>400°C)?
A high aluminate refractory cement made by LAFARGE called Fondu Cement.
Contact Refractory and Ceramic (03) 9560-4477or Farinosi (Mitre 10) on (08) 9328-7311 for further information on sourcing Fondue cement.
2. Is 50/50 Cream (or 50/50 Grey) the same as Cockburn Cement’s Brickies Lite (or 50/50 Grey)?
Yes – 50/50 Crème is the same as Brickies Lite and 50/50 Grey is the same as Brickies Grey since 2014 these products come in 17.85kg bags which is the the typical cement quantity required for making an M3 class mortar in a 3.5 ft3 mixer.
3. Is 50/50 Cream the same as Brightonlite Cream?
No Brightonlite Cream is a pure Portland Cement whereas 50/50 Cream is a 50/50 blend by volume of Portland cement with Marvelime. Blends of cement with hydrated lime is not suitable for making concrete, blended cements are used to make mortars for bricklaying and rendering.
4. Can I use 50/50 Cream (or 50/50 Grey) 0 To 1km from the coast for external brickwork?
No. Masonry code requires that you use a M4 mortar. See our Ready Reckoner
Download our Easy Whitewash guide
Download our Efflorescence Information Sheet
7. What cement content (mixes) should I use?
See our Ready Reckoner
8. What are the classes of normal concrete?
There are 5 classes of concrete in common use, N20, N25, N32, N40 and N50. The “N” stands for normal and the number following stands for a compressive strength rating the numeric value is a value at which approximately 95% of test results will fall above, measured in MPa (Mega Pascals). For further information please refer to AS3600.
For more information see our Ready Reckoner.
9. What are the variable criteria for normal class concrete?
To Specify a normal class concrete you must supply three variable criteria: 1) The compressive strength rating in Mega Pascals; 2) The workability slump in millimetres; 3) The maximum diameter of the coarse aggregate in millimetres. So a specification might look something like:
N32/80/20 (N for normal, 32 for 32MPa, 80 for 80mm slump and 20 for 20mm max diameter coarse aggregate).
For more information see our Ready Reckoner.
10. What class of concrete would commonly be used for domestic footings and on ground slabs?
N20 – For further information please refer to AS3600.
Our Ready Reckoner also has some relevant information.
The minimum compressive strength rating would be 40MPa, cured in accordance with AS3600 guidelines for exposure classification B2. The “B2” relates to the use of a specific curing practice, with the concrete reaching a minimum compressive strength after 7 days of continuous curing. Also the reinforcement steel must have a minimum of 45mm of effective concrete cover. For further information please refer to AS3600 section 4 “Design for Durability”.
For more information see our Ready Reckoner.
12. I am close to the coast but I am going to render / paint my house do I still need M4 cement?
No, the environmental exposure requirement is for external face brickwork and is designed to prevent mortar fretting due to the presence of salts. If you are going to cover the surface with render or paint the brickwork the exposure requirement no longer applies but a structural requirement for M4 may still remain so consult AS3700.
13. Can I make my mortar without hydrated lime?
Technically the answer is yes but from a practical perspective the addition of hydrated lime enhances the mortar giving better workability, increased “fat” that aids trowelling, lightens the mortar colour and improves self-healing properties. We recommend always using hydrated lime to improve the product or for better control use one of our pre-blended products, this will assist you to get the right ratio of lime to cement for your project.
14. My bricks are bigger than the standard bricks used on the easy estimator what do I do?
The easy estimator mortar quantities are based on bags per 1000 standard sized bricks. If you know the number of bricks you can make a simple adjustment for the larger sized bricks used in most building eg verticore, maxi’s and fastwall multiply your quantities by 1.3. If you are doing a non-standard joint width eg limestone block walls are typically 20mm thick, give us a call and we can help you with more detailed calculations.
15. What is the difference between concrete sand, bricklaying sand and plastering sand?
All sands contain clay and fine silts. As the clay content goes up the sand colour around Perth goes from straw yellow to a dark yellow or even orange colour. The higher the clay content the easier the product is to trowel, the better able the material is to hold water but also the higher the required cement content for the same strength and the higher the shrinkage. In order clay content decreases from brickies sand (high), plastering sand (medium), concrete sand (low) and finally white washed sand (very low).
16. I want a crème coloured mortar is your 50/50 Cream or Crème the right product to use?
This is a common misconception, cement is not coloured. Cement will either lighten or darken the underlying colour of the sand used in the project – crème cement will lighten the sand colour and grey will deepen the sand colour. Other factors include how wet the mortar is at the time of tooling as this impacts on the quantity of fines (usually cement) bought to the surface and whether the surface is tooled or raked. The only real solution for colour matching or colour testing is to make some small panels using the tools and materials you wish to use on the final job and leave the panel at least 14 days to ensure the mortar has dried sufficiently so a final colour can be accurately determined.