CMAA - Frequently Asked Questions


1. Who can join the CMAA?

Our members include manufacturers of concrete masonry products as well as companies that are associated with, and support the industry.

Click here for more information to become a member.

2. I have a technical question, how can I get some help?

Before you contact the CMAA, please check if the answer to your question can be found on our Technical page or from our FAQs . If you still require assistance, the most efficient way to have your question answered is by emailing us at info@cmaa.com.au, or call us at (02) 8448 5500 and speak to our technical team.

3. Where can I find the Lockpave or Permpave software?

First launched in 2008, PermPave is a software package developed to assist civil engineers and landscape architects in the design of permeable concrete block paving (PCBP) systems. LockPave was first launched in the 1990s for the design of concrete block paving systems. Both were developed by Dr Brian Shackel and, in the case of PermPave, in collaboration with Professor Beecham of the University of South Australia.

 

These software programs are currently unavailable while the software is being upgraded.

4. How can I find out more about the Golden Trowel Award?

The biennial Golden Trowel Award is Australia’s only team competition for brick and blocklaying apprentices. Please click here for more information.

5. How do I remove stains from my concrete masonry wall?

The CMAA technical manual CM03 ‘Concrete Masonry – Cleaning and Maintenance’ provides a guide to cleaning and maintaining concrete masonry walls. We recommend hiring an accredited cleaner.

6. Where can I find a cleaner to clean my concrete masonry wall?

Think Brick Australia maintains a list of accredited brick and masonry cleaners on their website at http://www.thinkbrick.com.au/accredited-brick-cleaners

7. I would like a representative from CMAA to come talk to our organisation.

The CMAA has technical expertise in a number of masonry subjects and it is part of our goal to increase awareness and educate students on masonry in engineering and building design.

 

If you would like us to lecture at your educational institute, or give talks on subjects such as recent changes to the Australian Standards affecting Concrete Masonry or the benefits of segmental paving for urban design in public areas, please email us at info@cmaa.com.au or call us on (02) 8448 5500.

8. How do I become a bricklayer or blocklayer?

Please contact the Australian Brick and Blocklaying Training Foundation (AABTF) at 1300 30 44 77 www.becomeabricklayer.com.au.

9. My question is related to poured concrete (such as for garage floors and driveways)

The CMAA is an industry association for concrete masonry manufacturers. For information on poured concrete, please contact the Cement, Concrete and Aggregates Association at (02) 9667 8300 www.ccaa.com.au

10. I want to purchase concrete masonry products, where can I find a supplier?

You are welcome to contact any of our members, who can help you find the right product in your state. Their contact details are:

 

 

1. What are the different types of masonry walls?

1 - Single Leaf Walls (Reinforced and unreinforced)

2 - Veneer Walls 

3 - Cavity Walls (Reinforced and unreinforced)

4 - Hybrid Walls (Reinforced Cavity and Diaphragm)

2. How can I work out the Fire Resistance Level (FRL) for a load bearing fire wall to be built in an office building?

Fire Resistance Levels are listed in Tables 1.3, 1.4 and 1.5 of CMAA Manual MA 55 Part B Chapter 1 Section 1.4 Design for Fire.  If the proposed fire wall is for an office building, the Common Walls and Fire Walls FRL values will be 120/120/120 minutes for Structural Adequacy/Integrity/Insulation.

3. We are designing in a bushfire area - BAL - FZ. Will the 200 series blockwork or 100 series block veneer comply with AS 3959?

All concrete and clay masonry walls are deemed ‘incombustible’, the values of FRL depend on the wall thickness, unit densities, raw materials and type of walls (i.e., load bearing, veneer etc).  This information can be obtained from the manufacturers of these masonry units.

4. I am designing a 190mm masonry wall, fully grouted with 16mm steel reinforcement. How can I calculate the minimum cover and maximum effective steel depth?

Please refer to the CMAA Manual MA 55 Part B Chapter 8 Section 8.3 on Standard Designs. Depending on the exposure conditions, the required grout cover (c) value is 30mm for Very Severe Exposure, 20mm for Severe Exposure and 15mm for other applications. The values of the maximum effective steel depth (d) will be 117mm, 127mm and 132mm respectively.

5. I am designing an external masonry wall, with the lower part embedded below ground level against an existing retaining wall. What should I do to ensure weather tightness of the wall?

I am designing an external masonry wall, with the lower part embedded below ground level against an existing retaining wall. What should I do to ensure weather tightness of the wall?

6. What is Thermal Mass and how does it relate to the R-value?

Thermal Mass (also known as Thermal Inertia or Thermal Capacitance) is a measure of a material’s ability to retain its current level of heat energy when subjected to an external temperature differential. Thermal resistance (R-value) is the measure of the resistance to heat flow per unit temperature difference of the full thickness of the heat barrier. Masonry walls have high thermal mass. 

7. I am a masonry builder.How are windows and doors lintels are formed in current masonry construction? I have seen the old steel angle lines used before but not lintel blocks.

Please refer to CMAA Manual MA 54 Single-Leaf Masonry – Design Manual, which covers all areas of construction of masonry walls.Currently, the use of core filled lintel blocks above wall openings are the most common type of lintels. Start with selecting the right lintel blocks to suit your masonry wall, place the blocks at the right heighton supported form work, build the lintel blocks with mortar, place steel reinforcement as required, pour concrete fill 

(grout), leave the lintel until the concrete hardens, pull the form work and carry on with the next part of construction.

8. What’s the minimum length for lintels to be supported over masonry abutments?

AS 3700 Clause 4.12 requires that lintels be supported on the masonry abutments for a distance of at least 100 mm with opening length up to 100mm and 150mm for wider openings.

9. Why does the grout in masonry walls requirea high water content?

Grout must be of pouring consistency because filling cores is more important than high grout strength.  Also, units remove much of the water from the grout and a limit is placed on the grout strength that can be used in design calculations.

10. How do I remove white deposits and efflorescence from my block wall?

The CMAA Manual CM03 provides a detailed guide to concrete masonry cleaning and maintenance. In summary, efforescence can be removed by dry brushing.  If this is not effective, water washing, with or without pressure, can be used. Chemical cleaning such as acid treatments  is not recommended as this often causes etching of the concrete masonry, as well as fading, streaking and colour changeson the wall.

11. How do I calculate the amount of grout I need for my project?

Manufacturers usually have data tables for “Blocks Filled per Cubic Metre”. Please contact your supplier for this information.

12. What should I consider for core-fill reinforced construction?

Before placing the grout, it is important that the cores should be clean and free of mortar ‘dags’ projecting into the core. A steel rod is pushed down the core to knock off these ‘dags’ and to break up any mortar that has dropped onto the footing. The cores are then hosed or swept out from the bottom of each core through the ‘clean-out’ space. The vertical steel rods are tied to the starter bars, and the clean-out blocks are covered with formwork, ready for grouting (see ‘Retaining Wall Details’ in  CM01 Concrete Masonry – Handbook). An alternative method, which may be used in low height walls, is to leave a gap in the mortar bed at the bottom of each core and to hose out the dropped mortar and dags before the mortar has set.

 

When grouting Series 150 Blocks, lifts should be reduced to 800mm (4 courses) to ensure no voids are left in the wall.

13. What is the thermal performance for concrete blocks with different densities and sizes?

The thermal resistance values of concrete blocks (R) with different densities and sizes can be found in the CMAA Manual MA 55 Part B Chapter 9 – Thermal Performance http://www.cmaa.com.au/walling.html Please refer to the Table – THERMAL RESISTANCE, R on page 7.

14. Can I use M3 mortar mix to fill concrete block cores instead of grout?

Mortar is not grout – grout has to flow freely to surround steel and completely fill cores. Groutusually contains 10 mm aggregate and must beof at least 12 MPa minimum strength. Mortar uses fine aggregates (e.g. sand) and has a paste-like consistency and usually has around 8-10 MPa strength – so broadly you cannot replace mortar for grout. However, if you can achieve the above minimum grout requirements with a mortar then that might suffice, providing all core spaces are completely filled.

15. Where can I find information on Fire Resistance Level (FRL) of concrete masonry walling?

Please refer to our technical manual MA55 ‘Design and Construction of Concrete Masonry Buildings’ Part B - Chapter 4 Fire. You can download this for free from our Technical page  http://www.cmaa.com.au/walling.html

16. What is the thermal resistance requirement stated by the National Construction Code? How can I achieve the R-value requirement?

Please refer to the latest National Construction Code, available from the Australian Building Codes Board at https://services.abcb.gov.au/NCCOnline/. To assist with your calculations, you may use the CMAA’s Mass-enhanced R-value calculator for concrete block

17. Which Australian standard should I use for masonry structures?

AS3700, Masonry structures, is the main standard for design, material and construction of masonry structures. AS4773, Masonry in small buildings, is a “minimal calculation” standard for use by small building designers and specifiers. For more information regarding Australian standards on masonry, please contact our technical team at (02) 8448 5500.

18. Under AS2870, no masonry articulation is warranted for masonry veneer constriction but if arctic masonry veneer is used, do some joints need to be installed in the blockwork? If so what centres?

Under AS2870, no masonry articulation is warranted for masonry veneer constriction but if arctic masonry veneer is used, do some joints need to be installed in the blockwork? If so what centres?

19. Could I use CMAA’s manuals for designing my project in place of services from professional consultants?

While CMAA’s publications are based on wide industry experience and deep knowledge, the information we provide is intended for general guidance only and in no way replaces the services of professional consultants who will be able to give you detailed advice on your specific project.

20. What is the density (kg/m3) of 190mm wide x 390mm long x 190mm high core filled standard and lightweight concrete masonry blocks?

Concrete masonry density can vary between different manufacturers, due to a number of factors such asthe density of the raw materials used as well as the manufacturing processes. The CMAA Manual MA 55 includes a list of a number of block density options to cover these differences. Typically, fully core filled block densities range from 1850kg/m3 to2200kg/m3.

1. What type of mortar is used with Segmental Retaining Wall Blocks?

Segmental Retaining Wall Blocks (such as Allan Block, Anchor, Cornerstone etc.) are mortar-less systems, they are built as gravity walls or as reinforced soil walls using geo-grids.

2. Can the exposed stem of Type 1 cantilever retaining walls in manual RW01 go up to 4.4 m?

No, the maximum height is 3600 mm for a Type 1 Footing. Refer to Manual RW-01 – Concrete Masonry – Reinforced Cantilever Retaining Walls (link to manual), where a design example is provided in Appendix B. If the retaining wall needs to reach 4400 mm, engineers mayuse this design example to set up their own equations checks.

1. What are the differences between segmental and permeable paving?

Both segmental paving and permeable paving are designed to carry traffic but permeable paving can act as a drainage facility to reduce or eliminate run-off, trap pollutants and harvest water for future reuse.

2. I am an architect designing a permeable paving area for industrial application. What type of masonry paving should I use to meet the required design loading? How do I obtain the pavers?

Please refer to our Manuals and Technical Papers onpermeable paving design and construction. http://www.cmaa.com.au/paving.html Please contact our member companies directly for assistance on available types of permeable paving.

 

3. What is the maximum cavity width for cavity masonry structures?

The Australian Standard AS 3700 and the Building Code of Australiacurrently do not have any requirements on maximum cavity width of cavity masonry structures. If you use 90 mm masonry units, a cavity width of at least 40 mm isrecommended. If you are using 110 mm masonry units, the cavity should be equal or larger than 50 mm. The maximum cavity width does depend on the thickness of the insulation in the cavity and wall tie length. For residential houses, we recommend that the cavity width should not be larger than 100 mm. If the building requires high levels of acoustic isolation, then the cavity width can be up to 450 mm, but heavy-duty wall ties have to be used.