Product Catalogue: Cement

Off White Cement


Blue Circle® Off White Cement is a general purpose cement complying with AS 3972, type GP. Blue Circle Off White Cement is produced from a specially manufactured light coloured portland cement clinker which provides the unique colour of this cement.

    Features & Benefits

  • Produces a high strength, light coloured mortar that highlights the texture and tones of modern bricks.

State Availability

NSW, 
ACT, 
VIC

Product Range

Bulk Cement

Application / Use

Coloured Concrete, 
Concrete Masonry, 
Specialised Applications, 
Precast Concrete Elements

Type 

GP, 
HE


Uses
Blue Circle® Off White Cement is combined with selected sands, aggregates and oxides to provide a wide range of attractive architectural finishes in brick and blockwork mortar, rendering, exposed aggregate pavements, panels and terrazzo.

Major projects which demonstrate the range of aesthetic and structural qualities of Blue Circle® Off White Cement include: The Regent Hotel, Sydney; The High Court, Canberra ACT; The State Library extension, Sydney; The Brisbane Cultural Centre, Qld; Department of Foreign Affairs, Canberra.


Properties
The following table provides an example of some typical properties:



Property Off White AS 3972
Setting Time: Typical: Requirement:
Initial 1-2 hours   45 mins min
Final 2-3 hours 10hrs max
Soundness: 1.0mm 5.0mm max
Fineness: 400-460m2/kg  
Comp. Strength:    
3 day 32-40 MPa  
7 day 43-51 MPa 35 MPa min
28 day 56-65 MPa 45 MPa min
Mineral Additions: up to 5%  



Compatibility
Off White Cement may be mixed or blended with other cements complying with AS 3972. It also may be blended with fly ash complying with AS 3582.1 so long as the minimum proportion of portland cement is maintained. Blending with other products will affect the consistency of the colour and is not recommended where colour control is required.

Off White Cement is compatible with admixtures complying with AS 1478. Some admixtures may affect the consistency of the concrete colour or cause staining. Refer to your admixture supplier for advice.


Colour
Colour Comparison: The colour of Off White Cement is controlled within close tolerances using a reflectometer test. The colour falls mid-way between the grey normally associated with Portland cements and pure white.

Colour Control in Concrete: The colour of concrete will be influenced by the mix design, water content and the colour of the fine aggregates. For projects likely to continue over a long period of time only those sands that have an acknowledged colour consistency, or those which can be stockpiled in sufficient quantities, should be used.

Slump control is essential. It is recommended that concrete which fails to comply with the slump tolerances contained in AS 1379 not be placed in areas where colour control is critical.


Colour Control in Mortar: For a light off white colour, best results are achieved by the careful selection of a white-coloured bricklayer’s sand. Coloured bricklaying sands may be used to produce some natural coloured mortars, e.g. creams to yellow.

Mix proportions must be kept consistent to prevent variations in colour. Sand, cement and water quantities for each batch must be measured out using a bucket or other measuring device. Maintaining a constant water-to-cement ratio and sand to cement ratio is critical for colour control.

Quantities of sand sufficient to complete the project should be stockpiled and protected from contamination.


Mortar Properties
Mix Design: The table on the following page provides recommendations for use of Blue Circle® Off White Cement for various exposure conditions. 
 

Exposure Condition Off White Cement Hydrated Lime Sand
External – exposed to sea air or spray (within 1km of the coast) 1 0.5 4
External – Other 1 1 6
Internal – Above damp course 1 1 6
Internal – Below damp course 1 0 3



Batching: Batching must be carried out using an approved measuring device. Accurate measurement of each material, including water, is essential to produce a consistent product.

Additives: Plasticisers and water thickeners may be used but must be added strictly in accordance with the manufacturer’s instructions. A serious loss of bond strength may occur if these products are overdosed.

Blue Circle® Hydrated Lime (Plaster Lime): is recommended if improved workability is desired. Hydrated lime may also be used to lighten the colour of mortar.


Concrete Properties
Mix Design: When determining optimum cement contents, reference should be made to AS 1379 “The Specifications and Manufacture of Concrete”. The cement content for each grade of concrete depends on the nominated target strengths.

AS 3600 “Concrete Structures” recommends minimum strengths and minimum cement contents to achieve adequate concrete durability for more severe exposure conditions. e.g. Exposure classification B1 (locations close to the coast) requires a minimum N32 MPa (normal concrete). For site mixed concrete the following mix proportions are recommended.


Mix Proportions by Volume – 20mm Graded Aggregate

Application Builders Cement 10mm Stone/Gravel Sand
High Strength & Watertight 1 3 2
General use: paths, floors etc. 1 4 2.5



Mixing
AS 1379 gives requirements for material quality and mixing of ready-mixed concrete. Recycled water may be used only where testing can demonstrate compliance with the relevant section of AS 1379. Dissolved salts and organic matter may adversely affect the strength, durability and appearance of the concrete. Salt and organic matter in sand will have a similar detrimental effect.

Strength Development: The strength development of Blue Circle® Off White Cement is primarily dependent on the water to cement ratio. The following graph gives indicative data on the strength development of concrete.


Compressive Strength % Comparison Off White Cement
Off-white compressive strength graph
Effect of Excess Water
Use only the minimum amount of water to mix and place the concrete. The following graph shows the reduction in compressive strength of concrete with increased water addition.


Effect of Addition of Excess Water on Concrete Strength & Slump
Effect of Addition of Excess Water Graph

Placing
AS 3600 gives requirements for handling, placing and finishing concrete. Minimum cover to reinforcement is 20mm for the lowest exposure classification. The cover needs to be increased where concrete is cast against the ground, for fire resistance and for exposure classifications other than A1.


Curing
A minimum curing period of seven days is recommended for all exposure classifications. Concrete should be maintained in a moist condition where practicable. Use of water-application techniques, such as water sprays and wet sand or water-retaining techniques, such as polyethylene sheets or curing compounds, are recommended. Curing should begin as soon as the selected technique allows. 

For normal-class concrete, curing can produce a compressive strength 80% to 100% greater than concrete not subjected to curing. Water-application curing is more suitable for lower grades of concrete. For concrete strengths of 40MPa and above, curing is equally important, however, the type of curing mechanism is less critical.

Curing will also affect other concrete properties such as:
• Reduction in the potential for plastic shrinkage cracking.
• Improvement in surface quality and a reduction in air permeability.
• An improvement in abrasion resistance, particularly in higher grades of concrete.
• Reduction in the carbonation rate.

Variations in the duration of curing or the uses of different curing methods may affect the initial colour of concrete.


Availability
Blue Circle® Off White Cement is available in bulk and 20kg multi-walled paper bags.


Cleanup & Storage
Avoid generating dust. Clean up by vacuum or sweeping. Contact with air and moisture will cause hydration of the cement and alter the cement properties. The ‘shelf life’ of Blue Circle® Off White Cement is, therefore, dependent on the storage conditions.

Bagged product should be stored off the ground and stacked to allow free circulation of air. Bags are not waterproof. It is recommended that Blue Circle® Off White Cement be retested prior to use if the age of the cement exceeds three months.


Safe Handling
This product contains cement chemicals and trace amounts of Hexavalent Chromium. Avoid generating dust. Use personal protection equipment against exposure and alkali burns. Wash product off unprotected skin immediately with water. The use of goggles, dust masks, barrier creams and rubber gloves is recommended.

Manual Handling of this product without proper training may result in personal injury. Wherever possible, use mechanical aids or share the load with another person.

For further safety information consult the Material Safety Data Sheet for the product.

Delivery / Packaging:


Bulk Delivery