Blue Circle® Sulphate Resisting (SR) Cement complies with AS3972, Special Purpose Cement, Type SR. It is manufactured from the ingredients of specially selected cement clinker, gypsum and ground granulated blast furnace slag, which result in significantly better sulphate resistance and lower heat liberation than that of a comparable Portland cement.
Blue Circle® Sulphate Resisting Cement is recommended for use in aggressive sulphate-rich environments where increased resistance to salt attack is required. Where concrete is expected to be in contact with sulphates or other aggressive salts or solutions, analytical surveys must be completed and appropriate grade of concrete selected.
Blue Circle® Sulphate Resisting Cement can also be used in mass concrete where reduced heat liberation is required. As with Portland cements, the resistance to acid solutions is limited, but concrete life expectancy will be maximised by using Blue Circle® Sulphate Resisting Cement at high cement content and low water to cement ratio in fully compacted and cured concrete.
The following table provides typical example of Blue Circle® Sulphate Resisting Cement physical properties.
Blue Circle® Sulphate Resisting Cement can be mixed with other AS 3972 compliant cements or AS 3582 compliant SCM’s but this practice is not recommended unless testing is undertaken to verify the performance of the new blend as this may alter sulphate resistance, strength, heat evolution properties or other durability parameters. Blue Circle® Sulphate Resisting Cement is compatible with admixtures complying with AS 1478.
Australian Standard AS 3972 specifies an upper limit of 900 microstrain for mortar bar expansion for Type SR cement. Typically, Blue Circle® Sulphate Resisting Cement mortar bar expansion is below 250 microstrain.
The following graph demonstrates the SR performance of Blue Circle® Sulphate Resisting Cement relative to a Blue Circle® GP/SL cement.
Sulphate Resistance of Blue Circle® Marine Cement & Blue Circle® GP/SL Cement
Australian Standard AS 3972 limits the peak temperature rise of Type LH cement to below 23 degrees when tested in accordance with AS 2350.7 – Langavant Test. Blue Circle® Sulphate Resisting Cement Peak Temperature Rise is typically under 22 degrees, and heat evolution rate is significantly lower than in the conventional Portland cements.
The following graph demonstrates the heat evolution of Blue Circle® Shrinkage Limited (SL), High Early Strength (HES) and Sulphate Resisting Cements.
The composition of Blue Circle® Sulphate Resisting Cement is formulated to deliver lower heat of hydration and superior sulphate resistance. This results in slower strength development by the Blue Circle® Sulphate Resisting Cement, with significantly lower early age strength, but a greater potential for later age strength development. Typically the early age strength of concrete containing Blue Circle® Sulphate Resisting Cement may be half that of similar concrete containing General Purpose cement at the same water to cement ratio, but the later age strength will not be significantly lower.
The following graph gives an indication of the rate of strength development of Blue Circle® Sulphate Resisting Cement.
Rate of strength development of Blue Circle® Sulphate Resisting Cement.
Effect of Excess Water
Use only the minimum amount of water to mix and place concrete. Excess water will have a detrimental effect on the compressive strength and other properties of concrete. The following graph shows the reduction in concrete strength with increased water addition.
Effect of Addition of Excess Water on Concrete Strength & Slump
Dense, fully compacted concrete of low permeability is essential to minimise the aggressive effects of sulphate and chloride attack. Careful selection of mix components is essential and reference should be made to AS 1379 – The Specification and Manufacture of Concrete and AS 3600 – Concrete Structures, when selecting the required strength and cement levels appropriate for the sulphate concentration.
Where the total sulphuric anhydride (SO3) lies between the limits listed below, the minimum cement levels and the maximum free water-to-cement ratio limits must be observed.
AS 1379 gives requirements for material quality and mixing of ready-mixed concrete. Presence of salts and organic matter in aggregates and mixing water may affect concrete performance and relevant requirements of AS1379 must be observed.
AS3600 gives requirements for handling, placing and finishing of concrete. Exposure classification usually determines both the quality of concrete and the depth of cover to reinforcement. Appropriate selection of the exposure classification is therefore critical.
A minimum curing period of 7 days or longer, depending on the exposure classification, is required and should begin as soon as practicable. Wet or moist curing is recommended, but other techniques may be suitable, including curing compounds to AS 3799 or polyethylene sheeting.
Concrete will benefit from curing in terms of reduction in shrinkage cracking potential, improved surface quality with respect to abrasion resistance, permeability to air and water and improved carbonation resistance.
Blue Circle® Sulphate Resisting Cement is available in bulk only. Details on the price and availability of the product will be provided upon request by contacting the Sales Manager on the numbers listed on the front sheet.
The “shelf life” of Blue Circle® Sulphate Resisting Cement is dependent on the storage conditions, as contact with air and moisture will cause deterioration in cement performance. Cement storage silos must be kept in good repair, with no damp air or moisture ingress.
It is recommended that Blue Circle® Sulphate Resisting Cement be retested if the age of cement exceeds three months.
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.
For further safety information consult the Material Safety Data Sheet for the product.