Concrete is a proportioned blend of dry aggregate, graded sands and cement suitable for all general purpose concrete applications where a quality concrete is required.
General smaller concreting jobs like foot Paths, Slabs, Footings, Garden Edges etc.
Where a more structural concrete is required you may need to add neat cement to the premixed bag. As a guide, an addition of 1kg to 1.5kg per 20kg bag of Blue Circle® Concrete can be used to achieve around 32 MPa concrete (under normal conditions).
Formwork made from 25mm thick timber is commonly used to mould the concrete. Use a builders square to ensure that corners are at right angles. Lightly oil the insides of the boards before mixing and laying the concrete. Lower the formwork on one side to allow a slight fall for water run off when doing pathways and slabs.
Use either a wheel barrow with a ‘larry’ hoe, shovel or mechanical mixer. Add about 75% of the water to the mixing vessel and slowly add the contents of the bag. Add sufficient remaining water gradually to achieve a workable mix. As a guide, use around 2 litres of water per 20kg bag.
Do not over water unless you need to achieve a sloppy mix. The less water the stronger the concrete.
Placement of concrete
Prior to placement, lightly soak the base with water to prevent excess moisture loss. The base should be compacted (crushed rock or sand). Placement can be done by shovel ensuring all corners are reached. For larger jobs a poker vibrator may be needed to ensure no entrapped air is in the mix.
Use a straight edge to screed off the concrete to the height of the formwork. Float or trowel the concrete as soon as possible after screeding without overworking the surface. Wait until all excess bleed water has dissipated and then finish off.
Use a jointing tool to cut joints every 1 – 2 metres. Use an edging tool to smooth off edges and prevent chipping.
Smooth finish with a steel trowel or non-slip finish with a shelling trowel or broom finish.
Caution on hot weather
It is advisable to delay concreting until weather cools down below 32 degrees. High temperatures can dramatically affect the properties of concrete by drying out too rapidly.
Fresh concrete must be protected from loss of moisture as soon as the surface is firm. Plastic sheeting can be used, also Hessian kept damp at all times laid over the concrete. Curing should be done for a minimum of seven days and longer under certain conditions. Keep formwork in place whilst curing to protect the edges.
One 20kg bag will cover an area of 1.1m2 to a depth of approximately 10mm. Or 108 x 20kg bags equates to one cubic metre of mixed concrete.
Bags required for the job:
Blue Circle® Concrete Mix comes 20kg plastic lined, multi-walled paper sacks, and small handy 10kg plastic bags.
Cleanup & Storage
Clean all tools and equipment with water promptly after use.
Contact with air and moisture will cause hydration of cementicious products. Store in a cool dry place and seal any unused material. It is recommended to dispose of any cement based products over 12 months old.
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 bagged products without proper training may result in personal injury. Wherever possible you should use mechanical aids or share the load with another person.
For further safety information consult the Material Safety Data Sheet for the product.