READY-MIX CONCRETE (RMC)
Ready-mix concrete is manufactured in a factory or batching plant to specified mix proportions and then delivered to site by lorry-mounted transit mixers. This results in precise mix proportions being delivered in pre-ordered quantities (measured by volume in m3), which can be custom-made to suit many different construction applications. Ready-mix concrete is manufactured under computer-controlled operations and transported and placed at site using sophisticated equipment and methods. Ready-mix concrete provides customers with numerous benefits but a few disadvantages.
The advantages of ready-mix over site-mixed concrete are
• a better and more consistent quality concrete is produced;
• there is no need for storage space for basic materials on site;
• the elimination of procurement/hiring of mixing plant and machinery;
• wastage of basic materials is avoided;
• the time required is greatly reduced;
• noise and dust pollution on site are reduced.
However, ready-mix concrete does have a number of disadvantages:
• The materials are batched and mixed at a central plant, so the travelling time from the plant to the site is critical over longer distances. Some sites are just too far away!
• Concrete’s limited lifespan between mixing and ‘going off’ means that ready-mix should be placed within 2 hours of batching at the plant. Concrete is still usable after this point but may not conform to relevant specifications.
• It generates additional road traffic. Furthermore, access roads and site access have to be able to accommodate the weight and size of the truck and load.
• Any shortfall in quantity, due to a miscalculation, could result in work already done being wasted. Conversely, over-ordering will result in costly wastage of unused concrete.