Adding Value To Aggregates
Using mobile volumetric dispensers to sell concrete can provide aggregate producers with a speedy return on investment, as Richard Calder, technical manager with Armcon Cementech, explains
Quarry owners are rapidly discovering the benefits of adding value to their aggregates by selling concrete. Traditionally this involved heavy investment in static batching plants and the necessary planning requirements surrounding such projects. Additionally, the associated truck fleet to deliver the concrete required applications for operator’s licences and resulted in more form-filling and ongoing management commitments.
Today, however, the opportunity to add value and realize a speedy return on investment is easier than it has ever been through the use of mobile volumetric concrete dispensers.
First seen in the UK market 10 years ago, these machines were initially regarded with some scepticism as it was widely believed that mixing by volume could not produce consistent high-quality concrete. This myth has been firmly dispelled by the new generation of operators who have shown they can supply high-quality concrete to builders, civil engineering projects, highways authorities, councils and railway contractors, all areas where consistent high quality is demanded.
Specifiers and contractors have not been slow to recognize the benefits of concrete mixed on site and many now choose volumetric mixed concrete in preference to traditional batched concrete. Many quarry owners have even made the next step up from selling concrete to manufacturing concrete products, such as pre-stressed Tee-beams, lintels, wall panels, floor panels and concrete blocks, thus adding further value to their aggregates.
So how does the volumetric concrete dispenser work? Stone, sand, cement, water and admixtures are carried in individual compartments and blended by volume before being mixed in a continuous screw mixer on the machine. The customer can have the precise amount of fresh concrete he or she requires – ‘on tap’. Furthermore, they can have the exact specification or even have more than one type of concrete in a single delivery. Each delivery is recorded by an on-board computer and a delivery ticket is produced showing cubic metres, times, dates, specification and quantities of materials supplied. The computer will also assist in stock control and the reordering of materials.
The key to the accuracy of the machine is to be found in the consistent metering of the cement and aggregates to the mixer on the machine. The cement metering system must be self-cleaning and mechanically linked to the conveyor system which delivers the aggregates. The aggregate bins should be designed to ensure a constant flow of aggregates to the mixer throughout the delivery process. Finally, the counting method used to measure the output of concrete must be sufficiently fine to achieve the ±3% tolerance required by EN206-1 BS 8500.
Calibration of the machines is an important factor in controlling both mix designs and costs. The procedure developed by QSRMC (The Quality Scheme for Ready Mixed Concrete) and Armcon Cementech, the leading supplier of volumetric machines in the UK, ensures this control can be easily managed. The calibration procedure involves the weighing of the quarry’s raw materials through the machine to create a set of parameters from which any mix design can be formulated. Calibration is a simple process carried out on site by an independent engineer, providing third party accreditation for the business.
Alongside the calibration process it is important to operate a concrete testing regime from the outset. Nothing is more important when it comes to winning business than a portfolio of concrete test results for the mixes on offer. These are the passport to regular work with county councils and highway authorities, and will be invaluable when talking to specifiers and contractors. Testing will also reveal if too much or too little cement, the most expensive component in concrete, is being used, allowing the operator to ‘tune’ mix designs to produce the optimum quality of concrete.
As with any machine, there are factors in the design which contribute to accuracy, longevity and low maintenance, but choosing the right machine requires careful consideration. Operators should look for a supplier who understands the concrete business and can offer both technical and commercial training. They should also look for a machine with a proven track record that is already operating within recognized quality schemes. Finally, no machine will run forever without some maintenance, so a comprehensive spares stockholding and knowledgeable engineering staff will help ensure minimum downtime.
For a quarry owner looking to start a concrete business, the set-up costs are easily managed. All that is needed is a supply of cement and a volumetric mobile concrete dispenser. Indeed, the volumetric dispenser does not even need to be mobile; a number of owners operate a ‘collect’ concrete service using a static machine. Cement is available in 25kg bags, 1-tonne bulk bags and in bulk. Bulk cement offers significant advantages including reduced cost, faster loading and no bag disposal, and it is cleaner environmentally. The use of transportable low-level silos is common today and allows easy relocation, when necessary, along with minimal site preparation. Planning consent is not normally required for these moveable structures. Another important consideration is that the operation of mobile volumetric concrete dispensers does not require an operator’s licence.
Volumetric concrete dispensers have rapidly developed an enviable reputation for providing good concrete and good service. Customers appreciate the level of service that comes with this method of delivery and they appreciate personally seeing the production of the concrete on site. Concrete slump can easily be changed along with mix design to suit the job in hand, which is particularly useful for pump jobs and pattern-imprinted concrete.
The high level of service is probably the most significant factor in winning and retaining customers, and it is rare for a customer to revert to traditional concrete delivery methods once they have experienced the benefits of on-site volumetric mixing. Mobile volumetric concrete dispensers can deliver into barrows, pumps or footings and slabs. The nature of the delivery method and the ease of changing the mix design mean that these machines are particularly suited to a ‘milk round’ style of operation, with the truck leaving the yard full and moving from job to job until it is empty. The economies of this style of operation are obvious, but less apparent are the benefits of flexibility in shipping, which allow the operator to offer much higher levels of service and to cope with increasing journey times on the increasingly busy roads.
One aspect of the concrete business that is particularly attractive is the method of payment. Most concrete customers pay on delivery by cash, cheque or, increasingly, credit card through an on-board reader. The effects on cash flow are obvious and can help the new business get off the ground quickly, with reduced borrowings. Accounts should be reserved for customers who order regularly and pay on time, typically local councils who are always reliable payers. Coupled with a finance or leasing package, it is possible to grow the business in a controlled way to the point where a second machine becomes necessary to cope with growing demand. Most owners add a second machine during their first year of operation and many go on to operate three, four or more machines.
The most effective medium for attracting business is Yellow Pages, in connection with direct mail and leaflets. Leaflets and/or postcards left in builder’s merchants, sandwich bars, cafes etc, or anywhere builders go, will reap rewards. Direct mailing to contractors and councils will also generate interest along with websites to promote the benefits of the service. Planning applications available through local planning offices also offer a source of potential customers. Promotions can be another source of new customers and there are many ways to do this; one which works well is to offer the first half metre of concrete free of charge to new customers. Experience has shown that once customers try concrete from a volumetric mixer, they rarely go back to traditional suppliers, and once a customer base begins to develop recommendations will ensure that it grows rapidly.
In summary, volumetric concrete dispensers can offer companies or individuals looking to add value to their aggregates the opportunity to develop a highly profitable and sustainable business. Choosing an experienced, knowledgeable supplier will accelerate the initial growth and ensure the growing pains of the new operation are minimized.
