WHAT IS CBV
The CBV (Concrete Batching Vehicle) is a brand new concept in the construction industry – a 4WD vehicle that operates as a true batching plant, allowing the production of certified concrete in any setting, anywhere in the world. The CBV’s advanced technology makes ambitious projects feasible, even under extreme conditions where it was almost impossible to certify the quality of the concrete produced on-site. Its electronic control system leads the operator to produce consistent batches of concrete mix anywhere in any conditions.
The CBV differs from an ordinary self-loading concrete mixer for a number of reasons:
- It can weigh and measure out the different components (gravel, sand, cement, water, admixtures, etc…) with extreme precision
- It allows you to dump excess materials (the tip-off function), weighing them at the same time
- It prints out a report of the mix produced and verifies that it corresponds to the programmed recipe
The CBV is not only a weighing system, by means of the Fiori Batch Controller the operator will be able to:
- Program and store up to 20 concrete mix recipes including 32 different components each
- Diagnose the end of the mixing process (and homogeneity of the slump) in virtue of the stabilization of the drum reductor’s pressure
- Control the mixing time, number of the revolution and the RPM of the drum, thanks to the drum rotation sensor
- Accurate water/cement ratio, the Fiori Batch Controller automatically stops the flow of water into the drum in accordance to the mix design.
- Admixture Tanks (2 nos. with a total capacity of 30 liters and pump it into the drum according to the mix design.
In many projects the concrete batching process must be controlled or certified in compliance with the current standards of the country in question.
The major breakthrough made by the CBV is the ability to certify the concrete produced by the vehicle itself. Up until now, only concrete produced by batching plants could be certified.
This innovative concept makes possible to certify the quality of the concrete through two elements:
The CBV system allows you to program the desired recipe, accurately measure out the components and then provide a print-out documenting the quality of the product obtained. Its highly advanced mixing system balances admixtures and aggregate’s moisture to assure that the water/cement ratio is kept under control.
The system’s extreme precision and its electronic control makes it possible for the operator to produce uniform batches of concrete mix with the same composition and durability.
The technology and electronics implemented in the CBV vehicles has been developed according to main international standards providing an integrated system that leads the operator to reduce human errors and respect the three “pillars” of concrete performance :
- compressive strength
- fresh-state workability
Mix design of Concrete
The approximate formulation of 1 m3 of concrete is reported in the picture above, but of course it may vary depending on the specific characteristics of the materials used (e.g. shape, density and grain size distribution of aggregates) and on the specific performance required from the concrete (workability, strength, etc.). For this reason, when a new concrete formulation must be set-up, mix design methods can be very helpful. Starting from the characteristics of the single components (cement, aggregates, etc.) and the desired characteristics of the final concrete, these methods allow us to outline an approximate concrete recipe.
For the manufacturing of a good quality structural concrete, the amount of the single components must be measured with suitable accuracy. Materials can be measured by mass or (according to some standards) by volume. National and international standards fix the tolerances to be respected in the measurement of cement, water, aggregates and chemical admixtures. The moisture of aggregates must be taken into account too.
Mixing must be efficient, i.e. give a homogeneous material in reasonably short time. A too prolonged mixing may lead to several problems, such as air entraining (and, hence, strength decrease). Moreover, mixing cannot delay setting, as hydration nevertheless occurs: conversely it might destroy the newly formed hydrated compounds. During too prolonged mixing, water is always added in order to maintain some fluidity, but it is extremely harmful for final compressive strength.
Workability of concrete
Workability is meant as the ability of fresh concrete to flow and properly fill the formworks. Workability is measured by the slump cone (also known as Abrams cone), according to a standard testing procedure (slump test). Slump greatly decreases with time (especially in hot climate), due to concrete setting, hence the required fluidity must be ensured at the moment of casting.