FAQ
FREQUENTLY ASKED QUESTIONS
As the inventor of the volumetric concrete mixer and a family-owned and operated business, Zimmerman Industries brings over 60 years of innovative experience to the industry.
What sets a Zim-Mixer apart from other volumetric concrete mixers?
What is a volumetric concrete mixer?
A volumetric concrete mixer, or mobile mixer, is a piece of equipment that carries the ingredients needed to make concrete in separate compartments. It can be stationary or mounted onto a trailer or truck. It produces a stream of concrete that can be stopped at any point, and adjusted as called for.
How do volumetric concrete mixers work?
Volumetric mixers deliver each of the desired ingredients by volume from the bins or tanks through calibrated openings or flow meters to a mixing auger. The auger blends the ingredients into a homogenized mixture.
What is the concrete production rate of a volumetric concrete mixer?
The production rate of a volumetric mixer is based upon the mix design being produced. A typical volumetric mixer can produce about 60 cubic yards per hour at full speed.
What are the advantages of a volumetric concrete mixer versus a traditional concrete mixer?
The primary advantages that a volumetric has over a barrel truck are the quantity of material, quality of material, and time needed to deliver the material.
Since a volumetric mixer produces only what is needed, there is no wasted material. This is an advantage to the purchaser since no minimum quantity is required, the customer does not have to pay for what he does not use. It is also an advantage for the producer in that he can utilize all of the materials on the mixer, and at the same time minimize waste and clean up.
Because a volumetric mixer produces concrete fresh on-site, adjustments can be made to overcome site or weather conditions that may arise. Properties such as slump or air content can be easily adjusted and controlled. This ensures that the quality of the material delivered can be maintained throughout the delivery.
A volumetric mixer delivers a stream of material, which can be stopped and started at any time. The issues that arise in a drum truck that are time-based, such as distance from the plant to the job site, and the need to offload the material in a short amount of time, do not occur with a volumetric mixer. If the delivery is delayed due to any situation, it can be started again with no change in the quality of the material being produced.
How can a volumetric concrete mixer benefit my company?
If your company is a purchaser of concrete, a volumetric concrete mixer can benefit by minimizing waste and allowing the purchase of only as much material as is needed. A volumetric mixer can also allow for more efficient use of personnel, as the time of delivery can be controlled and adjusted to meet job conditions.
If your company is a producer of concrete, a volumetric mixer can benefit by minimizing wasted materials, thus increasing profits. It also allows for a business to operate from a smaller property, since much less space is needed than a batch plant.
Is there a certification I can get to ensure quality concrete mixing?
There are two levels of certification that are available, for equipment and operators.
The National Ready Mixed Concrete Association (NRMCA) has three divisions that certify equipment, these are the Concrete Plant Manufacturers Bureau (CPMB), the Truck Mixer Manufacturing Bureau (TMMB), and the Volumetric Mixer Manufacturers Bureau (VMMB). Each of these Bureaus has a set of standards concerning the accuracy and consistency of materials produced by and delivered from the mechanisms.
When a manufacturer meets these and passes independent testing verifying this compliance, a rating plate is provided for installation on the approved equipment. This also verifies that the equipment meets the requirements American Society for Testing and Materials (ASTM).
This rating plate on a Volumetric Mixer will ensure that the unit can produce quality concrete, and is required by many states for use on specification projects.
The NRMCA and VMMB have developed a Volumetric Mixer Operators Certification program. The certification offers instruction on Safety; Concrete Technology; Operation, Calibration, and Maintenance; Customer & Company Relations. Upon completion of the course, the operator must pass a test to obtain a nationally recognized 5-year certification.
How is the quality of concrete measured?
The quality of concrete is typically measured through a series of standardized tests. These tests are used to ensure that the design criteria that are called for are attained. Some tests are done on the fresh material and other tests on the hardened material. The most common criteria are compressive strength, which measures how much force is required to cause the concrete to fail. This is usually noted in either psi (pounds per square inch) or the metric equivalent.
Does a volumetric mixer produce higher quality concrete than a standard concrete mixer?
A volumetric mixer can produce concrete meeting any standard or specification. In independent testing conducted by the VMMB, concrete produced from a volumetric mixer gained a higher PSI than the same concrete delivered from a drum truck using the same materials.
While high-quality concrete can certainly be produced using a drum truck, the fact that the concrete from a volumetric mixer is fresh will generally result in a higher quality product.