Innovative measuring unit for concrete paver production
Manufacturers of concrete products, in particular manufacturers of paving blocks, know relatively little about the qualitative nature of their freshly manufactured products. However, for determining the quality of concrete products directly after their manufacture in order to ensure and guarantee the following production it should be possible to ascertain and record the physical properties of the products. From now on a measuring unit has become available that determines relevant fresh-concrete properties in only a few minutes.
The Qaver – it records such values as density, height, weight and the quality of compaction of the facing and backing layer of the fresh concrete product. Based on these findings, the quality requirements can be defined and monitored. The Qaver is a control instrument for maintaining one’s own quality standard and enables in that way instant intervention in the production when this is not adhered to. In addition, all measured data are documented and can be subsequently evaluated by one’s own data program.
The innovative quality measuring system Qaver® (= Quality for Paver) does all this. The innovative measuring unit was developed by the Qaver®tec GmbH (Flensburg, Germany) – a company that focuses on the special concerns of quality requirements and controls in concrete products production – following three years of research and testing up to marketability. The Qaver is an ideal tool for lowering production costs by optimizing concrete mix designs, to reduce rejects and for controlling the addition of binders at the specification limit. The unit consistently monitors the production process and delivers objective results independent from the personnel.
With this measuring unit, the company from Flensburg fills a market gap. The reason the new system with its mobile measuring station and special software is revolutionary is that until now only very few elements for testing and/or measuring possibilities existed and no uniform and interconnected control system. In collaboration with a handful of selected manufacturers, the properties of the Qaver are permanently practice-oriented developed. The Qaver, with its hardware and the special purpose-programmed software is an absolute novelty.
Additionally the development was scientifically accompanied by the department of civil engineering,
specialist area construction materials and concrete technology, of the Cologne University of Applied Sciences, headed by Prof. Dr.-Ing. Rudolf Hoscheid.
The Qaver is an innovative quality measuring unit for freshly manufactured concrete products for which a patent has already been applied for: The unit can measure and save the physical properties of the fresh concrete products through simple handling immediately after they have left the block machine. The measured results are compared with specifically determined boundary values and displayed according to the tolerances. The unit thus immediately identifies the quality properties of a product and shows the user whether his own quality requirements are met or not. The following physical properties are recorded and assessed:
» Compaction quality in the facing and backing concrete – determined via gas permeability
» Density (actual product height and product weight as well a the geometry form the basis for the calculation)
All these measurements serve moreover as the basis for the actual quality prediction of the hardened concrete products.
Integrated control safely guides the user through the measurement
The autarkic Intranet-capable PC control on the Qaver safely and easily guides the user through the measuring process: the operator takes hold of a block from the board with the tool holder without having to stop production and guides it to the measuring table. The measuring unit records the compaction quality of the facing concrete already while the block is being removed. After the block is deposited on the measuring table, the remaining measurements, e.g. recording of the block heights, determination of the compaction in the core and determination of the product weight are carried out semi-automatically. This measuring process can be completed within one minute.
Rapid evaluation with visualized display of the results
The measured results are evaluated immediately afterwards. Every individual result is compared with the tolerances allocated to it and shown in the traffic-light colors yellow, green and red. Through this representation in signal colors, the user can see at a glance whether the block meets the specified requirements (green), lies within the critical area (yellow) or deviates markedly from the specifications (red). With the Qaver, the quality objectives can be directly determined and measured. Together with the data on the hardened concrete that are added later on, the quality properties of the concrete product can be assessed based on one’s own prediction model. All deviations as well as outliers are recorded and documented in detail.
Laboratory analysis monitors and checks the total production process
Direct measuring in the production hall is followed by the evaluation in the lab by an external program. This software can be installed in every PC. The evaluation program permits via a search function the identification of the machine operator that has manufactured a given product, specifically related to the individual production periods (date, time). The respective areas of the measured values can then be represented and printed individually or directly in comparison via a time axis as graphs.
The Qaver, moreover, offers the additional possibility to replace the fresh concrete products removed with a transponder chip. For this, a transponder chip is read in before a fresh-concrete test is carried out and positioned on the production board. This transponder serves to mark the board, thus enabling subsequent allocation of the fresh-concrete properties to the hardened-concrete properties on the same board. Through this possibility of comparison, one’s own quality requirements can be further enhanced and/or the mix design still further optimized. The primary advantage of the laboratory analysis is that the entire production process can be viewed and checked in retrospect and that in this way the continuity of the production of the product can be precisely represented over specific periods of time.
Complete production boards can also be precisely evaluated
With a special program option on the Qaver, the individual qualities of a complete production board can be recorded within a very short time in that all block on a board are systematically tested. With the subsequent evaluation program, the quality differences of all measuring areas on a board can be visualized three dimensionally. This view particularly enables the machine parameters to be optimally set.
Individual measuring unit with high reproducibility and significance
The Qaver is an individual measuring unit of high reproducibility and significance, whose capabilities result the fact that the compaction quality of the fresh paving blocks are recorded via the specific pore surface in the core and facing concrete. In addition, the density is determined via the height and weight of the product and shown.
The measuring unit thus enables the specific identification of the quality. In this way, waste can be noticeably reduced. The unit, moreover, leads to an optimization of the machine setting and increase the personnel’s quality consciousness. The Qaver thus presents itself as an ideal tool for lowering production costs and to even more sharply optimize the economy of the constituents of the mix design. As compact measuring unit, the Qaver has the function on an independent tester, since the measured values – thanks to the special properties of the software – cannot be falsified. The measuring unit thus guarantees consistent monitoring of the plant and product – independent of personnel and objectively.
The Qavertec team stands by to demonstrate the Qaver in precast plants.
Sönke Hansen, Flensburg
