The rules and regulations for aggregates are subjected to constant change. Therefore, various construction methods require the adherence to a number of standards, technical terms of delivery and contract conditions. For this purpose, about 60 representatives from the stone and quarry industry as well as from planning and architectural offices and road authorities visited the 11th Technology Day of the gravel industry, which took place on September 18, 2014. It was hosted in cooperation with the company KE Kies- und Schotterwerk Mundelsheim GmbH & Co. KG, the Industrieverband Steine und Erden Baden-Württemberg e.V. (ISTE) (industrial association stone and quarry Baden Württemberg) and the Güteschutz Naturstein Baden-Württemberg e.V. The participants took the chance to get informed about the current development in the gravel industry. The participants were welcomed by the chairman of the Fachgruppe Naturstein and Güteschutz Naturstein, Peter Rombold, by the managing director of the KE Kies- und Schotterwerk Mundelsheim and by the host of the event, Baptist Schneider.
National and European regulations complement each other
The processing of raw materials, their further processing into products and the manufacturing of commodities are subjected to a complex quality control system which, in turn, is subject to national and European rules. “On national level, quality assurance of materials for base layers without binding agent is regulated by the RAP Stra. On European level, the accredited supervisory and certification body plays a central role“, says Jan Herrmann, managing director of the IBE Institut für Baustoffprüfung und Umwelttechnik GmbH, on the occasion of the technology day of the gravel industry.
“According to the RAP Stra, parameters are examined consistent with Technical Delivery Conditions, Technical Test Regulations, Additional Technical Contract Conditions and Amendments to the Technical Contract Conditions,” the expert continues. “The national regulations require structural-physical investigations and in-house production control for frost-resistant and gravel base layers. These are real product tests which, as far as aggregates for asphalt and concrete are concerned, are actually not provided for by the conformity assessment and certification system 2+.”
However, the European system requires the purchaser to carry out an incoming goods inspection of the product. For this purpose, the voluntary product inspection according to the recommendation of the professional associations was implemented, which makes incoming goods inspections in asphalt mixing or concrete works superfluous. “This process bridges the gap between national and European rules”, says Jan Herrmann.
System of different examinations ensures product safety
Jan Herrmann attaches particular importance to sampling. “It should be carried out at different places and in different depths, and in the ideal case across the entire structure,” the expert recommended. “In particular in case of coarse aggregates, decomposition often occurs in stockpiles.” In order to counteract this effect, the center of the stockpile could be excavated by means of a wheel loader and, with a few bucket loads from this area, an earth bank could be built from which the sample could be taken. Regarding individual or bulk samples that have to be divided, Herrmann emphasizes that this could also be done in advance, if they are too big for the receptacle. “Restricted subsamples shall than be subsumed in advance.”
According to Herrmann, the grading curve is one of the most important criteria of quality control. “Because, if decomposition symptoms arise, they cannot be homogenized,” says the expert. “The consequences in road construction are, among others, frost damages or cracks in the asphalt covering layer.” In case of a damage, strength and grain shape are decisive assessment criteria.
Specifications of the European Construction Products‘ Regulation must be fulfilled
In the second lecture of the morning, Technical ISTE specialist and managing director of the Güteschutzes Naturstein, Kai Fischer, explained that the CE-Label is neither a quality label in the traditional sense, nor a usability label, but rather a label of usefulness. This given, a CE-labelled product is regarded as useful only according to the European Construction Products’ Regulation (BauPVO). To enable the CE-labelling of construction products, they must fulfill the essential requirements in the fields of fire and noise protection, hygiene, health and environmental protection, safety in use, energy savings and heat insulation, mechanical strength and stability.
The declaration of performance (previously declaration of conformity) is the ‘calling card’ of the construction material. According to the speaker, it includes the warranty of the characteristics, which are set out in the BauPVO. Apart from the identification code of the product type, the declaration of performance includes the intended use according to the EN standard, the type number or other characteristics for the clear identification and retraceability of the construction product. On the online platform DoPCAP (Declaration of Performance - Common Access Point) created by several construction material associations, companies will be able to digitally submit their declarations of performance. A delegated act of the EU commission has been allowing this since the beginning of the year, ensuring legal compliance.
Guided tour through the quarrying site as elementary part of the event
During the Technology Day, participants could learn how natural stone products are produced in practice in the production site of the KE Kies- und Schotterwerk Mundelsheim GmbH & Co. KG (Fig.). The technical manager, Dr. Peter Antweiler, explained the adjoining geology of the Upper Muschelkalk and the different production processes up to the finished product. A new impact roll crusher as a primary crushing stage as well as the related conveyor lines were installed. Due to the extensive conversion measures, the location Mundelsheim is technically prepared for the years to come.