Demo 2: Production of SRM construction products for building and civil engineering applications

Production of SRM construction products

As part of the pilot demonstrations of our CINDERELA project (H2020), we established the pilot production plants in Maribor (Slovenia), Madrid (Spain) and Skopje (North Macedonia). With the pilot production plants, we aim to demonstrate the technical, technological, and administrative possibilities of processing and using of various non-hazardous construction as well as some other waste types to produce more sustainable construction products. Following the pilot production, the secondary raw material (SRM) based products will play an important role in construction demonstration where we plan to revitalize three degraded areas, build two small facilities with acompanying access roads. However, as the waste is not suitable for direct use in construction projects, it has to be pre-processed.

The pilot production is planned at the development phase of Technology Readiness Level (TRL) 7, which means that certain basic knowledge has already been acquired, some from lower-level development projects, and some from practice and literature studies.

From the technilogical point of view, it is important to consider the following:

• Waste recovery processes i.e. crushing, sieving, mixing;
• Capacity of the waste treatment plant;
• Acceptability of waste for recovery;
• Waste pre-treatment requirenments;
• Storage of material (separated waste) during the processing;
• Expected end results and preparation of specific mixtures;
• Certification of end products;
• Method of storage of processed materials;
• Product delivery logistics

Maribor, Slovenia

With the means of processing waste by crushing, sieving, and mixing as part of the pilot production, new construction materials will be obtained and used in three different demos, which will be carried out in the area in Dogoše, Maribor, Slovenia as part of the CINDERELA Project. These demos are revitalization of the degraded area, construction of a small facility, and road construction.

The pilot production plant is producing the following four groups of SRM-based products:

• Recycled aggregates;
• Geotechnical composites;
• Green concrete;
• (recycled soil).

A comprehensive system of recovery and monitoring of mass flows is envisaged for the processing of waste before treatment. We will monitor the entire flow through the processes of acceptance, input control, pre-treatment, all processing procedures, control and certification of output products, the definition of use, fitting, and evaluation of the results of the materials.

We produced the first green blocks for separation units made of recycled aggregates in Dogoše on November 13, 2020. These will be later used for the construction of a small demo facility and the construction of concrete partition walls at the landfill to separate aggregates. The recipes to produce green concrete were prepared by our project partner, the Slovenian Nationa Building and Civil Engineering Institute (ZAG), based on previous laboratory tests of delivered samples of various secondary raw materials. The green concrete was produced with the mobile concrete batching plant of the Danish manufacturer FIBO and installed in the prepared formwork elements for blocks of the Dutch supplier Betonblock.

Madrid, Spain

The main demonstrations in Spain are being implemented at the the CTC headquarters in Madrid (Spain). The first step in the process includes the demolition of former ceramic kilns has started in early autumn 2020. In order to facilitate the work in the future and to ensure the best possible conditions for further processing, it is necessary to use the method of selective demolition. It is necessary to separate the CDW as much as possible. The CDW as well as other materials needed to perform construction works will be treated by the main subcontractor with a CDWs treatment license.

In addition to processed CRD material to be used in the development of the demo cases in Madrid, Spain, the following materials will be used:

• the rubble produced by the planned demolition of the old kilns structures currently located inside CTC SERVICIOS facilities: mixed CDW;
• the waste currently located in the area: natural clay, bricks, ceramic, aggregates;
• road waste: reclaimed asphalt;
• wastes from other recycling plants close to the pilots: concrete based CDW, mixed CDW residues, waste asphalt.

The additional processing will be executed at the local asphalt plant to form SRM- based products i.e. recycled concrete for floor, reflective green concrete, recycled asphalt. The final developed products will be used to develop a new working area for CTC Servicios to develop the activities of temporary storage and treatment of waste material inside the main headquarters.

The use of CDWs to develop new SRM based products will allow us to analytically compare various material characteristics as vell as its response to the real environment once installed in pilots. Furthermore, the compliance with the standards and regulations will also be closely looked upon to assure the safety and improvement in the use of these new materials. Following the technological requirements to use this kind of product in construction, the main regulation to be used is the CE Standards as the European directive of construction products and the Spanish regulations on the use of Construction materials.

The waste treatment process will be done by machinery used for the treatment of the waste, as elements of the pilot production plant which will be the following:

• mobile debris crusher to reduce the size of the mixed construction,
• mobile screen for appropriate size classification,
• mixing machinery.

A tracked excavator will feed the mobile pilot plant.

The waste processing unit in CTC SERVICIOS will consist of three separate sets of technological equipment: crushing, screening, and mixing units. The products of every process will be collected to feed the next machinery.

Skopje, North Macedonia

In the scope of the CINDERELA project three pilot demonstrations are being implemented (a truck parking plateau, asphalted access road (reconstruction), with intersection and shoulders and partition walls of concrete blocks), which will be built mostly from secondary raw materials in the area of Makstil factory. To obtain and to treat the material a pilot production plant is being established. In the pilot production process we are analyzing the technical, technological, and administrative possibilities to process industrial waste (black and white slag) to produce SRM- based material. The pilot production plant consists of separate sets of technological devices: sieving/crushing unit, additional sieving unit, asphalt production unit, and concrete production unit. All of the above-mentioned technological sets of devices can operate independently, but assembled will represent one whole.

At the moment first part of pilot production (crushing and sieving of black slag) is up and running. After sufficient amount of material will undergo the first treatment stage, the second production stage is planned. In early spring of 2021, the asphalt and concrete production will be launched. The following machinery is being used in pilot production process. TEREX crusher will be used for crushing of 25 % of black slag (lumps). It is a mobile crusher with wheels that moves. The crusher can also work as a screener.

The screener for additional sieving of the sowed black slag for asphalt production is a product of Metso Minerals, Sweden. That is a mobile screen type CVB 1845 – 4.

A comprehensive system of recovery and monitoring of mass flows is envisaged for the processing of waste before treatment. We will monitor the entire flow through the processes of acceptance, input control, pre-treatment, all processing procedures, control and certification of output products, the definition of use, fitting, and evaluation of the results of the materials.

We produced the first green blocks for separation units made of recycled aggregates in Dogoše on November 13, 2020. These will be later used for the construction of a small demo facility and the construction of concrete partition walls at the landfill to separate aggregates. The recipes to produce green concrete were prepared by our project partner, the Slovenian Nationa Building and Civil Engineering Institute (ZAG), based on previous laboratory tests of delivered samples of various secondary raw materials. The green concrete was produced with the mobile concrete batching plant of the Danish manufacturer FIBO and installed in the prepared formwork elements for blocks of the Dutch supplier Betonblock.