A 100-metre road was built near Tata from 100 tonnes of waste

Made from concrete cigarette butts and leaves

The first tests of the WLC additive formula were conducted by Károly Bus in 2003. Four years later, he completed the patent for polystyrene concrete, and by 2015, he had produced approximately 150 different waste mixture samples and submitted the patent for waste concrete. At the same time, the practical use of these materials also began. In 2023, production, research and development, and utilisation were organised under a single brand name, resulting in the creation of WLC – Waste Light Concrete.

Today, there are nearly 400 concrete samples. The composition of the possible mixtures is extremely varied: light and heavy plastics, electronic waste, packaging and insulation materials, as well as wood, leaves, cigarette butts, glass and car tyres are among the ingredients. The key to WLC technology is an additive developed after extensive experimentation and testing, Krisztián Méhes told our portal.

The role of the additive is to create a stable, evenly distributed mixture from plastic waste that would otherwise separate when mixed with water and cement.

The managing director of Makrópa Kft. added that the emulsion and mixing formula offer a unique solution for the end use of waste in the form of walls, building elements, foundation concrete or road bases.

Teamwork

One important stage in the rollout of WLC technology is the 8119 main road near Tata. Here, with the professional and financial contribution of Magyar Közút Nonprofit Zrt., a 100-metre-long experimental section was established between km 55+820 and km 55+970, to which a further 50-metre control/reference section is connected. The project was carried out by Colas Út as a subcontractor, with the research and development process supported by Colas. The joint work began during the preparation of the tender and included laboratory tests, trial mixes and trial casting at the Betonsped Kft. mixing plant in Komárom. The tasks of Colas also included installation and on-site testing to ensure that the new technology was comparable in practice to traditional Ckt solutions in road construction.

Traditional mixers and machinery assisted in the construction

The preparation of waste materials does not require significant additional work. It is important that no aluminium powder or waste containing oily substances is added to the crushed material used for the road base. We learned from the contractor that the 0-10 mm plastic granules were transported to the mixer in 1 m³ big bags and filled into the designated fraction. No special machinery was required for either mixing or installation, the contractor informed our portal.

The experimental and control phases are compared.

The 100-metre test section was immediately followed by a 50-metre control section, allowing the behaviour of the two materials to be compared under identical conditions. The specialists at Colas Út constructed the two-lane, 8-metre-wide main road sections with the following parameters:

The experimental phase:

•         40 mm AC 11 wearing course (mF) asphalt wearing course
•         100 mm AC 22 binder (F) asphalt binder layer
•         200 mm base layer containing hydraulic binder and plastic granules

The control/reference section:

•         40 mm AC 11 wearing course (mF) asphalt wearing course
•         100 mm AC 22 binder (F) asphalt binder layer
•         200 mm CKT base layer

100 tonnes of plastic recycled in road base

During construction, two types of CKT were used on the section under investigation: traditional CKT and ÖkoCKT. (The latter is a more environmentally friendly version of traditional cement-bound load-bearing road base, in which some of the raw materials are replaced with secondary or industrial by-products.) The two materials were incorporated continuously, so the method was the same. Approximately 100 tonnes of plastic waste were used in the construction of the test road.

How has plastic changed the properties of concrete?

The expected mechanical properties of concrete are influenced by the properties of the waste materials used as raw materials. The lower the bulk density of the raw material (e.g. refrigerator insulation is used), the lower its compressive strength, but the better its thermal insulation properties, for example. Waste with a higher density is ideal for road base construction. During construction, Colas experts found that the density of the mixture decreased as the amount of plastic granulate increased. The weight of the finished mixture was approximately 70% of that of the traditional material. Based on Colas's measurements, the use of plastic did not significantly affect the strength. According to calculations by the company providing WLC technology, the use of waste in certain mixtures could replace 70% or even 100% of the gravel and sand. A 100-metre section of the experimental road contained 160 m³ of ÖkoCKT, which could replace 130-150 tonnes of gravel/sand.

Monitoring and long-term studies

The evaluation of the technology does not end with the handover of the test road. Makrópa Kft. has committed to conducting annual dynamic deflection measurements, asphalt unevenness measurements and visual surface inspections on both the trial and reference sections for a period of 60 months, i.e. five years. The aim is to determine how the WLC base behaves in the long term under traffic and environmental influences.

The surfaces built five years ago have not been damaged even under heavy loads.

WLC technology has previously been used on walls, concrete surfaces and in road construction. Károly Bus said of the experience so far: according to measurements, the surfaces are more solid and flexible than traditional ones, and have better water resistance and fire resistance.

„Despite significant truck traffic, there has been no displacement on our surfaces installed five years ago, while the same section is becoming unusable with standard road bases. The elasticity of the material exceeds that of traditional CKT, as its watertightness and uniform structure prevent it from sinking and cracking.”