MICROPLASTICS

DESCRIPTION OF THE INVENTION

The invention relates to the technological eco-innovation of introducing polypropylene microplastics in the recipe of the asphalt mixture and of partially replacing the natural resources with the waste grit from the blasting process of the ship's hulls.

Hot-prepared asphalt mixture is a construction material made by a technological process that involves heating natural aggregates and bitumen, mixing the mixture, transport and commissioning, by hot compaction (Standard AND 605-2016: STAS SR EN 13108).

The asphalt mixture used for the execution of the wear layers (rolling) is called asphalt concrete with crushed stone BA F, where F is the maximum size of the granule (STAS SR EN 13108).

Asphalt or bituminous mixtures for roads generally use pre-washed river ballast as natural aggregates, mixed with quartz sands (extracted from gravel pits or riverbeds) and crushed stones (taken from quarries as a result of rock crushing and sorting processes) or sands of crushing (fine fraction of quarrels from quarries) (SR EN 4032-1, SR EN 13108, SR EN 13043/2003 + AC / 2004).

The recipe of the asphalt mixture type BA 8 consists of 33.5% crushed siliceous stone chipping with a granulation ranging between 4.0 and 8.0 mm, 50% crushed sand with a granulation ranging between 0.0 and 4.0 mm, 10% sort limestone filler and 6.5% road bitumen type 50/70 (STAS 11348-87, AND 546-2013).

The binder used for the asphalt mixture is road bitumen type D 50/70 (STAS SR EN 12591 : 2009) which has a high capacity to incorporate and agglomerate by monolithization divided solid materials. Moreover, this bitumen offers stability over time and resistance to the action of water and other exogenous agents (light, freeze-thaw, mechanical wear).

At international level, a number of patents are known that refer to compositions and processes for obtaining asphalt mixtures:

• CN107963832A presents an asphalt mixture recipe, consisting of asphalt, gravel, mortar, continuous basalt fibers and carbon powder.

• BRPI1009419A2 presents an asphalt mixture recipe that includes aggregates, a polyamide resin and asphalt.

• JP2003147708A shows the replacement of hard aggregates in the asphalt mixture with oxidized hard slag particles 8 in the electric arc furnace.

• JPH1088000A shows an asphalt mixture obtained by the reciprocal mixing of aggregates, filler, asphalt and a plastic material similar to the granular size of the aggregates. • R000116617 presents a concrete composition, consisting of cement and degreased silico-chalco-sodium glass waste, sorts, water.

• RO00117468 refers to a geoeomposite made of glass yarn, a geotextile interwoven of polyester fibers and impregnated with bitumen at the manufacture, for the reinforcement of bituminous road pavement and cement concrete.

Reducing carbon dioxide is known to be a commitment of each country under the 2030 AGENT Sustainable Development. Thus, road builders must meet two basic requirements: extraordinary mobility and protection of the natural environment (COM (2018) 773). Shipyards use a material called grit with the composition of S1O2, Fe2C>3, AI2O3, CaO, MgO, ZnO, MnO, SO4 ^'2 and Cl in the operations of blasting of the ship's hulls (Negoita, 2007). Grit waste resulting from the blasting process presents a major problem in terms of its storage and environmental protection measures because light fractions form flying dust (significant quantities are found carried on the banks of the Danube).

In the Road Testing Laboratory of the Tancrad Company we performed experimental tests and successfully replaced 25% of the amount of natural quartz sand with waste grit with similar granulometry (0.0-2.0 mm) (Buruiana, 2013) ; the resulting asphalt mixture presents both the physical-mechanical characteristics and the wear resistance superior of the asphalt mixture BA 8 (STAS SR 1744-1 / 2009).

Bitumen is considered the most expensive material in the composition of asphalt mixtures due to the fact that its price is closely related to the price of a barrel of oil and the goal of road constructors is to reduce or partially replace the amount of bitumen in asphalt

(Buruiana, 2013).

Microplastics are solid plastic particles smaller than 5 mm in size. Microplastics are a cause for concern worldwide due to the negative effect on the environment and implicitly on human health (De Sa, 2018). Among plastics, polypropylene has a melting point of 160 °C, good dielectric properties and is non-toxic (Longo, 2011).

We propose an improvement of the BA 8 asphalt mixture recipe by adding polypropylene- based microplastic particles to the optimized recipe (Buruiana, 2013), in order to improve the mechanical and wear resistance to water and other exogenous agents (light , freeze- thaw, mechanical wear).

The technical problem solved by the invention is to replace the natural quartz sand with the waste grit and to protect the environment by introducing a quantity of microplastics, which lead to the improvement of the properties of asphalt mixtures reducing the risk of cracks in different weather conditions.

The new elements consist in the introduction in the recipe of the asphalt mixtures of the waste grit together with the microplastics based on polypropylene.

Asphalt mixture recipe: 33.5% crushed siliceous stone chipping with a granulation ranging between 4.0 and 8.0 mm, 25% crushed sand with a granulation ranging between 0.0 and 4.0 mm, 25% waste grit with a granulation ranging between 0...2 mm, 10% sort limestone filler with a granulation ranging between 0.063...0.100 mm, 6.2% 50/70-type road bitumen and 0.3% polypropylene-based microplastics with a granulation similar to waste grit particles. In the Tancrad Testing Laboratory a load of 2000 kg was tested, the following quantities were added: 748 kg of crushed sand with a granulation ranging between 4.0 and 8.0 mm, 468 kg of crushed sand with a granulation ranging between 0.0 and 4.0 mm, 468 kg grit waste with a granulation ranging between 0...2 mm, 186 kg sort limestone filler, 124 kg 50/70-type road bitumen and 6 kg polypropylene-based microplastics.

The recipe proposed according to the Recipe Study no. 1 / BA 8 of 14.10.2020 for the preparation of hot asphalt concrete according to SR 174-1 / 2009 was subjected to the Marshall test and the results are presented in Table no. 1.

Table no. 1 Physical and mechanical characteristics obtained on asphalt concrete type: BA 8 tread (Tancrad Laboratory)

According to the results obtained, recipe II is considered optimal, because it performed best in the experimental study in the Tancrad Laboratory, managing to successfully introduce a percentage of microplastics (MP) of 0.3% in the asphalt mixture type BA 8.

By applying the innovative recipe, the advantages are obtained:

1. Reducing the cost of asphalt mixtures, smaller amounts of bitumen.

2. Reducing the risks of micro / macro cracks in asphalt mixtures at temperature variations and in contact with the material used as a non-slip.

3. Reducing the viscosity of the asphalt binder (bitumen), saving energy we reduce the emission of carbon dioxide (CO2).

4. Increasing the physical properties as well as increasing the rheological properties of the binder due to the microplastics used in the hot mixture.

5. Improving the wear resistance of asphalt mixtures (waste grit mixture - microplastics).

6. Partial replacement of natural quartz sand with waste grit resulting from ship hull sandblasting operations.

7. Considerable improvement of the characteristics of the asphalt mixture due to leachate components with a particle size of less than 0.2 mm from the waste grit.

8. Utilization of the waste grit as an environmentally harmful industrial by-product.

9. Recovery of microplastics in order to reduce the negative effect on the environment and the health of the population.

References

AND 605 - 2016, Normative regarding hot-run asphalt mixtures technical conditions for the design, preparation and installation of asphalt mixtures.

STAS SR EN 13108-1: 2006, Asphalt mixtures. Specifications for materials. Part 1:

Asphalt concrete.

STAS SR 4032-1 : 2001, Road works. Terminology.

STAS SR EN 13043: 2003 / AC: 2004, Aggregates for bituminous mixtures and for finishing surfaces used in the construction of roads, airports and other traffic areas.

STAS 11348-87, Road works. Bituminous pavements for the bridge path. General technical quality conditions.

AND 546-2013, Norm on the hot execution of bituminous coatings for the bridge path. STAS SR EN 12591: 2009, Bitumen and bituminous binders. Specifications for road bitumens.

Huang Ming. CN107963832A- Asphalt mixture, International patent, Application CN201711258642A, Publication date: 2018-04-27, https://worldwide.espacenet.com/patent/search/family/0619993 39/publication/CN1079638

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Fukuyama Yukihiro, Kao Corp, Kawano Masakazu, Murayama Masato. BRPI1009A2- Asphalt mixture, Application US201013203348A, Publication date: 2012-03-08, https://worldwide.espacenet.com/patent/search/family/0427283 37/publication/US2012059 093A1 ?q=Asphalt%20mixture

Fuchigami Eiji, Hoshino Kumao, Tsuruyama Keiichi. JP2003147708A- Asphalt mixture, Application JP2001348443A, Publication date: 2003-05-21, https://worldwide.espacenet.com/patent/search/family/0191612 64/publication/JP20031477

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Fujimoto Kazuyoshi, Ishida Kotaro, Marioki Masakatsu. JPH1088000A- Asphalt mixture, Application JP24978896A, Publication date: 1998-04-07, https://worldwide.espacenet.com/patent/search/family/0171982 39/publication/JPH1088000

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Petcu Gheorghe. R000116617- Concrete composition, Patent application number 97- 01472, Filing date: 1997-08-05.

Feodorov Valentin, Vintila Bogdan, Strunga Vasile, Alexan Alexandru, Bostenaru Dan Maria Magdalena. R000117468, Patent application number 200001187, Filing date: 2000-12-05,

COM (2018) 773 - COMMUNICATION FROM THE COMMISSION TO THE EUROPEAN PARLIAMENT, THE EUROPEAN COUNCIL, THE COUNCIL, THE ECONOMIC AND SOCIAL COMMITTEE, THE COMMITTEE OF THE REGIONS AND THE EUROPEAN INVESTMENT BANK, Brussels, 28.11.2018.

D. Negoita (Buruiana), Contributions to the reduction of pollution caused by the operation of a shipyard, Doctoral thesis, "Dunarea de Jos" University of Galati, 2007.

D. L. Buruiana, M. Bordei, I. G. Sandu, A. I. Chirculescu, I. Sandu, Recycling waste grit in asphalt mix, Revista Materiale Plastice, vol. 50, no. 1, pp. 36-39 (2013).

STAS SR EN 1744-1 : 2009, Tests for determining the chemical properties of aggregates. Part 1: Chemical analysis.

D. L. Buruiana, M. Bordei, A. V. Sandu, A. I. Chirculescu, I. G. Sandu, Studies on Grit Use in Asphalt Mixtures (II), Revista Materiale Plastice, vol. 50, no. 2, pp.113-118 (2013).

L. C. De Sa, M. Oliveira, F. Ribeiro, T. L. Rocha, M. N. Futter; Studies of the effects of microplastics on aquatic organisms: what do we know and where should we focus our efforts in the future? Sci. Total Approx. 645, 1029-1039 (2018).

C. Longo, M. Savaris, M. Zeni, R. N. Brandalise, A. M. C. Grisa, Degradation study of polypropylene (PP) and bioriented polypropylene (BOPP) in the environment. Mater. Res. 14, 442—448 (2011).