Institute of Fundamental Technological Research
Polish Academy of Sciences

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Allesandro Fantilli

Politecnico di Torino (IT)

Recent publications
1.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., Denis P., Bio-fibres as a reinforcement of gypsum composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14174830, Vol.14, No.17, pp.4830-1-14, 2021

Abstract:
Three series of tests performed on fibre-reinforced gypsum composites are described herein. Sheep wool fibres and hemp fibres were used as reinforcement. The aim was to evaluate the capability of these biomaterials to enhance the fracture toughness of the gypsum matrix. The mechanical properties were measured by means of flexural tests on small specimens, whereas scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction were used to analyse the microstructure and composition of the fibres and of the gypsum composites. As a result, wool fibres were shown to improve the mechanical performance of the gypsum matrix, better than hemp fibres. This is due to the high adhesion at the interface of the fibre and gypsum matrix, because the latter tends to roughen the surface of the wool and, consequently to increase the bond strength. This preliminary research carried out shows that this type of biofiber—a waste material—can be considered a promising building material in sustainable and environmentally friendly engineering.

Keywords:
organic waste material, fibre-reinforced gypsum, mechanical properties, microstructure

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN
Denis P. - IPPT PAN
2.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., Special issue: supplementary cementitious materials in concrete, part I, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14092291, Vol.14, No.9, pp.2291-1-6, 2021, EDITORIAL
3.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., Influence of Portland cement alkalinity on wool reinforced mortar, Proceedings of the Institution of Civil Engineers - Construction Materials, ISSN: 1747-650X, DOI: 10.1680/jcoma.20.00003, Vol.174, No.3, pp.172-181, 2021

Abstract:
Natural wool is a good insulating material, both thermal and acoustic. Nevertheless, with the increase in demand for the use of waste materials, other applications, such as the use of wool as a fibre-reinforcement in mortars and concretes, have been found. Unfortunately, wool, like other natural organic materials, dissolve in alkaline environment and, consequently, the performances of the reinforcement cannot be guaranteed for a long time. To solve the above issue, three series of reinforced mortar beams, with various contents of alkalis in cement, are investigated herein. The chemical compatibility, and the effects of alkalinity on the mechanical performances, are investigated by testing the beams in three point bending and, subsequently, by analysing the microstructure of the mortars through a scanning electron microscope equipped with energy dispersive X-ray spectroscopy. The results reveal that the lower the alkalinity of the cement paste, the better the resistance of wool fibres in cementitious matrix, which guarantees larger post-cracking residual stresses in the wool reinforced mortars.

Keywords:
fibre-reinforcement, fracture & fracture mechanics, microstructure, waste valorisation

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN
4.  Jóźwiak-Niedźwiedzka D., Fantilli A.P., Wool-reinforced cement based composites, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13163590, Vol.13, No.16, pp.3590-1-13, 2020

Abstract:
In this paper, an overview of the latest research activities in the field of cement-based composites incorporating sheep wool reinforcement is presented. First, the characteristics of this type of natural fibre are described. Then, the current use of sheep wool fibres in cement-based composites is discussed. The research problems regarding the properties of cement matrix composites reinforced with sheep wool are divided into four groups: thermal and acoustic properties, mechanical behavior, durability issues, and microstructure aspects. The latter two groups are analysed separately, because both durability and microstructure are of particular importance for future applications of wool reinforcement. Finally, the main directions of future researches are presented.

Keywords:
natural fibres, sheep wool fibres, mechanical properties, durability, microstructure

Affiliations:
Jóźwiak-Niedźwiedzka D. - IPPT PAN
Fantilli A.P. - Politecnico di Torino (IT)
5.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., The effect of hydraulic cements on the flexural behavior of wool reinforced mortars, Academic Journal of Civil Engineering, ISSN: 2680-1000, DOI: 10.26168/icbbm2019.41, Vol.37, No.2, pp.287-292, 2020

Abstract:
It is known that natural wool is a good thermal insulating material, but recent results suggest another application: the use of wool as a fiber-reinforcement in mortars and concretes. Indeed, the mechanical properties of wool filaments are comparable to those of some synthetic polymeric fibers (e.g., made with polypropylene). However, wool can dissolve in alkaline environments and, therefore, the performances of reinforced cement-based matrixes cannot be guaranteed for a long time. Accordingly, three series of reinforced mortar beams have been made with low alkali, high alkali, and sulfoaluminate cements. To investigate the chemical compatibility, and the subsequent effects on the mechanical performances, the beams have been tested in three point bending. As a result, the lower the alkalinity of the cement paste, the better the post-cracking capability of wool fibers to arrest the growth of cracks.

Keywords:
wool reinforcement, low alkali cement, high alkali cement, sulfoaluminate cement

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN

List of chapters in recent monographs
1. 
Jóźwiak-Niedźwiedzka D., Fantilli A.P., Energy efficient, sustainable building materials and products, rozdział: Cement based composites with multifunctional addition of unused wool fibres, CRACOW UNIVERSITY OF TECHNOLOGY, Warszawska 24, 31-155 Kraków, pp.267-282, 2017

Conference papers
1.  Jóźwiak-Niedźwiedzka D., Fantilli A.P., Influence of cement type and curing conditions on the flexural strength and microstructure of mortars reinforced with sheep wool fibers, RACTSI, International Conference on Recent Advances in Concrete Technology and Sustainability Issues, 2022-07-13/07-15, Milan (IT), No.SP 355, pp.283-292, 2022

Keywords:
cement, durability, fracture toughness, microstructure analysis, natural fibers

Affiliations:
Jóźwiak-Niedźwiedzka D. - IPPT PAN
Fantilli A.P. - Politecnico di Torino (IT)
2.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., Sheep wool as fiber-reinforcement of gypsum composites, ICBBM'2021, 4th International Conference on Bio-Based Building Materials, 2021-06-16/06-18, Barcelona (ES), pp.108-111, 2021

Abstract:
Depending on the intended use, some cement-based construction materials, such as paste, mortar and concrete, need to be fibre reinforced. In these materials, fibres play the same mechanical role as ossein, the elastic collagen fibres in animal bones that guarantees the resistance to fracture. Although commonly used fibres are made of various materials, such as steel, glass, polymers etc., animal and plant fibres can also be used in building materials. Among them, wool of sheep, a waste material in several countries, can effectively reinforce pastes, mortars and concretes. In addition to the research already performed in the field of cement-based composites, the use of sheep wool as reinforcement of gypsum-based composite is experimentally investigated herein for the first time. As a result, sheep wool reinforcement provides high fracture toughness, due to an excellent adhesion, and could be a valid alternative to the current industrial fibres in reinforced gypsum manufacts.

Keywords:
sheep wool fibres, gypsum-based composite, mechanical properties, microstructure

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN
3.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., The effect of Hydraulic Cements on the Flexural Behavior of Wool Reinforced Mortars, ICBBM2019, 3rd International Conference on Bio-Based Building Materials, 2019-06-26/06-28, Belfast (GB), pp.287-292, 2019

Abstract:
It is known that natural wool is a good thermal insulating material, but recent results suggest another application: the use of wool as a fiber-reinforcement in mortars and concretes. Indeed, the mechanical properties of wool filaments are comparable to those of some synthetic polymeric fibers (e.g., made with polypropylene). However, wool can dissolve in alkaline environments and, therefore, the performances of reinforced cement-based matrixes cannot be guaranteed for a long time. Accordingly, three series of reinforced mortar beams have been made with low alkali, high alkali, and sulfoaluminate cements. To investigate the chemical compatibility, and the subsequent effects on the mechanical performances, the beams have been tested in three point bending. As a result, the lower the alkalinity of the cement paste, the better the post-cracking capability of wool fibers to arrest the growth of cracks.

Keywords:
Wool reinforcement, low alkali cement, high alkali cement, sulfoaluminate cement

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN
4.  Fantilli A.P., Jóźwiak-Niedźwiedzka D., Gibas K., Dulnik J., The compatibility between wool fibers and cementitious mortars, ICBBM & EcoGRAFI, Second International RILEM Conference on Bio-based Building Materials 1st Conference on ECOlogical valorisation of GRAnular and FIbrous materials, 2017-06-21/06-23, Clermont-Ferrand (FR), DOI: 10.26168/icbbm2017.4, pp.42-47, 2017

Abstract:
The addition of natural fibers residue in cement based materials can be a sustainable technological alternative for traditional dispersed reinforcement, and can improve the performance of brittle matrix materials. The presence of a wool reinforcement can increase the fracture toughness and, at the same time, can reduce the environmental impact of cementitious mortars. The beneficial effects are similarly to those observed in presence of vegetal fibers (e.g., hemp), which have been largely investigated in the literature. However, there are some limits in the use of wool fibers due to their chemical compatibility with the cement matrix, as they can dissolve in alkaline environments. In the present paper, to investigate the compatibility between wool fibers and cementitious mortars, laboratory prototypes have been taken into consideration. Three series of wool-reinforced mortar beams have been cast and cured in water (20°C) or in dry conditions (temp. 20 °C, 50% R.H.) for some days. Portland-limestone cement CEM II has been used, whereas the content of fibers has been limited to about 1% in volume to maintain the workability of the mortars. To investigate the chemical compatibility, and the subsequent effects on the mechanical performances, prototypes have been tested in three point bending. After the mechanical test, the mortars microstructure was evaluated through SEM images and by thin section in transmitted light, in order to individuate a possible relationship between the dissolution of wool and curing conditions. The microstructure observation revealed the capability of wool fibers to bridge the cracks, and to reduce the brittleness of plain mortars. The differences in the mortars microstructure due to alternative curing conditions were also observed and described in the paper. Accordingly, wool could be effectively used to reduce the plastic shrinkage of cementbased composites, like the industrially manufactured polypropylene fibers.

Keywords:
Wool fibers, Plain cement-based mortar, Fiber-reinforced mortar, Polypropylene fibers, Three point bending tests, SEM analyses

Affiliations:
Fantilli A.P. - Politecnico di Torino (IT)
Jóźwiak-Niedźwiedzka D. - IPPT PAN
Gibas K. - IPPT PAN
Dulnik J. - IPPT PAN

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