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Numerical and experimental characterization of the instantaneous and long-term behaviour of innovative and sustanaible concretes

Keywords: Fibres, FRC, MSFRC, SFRC, SCC, cracking, long-term behaviour
Fig. 1. Long-term tests on cracked FRC beams (Buratti).
Fig. 2. Uniaxial tension test on notched FRC specimens (Buratti).
Fig. 3. Development with time of creep for different SCCs (Mazzotti).

Fibre reinforced concretes are standard or high strength concretes to which steel, synthetic or natural fibres are added. The properties of this composite materials depend on the characteristics of the different components and on their dosages; in particular, for a given percentage volume of fibres the most important parameters are the mechanical and geometrical properties of the fibres, and the fibre-concrete bond. As part of this research, experimental tests have been carried out in order to evaluate the flexural tensile strength of FRC prisms, the long-term behaviour of plain and self-compacting concrete reinforced with either steel or synthetic fibres, the effects of temperature and the durability in aggressive environments of FRC beams. The results of the experimental tests allowed to compare the behaviour, for ultimate and serviceability loads, of elements reinforced with different types of fibres. Using the experimental data gathered, different hinge-based and sectional models were developed to describe the short-term mechanical behaviour of the FRCs as well as constitutive inverse analysis procedures to define the constitutive relationships for the FRCs. The long-term behaviour of selfcompacting concrete was also studied as the higher amount of fines suggests the possibility of developing a greater deformation. Several experimental campaigns aiming at the study of both viscosity and shrinkage of SCC have been conducted. The development over time of both longitudinal and transverse deformation as well as other mechanical properties were measured and different stress levels were also considered. Based on the results obtained, a prediction model based on the Model Code 1990 was developed, modified by including the dependence on certain mix parameters and the development of resistance over time. SCC mixes were also used to cast beams in order to observe the development of deflection, the cracking behaviour with time and the residual strength at the end of the long-term loading. Current studies are mainly focused on the mechanical behaviour of SCC made with various types of fibres and recycling aggregates.

Main publications

Ciancio D., Manca M., Buratti N., Mazzotti C. (2016). Structural and material properties of Mini notched Round Determinate Panels. Construction and Building Materials, Vol. 113, pp. 395-403. Jin, C.,

Buratti, N., Stacchini, M., Savoia, M., Cusatis, G. (2016). Lattice discrete particle modeling of fiber reinforced concrete: Experiments and simulations. European Journal of Mechanics, A/Solids. Vol. 57, pp. 85-107.

Buratti N., Mazzotti C. (2015). Experimental tests on the effect of temperature on the long-term behaviour of macrosynthetic Fibre Reinforced Concretes. Construction and Building Materials. Vol. 95, pp. 133-142.

Ciancio D., Mazzotti C., Buratti N. (2014). Evaluation of fibre-reinforced concrete fracture energy through tests on notched round determinate panels with different diameters. Construction and Building Materials. Vol. 52, pp. 86-95.

Manzi S., Bignozzi M. C., Mazzotti C. (2013) Short and long-term behavior of structural concrete with recycled concrete aggregate. Cement & Concrete Composites 37, 312-318.

Buratti N., Ferracuti B., Savoia M. (2013) Concrete crack reduction in tunnel linings by steel fibre-reinforced concretes. Construction and Building Materials 44, 249-259.

Mazzotti C., Savoia M. (2012) An Experimental Campaign on the Long-Term Properties of Self Compacting Concrete. Advances in Structural Engineering 15, No.7, 1155-1166.

Buratti N., Mazzotti C. (2012) Effects of different types and dosages of fibres on the long–term behaviour of fibre–reinforced self–compacting concrete. 8th RILEM International Symposium of Fibre Reinforced Concrete, 19-21 Semtember, Guimaraes, Portugal.

Buratti N., Mazzotti C. (2012) Temperature effect on the long term behaviour of macro–synthetic– and steel–fibre reinforced concrete. 8th RILEM International Symposium of Fibre Reinforced Concrete, 19-21 September, Guimaraes, Portugal.

Mazzotti C. (2011) Long term behavior of selfcompacting concrete: comparison between experimental results and predicting models. 2nd Workshop on The new boundaries of structural concrete. 15-16/09/2011, Ancona, Italy.

Buratti N., Mazzotti C., Savoia M. (2011). Postcracking behaviour of steel and macro-synthetic fibre-reinforced concretes. Construction and Building Materials 25, 2713-2722.

Buratti N., Mazzotti C., Savoia M. (2011). Long– term behavior of cracked SFRC elements exposed to chloride solutions. Advances in FRC Durability and Field Applications, 72-85.

Bottoni M., Mazzotti C., Savoia M. (2009) Longterm experimental tests on precast beams completed with cast in situ concrete. European Journal of Environmental and Civil Engineering, 13(6), 727-744.

Mazzotti C., Savoia M. (2009) “Long-term deflection of reinforced Self Compacting Concrete beams”, ACI Structural J., 106(6), 772-781.

Mazzotti C., Ceccoli C. (2008) Comparison between long term properties of self compacting concretes with different strength. SCC 2008, October 2008, Chicago, USA.

Mazzotti C., Savoia M. (2003) Non linear creep damage model for concrete under uniaxial compression, J. Eng. Mech. ASCE, 129(9), 1065- 1075.

Mazzotti C., Savoia M. (2002) Non-linear creep, Poisson’s ratio and creep-damage interaction of concrete in compression, ACI Material Journal, 99(5), 450-457, 2002..

Research projects

2016-18: “Mater-SOS - MATERiali SOStenibili per il ripristino e la realizzazione di nuovi edifice”, 2016-2018, founded by Regione Emilia Romagna, in the framework of the project PORFESR 2014-2020.

2010-2013 e 2014-16: Research project funded by the Department of Civil Protection - Reluis tasks 1 and 3: “Reinforced Concrete Structures”; “Development and analysis of new materials for seismic retrofit (including new concretes)”. National Coordinators: Proff. G. Manfredi, L. Ascione