Steel Reinforced Grout (SRG) is a mortar-based composite recently developed for structural retrofitting, which provides high tensile strength with limited increase in mass and in stiffness, and whose effectiveness relies on the good interaction between steel cords and inorganic matrices. Many companies already supply SRG systems for rehabilitation activities and the scientific community has been working intensively on experimental and numerical investigations to demonstrate their effectiveness for structural applications, which also led to the inclusion of SRG in national and international standards for product qualification and design. However, a clear view of the mechanical properties of these systems is still lacking, due to their variability, which, in turn, strongly depends upon cord layout, textile architecture, and characteristics of the matrix. This paper provides an overview of the mechanical properties of SRG composites on the basis of the tests carried out at Roma Tre University and of the other experimental evidences available in the literature. The results of tensile tests on bare textiles and SRG coupons with different inorganic matrices, and of bond tests on masonry and reinforced concrete substrates are collected and the performances of the different SRG systems are compared. The influence of the mortar matrix on crack spacing, ultimate strain and tension stiffening in tensile tests is analysed. The capacity of the steel cords to ensure a proper shear transfer through interlocking within the matrix and the effect of cord density on failure mechanisms in bond tests are also discussed.

Full document

The PDF file did not load properly or your web browser does not support viewing PDF files. Download directly to your device: Download PDF document


[1] Wobbe, E. Silva, P. Barton, B.L. Dharani, L.R. Birman, V. Nanni, A. Alkhrdaji, T. Thomas, J and Tunis, G. Flexural capacity of RC beams externally bonded with SRP and SRG. In: International SAMPE Technical Conference, (2004), pp. 3009-3016.

[2] Grande, E. Imbimbo, M. and Sacco, E. Modeling and numerical analysis of the bond behavior of masonry elements strengthened with SRP/SRG. Composites Part B: Engineering (2013) 55: 128–138.

[3] De Santis, S. Napoli, A. de Felice, G. and Realfonzo, R. Strengthening of structures with Steel Reinforced Polymers: A state-of-the-art review. Composites Part B: Engineering (2016) 104: 87-110.

[4] Razavizadeh, A. Ghiassi, B. and Oliveira, D.V. Bond behavior of SRG-strengthened masonry units: Testing and numerical modeling. Construction and Building Materials (2014) 64: 387–397

[5] De Santis, S. and De Felice, G. Tensile behaviour of mortar-based composites for externally bonded reinforcement systems. Composites Part B: Engineering (2015) 68: 401-413.

[6] De Santis, S. Bond behaviour of Steel Reinforced Grout for the extrados strengthening of masonry vaults. Construction and Building Materials (2017) 150:367-382.

[7] Malena, M. Closed-form solution to the debonding of mortar based composites on curved substrates. Composites Part B: Engineering (2018) Volume 139: 249-258.

[8] Borri, A. Castori, G. and Corradi, M. Shear behavior of masonry panels strengthened by high strength steel cords. Construction and Building Materials (2011) 25: 494–503.

[9] Thermou, G.E. De Felice, G. De Santis, S. Alotaibi, S. Roscini, F. Hajirasouliha, I. Guadagnini, M. Mechanical characterization of multi-ply steel reinforced grout composites for the strengthening of concrete structures. 9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering. (CICE 2018) pp. 298-305.

[10] Thermou, G.E. De Santis, S. de Felice, G. Alotaibi, S. Roscini, F. Hajirasouliha, I. Guadagnini M. Bond behavior of Multi-Ply Steel Reinforced Grout Composites. Construction & Building Materials. (To appear)

[11] Huang, X. Birman, V. Nanni, A. and Tunis, G. Properties and potential for application of steel reinforced polymer and steel reinforced grout composites. Composites Part B: Engineering (2005) 36: 73–82.

[12] Da Porto, F. Stivanin, E. Gabim, E. Valluzzi, M.R. SRG applications for structural strengthening of R beams. ACI Spec Pub (2012); 286: 119-132.

[13] Napoli, A., Realfonzo, R. Reinforced concrete beams strengthened with SRP/SRG systems: Experimental investigation. (2015) Construction and Building Materials, 93, pp. 654-677.

[14] Thermou, G.E. and Hajirasouliha, I. Compressive behavior of concrete columns confined with stee-reinforced grout jackets. Composites Part B: Engineering (2018); 184: 56-65.

[15] De Santis, S. Roscini, F. and de Felice, G. Full-scale tests on masonry vaults strengthened with Steel Reinforced Grout. Composites Part B: Engineering (2018) 141: 20-36, ISSN 1359-8368.

[16] De Santis, S. De Canio, G. de Felice, G. Meriggi, P. Roselli, I. Out‑of‑plane seismic retrofitting of masonry walls with Textile Reinforced Mortar composites. Bulletin of Earthquake Engineering (2019) 17(11):6265-6300.

[17] de Felice, G. De Santis, S. Realfonzo, R.Napoli, A. Ascione, F. Stievanin, E. Cescatti, E. Valluzzi, M.R. Carloni, C. and Camata, G. State of the art of steel reinforced grout applications to strengthen masonry structures. American Concrete Institute, ACI Special Publication (2018) June, Issue SP 326.

[18] Carloni, C., Ascione, F., Camata, G., De Felice, G., De Santis, S., Lamberti, M., Napoli, A., Realfonzo, R., Santandrea, M., Stievanin, E., Cescatti, E., Valluzzi, M.R. An overview of the design approach to strengthen existing reinforced concrete structures with SRG (2018) American Concrete Institute, ACI Special Publication, 2018-June (SP 326).

[19] de Felice, G. Aiello, M.A. Caggegi, C. Ceroni, F. De Santis, S. Garbin, E. Gattesco, N. Hojdys, Ł. Krajewski, P. Kwiecień, A. Leone, M. Lignola, G.P. Mazzotti, C. Oliveira, D.V. Papanicolaou, C. Poggi, C. Triantafillou, T. Valluzzi, M.R. Viskovic, A. Recommendation of RILEM TC 250-CSM: Test method for Textile Reinforced Mortar to substrate bond characterization. Materials and Structures (2018) 51(4):95.

[20] ICC-ES (International Code Council - Evaluation Service). (2013). AC434 Acceptance criteria for masonry and concrete strengthening using fiber-reinforced cementitious matrix (FRCM) composite systems. Whittier, CA, US.

[21] CNR (Italian National Research Council). (2019). CNR-DT 215/2018. Istruzioni per la Progettazione, l’Esecuzione ed il Controllo di Interventi di Consolidamento Statico mediante l’utilizzo di Compositi Fibrorinforzati a Matrice Inorganica. (In Italian).

[22] ACI-RILEM (ACI 549 0L – RILEM TC 250-CSM Liason Committee). (2019). Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix (FRCM) and Steel-Reinforced Grout (SRG) Systems for Repair and Strengthening Masonry Structures (to appear).

[23] EOTA (European Organization for Technical Assessment). EAD340275-00-0104 Externally-bonded composite systems with inorganic matrix for strengthening of concrete and masonry structures. (to appear)

[24] Roscini, F. Malena, M. and de Felice, G. Experimental evidences and numerical modelling of SRG systems under uniaxial load. 10th International Conference on FRP Composites in Civil Engineering (CICE 2020), Istanbul 1-3 July 2020

[25] De Santis, S. Ceroni, F. de Felice, G. Fagone, M. Ghiassi, B. Kwiecień, A. Lignola, G.P. Morganti, M. Santandrea, M. Valluzzi, M.R. Viskovic, A. Round Robin Test on tensile and bond behaviour of Steel Reinforced Grout systems. Composites Part B: Engineering (2017) 127:100-120.

[26] De Santis, S. Hadad, H.A. De Caso y Basalo, F.J. de Felice, G. Nanni, A. Acceptance Criteria for Tensile Characterization of Fabric Reinforced Cementitious Matrix (FRCM) Systems for Concrete and Masonry Repair. Journal of Composites for Construction (2018) 22(6):04018048.

[27] de Felice, T. D’Antino, A. De Santis, S. Meriggi, P. Roscini, F. Lessons learned on the tensile and bond behaviour of Fabric Reinforced Cementitious Matrix (FRCM) composites. Frontiers in Built Environment, section Earthquake Engineering.

[28] Arboleda, D., Carozzi, F.G. Nanni, A. Poggi, C. Testing Procedures for the Uniaxial Tensile Characterization of Fabric-Reinforced Cementitious Matrix Composites. Journal of composites for construction (2016) 20(3), p.04015063. ISSN: 1090-0268 , 1943-5614.

[29] Roscini, F. De Santis, S. and de Felice, G. Experimental investigation on the mechanical behaviour of mortar-based strengthening systems. Proceedings of 10th International Conference on Structural Analysis of Historical Constructions (SAHC2016), 12-16 September 2016, Leuven, Be.

[30] Ascione, F., Lamberti, M. Napoli, A. Realfonzo, R. Experimental bond behavior of Steel Reinforced Grout systems for strengthening concrete elements. Construction and Building Materials (2020) 232 117105.

[31] De Santis, S. and de Felice, G. Steel reinforced grout systems for the strengthening of masonry structures. Composite Structures (2015) 134:533-548.

[32] Bilotta, A. Ceroni, F. Nigro, E. Pecce, M. Experimental tests on FRCM strengthening systems for tuff masonry elements. Construction and Building Materials (2017) 138: 114–133.

[33] Cancelli, A.N. Aiello, M.A. Casadei, P. Experimental investigation on bond properties of SRP/SRG – Masonry systems. Proc. 8th Int. Symp. on FRPRCS-8 University of Patras, Patras, Greece, July 16-18 (2007).

[34] De Santis, S. Stryszewska, T. Bandini, S. de Felice, G. Hojdys, Ł. Krajewski, P. Kwiecień, A. Roscini, F. Zając, B. Durability of Steel Reinforced Polyurethane-to-substrate bond. Composites Part B: Engineering (2018) 153:194-204.

[35] De Santis, S. Meriggi, P. de Felice, G. Durability of Steel Reinforced Grout composites. 17th International Brick and Block Masonry Conference (IB2MaC 2020)

[36] Meriggi, P., de Felice, G., De Santis, S., Morganti, M., Roscini F. Durability of Steel Reinforced Grout systems subjected to freezing-and-thawing conditioning. 1st fib Italy YMG Symposium, 15 October 2019, Parma, Italy.

Back to Top

Document information

Published on 30/11/21
Submitted on 30/11/21

Volume Repair and strengthening strategies and techniques, 2021
DOI: 10.23967/sahc.2021.183
Licence: CC BY-NC-SA license

Document Score


Views 15
Recommendations 0

Share this document

claim authorship

Are you one of the authors of this document?