American Society of Civil Engineers

Flexural Strengthening of RC Beams with Cement-Based Composites

by Angelo D’Ambrisi, (Associate Professor, Dipartimento di Costruzioni e Restauro, Università di Firenze, Piazza Brunelleschi 6, 50121, Firenze, Italy.) and Francesco Focacci, (corresponding author), (Assistant Professor, e-Campus Univ., Via Isimbardi 10, 22060, Novedrate (CO), Italy. E-mail:

Journal of Composites for Construction, Vol. 15, No. 5, September/October 2011, pp. 707-720, (doi:

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Document type: Journal Paper
Abstract: In this paper, the effectiveness of fiber-reinforced cementitious matrix (FRCM) materials for the strengthening of reinforced concrete (RC) beams is experimentally investigated. Bending tests on RC beams strengthened with different FRCM materials, made out of (1) carbon fiber nets; and (2) poliparafenilenbenzobisoxazole (PBO) fiber nets embedded in cement-based matrix, are performed. For case (2), different net shapes, cementitious matrices, and a number of net layers were considered. Depending on the type of fibers and matrix, different flexural debonding failure modes are identified. The fiber strain at debonding is evaluated by comparing the experimental results with those obtained with two different theoretical models. The results obtained in this study confirm the effectiveness of FRCM materials for the strengthening of RC structures and encourage further experimental and theoretical work on the topic. A better understanding of the debonding phenomenon is crucial for an optimal design of the strengthening material. The way in which the nature of fibers and matrices and the number of layers control the performance of the strengthened members is also investigated in the present paper.

ASCE Subject Headings:
Fiber reinforced materials
Concrete beams
Flexural strength
Material tests
Composite materials

Author Keywords:
RC strengthening
Cement-based matrix
Mechanical testing