Civil Engineering Association

A high performance fibre reinforced cement based plaster for retrofitting RC members

A high performance fibre-reinforced
cementitious composite (HPFRCC) material is developed
to be used for retrofitting reinforced concrete
members. It can be applied to the face of a concrete
member to the desired thickness as a wet mix or as an
adhesively-bonded prefabricated slab or strip. The
material is compatible with concrete and possesses
favourable strength and ductility properties, desirable
for seismic retrofit. It overcomes some of the problems
associated with the current techniques based on
externally bonded steel plates and fibre-reinforced
polymer (FRP) laminates caused mainly by the
mismatch of their tensile strength and stiffness with
that of the concrete member being retrofitted. An
extensive rheological analysis is undertaken to
develop the appropriate mixes using different types
and mix proportions of constituent materials including;
fine steel fibres, fine quartz sand, silica fume,
cement and superplasticizer. Much reduced amounts
of steel fibres are used compared to the previous
studies so that ordinary mixing procedures could be
applied and a more cost-effective retrofitting material
could be developed. Samples made of the optimum
mixes are shown to posses very high compressive and
tensile strengths and sufficient ductility for the composite
plaster to be used externally for strengthening
and seismic retrofitting of concrete members.