dimensions
152 · 152 · 914 mm (6 in. · 6 in. · 36 in.). The
bottom 25.4 mm of these beams was a ferrocement
laminate, with steel wire mesh as reinforcement. The top
127 mm of concrete with a No. 10 (No. 3 in US Customary
System of units) rebar was cast on top the ferrocement
laminate. The rebar was located at 12.7 mm
above the ferrocement laminates.
A total of 24 simply supported composite beams were
tested under a two-point loading system. All beams are
designed to be minimally-reinforced. Details of the
beam specimens are summarized in Table 1. The beam
specimens are classified into two groups. Group (A1)
consists of a total of four beams: three composite beams
having 4, 6, and 8 layers of square mesh in the one inch
thick ferrocement layer, respectively, and one reinforced
concrete beam. Group (A2) consists of a total of four
beams: three are composite having 4, 6, and 8 layers of
hexagonal mesh in the one inch thick ferrocement layer,
respectively, and one reinforced concrete beam. Both
groups (B1) and (B2) are reinforced with one (No. 10)
rebar as the main reinforcement in the concrete layer.
On the other hand, Groups (B10 and (B2) beams have
different types of shear studs introduced to study the
composite behavior of both layers and the minimum
number of studs required to ensure flexural rather bond
type of failure.
The mix design used for mortar was according to the
guidelines of ACI Committee 549 [3] for design and
construction of ferrocement. The mortar was placed in a
plywood mold to a depth of one half inch. The molds
are placed on a vibrating table to ensure proper compaction
and to eliminate any air voids in the mortar. The
steel mesh was placed on the mortar with proper spacers
to maintain a minimum cover. The top 12.7 mm (halfinch)
of the mortar was then placed over the mesh and
the mold is vibrated again. Shear studs are provided to
prevent horizontal shear failure. The shear studs were
made of No. 10 (No. 3) reinforcement and were tied to
the mesh prior to casting. For Group A beams, five
shear studs were placed at equal distances over the beam
span and along the centerline of the ferrocement laminate.
The studs were made in the shape of hooks and are
63.5 mm (2.5 in.) long. The final finish of the mortar was
kept rough in order to provide bonding with the concrete
layer. The ferrocement laminate was cured for 24
h. Cylinders 101.6 · 203 mm (4 in. · 8 in.) were taken to
test the compressive strength of the mortar. The volume
fraction of the reinforcement for both sets were within
the provisions given in the ACI Committee 549 guidelines
(Section 4.5), which requires the total volume
fraction for non-pre-stressed water retaining structures
to be a minimum of 3.5%.
Each No. 3 rebar was installed with one pre-wired
strain gage having a gage resistance of 350 ohms. After
installation, a protective Teflon tape was used to cover
the gage. Finally, a layer of M-Coat J was applied over