Building Materials, Third Edition

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are used. These two stages–the linearly elastic and quasi elastic constitute the practical elastic
working ranges of ferrocement.

g—™2‚— Further increase of stress causes very definite plastic deformation of the
colloids as well as the crystalline grids, which in turn is resisted by the reinforcement. This is
the time of the formation and widening of the exploitation cracks. The stress-stain curves
deviates from linearity and an increasing number of cracks rather than increasing width of
cracks are observed with increasing stress. The cracks are very fine in this stage and are a
function of the specific surface of the reinforcement.

‰ 2‚— As the load is increased the process of crack widening continues at a uniform rate.
The maximum number of cracks that are going to develop have already developed before this
stage. Increasing mortar stains are caused due to the increasing width of cracks. Composite
action between the mortar and reinforcement continues up to the attainment of crack width of
about 100 microns and thereafter, the reinforcement carries all the tensile forces.

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