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High
performance cement based materials and holistic design
for sustainability in construction (Part II)
R.N.
Swamy
The
cement/concrete industry is faced with two major challenges
- an infrastructure crisis and a sustainability problem.
Both are worldwide issues with tremendous implications
not only for ourselves but also for the lives of generations
to come. The focus of this paper is to show that a
holistic approach to the formulation and fabrication
of concrete materials with emphasis on durability,
ductility, environment and sustainability can lead
to the development of a large number of eco-friendly
and innovative cement-based construction materials
for a wide range of applications in infrastructure
regeneration and reconstruction. Quality of life is
the one single goal that all humanity wants and aspires
for, and a judicious combination of pozzolanic/cementitious
materials, chemical admixtures, fillers, fibres and
other appropriate constituents can meet the insatiable
demand for basic infrastructure facilities and at
the same time contribute to sustainable growth with
the least damage to our environment. The paper illustrates
this philosophy of manufacturing and designing sustainable
concrete materials for durability rather than for
strength with various examples such as fly ash/slag
concrete, high volume fly ash concrete, structural
lightweight aggregate concrete, low energy-cements,
and fibre reinforcement. It is also shown that the
philosophy of holistic design with emphasis on material
stability, structural integrity and ductility can
successfully meet the challenges of the infrastructure
crisis and sustainable development of the concrete
industry.
Optimal
design of precast pipe racks
Arnab
K. Bhattacharya, Devdas Menon and K. Rajeevan
Precast
concrete pipe racks are an economically advantageous
alternative to steel pipe racks in industrial projects
like refineries and petrochemical plants. One major
reason for this is the elimination of fire proofing
needs for the precast element. Optimal design of the
concrete elements would further lower the cost. This
paper deals with the optimal design of precast concrete
pipe racks, considering design variables such as member
sizes, grades of concrete and steel, and reinforcement
area. Genetic algorithms (GA) have been used for optimisation
and a program in VC++ has been developed to arrive
at the optimal solution, which corresponds to overall
cost, satisfying design criteria for strength and
limiting deflection. Proposals for most favourable
jointing mechanisms in terms of cost and constructability
have also been given.
Material
characterisation of engineered cementitious composites
in 1D, 2D and 3D specimens under uniaxial tension
J.D.
Rathod, S.C. Patodi and B.K. Parikh
Uniaxial
direct tension test on any cementitious composite
is a very sensitive and difficult test to perform.
There is a need to develop robust uniaxial tensile
test which without involving expensive experimentation,
complex specimen configuration and difficult test
set-up can provide reasonably reliable and consistent
results. In the present work, for testing engineered
cementitious composite (ECC) which exhibits strain
hardening behaviour through multiple cracking with
good tensile strain capacity, three different types
of specimens i.e. briquette, coupon and dog bone specimens
were designed and tested and their response was compared.
An ECC performance criterion was evaluated with respect
to 1D, 2D and 3D orientation of fibres in addition
to fibre volume optimisation. Study of fractured surface
through scanning electron microscope provided useful
information about the fibre performance mechanism
that governs the behaviour of the ECC matrix.
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