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A
comparative assessment of selected Indian and South
African cement clinkers
Ramesh
B. Chockalingam, M. Santhanam, Y. Ballim and P.C.
Graham
Knowledge
of the thermal response of cement is important in
the design and construction of high early strength
concrete mixtures as well as mass concrete structures.
This is because such structures present a high potential
for cracking as a result of stresses induced by temperature
gradients within the concrete. Heat is generated from
the cement hydration reactions and both the quantity
of heat as well as the rate at which this heat is
evolved depends on the mineralogical and morphological
characteristics of the cement clinker. This paper
presents an assessment of the heat evolution of cement
clinkers obtained from three cement production plants
in South India. Cements were prepared in the laboratory
by grinding the clinkers with gypsum from a single
source and testing in an adiabatic calorimeter to
determine the heat evolution characteristics of each
of the clinker samples. X-ray fluorescence (XRF) analysis
and optical microscopy were used to determine the
chemical composition and to characterise the crystal
size, morphology, and distribution of clinker phases.
To provide an external basis for comparison, the results
obtained from the Indian clinkers are compared with
those of cement clinkers drawn from two production
plants in South Africa.
Cryoporometry
based evidence of pore refinement in cementitious
composites
M. Sappakittipakorn,
N. Banthia and Z. Jiang
Permeability
plays an important role in governing the durability
of concrete in deleterious environments. Previous
permeability tests using water as the permeating medium
have indicated that the addition of cellulose fibre
is effective in reducing water permeability both in
the presence and absence of stress and thereby making
concrete more durable. In this paper, further evidence
was sought of pore-refinement in concrete reinforced
with cellulose fibre using Cryoporometry (CP) and
Mercury Intrusion Porosimetry (MIP) methods. Cryoporometry
was carried out using a Differential Scanning Calorimeter
(DSC). Two volume fractions-0.1% and 0.3%-of a treated
cellulose fibre were investigated. The results indicated
a definite pore refinement due to cellulose fibre
addition and a related improvement in durability.
Behaviour
of non-integral in-filled frames with openings - A
case study
A.K. Gupta
and Mohan Kumar P. Hampali
The
behaviour of in-filled frames is influenced by the
presence of openings such as doors, windows and ventilators
in the claddings or walls. The openings reduce the
stiffness affecting strength and failure pattern.
Their size and location have a bearing on the interaction
between frame and infill panel altering the behaviour.
Parameters such as structural displacement, compressive
and tensile stress trajectories in the panel and support
reactions and forces in frame members were investigated
for a single storey infilled frame. The frame was
analysed for a centrally located window and a door
located at the centre and at two end positions near
the columns. The analysis followed finite element
method and used incremental load. It accounted for
the non-linearity at the interface and the elastic
properties of the frame and the infill. It shows that
the stiffness of the infilled frame decreased by 20-80%
due to openings.
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