High Performance Concrete
Introduction:
Long-term performance of structures has become vital to the economies of all nations.
definition of HPC(high performance concrete) :
Concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing and curing practices
The Normal strength type has compressive strength compressive strengths not
exceeding 42 Mpa. Whereas the High Strength Concretes have a compressive strength of 140 Mpa.
Salient Features of HPC:
-Compressive strength greater than 80 Mpa ,even upto 800 Mpa
-Reduced flocculation of cement grains
-Water-binder ratio =0.25-0.35 and hence very little free water is present
-Wide range of grain sizes and Reduced flocculation of cement grains
-Densified cement paste
-No bleeding homogeneous mix
COMPOSITION OF HPC:
both pozzolanic and chemical
admixtures are generally present in HPC along with the other components in normal cement. the w/c ratio Ëœlawâ„¢ proposed by abrams is applied for this cement.
CURING of HPC:
HPC has very low water/binder ratio .due to this, the early stage hydration rate of HPC is higher. Filling of the voids by hydration
product in HPC is much faster than that of CCC. moisture loss due to capillary action stops earlier. These facts show that the requirement of curing duration for HPC is less compared to CCC.
for more details, refer this pdf:
http://iricen.govprojects/624/High%20Per...ncrete.pdf