ANALYSIS ON THE INTEGRITY, SURFACE HARDNESS AND POROSITY OF AUTOCLAVED LIGHTWEIGHT CONCRETE

Autoclaved lightweight concrete is manufactured from sand, lime and cementto which is
added a gas-forming agent. Sand is grounded to a required fineness in a ball mill and
stored while cement and lime are stored in silos. Water and aluminium powder (gasforming
agent) are then added to the mixture. After mixing, the cement slurry is poured
Into amouid for few hours before being transported to cutting machine. The final curing
>f the product takesup to 12hoursunderhighsteampressurein an autoclave.
n this, project^ the surface hardness, integrity and also total porosity of autoclaved
ightweight concrete are being analyzed using rebound hammer, Ultrasonic Pulse
Velocity (UPV) test and porosity test respectively. There are ranges of autoclaved
ightweight concrete blocb varying in thickness of 25mm increment from 50mm to
£50mm. However,, only blocks coded 62100 are chosen for this project which represents
ettgth of^SGOmm, thickness of 2G0mm and heightof 100mm. The results are compared
vith conventional 150mmconcrete samples of 1:2:4 mix that are water and air cured. All
•ampies are evaluated at 7,28 and 56 days.
\utoelaved lightweight concrete is much inferior compared to water-cured and air-cured
conventional concrete in all the three tests performed. For UPV, the average pulse
velocity recorded for autoclaved lightweight concrete is approximately half of the value
)btained for normal weight concrete. In terms of surface hardness, the values are much
>etter withup to 70%of that exhibited by conventional concrete. Therefore, although the
otal porosities are twice more higher than normal weight concrete, these figures are
jroved to be less significant to the surface hardness of lightweight concrete but yet
iffecting much of its integrity.