INVESTIGATION ON PROPERTIES OF CONCRETE WITH ADDITION OF NANO SILICA AND PARTIAL REPLACEMENT OF CEMENT WITH FLYASH
Chevuri Rajasekhar, Dr. Panchagam Sri Chandana, Valikala Lakshmi Prasanna
Fresh Concrete, Workability, Pull-Out Strength
Workability is one of the physical parameters of concrete which affects strength and durability as well as cost of labour and appearance of the finished product. It is a vital property of concrete that must be measured correctly to ensure good quality concrete. This research study is directed towards exploring the pullout test as an alternative test for workability of fresh concrete. The study measured the slump, compacting factor and pullout strength for fresh concrete with water/cement ratios of 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 representing very low, medium and high workability. Result showed that a pull-out strength of 72 – 94N/mm2 is required for concrete of very low degree of workability while pull-out strength of 62 – 65N/mm2 is required for concrete of high degree of workability in accordance with the requirement of Road Note No. 4. The result was validated by comparing measured and calculated compacting factor. The average ratio of calculated and measured compactive factor was found to be 1.01. The calibration of calculated and measured compacting factor resulted in coefficient of determination R2 of 0.998. These results indicate that pull-out strength is a good predictor of compacting factor and by extension workability of fresh concrete. The simple pull-out test was recommended as an alternative test to compacting factor, slump and V-B consistometer tests in measuring workability of fresh concrete.