Void at the bottom su rface of concret e c y linder indicates the condition of porous con crete. The bottom surfa ce of concret e cylind er was dyed wi th c olor stam p pad . The dyed bottom surfa ce was then dried, photograp hed and compared. The stre ngth of concret e was also determined. This series us ed concret es with designe d void rati os of 15%, 20% a n d 25%, flow values of 150, 190 and 230 mm; 1.0% SP; and vibrat ing energy of 90 kN m/m