In favourable circumstances a 15 cm concrete cube after 28 days, attains a maximum crushing strength______________? January 14, 2019 – by admin In favourable circumstances a 15 cm concrete cube after 28 days, attains a maximum crushing strength______________? A. 100 kg/cm2 B. 200 kg/cm2 C. 300 kg/cm2D. 400 kg/cm2