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Dear Imran sb, Thank You, very much, we are on it. Slab is octagonal and pouring is done 4 portions first and then a gap and 4 are poured, temp is monitored by embedded sensor and readings are okay, a canopy is set above the slab and heaters are placed to maintain the temperature difference normal, scanning results are received, 50 readings, top/bottom 25/25, 50 percent are crossing into the core area or below the top bar, mostly are top side cracks, crack depths are max 20cm, cover to top rebar is 8cm. one thing i observed that mix design recommends 3 days strength 60/90 but in actual testing it is 87/90 in 3 days, rate of hydration is more then recommended or observed during trial mixes, please some data/example to calculate crack widths. Thank You

Dear Waqar please check the pouring methodology and measures adopted to control temperature for mass concreting, if any. Then you can calculate the temperature rise during hardening of concrete and compare the difference of atmospheric temperature and concrete temperature. As very high cement content is anticipated so stringent temperature control requirements should have been adopted. By this you would be able to figure out whether these are temperature shrinkage cracks or otherwise. Moreover please calculate the crack width. As cover is high therefore there is a possibility that you may end up in calculating the crack width equivalent to whatever is visible there in the slab. Pattern of cracks you highlighted indicates the temperature shrinkage nature of cracks however calculations are needed to confirm the anticipation.