Bagasse ash can be optimized as a partial cement replacing material in a concrete mixture.rnOther than guaranteeing mechanical properties, this pozzolana could be used as a thermalrnretarder for mass concrete placement, despite the fact that its property was not examinedrnunder various ambient temperatures. This research aims at studying the early age thermalrnand mechanical properties of bagasse ash concrete under different ambient temperatures.rnA semi-adiabatic temperature rise data of four different concrete mixtures (containing purernPortland cement, 6.5%, 13% and 20% dosage of bagasse ash by volume) are determined.rnInsulated concrete specimens of size 30*30*40cmrn were cast and the internal heat ofrnhydration was measured at three different locations for every 30 minutes of interval. Forrnsimulating different ambient temperatures, a chamber has been constructed in the AAiTrnmaterial laboratory. The temperature chamber is capable of simulating average ambientrntemperatures of 25.15rn3rn0rn0rn, 35.54rn0 rn and 43.77rnC. rnAs the experimental outcomes indicate, there is reduction in early age compressive,rnsplitting tensile, and flexural strength of concrete containing different dosages of bagassernash. On the other hand, enhancement of strength is observed in bagasse ash concreternspecimens at late age testing (with exception of 20% replacement level). The laboratoryrntesting program revealed that, the presence of bagasse ash in the concrete mixture shiftsrntemperature rise-time curve, reduces the total heat of hydration and decreases the thermalrngradient in the specimens. Moreover, the total heat of hydration of all mixtures wasrnsignificantly influenced as the ambient temperature increased, but mixtures containingrnbagasse ash show slower heat liberation rate relative to the control group. rnHeat of hydration and thermal cracking risk were also simulated using Hacon-3 finiternelement software. The FES results show a good agreement with the real measurement inrntemperature gauges. The presence of bagasse ash in concrete up to 13% decreases therncracking risk. However, incorporating bagasse ash at a higher dosage could retard thernstrength development and consequently escalates the risk of cracking. This investigationrnproves, the main driving force that controls early age cracking risk depends on bothrnstrength development and heat liberation of concrete.