Please answer in context of cementitious composites. Is both are same? as from their analysis/graph I seen similar peaks at approximately similar temperature.
they are not the same. dtg measures the rate of mass change and dsc the rate of enthalpy change. if you heat your hardened cement sample until it starts losing water, you will see very similar peaks in dtg and dsc. but if you look at the cement hydration, dsc would show an exothermic peak and dtg would show nothing because there is no mass change.
They are completely different. DTG is the derivative signal of TG curve that measures the sample mass variation as a funtion of temperature. This way to plot the data (the derivative signal instead of the original mass) is useful to better localize the mass loss for overlapped events. DSC is a calorimetric measurement that measures the heat flows involved in exothermic or endothermic events (melting, crystallization and so on) occurring as a function of temperature in a sample.
DSC measures heat flow differences to detect phase transitions and chemical reactions, while DTG measures mass differences to detect changes in composition
TGA is a technique usually used in thermal analysis. It is used to characterize materials by recording their change in mass at different temperatures. This measuring technique can give information about material properties and behavior like; composition, purity, decomposition reactions, decomposition temperatures, and absorbed moisture content. while, the DSC signal provides additional information that cannot revealed by TGA alone, as the solid-solid phase transitions. Therefore, TGA is often used together with the DSC because the two techniques together provide supporting information to give a full explanation for a thermal analysis experiment.
If your sample show peak at same temperature in both DTG and DSC that's mean that sample is thermally degrade or decomposed at that temperature and that peak can not be consider as a melting peak.