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In general, anything you do, if it is normally irreversible, will mean that the end product is energetically more stable than what you started out with, and that energetic stability will cause heat to be given off in the process. How much heat can depend on many things, but even just dissolving salt into water will give off some slight heat.
The Portland cement that is used in making concrete is very alkaline and contains a number of hydroxides including calcium and sodium hydroxide. When this is mixed with water the reaction gives off heat as it sets. The setting times can also vary (quick setting) depending on extra included chemicals such as ammonium sulphate? The quick setting stuff also gives off more heat as it sets.PS. Its important to wear gloves etc when mixing and using cement as prolonged exposure to skin can also cause caustic burns.
What else produces heat as it gets hard ?
You may be right lightarrow, when it comes to chemistry I'm dumbish.I know sodium hydroxide can create heat when mixed with other substances, was not sure about the calcium.The quick setting stuff gives off a strong smell of ammonia but I'm not sure what the ammonia does exactly except evaporate quicker and smell bad. The floor levelling stuff can be hard in less than 15 minutes!