Abstract: A cementitious composition is created by adding sodium carbonate (also known as soda ash, natron, sodium carbonate decahydrate, sodium carbonate anhydrous, trona, etc.) and one or more rocks or minerals selected from the calcium carbonate group. A new product is claimed by combining sodium carbonate and one or more rocks or minerals selected from the calcium carbonate group. The combination of sodium carbonate and one or more rocks or minerals from the calcium carbonate group can be either layered or mixed in a dry or wet state. An exothermic reaction starts after the addition of water to the cementitious composition. The composition of the cementitious material can vary between 10% sodium carbonate and 90% of one or more rocks or minerals from the calcium carbonate group to 90% sodium carbonate and 10% of one or more rocks or minerals selected from the calcium carbonate group. Organic or inorganic additives may be added to the mixture to enhance the composition and/or the final cementitious composition.