^{Ready-mix concrete is the mixture of fine and coarse aggregate, along with water and cement and various additives.  Once these ingredients are combined, a chemical reaction occurs between the cement and water and this paste hardens around and between the aggregates to form a rock-like mass. Cement usually constitutes approximately 7 to 15% of the total volume of concrete, while aggregate totals between 60 to 75%.}

     ^{Different additives for ready-mix concrete include air entrainment, water reducing agents, retarder, and accelerator.  Air entrainment adds tiny air bubbles within the concrete to permit flexibility, and movement for the expansion and contraction due to freeze and thaw cycles.  Water reducing agent allows the reduction of water in the concrete mix, and therefore results in a lower water cement ration, with increased strength, lower absorption, increased resistance to weathering, and less volume change during curing.  Retarder slow down the curing or setting time of the concrete, while accelerator speeds up this process.}