The effect of caffeine molecule on the physico-chemical properties of blended cement

Abstract

Caffeine is a nontoxic and eco-friendly natural molecule used in the food industry as well as a corrosion inhibitor in various corrosive media. However, its behavior and performance as an additive in the construction industry has not been explored. This paper investigates the effect of caffeine as an additive on strength, water demands, setting time and hydration mechanism of cement. In the first instance, the water demand, volume expansion and setting time of cement pastes, incorporating 0, 25, 50 and 75 ppm of caffeine were determined. In the second section, the rate of hydration and cement pastes’ products were conducted by means of X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR), thermal analysis and scanning electron microscope (SEM) at 28 days. Finally, the cement mortars’ compressive strengths were determined at 2, 7 and 28 days intervals. Consequently, mortars containing 75 ppm caffeine registered higher strength than the pure cement mortars due to high quantities of primary C-S-H gel, chemically bound water, compact structure at 28 days. Furthermore, by result of analysis and experiments, it was determined that caffeine had no negative effect on cement.