Comparing the effects of jouravskite and ettringite on the hydration of the clinker

Manganese enters the clinker from alternative fuel and alternative raw materials. It is present in the iron ores utilized in the cement burning and is found in the slags employed as supplementary cement materials. The jouravskite, as a member of the ettringite family, may form in limestone cement when exposed to sulfate media. To understand its effect on the hydration process, the expansion of small cylindrical clinker pastes doped with synthesized jouravskite and ettringite in magnesium sulfate solutions was measured with a micrometer; and the compressive strength of representative cubes was monitored. The phases formed were characterized by means of X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The jouravskite is found to be a strong retarder for clinker hydration probably due to its adsorption on the cement hydrates.