Chemistry and microstructure of cement pastes admixed with organic liquids

The influence of organic admixtures on hydration of cement pastes have been investigated to assess the possibility of immobilizing toxic organic wastes in cement-based materials. The model organic waste used is a mixture of water, methanol and 2-chloroaniline: 100/76/4 volume ratios, respectively. Four pastes were obtained admixing this solution with two different cements (ordinary and white Portland), with weight ratios equal to 0.40 and 0.65, respectively; in addition, cement pastes without organic wastes were prepared (water to cement ratio 0.40). The progress of hydration process of these six series of samples was monitored for the first 8 months of ageing by thermogravimetric analysis; moreover, a detailed microstructural investigation on mature pastes was performed by quantitative X-ray diffraction and scanning electron microscopy. Dynamic leach tests were carried out on samples cured for 28 days, according to the international standards.