29Si and 27Al NMR and FTIR have been used to study the products of OPC hydration in the presence of a heavy metal containing stabilized waste which is commercially solidified, selected organics and pulverized fuel ash. 29Si NMR unambiguously quantifies the extent of silicate polymerization, which is severely retarded in mixes containing the stabilized waste. 27Al NMR spectroscopy indicates the presence of both ettringite and monosulfate in a cement containing 2% of the stabilized waste, while only ettringite is detected in the spectra of samples with 19 and 30% additions. Phenol and ethylamine also reduce silicate condensation, although a sample containing both the metal waste and mixed organics showed silicate condensation levels similar to those found in a normal OPC paste. It is difficult to draw firm conclusions from the FTIR results due to band overlap in the region of interest.