Many heavy and toxic metals are found in variable concentrations contained in the High Calcium Ash (HCA) produced

by direct combustion of the bituminous limestone. Huge quantities of ash will be produced when bituminous limestone

is utilized as energy source for electricity production or retorting process to produce crude oil in Jordan. One of the main

serious environmental impact of this ash is the leachability of heavy metals and its potential contamination of the surface and

groundwater reservoirs in the catchment area of Wadi Al-Mujieb.

Encapsulation of Lead, Zinc, and Manganese ions were investigated by mixing of HCA with sand, cement and clay (kaolin)

mortars. HCA was added with different percentages (e.g. 0%, 3.5% and 10%) to variable ratios of sand-cement-clay mixtures.

Beside=heavy=metal=encapsulation=analysis;=the=unconfined=compressive=strength,=water=consumption=and=permeability=were

carried out for the produced mortars. The results shows that an effective heavy metal encapsulation were achieved with 10%

HCA added to 25% clay, 50% sand and 25% cement mixture. Pb and Mn was encapsulated, very low Zn was detected and

leached=from=the=mortarsK=ln=the=other=hand,=the=maximum=unconfined=compressive=strength=(NSKUP=MmaF=was=reached=when

10% HCA was added to the mixture of 25% clay, 25% sand and 50% cement. The permeability was decreasing with increasing

HCA, because of the pozzolanic composition of HCA similar to Ordinary Portland Cement (OPC).