Journal of Environmental Analytical Chemistry

The molecular sieve used in the gas industry to remove the water in this gas is discarded after four years of use as these molecular sieves are no longer effective. Molecular sieves used in dryers in the gas industry to remove water from the gas to avoid clogging of pipes during storage that is at low temperature are discarded after four years of use. These used molecular sieves are no longer effective because, after various heating and cooling of the dryers, these molecular sieves are charred and crushed. After analysis of these used molecular sieves, it is found that they contain a considerable amount of silica iron (SiO₂). The idea was to add these molecular sieves after finely grinding them to a diameter less than one micron of the added ones to the cement. Fine silica combines with the lime released during the hydration of the cement and forms hydrated calcium silicates that develop within the capillary network by reducing the number and size of pores of the concrete.