Abstract: In the manufacture of slabs and panels of ceramic material according to the vacuum vibrocompaction method described in Italian patent 1,311,858, the initial mix is formed using ceramic having the form of sands having a grain size of less than 2.5 mm, preferably less than 1 mm, and ceramic powders, together with a binding additive in the form of an aqueous solution consisting of sodium silicate in a concentration greater than 24° Baumé, fibers of high-melting transparent inorganic material, preferably high-melting glass, also being added to the mix. The slabs obtained have an improved mechanical strength, a reduced porosity and improved aesthetic properties, in addition to being free from cracks and microscopic fissures.