Patent ID: 6886304

Claim:
A process for the preparation of a multi-layer composite slab product, comprising first and second dense layers of stone material agglomerate and binding agent; and an expanded material layer in direct contact with the first and second layers and intermediate the first and second layers, the first and second dense layers being surface layers, and the expanded material layer being less dense than each of the first and second dense layers comprising the following steps: distribution of a stone material agglomerate together with a binding agent in a mold or on a molding belt to form a first, lower layer of the product; prior to any vibro-compression, positioning on said first layer at least one pre-cast support made of expanded agglomerate and a binding agent to form an intermediate layer of the product; distribution of a further stone material agglomerate together with a binding agent on said at least one pre-cast layer to form at least a second, upper layer of the product; vibro-compression, in a single step, of said stone material agglomerates and binding agents and of said at least one pre-cast support; and hardening of the mixture via thermal reaction.