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Raw materials used by the ceramic industry in Jaén (southern Spain) consist of mixtures of carbonated clays from the Guadalquivir Basin and red clays from the Iberian Massif. The mixtures formulation usually obeys empirical experience developed by this industry for many generations. This work, evaluates different possibilities of using these raw materials to manufacture new ceramic products on the basis of clay physical-chemical properties and analyzes limitations to produce high added value products. As an alternative to overcome these limitations, the mixture of these clays with raw materials from near regions (pyrophyllite clay) and with different industrial wastes is proposed. These wastes are screen glass from monitors and oil impregnated diatomaceous earth. The study of the technological properties shows that the new mixtures are suitable for the processing of ceramic products in which structural and thermal insulating properties are improved or kept.

A B S T R A C TIncorporation of waste into ceramics can be an eco-friendly alternative for modification of their microstructure and related properties such as porosity, pore size and, therefore, permeability and mechanical properties. In this work, two wastes are added to a common clay mixture traditionally used for porous ceramics manufacturing: Screen Glass, G, from monitors and TV panels, and Diatomaceous Earth, D, from oil-filtering processes. Processing of the reference clay-based material (R) and two waste-containing formulations (10 wt.% of Screen Glass, R10G, and 10 wt.% of Diatomaceous Earth, R10D) was carried out through vacuum extrusion shaping and firing of test specimens at three maximum temperatures: 850, 950, and 1,050˚C. Final sintered specimens were characterized to determine density, bending strength, and water absorption. Microstructure was observed by SEM while pore size distribution was determined by mercury intrusion porosimetry. Permeability coefficient was calculated from these experimental parameters. Materials containing Glass waste have lower porosity and larger pore size due to partial melting of glass. As a consequence, mechanical strength of R10G increases around 10% due to the lower porosity while, contrary to expectations, permeability also increases due to the larger pore size. In the case of R10D materials, extra porosity created by oil combustion during sintering also leads to larger permeability values although a significant decrease of mechanical strength and reliability is observed.