Influence of the inner surface of drying green ceramic products on their moisture-dependent tensile strength

Test results relating to the moisture-dependent tearing strength of green brick products are described. A detailed presentation of these relations will be included in the Zi Annual 2010. This also takes into account the strength development in the first drying section and the partly extreme strength increase which is attainable with very high dryness, but which unfortunately falls back again to the base values under “normal” atmospheres.

1 Introduction

The determination of the pore size distribution by means of mercury penetration porosimetry leads as a secondary result to the specific pore surface a (total pore area) of the dry specimen. This is given mostly in m²/g and for clayey and other mineral materials is equal to the mass-specific free particle surface.

As described in greater detail in [1], for clay particles in normal moist atmospheres these surfaces are always completely covered by thin water sheaths, which merge into each other at the contact points between individual mineral particles.

Consequently the water...

Related articles:

Issue 2010-03

Causes and avoidance of damage on account of diffusion-dependent reactions in the preheating zone of tunnel kilns with specific consideration of the pore structure of green bricks

1 Background After they have been dried, green clay bricks enter the preheating zone of the tunnel kiln with a varying residual water content. In this preheating zone, the following processes take...

Issue 2011-6

Enhancement of the hydrostatic capillary tension in wet brick green bodies for a reduced susceptibility to cracking during drying

1 Context and problem statement After shaping, brick green bodies exist as capillary-porous solids, the pores of which are filled with water and which are enclosed by a water sheath. Capillary suction...

Issue 2018-6

Modelling shrinkage-related deformation during the drying of green bricks

During drying-related shrinkage of green products, non-linear changes in the body geometry occur. These are not caused by an isotropic shortening of length, but shrinkage progressing from the drying...

Issue 2019-6

Effective dryer control

Non-destructive moisture measurement systems work from the surface to determine moisture content. As a result, the water content of near-sensor layers has the strongest influence on the delivered...

Issue 2017-6

Effective dryer control based on material-specific moisture content – Part 1: Material data

Drying green products is easily the most energy-intensive process step in clay brick and tile production. For the purpose of process control, it is interesting to know the distribution of moisture in...