Influence of the pH value on the plasticity of clay bodies for bricks

The findings of a study on the active principles and effects of a change in the pH value with regard to shaping, drying and firing behaviour as well as the leachability of heavy metals in the product are discussed The natural souring process was artificially replicated by means of the addition of acid residues. The reason for this is an improved clay disintegration during the souring process, which can be attributed to the formation of acid decomposition products. Improved clay disintegration leads to an increase in plasticity. From these results a saving of energy in the shaping and drying processes as well as improved product quality. The increase in plasticity in the acid range is caused by the changing interaction of the clay minerals. This results in a change in the surface charges, which leads to increased formation of a house of cards structure. In addition, the achieved body/brick properties are compared as a function of different storage times and the possibilities for selection of the residues used for the brick product are examined more closely.

B.eng. Daniel Schnabel, Institut für Ziegelforschung Essen e.V.

x

Related articles:

Issue 2011-12

Assessing the suitability of selected wastes as additives to clay bodies in brick manufacture

1 Introduction Clay bricks are made by shaping suitable clays and shales, mostly by extrusion of clay pastes to units of standard sizes, which are dried and fired to temperatures in the range of...

more
Issue 2012-6

New clay preparation, souring and shaping line at Wienerberger’s Rumst facility

Ceratec successfully delivered a new clay preparation line, a clay souring plant and a shaping/extrusion line to Wienerberger’s Porotherm site located at Rumst, Belgium. This new plant enables...

more
Issue 2010-06

From quarry to shaping – prerequisites for optimally planned preparation and shaping plants

1 Planning principles The ground rule of plant design is to proceed according to the efficiency rule, i.e., to make an investment successful for the lowest cost possible. Referred to successful...

more
Issue 2013-05

Test methods for heavy clay ceramic raw materials: ceram-technological behaviour (secondary properties) – part 2

3 Ceram-technological behaviour (secondary properties) The primary properties of a clay or a batch result in a definite ceram-technological behaviour, which can be simulated under laboratory...

more
Issue 2014-06

Differences in the production-related properties of the three primary clay minerals kaolinite-illite-montmorillonite (Part 2)

4 Shaping properties To this day, there is no uniform laboratory process for measuring plasticity as this is used as a collective term for many complex properties such as viscosity, yield or...

more