'Closing the clay-brick cycle', options for the recycling or reuse of masonry debris

In the Netherlands each year about 16 million tons off building demolition waste is produced. The stony fraction is about seventy percent and consists for about sixty percent of concrete and forty percent of masonry, limestone etc. After size reduction about ninety-five percent of the stony fraction is being reused as a road base material. The amount of concrete partly made of recycled concrete aggregates is only small, but in the near future the concrete industry wants to promote K use of concrete aggregates. This means that for masonry debris another utilization must be found in the near future. In the Netherlands a process is developed to deal with the recycling of masonry debris. The first step in this process is to reuse whole clay-bricks: During the demolition process the waste streams are separated on site and the pieces of demolition debris are as big as possible. The masonry debris is given a thermal or mechanical treatment to separate the mortar and the bricks. The bricks can be reused as such. The other fraction contains broken brick parts and mortar. This fraction is crushed to a fraction smaller than 4 millimeter, and after a thorough separation of the mortar the masonry is mixed with clay and fired in a kiln, to produce clay-bricks. The sand is reused and also the cementstone is reused as a concrete filler in concrete production. Another option is not to separate the mortar and clay-brick parts, but to crush the material to a fraction smaller than 0,5 millimeter. The material is mixed with clay and fired id a kiln to produce clay-bricks. This paper focuses on the production of clay-bricks with a high percentage of granulate in the clay mixture. The soft-mud process is used to mold the 'green' clay-bricks, because it is the most common production method in the Netherlands. The effect on molding the mixtures, linear drying shrinkage and the effect on the 'green', strength of the product are determined. The research is started in November 1998, with a literature study which took about one year. Also some laboratory experiments were done. In November 1999 a laboratory research was started on a larger scale. After the evaluation of the laboratory research a decision will be made how to start a pilot project in the Dutch ceramic industry. This pilot project should start in the beginning of 2001.