4831621738

186

and finally its ash content using thermogravimetric analysis (TGA) (TA Instruments® Q600 SDT). The ash content is the weight percent of materiał remaining after coal sample is totally bumed out at 815 °C for two hours.

7.2.4 Laboratory brick samples manufacturing

Tlie procedurę followed to manufacture fired bricks is described in Figurę 7.3. DifTerent mixtures of wastes and shales were prepared to produce bricks containing up to 100 wt.% of wastes (Table 7.1). The mixtures were then homogenized, mixed with adequate amount of water. pressed under 6 MPa using a hydraulic press to produce two forms of samples; rectangular prism proofs 100 x 20 x 12 mm to assess the engineering performances of bricks and cylindrical blocks 5.4 mm 0 x 38 mm high to evaluate their leaching behavior. Tlie green samples were then dried at room temperaturę during 24h followed by a controlled drying proeess in an electric oven at 60 C for 24h. Once dried, the bricks were fired. in a muffle fumace (Nabertherm©) with a heating ratę of 30 C li, held at the optimal temperaturę 1020°C for 5h. Tlie unflred and fired MO bricks are also presented in Figurę 7.3.

Table 7.1 Mixes realized to prepare fired bricks.

Mix design	CMWR (wt.%)	TCMT (wt.%)	ShB (wt.%)	Water (wt.%)	BaCOj (wt.%)
MO (reference)	0		100	ll	0.02
M60	60		40	ll	0.02
M70	70		30	ll	0.02
M80	80		20	ll	0.02
M90	90		10	ll	0.02