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-♦-MO    —•— MIO —M20    M30    ♦    M40

%- M30    ♦    M40

t

M *    i-- I

900    9S0    1000    10SO

Figurę 5.6    Evolution of llexural strength. apparent density. open porosity and

firing shrinkage with sintering temperaturę for calamine wastes based fi red bricks.

The relationship between the diiTerent brick samples properties sintered at 1050 C is highlighted in Figurę 5.7. It can be noticed that there is a good correlation between the tlexural strength and open porosity (r =0.964). the apparent density and open porosity (r 0.938). the flexural strength and apparent density (r=0.890) and finally between the open porosity and loss on ignition (r=0.976). These results support the previous assumptions regarding the dccrease of flexural strength with inereasing porosity. the decrease of apparent density with the growth of porosity which in tum depends on the loss on ignition. However. the correlation between these properties could be affected by other faetors sueh as the mierostructural properties of brieks. The later may explain the deeline of the tlexural strength with the addition of the TCPMT.