الفهرس 
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Abstract
This study investigated the production of lightweight brick in which total or partial quantities of sand are replaced by Partially Dealuminated Metakaolin (PDK) (by-product from aluminium sulphate industry) in addition to studying of partial replacement of cement with PDK. The best brick ingredients ratios using total replacement of sand with PDK were: 75.8 % PDK, 13.4 % cement, 8.9 % quick lime, 1.8 % gypsum and 0.08 % aluminum powder. The curing duration was 6 hrs. using full scale steam autoclave, at about 180οC and pressure of 12 bar. The achieved compressive strength by total replacement of sand with PDK was 5.7 N/mm2 was in compliance with the Egyptian specifications for light weight concrete blocks (ESS 1401/2005), the water absorption was 50 %, and density 0.56 g/cm3. Higher compressive strength (5.8 N/mm2) and lower water absorption (35%), and density 0.52 g/cm3 were achieved by replacing of 50 % of sand with PDK. In other trials in which the PDK replaced 15 % of the added cement. The best ratios became: 70 % sand, 2.25 % PDK, 12.75 % cement, 13 % quick lime, 2.0 % gypsum, and 0.083 % aluminum powder. This blend achieved compressive strength (5.5 N/mm2) water absorption 42%, and density 0.54 g/cm3.
Good resistance to the effects of chemical attack (5 % solution of NaCl and Na2SO4) was observed for the produced lightweight brick.
The findings of the study showed that lightweight brick can be produced by using PDK (industrial by product). The lightweight brick possesses good mechanical properties.
This application resulting in reduction of the environmental pollution and lowering the depletion rate of the natural resources and at the same time has an economic value.