ENGINEERING OF LOW COST GEOPOLYMER BUILDING BRICKS APPLIED FOR VARIOUS CONSTRUCTION PURPOSES

The aim of this article is to demonstrate various ways in producing geopolymer brick specimens with low production cost through using various sand ratios as well as decreasing the concentration of the added alkalis by utilizing cement kiln dust as a source of high free alkalis that can initiate and propagate geopolymerization reaction. Activators used are sodium hydroxide, sodium silicate and cement kiln with its high alkalis content, all calculated from the total binder weight. Geopolymer bricks prepared by partial binder substitution of metakaolin/ slag by various sand ratio from15 to 50 %, while other mixes are water cooled slag based incorporating various cement kiln dust in the ratio from 25 up to 75 %. The properties of the produced geopolymer bricks have been studied through measurement of compressive strength, water absorption, FTIR, XRD and SEM imaging. Results demonstrate the possibility of producing low cost geopolymer bricks with volunteer properties and possess high mechanical and microstructural characteristics by increasing the used sand ratio as well as cement kiln dust in producing geopolymer bricks with superior properties giving compressive strength values exceed that required for heavy duty bricks (more than 40 MPa) for mostly all the studied specimens except those incorporating high ratios of cement kiln dust which gives values near to 20 MPa for 50 % CKD and reaches to about 15 MPa for 75 % CKD after 90 days of curing.