Abstract
In order to bring a solution to the problem of waste foundry sand (WFS) in the foundry sector and achieve its reuse, geopolymer building material (as a cementless technology) was produced from the WFS for the first time in the literature in this study. The physical and mechanical characteristics of this material were determined. In the first part of the experimental step, the sieve analysis, loose/tight unit weight, and loss of ignition of the WFS were obtained as well as the ultimate analysis. In the second step, the water absorption percentage, porosity, unit weight, and compressive strength tests were conducted on the WFS-based geopolymer specimens activated by chemical binders (sodium hydroxide: NaOH and sodium silicate: Na2SiO3). As the unit weights of all the produced samples were lower than 1.6 g/cm3, they may be considered as lightweight building materials. The minimum compressive strength value for building wall materials was accepted as 2.5 MPa by national standards. In this study, the maximum compressive strength value was measured as 12.3 MPa for the mixture incorporation of 30% Na2SiO3 at the curing temperature of 200°C in 28 days. It was concluded that this geopolymer material is suitable for using as a building wall material.
Highlights
The unit weight (UW) values of all the specimens produced with NaOH were lower than 1.6 g/cm3, and these may be considered as lightweight building materials
Among the geopolymer building material specimens prepared by using NaOH binder and the waste foundry sand (WFS), the material produced by 10% NaOH addition at a curing temperature of 100°C had the highest compressive strength (CS) value (2.5 MPa) at 28th day
Different amounts of NaOH added into the WFS-based samples led to losses in CS values. ese losses had the highest value in the specimens produced with 30% NaOH addition. is result showed that usage of NaOH binder and the WFS is not effective on CS values of the specimens
Summary
Classification of foundry sand may depend upon the type of binder (bentonite or resinous). e WFS used in this study contained bentonite, and it was supplied from the province of Konya in central Turkey. E WFS used in this study contained bentonite, and it was supplied from the province of Konya in central Turkey. In this study, it was worked on 4 different types of WFS, and it was decided to continue with one type after the preliminary results. It was worked on 4 different types of WFS, and it was decided to continue with one type after the preliminary results Elemental analyses of this WFS were carried out, and preliminary experiments (the sieve analysis, loose/tight unit weight, and loss of ignition tests) were conducted on this material. According to TS EN 933–10 [42], the material was categorised based on size
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