Synthesis of a Geopolymer with the Blend of Clay from Share Deposit and Cullet of Cathode Ray Tube
Abstract
The potentiality of Share clay as an ingredient for synthesis of metakaolin based geopolymer and the effect of partially substituting the clay with the cullet of cathode ray tube (CRT) was investigated. Calcined clay in partial substitution with powdered CRT in the mix proportion of 0%, 25%, 50% and 75% by weight was reacted with sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The resulting geopolymer samples were used to produce test specimens and the effect of different percentage addition of CRT on the physicomechanical properties were evaluated. The starting materials and the products were characterized using Scanning Electron Microscopy (SEM) to evaluate morphology, X-Ray Fluorescence (XRF) for oxides composition, X-Ray Diffractometer (XRD) for compositional phases, Atomic Absorption Spectroscopy (AAS) for elemental components and Fourier Transform Infra-Red microscopy (FTIR) for characteristic bonding. Results shows that the alumina and silica content of Share clay are 30% and 92% respectively while that of the CRT were 3% alumina and 29% silica. The water absorption of the geopolymer increases with increasing CRT addition. The Compressive strength in 24 hours ranged from 13 to 17 N/mm2. The drying shrinkage ranged from 0.5mm to 1.25 mm. CRT is as usable as other pozzolanic material to be used with kaolinite in the synthesis of geopolymer. This offers the opportunity for resource recovery from and beneficial use of CRT, which is considered a toxic e-waste.