Re ECF Project: 2007-10

Project Title: Recycling of CRT glass from discarded computer monitor and TV sets

Applicant: The Hong Kong Polytechnic University (Prof. Chi Sun Poon)

Total Approved Grant: $441,400 (ECF & WWGF: 50/50)

Duration: 03/08/2009 to 2/2/2011

Project Status/Remarks: Completed

Scope:
To develop a technology to beneficially reuse glass derived from recycling of cathode ray tubes (CRT) generated from discarded computer monitors and TV sets.

Summary of the Findings/Outcomes:
It is feasible to use crushed CRT glass (<5 mm) as a replacement of river sand (in proportions of 0%, 25%, 50%, 75% and 100%) in making cement mortar and concrete. Based on the results of this study, the following conclusions can be drawn:
(a) The initial flow and wet density of mortar and concrete increased with increasing CRT glass content.
(b) Incorporating CRT glass reduced the water absorption and drying shrinkage values. These were mainly attributed to the lower absorption capability of CRT glass than that of sand.
(c) The hardened density increased with the increase in CRT glass content because of its higher specific gravity compared to that of sand.
(d) Inclusion of CRT glass caused a reduction in flexural, splitting-tensile and compressive strengths. The reduction was due to the loss of bonding strength between the smooth surface of CRT glass and cement paste.
(e) The increase in CRT glass content led to an increase in ASR expansion. But all the mortar mixes showed innocuous behaviour with the use of appropriate amount of pozzolan such as fly ash in the mix design.
(f) Incorporation of CRT glass in mortar and concrete successfully prevented the leaching of lead as demonstrated by the toxicity characteristic leaching procedure (TCLP).
(g) The radiation-shielding properties of mortar based composite was significantly improved by the incorporation of CRT glass, particular for the application in high photon energy shielding.