4.7 Article

Recycling of waste cathode ray tube glass through fly ash-slag geopolymer mortar

Journal

CONSTRUCTION AND BUILDING MATERIALS
Volume 322, Issue -, Pages -

Publisher

ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2022.126454

Keywords

Cathode ray tube glass; Geopolymer; Alkali-silica reaction; Solidification; Alkali dosage; Silica modulus

Funding

  1. National Natural Science Foundations of China
  2. NSFC-Shandong Joint Fund [U2006223]
  3. Science and Technology Project of Shenzhen, China [JCYJ20190808151011502]
  4. Key-Area Research and Development Program of Guangdong Province [2019B111107003]
  5. Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering (SZU) [2020B1212060074]

Ask authors/readers for more resources

An effective method for recycling waste CRT glass is to use fly ash-slag geopolymer composite as fine aggregate. The silica modulus and alkali dosage have significant effects on the performance of the geopolymer. The optimal alkali dosage and silica modulus for recycling CRT glass with geopolymer are determined to be 6% and 1.5, respectively.
Large amount of waste cathode ray tube (CRT) glass containing the hazardous heavy metal Pb, discarded at landfill sites without proper recycling method, poses a great threat to the environment and public health. It is urgent to develop an effective and efficient recycling method to minimize the quantity of these hazardous wastes. In the present study, recycling of waste CRT glass as fine aggregate through fly ash-slag geopolymer composite were studied. The compressive strength, alkali-silica reaction expansion (ASR expansion) and Pb leaching of fly ash-slag geopolymer mortars containing CRT glass (FSGM-CRT), considering influence of silica modulus and alkali dosage, were comprehensively studied through toxicity characteristic leaching procedure (TCLP) test, Xray diffraction (XRD), thermogravimetry (TG), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM). The results showed that the solidification mechanism of geopolymer for waste CRT glass includes not only physical encapsulation, but also chemical solidification. As the silica modulus increased, the compressive strength and the ASR expansion first increased and then decreased, and the leached concentration of Pb significantly decreased. The increased silica modulus improves the chemical binding of Pb ions by generating lead silicate as it is resulted by microstructure evolution tests. Additionally, increase of silica modulus can significantly improve the interfacial transition zone (ITZ) and the total porosity, resulting in better physical encapsulation performance on the leached Pb ions. On the contrary, higher alkali dosage can hinder the poly condensation reaction of silicate and aluminum tetrahedrons, inhibiting the polymerisation of the geopolymer mortars, thus leading to weakening of both the solidification performance and the compressive strength of FSGMCRT. Considering combined structural and solidification performance requirements on compressive strength, ASR expansion and Pb leaching limit, the optimal alkali dosage and silica modulus for recycling CRT with geopolymer is 6% and 1.5, respectively.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available