Effect of processing conditions on the properties of recycled cathode ray tube glass foams

Abstract

Cathode ray tube glass waste was used to produce glass foams by a powder sintering route. The glass waste powder was mixed with small amounts (5 and 8 wt%) of coal fly ash, which acted as foaming agent, and the compacts of the mixed powders were heated at different sintering temperatures in the range 600-800°C for various dwell times (30-120 min). The effect of the different processing conditions on the microstructural characteristics (porosity, pore size and pore size distribution), mechanical resistance and thermal conductivity of the produced foams was investigated. The volume of pores tended to increase with sintering temperature and time, and glass foams (with a porosity higher than 50 %) were only achieved after sintering at 750°C. The average pore size increased with sintering temperature and dwell time, and pore growth was particularly accentuated at 800°C, where coalescence of the pores occurred, with a consequent decrease in compressive strength. Selected combinations of the sintering temperature, dwell time and foaming agent led to glass foams with a satisfactory microstructural homogeneity, which exhibited mechanical strength and thermal conductivity values similar to commercial foams used as thermal insulating materials.

Glass foams produced by glass waste, sodium hydroxide, and borax with several pore structures using factorial designs

“…Based on this fact, it can be suggested that temperatures superior to 750°C will have a more significant influence on the structure of glass foams, which is in agreement with other studies. 27,32,36 Normal plots of residuals are shown in Figure 5 to check the model used to estimate the effects. In this case, a model is said to be valid when the residuals plotted lie close to the line.…”

“…Several foaming agents to manufacture of glass foams are reported: sodium hydroxide, 25 porcine bones, 26 coal fly ash, 27 sodium carbonate, 19,20 carbon black, 28 silicon carbide, 29 calcium carbonate, and even eggshells. 2,30,31 In addition to foaming agents, other additives can be added to foams to modify their properties or facilitate processing.…”

Waste-to-Reuse Foam Glasses Produced from Soda-Lime-Silicate Glass, Cathode Ray Tube Glass, and Aluminium Dross

“…Millions of tons of SLS glass are produced (and become waste) worldwide in the form of container and float glass products [23]. Commercial foam glasses have 45-85 vol% porosity, 0.1-1.2 g/cm 3 apparent density, 0.4-6 MPa compressive strength, and 0.1-0.2 W/mK thermal conductivity [24][25][26][27][28][29]. Compressive strength is particularly important in the case of foam glass used in complex embankment applications as filling material to reduce vertical and lateral soil pressures, and to increase slope stability.…”

“…From an economical and environmental point of view, researchers use several waste materials, such as fly ash [30], cathode ray tube (CRT) glass, red mud, mineral wool waste [31,32], flat panel, and tailing waste [33] to produce building material [2,16,21,24,[34][35][36][37][38][39][40]. The amount of CRT glass arising from computer monitors and TV sets increases dramatically due to their replacement by the liquid crystal display (LCD) [41,42].…”

“…However, there are only a few CRT recycling facilities in Europe and the world [42,50]. In addition to the foam glass, CRT glass can be applied to produce a variety of building materials, such as glass-ceramic brick, geopolymer, and concrete [24,41,42,46,48,[51][52][53][54][55][56][57].…”