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The practical use of recycled concrete aggregate produced by crushing concrete waste reduces the consumption of natural aggregate and the amount of concrete waste that ends up in landfills. This study investigated two methods used in the production of fine recycled concrete aggregate: (1) a method that produces fine as well as coarse aggregate, and (2) a method that produces only fine aggregate. Mortar specimens were tested using a variety of mix proportions to determine how the characteristics of fine recycled concrete aggregate affect the physical and mechanical properties of the resulting mortars. Our results demonstrate the superiority of mortar produced using aggregate produced using the second of the two methods. Nonetheless, far more energy is required to render concrete into fine aggregate than is required to produce coarse as well as fine aggregate simultaneously. Thus, the performance benefits of using only fine recycled concrete aggregate must be balanced against the increased impact on the environment.

Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing reinforcing steel corrosion. This study investigates the effects of leaching behavior of calcium ions on the compression and durability of cement-based materials. Since the parameters influencing the leaching behavior of cement-based materials are unclear and diverse, this paper focuses on the influence of added mineral admixtures (fly ash, slag and silica fume) on the leaching behavior of calcium ions regarding compression and durability of cemented-based materials. Ammonium nitrate solution was used to accelerate the leaching process in this study. Scanning electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis were employed to analyze and compare the cement-based material compositions prior to and after calcium ion leaching. The experimental results show that the mineral admixtures reduce calcium hydroxide quantity and refine pore structure through pozzolanic reaction, thus enhancing the compressive strength and durability of cement-based materials.

This study investigated the effect of solid‐to‐liquid ratio (0.4–1.0) on the properties of geopolymer, in which some metakaolinite was replaced by solar panel waste glass (0–40%). The experimental results indicate that geopolymer containing 10% solar panel waste glass at a solid‐to‐liquid ratio of 1.0 has higher compressive strength than geopolymer without solar panel waste glass at 1 and 7 days of curing. Thus, geopolymer containing 10% solar panel waste glass is more suitable than geopolymer without solar panel waste glass for practical applications. Furthermore, the porosity of the geopolymer declined as the density increased. The experimental results showed that the degree of reaction of the geopolymer increased with the solid‐to‐liquid ratio. The Fourier transform infrared spectroscopy spectra revealed that the principal peaks from the geopolymer corresponded to the Si—O—Al bonds. The scanning electron microscopy of the geopolymer indicated that the main structure of a geopolymer that contained solar panel glass with a higher solid‐to‐liquid ratio was more compact and homogenous, which is consistent with the higher density and lower porosity. The experimental results showed that the solid‐to‐liquid ratio affected the properties of geopolymer considerably. In addition, we observed some positive influence of the solar panel waste glass on the compressive strength of metakaolinite‐based geopolymer; however, it was limited to the early compressive strength. Furthermore, the degree of reaction of the geopolymer that contained 10% solar panel waste glass was similar to that of the metakaolinite‐based geopolymer when the positive influence on the compressive strength diminished. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 797–803, 2013

Thin‐film transistor liquid crystal display (TFT–LCD) waste glass comprises mainly SiO2 and Al2O3, which are suitable raw materials for geopolymer. This study investigates the effects of the amount of foam agents on the properties of waste glass‐based cellular geopolymer. In this investigation, samples underwent a series of tests to determine their quality, including mechanical characterization, compressive strength, flexural strength, fire resistance, thermal conductivity, Fourier transform infrared spectroscopy, and scanning electron microscopy. The experimental results show that the mechanical strength and thermal conductivity decreased with the addition of foam agents, indicating that foam agents can reduce the thermal transfer. The pore volume increased with the amount of increase in foam agent. These results indicated that the amount of foam agent has a more substantial effect than waste glass replacement in geopolymers. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 538–550, 2014