A study on combination of geopolymer and cold-pressing technique to recycle fine BOF slag as compressed paving units

Chih Ta Tsai, Wei Hao Lee, Ta Wui Cheng, Chia Cheng Wu, Teng Ker Hsu, Yan Lin Huang, Juu En Chang

Research output: Contribution to conferencePaperpeer-review

Abstract

Basic oxygen furnace (BOF) slag is in general very difficult to reutilize due to its low volume stability. Around 1.6 million tons of BOF slag is generated annually in Taiwan. The coarse BOF slag (>4.75 mm) was mainly reused as aggregate for asphalt concrete. But the recycling of the remaining fine BOF slag (more than 600,000 tons per year), however, was very difficult. A new concept for stabilization and recycling of fine BOF slag using geopolymer (GP) combined with cold-pressing techniques to produce high-value green building materials (i.e., compressed paving units, CPUs) was tested and developed in this study. The modified densified mixture design algorithm (DMDA) was also adopted to design the geopolymer-based composites. Herein four alkali solutions with different concentrations were prepared and tested. Furthermore, more than 75% (by weight) of fine BOF slag was designed for the geopolymer-based composite mixtures. The test results show that the compressive strength of developed CPUs produced with 6M and 8M alkali solution at the age of 1-d and 3-d was more than 50 and 65 MPa, which meet the national standards CNS 13295 Class B and A, respectively. The compressive strength of CPUs produced with 4M alkali solution at the age of 1-d, 3-d, and 7-d was more than 45, 50, and 65 MPa, which meet the national standards CNS 13295 Class C, B, and A, respectively. Other properties of developed CPUs also conformed to the requirements of CNS 13295 Standard. The combination of geopolymer and cold-pressing technique, therefore, is not only a new and practicable concept to recycle fine BOF slag, but also reduces the energy consumption and CO2 emission as well.

Original languageEnglish
Publication statusPublished - 2020
Event15th International Symposium on East Asian Resources Recycling Technology, EARTH 2019 - Pyeongchang, Gangwon-do, Korea, Republic of
Duration: 2019 Oct 132019 Oct 17

Conference

Conference15th International Symposium on East Asian Resources Recycling Technology, EARTH 2019
CountryKorea, Republic of
CityPyeongchang, Gangwon-do
Period19-10-1319-10-17

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)

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