Properties of hardener-free epoxy-modified mortars utilizing pyrolysis tar replacement

This study focused on the performance of hardener-free epoxy-modified mortar (HFEMM) with pyrolysis tar (PT), a by-product of the green wood industry. HFEMMs were prepared with amounts of 1, 3, and 5% epoxy resin. For the HFEMM with a 1% epoxy resin mixing rate, 5, 10, 15, and 20% of the epoxy resin were replaced with PT. The highest hardening rate was observed for the HFEMM with 1% epoxy resin, whereas the amounts of hardened and unhardened epoxy resin were the largest at 5%. When 1% epoxy resin was replaced with PT, the hardening rate increased to 10%. When 10% PT was substituted with 1% epoxy resin, the compressive, flexural, and adhesive strengths increased because of the higher hardening rate. X-ray diffraction result showed that an increase in the epoxy resin content and the PT replacement rates resulted in lower amounts of calcium hydroxide and lower semi-adiabatic and maximum exothermic temperatures. These results showed that the use of PT in the HFEMM could improve its performance while providing an avenue to recycle PT.