Polymer mortar, consisting of a polymer binder and aggregates, offers superior properties such as enhanced strength, durability, and corrosion resistance compared to the traditional cement-based mortars. Within the polymer-based mortar, epoxy resin is one of the most commonly used resins owing to its high performance. However, its widespread adoption is hindered by costs and environmental concerns, particularly the dependence of bisphenol A-containing epoxide, a substance harmful to human health. In this work, a novel epoxy hardener derived from oregano oil (OEO) was developed to create a more eco-friendly and cost-effective binder for polymer mortar. The inclusion of OEO-based hardeners reduced the viscosity of the binder and accelerated the curing process. The Mannich base structure of the hardener induced more reactive sites in the epoxy system, resulting in a denser crosslinked network. Polymer mortars fabricated with this novel hardener exhibited improved mechanical properties, bonding strength, and corrosion resistance compared to conventional epoxy mortars. Scanning electron microscopy images also revealed a stronger interfacial bond between the epoxy resin and the aggregates. This study demonstrates the potential of OEO-based hardeners to enhance the performance of epoxy binders, providing a sustainable alternative for polymer-based mortar applications.
To enhance the engineering application range of fly ash-cement-based materials (FCM), the combined effects of hardening accelerator on FCM were investigated by using response surface methodology (RSM). Based on a three-factor three-level Box-Behnken design (BBD), the linear, quadratic and interaction relationships between the dosages of calcium chloride (CaCl 2 ), aluminum sulfate (Al 2 (SO 4 ) 3 ) and triethanolamine (TEA) on the primary properties (setting time, mechanical properties and shrinkage rate) of FCM were discussed. The prediction model was established to determine the optimal ratio of the composite system . The microscopic performance and the mineral fraction of the paste were explored by using X-ray diffraction (XRD), thermogravimetric differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results indicated that the paste performance was affected by the interaction of multiple factors, and the interaction between CaCl 2 and Al 2 (SO 4 ) 3 was the most significant. The optimum ratio of paste was 2.81 % CaCl 2 , 0.75 % Al 2 (SO 4 ) 3 and 0.12 % TEA, achieving a 28 d compressive strength of 40.48 MPa, closely matching the predicted value. The dominant hydration products of the composite cementitious system were C–S–H gel, AFt and Friedel's salt, with changes observed in the morphology of CH. With the prolong of curing age, the hydration products and unhydrated fly ash particles were bonded to each other, so that the slurry maintains a certain strength performance.
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