Journal of the Civil Engineering Forum
Vol. 12 No. 1 (January 2026)

Experimental Study on Compressive Strength, Flexural Strength, and Microstructure of Epoxy Mortar as Concrete Repair Mortar

Umbu Tay, Bonaventura Haryanto (Unknown)
Sutarja, I Nyoman (Unknown)
Widiarsa, Ida Bagus Rai (Unknown)



Article Info

Publish Date
19 Nov 2025

Abstract

his study investigates the potential of custom-formulated epoxy-based concrete repair mortar as an alternative material for structural applications. Conventional commercial mortars, while practical, often exhibit limitations in long-term strength and durability. This research evaluates the mechanical and microstructural performance of epoxy mortar using a self-mixed composition consisting of epoxy resin, cornice adhesive, and silica sand. Three variations were developed based on the ratio of epoxy resin to cornice adhesive (50%, 70%, and 100%), and were labeled as RE0.5, RE0.7, and RE1. A commercial epoxy–cement-based mortar, Sikafloor-81 Epocem (SF), was used as a benchmark for comparison. Specimens were prepared in the form of cubes and prisms and tested at curing ages of 7, 14, and 28 days for compressive and flexural strength. Microstructural characteristics were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). At 28 days, the compressive strength values were 30.88 MPa for RE0.5, 48.56 MPa for RE0.7, 51.84 MPa for RE1, and 18.00 MPa for SF. Flexural strength results at 28 days reached 25.74 MPa (RE0.5), 31.18 MPa (RE0.7), 32.54 MPa (RE1), and 8.32 MPa (SF). Elemental analysis confirmed that the high silica content in the fine aggregate and the presence of calcium sulfate in the filler contributed to a denser and more rigid matrix. Crystalline phase analysis revealed quartz as the dominant structure, and microstructural observations indicated fewer pores and cracks in RE1 and RE0.7 compared to SF. These results indicate that a carefully optimized epoxy mortar formulation can exceed the performance of commercial products such as SF, offering enhanced mechanical strength and improved microstructural integrity for use in concrete repair.

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Journal Info

Abbrev

JCEF

Publisher

Subject

Civil Engineering, Building, Construction & Architecture

Description

JCEF focuses on advancing the development of sustainable infrastructure and disseminating conceptual ideas and implementing countermeasures, particularly in the tropics, which are vulnerable to disasters. Specifically, we look to publish articles with the potential to make real-world contributions ...