Studi Eksperimental Sifat Mekanik Statik dan Pola Retakan Beton dengan Diperkuat Abu Cangkang Sawit dan Fly ash

Abstract

Cement production significantly contributes to global carbon emissions, necessitating eco-friendly material innovations utilizing industrial waste. This study aims to analyze the effect of partial cement substitution using a combination of Fly Ash (FA) and Palm Oil Fuel Ash (POFA/ACS) on the static mechanical properties and crack pattern characteristics of Engineered Cementitious Composites (ECC) mortar. The experimental method involved varying Fly Ash levels (10% and 15%) and ACS levels (0%, 5%, 10%, and 15%) by weight of cement. Tests included slump flow, density, compressive strength, split tensile strength, microstructural analysis using Scanning Electron Microscope (SEM) and EDS, as well as crack pattern analysis following static testing. The results showed that all mixture variations exhibited good flowability with T500 spread times between 0.4 and 1.6 seconds. This material combination effectively improved density, where the M44 variation (15% FA + 15% ACS) recorded the lowest water absorption of 0.78%. The optimum composition was achieved in the M43 variation with a combination of 15% Fly Ash and 10% ACS. At 28 days, this variation yielded a maximum compressive strength of 49.56 MPa and a split tensile strength of 6.83 MPa, categorizing it as high-strength concrete. Microstructural analysis confirmed the formation of massive and dense Calcium Silicate Hydrate (C-S-H) gel due to pozzolanic reactions and the filler effect. Furthermore, the addition of ACS proved to alter the material's failure behavior from brittle columnar crack patterns in control specimens to more ductile shear crack patterns through a mechanical interlocking mechanism between particles.