The Impact of Silica Fume Addition on the Early Age Compressive and Flexural Strength of Geopolymer Mortar with Various Binders

¹ Doctoral Program in Engineering, Universitas Syiah Kuala, Banda Aceh, Indonesia
² Department of Civil Engineering, Universitas Teuku Umar, Meulaboh, Indonesia
³ Department of Civil Engineering, Universitas Syiah Kuala, Banda Aceh, Indonesia
⁴ Department of Chemical Engineering, Universitas Syiah Kuala, Banda Aceh, Indonesia

^* Corresponding author: muttaqin@usk.ac.id

Abstract

The study aims to explore the early age strength of geopolymer mortars using three precursors: palm shell ash, rice husk ash, and clamshell ash, with varying silica fume additions (0%, 5%, 10%, 15%, 20%). The mortars were made with a 3:2 ratio of precursor to activator solution, using sodium hydroxide and sodium silicate in a 1:2 ratio. Beam specimens (4 cm x 4 cm x 16 cm) underwent a flexural test at three days old, followed by a compression test. Results show the highest compressive strength for geopolymer mortar with palm shell ash (GM-PSA) was 36.03 MPa, geopolymer mortar with clamshell ash (GM-CSA) was 32.47 MPa and geopolymer mortar with rice husk ash (GM-RHA) was 36.56 MPa. All of them were reached at 20% silica fume addition. The highest flexural strengths were also reached at 20% silica fume addition, which are 0.31 MPa, 0.24 MPa, and 0.34 MPa for GM-PSA, GM-CSA, and GM-RHA, respectively. Adding silica fume significantly enhanced the compressive and flexural strength of GM-RHA, GM-PSA, and GM-CSA.