White soil in mortar geopolymer with potassium hydroxide as the activator

Abstract

Reducing CO2 in nature is the reason for the development of alternative technologies such as mortar geopolymers. This will have an impact on reducing the use of Portland cement. Moreover, the potential of local materials is also feasible to be developed especially contains an ingredient that can support environmentally friendly alternative materials. This study aims to determine the mechanical behavior of geopolymer mortars that consist of sand, fly ash type F from Tanjungjati Jepara, white soil from Kupang NTT (as substitution of fly ash), and Potassium Hydroxide (KOH) 8M as an activator. The specimens were cube 5x5x5 cm3 and molds similar to number eight. The mix proportion was 1 binder : 3 sand. Binder is a mixture of fly ash, white soil, and KOH 8M solution with w/b of 0.5. Mortar dried in the oven until 24 hours at 60 °C. Specimens were tested for compressive and tensile strength, density, and porosity within a specified time. The results show that the substitution of white soil in geopolymer mortar can increase of the compressive and tensile strength, increase porosity, and make the weight of volume the mortar become lighter. The substitution of white soil at 10, 20, and 25% shows a trend that has a better result than the others, while the substitution of 5% has not been effected yet.

Comparative Study of Mechanical Properties of PPC Mortar and Geopolymer Mortar with NaOH Activator in Seawater Soaking

“…Sebagai perbandingan pada penelitian sebelumnya mortar geopolimer substitusi tanah putih (0% -25%) dan semen PPC yang telah direndam pada air laut, dengan kuat tarik variasi PPC mencapai 2,8 MPa dibanding dengan variasi geopolimer tanah putih mencapai 0,4 MPa sampai 1,5 MPa (Priastiwi, et al, 2021). Berbeda dengan rendaman larutan asam sulfat konsentrasi 10% variasi PPC tidak dapat bertahan terhadap serangan asam yang tinggi sehingga benda uji hancur dan keropos setelah perendaman namun variasi geopolimer tanah putih dapat bertahan dengan nilai kuat tarik mencapai 0,4 MPa sampai 1,1 MPa (Priastiwi, et al, 2021). Umumnya peningkatan kekuatan tekan juga akan diikuti dengan peningkatan kekuatan tarik pada tingkatan tertentu dan kekuatan tarik berpengaruh pada potensi retakan yang mungkin terjadi (Jaber et al, 2018).…”

“…Studi mengenai penggunaan aktivator Potasium Hidroksida (KOH) dan Sodium Silikat (Na2SiO3) pada campuran mortar geopolimer (Priastiwi et al 2021) diperoleh hasil kuat tekan mortar geopolimer tertinggi saat umur 28 hari pada mortar geopolimer yang menggunakan aktivator Sodium Silikat (Na2SiO3) yaitu sebesar 14,15 MPa dibandingkan aktivator Potasium Hidroksida (KOH) yang menghasilkan kuat tekan 10,14 MPa.…”