Study on Effect of Chemical Composition of Geopolymer to Improve Sludge by Using Fiber Materials

Abstract

Geopolymer, an environmentally friendly alternative to ordinary Portland cement, is currently receiving increased attention in academic and industrial communities for its ability to produce fly ash based geopolymer material in several applications. Geopolymer material is known as an inorganic-polymer composite and is synthesized by the aluminosilicate compound materials with alkali hydroxide and alkali silicate. Current researches on geopolymer are mainly focused on geopolymer concrete properties such as mechanical properties, paste properties and durability properties in laboratory. However, few specific publications are available concerning the feasibility of geopolymer modified soft soil (sludge) in the actual landslide area which is mainly due to earthquake and heavy rainfall. This paper presents the details of studies carried out on strength of sludge improved with various geopolymer contents. The composition of sludge is 60% silt, 40% clay and water content is 70%. Sodium hydroxide (NaOH) 12 Molar and sodium silicate solution (Na₂SiO₃) were prepared. The test specimens were made of 50 x 100 mm cylindrical mold and 20^oC temperature curing condition. By adding paper debris, the specimens were made immediately after mixing by compaction, in contrast without adding paper debris, after 24 hours the specimens were made with same conditions to compare. Compressive strength after 12 and 18 hours was measured. The results showed that the modified soil with paper satisfied the target (125kN/m²) with geopolymer content nearly 9% after 12 hours and all of them obtained enough strength after 18 hours. Moreover, modified soil without paper reached target after 12 and 18 hours but revealed lower strain performance.