Affiliation:
1. School of Resources Engineering, Xi’an University of Architecture & Technology, Xi’an 710055, China
Abstract
An efficient fabrication of fly-ash-based geopolymer is urgent and necessary to develop solid waste recycling techniques. Herein, an attempt to investigate the effect of binary composite activators on the microstructure of fly-ash-based geopolymers is conducted through the comparison of 24 experiments, which consisted of Na2SiO3·9H2O, Na2CO3, K2CO3, NaOH, and KOH through a facile preparation technique. The results demonstrate that the activator of Na2SiO3·9H2O + KOH presents the highest mechanical strength, due to the synergy activation between the inherent ≡Si-O-Si≡ silicon-chain precursor derived from the Na2SiO3 and K+’s catalysis. It reveals that the K+ plays a crucial role in the Na2SiO3-activated fly ash geopolymer, which is the rate-determining step of the enhanced crosslinking and propagation of N-(C)-A-S-H chains, leading to an increase in weight loss temperatures of specimens from TG/DTG results. Furthermore, the adding silica fume facilitates as-formed amorphous silicates, which also could fill into the pores of N-(C)-A-S-H amorphous gels and present a uniform and compact morphology, leading to an increase in the pore volume of the pore diameter less than 100 nm. It explores an efficient and cost-effective preparation of fly-ash-based geopolymer for developing solid waste recycling techniques.
Funder
Natural Science Foundation of Shaanxi Province
Social Science Foundation of Shaanxi Province
Key Laboratory of Solid Waste Treatment and Resource Recycling, Ministry of Education, Southwest University of Science and Technology
Subject
Geology,Geotechnical Engineering and Engineering Geology