Nanoindentation on micromechanical properties and microstructure of geopolymer with nano-SiO2 and nano-TiO2. (March 2021)

• Record Type: Journal Article
• Authors: Luo, Zhiyu; Li, Wengui; Gan, Yixiang; He, Xuzhen; Castel, Arnaud; Sheng, Daichao
• Is Part Of: Cement & concrete composites. Volume 117(2021)
• Publication Date: 2021-03
• Subjects: Geopolymer -- Nanoparticle -- Sodium-aluminium-silicate-hydrate (N-A-S-H) -- Statistical nanoindentation -- Nanomodification -- Microstructure; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2020.103883
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: Fly ash-based geopolymers incorporated with 2% nano-SiO2 (NS)/nano-TiO2 (NT) particles were subjected to microstructural and statistical nanoindentation analysis. With the addition of both types of nanoparticles, the compressive strength of geopolymer and the micromechanical properties of N-A-S-H gel were increased. NS exhibited higher reinforcement effect than NT on macro-strength. However, NT more significantly enhanced gel micromechanical properties. NT and especially the NS were found to have a positive effect on the early reaction rate of geopolymer. After 28 days, the gel proportion obtained by Backscattered electron (BSE) images analysis was close values of 49.16%, 55.69% and 54.02% for reference sample and NS, NT reinforced geopolymer, which were more than two times of that from the statistical nanoindentation. The effects of NS and NT on microstructure, gel proportion and gel micromechanical properties were discussed to reveal the macro-strength reinforcement mechanism. The results obtained from different techniques were also compared and discussed. Highlights: The 2% nano-SiO2 and nano-TiO2 particles help geopolymer gain 17.38% and 10.49% in strength at 28 days. The content of N-A-S-H gels obtained by SNT vary significantly, and are less than 50% of BSE results. The present of both nano-SiO2 and nano-TiO2 particles increase the early reaction in geopolymer. Around 5 nm N-A-S-H gel globules are found to pack into large gel particles with size more than 30 nm. Nano-SiO2 is compatible with sodium silicate solution and gel particles for good dispersion and high strength.