Interpreting the early-age reaction process of alkali-activated slag by using combined embedded ultrasonic measurement, thermal analysis, XRD, FTIR and SEM

By Ruilin Cao, Shunquan Zhang, N. Banthia, Yamei Zhang, Zuhua Zhang. 2020

233 citations recorded by the source corpus.

Abstract In the present study, the early-age reaction process of alkali-activated slag (AAS) pastes was in-situ monitored by using embedded piezoelectric transducer based ultrasonic monitoring system. The effects of different types of activator (sodium hydroxide and sodium silicate) on reaction process, products and their microstructure evolution were investigated. The experimental results reveal that the early-age reaction process of AAS can be effectively in-situ observed by use of the ultrasonic method. It is found that the early-age reaction process of AAS pastes made with sodium silicate can be divided into five stages: (Ⅰ) dormant period, (Ⅱ) acceleration period, (Ⅲ) deceleration period, (Ⅳ) second acceleration period and (Ⅴ) second deceleration period. However, only three featured stages could be identified in those activated with sodium hydroxide. The soluble SiO44− ions in activator solution are critical to the formation process of reaction products and the microstructure evolution, especially for the former four stages. In specific, when activation is with sodium silicate, the increase of its modulus (Ms, molar ration of SiO2 to Na2O) leads to the improvement of reaction extent in stage Ⅰ, prolongs the reaction time of stage Ⅱ; meanwhile, the deceleration period of stage Ⅲ is shortened due to the advancement of stage Ⅳ.

Subfields: Civil and Structural Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/eef085daafadb127308ba44d02054cab34002b20