Premium
Effect of cement additive on physical and mechanical properties of high calcium fly ash geopolymer mortars
Author(s) -
Kaya Mehmet,
Köksal Fuat
Publication year - 2021
Publication title -
structural concrete
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 34
eISSN - 1751-7648
pISSN - 1464-4177
DOI - 10.1002/suco.202000235
Subject(s) - fly ash , materials science , composite material , compressive strength , cement , flexural strength , mortar , calcium hydroxide , sodium hydroxide , ultimate tensile strength , absorption of water , porosity , chemistry
Geopolymer mortars were produced by replacement of high calcium fly ash with cement at the percentages of 5%, 10%, 15%, 20%, 25%, and 100%. Sodium hydroxide was used as the activator and sodium/binder ratios, by weight, were 10%, 12%, 14%, 16%, 18%, and 20% in mortar mixtures. Some physical properties such as unit weight, water absorption, apparent porosity and ultrasound pulse velocity tests were performed on specimens kept in ambient temperature. Flexural and compressive strength tests were made on specimens kept in ambient temperature, and exposed to temperatures of 200°C, 400°C, 600°C, and 800°C for residual performances of mortars. After exposing of specimens to high temperatures, ultrasound pulse velocity and loss in weights were also determined for deterioration levels. An experimental design is also achieved to find optimum solutions for Na/binder and cement/fly ash ratios by using D‐optimal design method after establishing response surface models for compressive and flexural tensile strengths. The highest compressive strength of 35.65 MPa was obtained in mortar specimens containing 14% sodium at 20% cement replacement with fly ash. Similarly, residual strengths were observed higher than those of other mortar specimens at the same sodium and cement replacement ratios.