Early age shrinkage cracking of restrained metakaolin-slag-palm oil fuel ash binder geopolymer mortars

The purpose of this study is to investigate the effects of a ternary geopolymer binder (MKSP) on the early-age shrinkage cracking, creep relaxation, and stress development of a restrained mortar containing alkali activated metakaolin (MK), slag(S), and palm oil fuel ash (POFA). Various mortars were prepared containing different proportions of these binder materials. The ASTM restrained shrinkage test was then conducted to determine the age at cracking, and strengths, free shrinkage and creep were also determined. The results indicate that MKSP with 40% MK, 40% slag, and 20% POFA exhibits the lowest shrinkage strain, possesses sufficient compressive strength (52 MPa) with a creep relaxation (4.2 MPa), and delays the age of mortar cracking for 18 days. Therefore, the use of a ternary MKSP is demonstrated to reduce the early age cracking in mortars. This finding has significant benefits for structures that require a high resistance to cracking, such as pavements