Experimental Study on the Effect of Material Components on the Shrinkage of Slag, Fly Ash, and Red Mud Based Geopolymer

In order to study the effects of different cementitious materials (such as slag(SL), fly ash (FA), and red mud (RM)) on the mechanical and shrinkage properties of geopolymer, the autogenous and dry shrinkage experiment of geopolymer mortar sample developed by single or mixed mixing of SL, FA, and RM were carried out. The flexural and compressive strengths were tested. The failure mode was analyzed. The relationship between ultimate shrinkage strain and compressive strength was also studied. The test results show that: the geopolymer made by sale FA or RM has lower strength, but it has larger shrinkage deformation; The double mixed SL-RM and SL-FA geopolymer has higher compressive strength, rapid chemical reaction, and compact structure; The autogenous shrinkage is slightly less than dry shrinkage. The shrinkage strain has linear relation with compressive strength. The RM-SL based geopolymer is an ideal geopolymer, because of its maximum flexural and compressive strength (5MPa, 36 MPa). and minimun autogenous and drying shrinkage strains.