2.2 Material Mix Proportions
Figure 2 Morphology of FA and GGBFS particles
Three batches of specimens were prepared,including PC mortar and concrete,alkali-activated slag(AAS)geopolymer mortar and gepolymer concrete,and alkali-activated slag-fly ash(AASF)blended geopolymer concrete.The mixing proportions for these three batches of specimens are summarized in Table 2,Table 3 and Table 4,respectively.Powder polycarboxylate superplasticizer was used here and its dosage was by the mass fraction of cement.It should be noted that the first batch and second batch specimens were prepared for comparison between PC mortar/concrete and AAS geopolymer mortar/concrete at three different target strength grades(30,50 and 70 MPa at 28 d).The third batch of specimens were prepared to observe the effect of material parameters on the fracture properties of geopolymer concrete.The test parameters included slag/fly ash ratio,water/binder ratio,alkali concentration(the percentage of Na2 O by mass of slag,n)and modulus of the alkali activator(i.e.the mole ratio of SiO2 to Na2 O,Ms),all of which are thought to have significant effects on the compressive strength of the GC concrete.The total water used to calculate the water/binder ratio included the water added and the water contained in the sodium silicate solution.In the tables,PCM and PCC represent ordinary Portland cement mortar and concrete,respectively;AASM and AASC represent the alkali-activated slag geopolymer mortar and concrete,respectively,for which slag was used as the sole precursor material;AASFC represents alkali-activated slag/FA blended geopolymer concrete.
Table 2 Mix proportions of PCM and PCC
Table 3 Mix proportions of AASM and AASC
Note:“n”means the alkali concentration and“Ms”means the modulus of alkali activator.
Table 4 Mix proportions of AASFC
Note:“n”means the alkali concentration and“Ms”means the modulus of alkali activator.