Effects of slag content on the residual mechanical properties of ambient air-cured geopolymers exposed to elevated temperatures

Figures & data

Table 1. Chemical compositions of class F fly ash and blast furnace slag.

Compound	SiO2	Al2O3	Fe2O3	CaO	Na2O	K2O	MgO	P2O5	SO3	TiO2	MnO	LOI
Class F Fly ash	51.11	25.56	12.48	4.3	0.77	0.7	1.45	0.885	0.24	1.32	0.15	0.57
Slag	32.50	13.56	0.85	41.2	0.27	0.35	5.10	0.03	3.2	0.49	0.25	1.11

Table 2. Mixing proportions of fly ash-slag blended ambient air-cured geopolymers.

Mix type	Mixing Proportion (kg/m^3)
	Fly ash	Slag	Sodium Hydroxide (8M)	Sodium Silicate
S1 (5% slag)	1250	67	167	417
S2 (10% slag)	1183	134	167	417
S3 (15% slag)	1116	201	167	417
S4 (20% slag)	1049	268	167	417
S5 (30% slag)	915	402	167	417

Figure 1. Geopolymer specimens inside the kiln.

Figure 2. Firing curves for different elevated temperatures in the kiln during heating.

Figure 3. SEM images of ambient air-cured geopolymers containing (a) 5%, (b) 15% and (c) 30% slag as partial replacement for fly ash.

Figure 4. Energy-dispersive X-ray spectroscopy (EDS) analysis of ambient air-cured geopolymers containing (a) 5%, (b) 15% and (c) 30% slag as partial replacement for fly ash.

Figure 5. SEM images of ambient air-cured geopolymers containing (a)5%, (b) 15% and (c) 30% slag as partial replacement for fly ash after exposure to a temperature of 400°C.

Figure 6. SEM images of ambient air-cured geopolymers containing (a)5%, (b) 15% and (c)30% slag as partial replacement for fly ash after exposure to a temperature of 600°C.

Figure 7. SEM images of ambient air-cured geopolymers containing (a)5%, (b) 15% and (c) 30% slag as partial replacement for fly ash after exposure to a temperature of 800°C.

Figure 8. XRD analysis of ambient air-cured geopolymers containing 5, 15 and 30% slag and fly ash geopolymers.

Figure 9. XRD analysis of ambient air-cured geopolymers containing (a) 5%, (b) 15% and (c) 30% slag as partial replacement for fly ash after exposure to 400, 600 and 800°C temperatures.

Figure 10. Comparison of XRD analysis of ambient air-cured geopolymers containing various slag contents and fly ash geopolymers after exposure to a temperature of 800°C.

Figure 11. TGA analysis of ambient air-cured geopolymers containing various slag contents and fly ash geopolymers.

Figure 12. Pore size distribution of various fly ash-slag blended geopolymers and fly ash geopolymers.

Figure 13. Mass loss of ambient air-cured geopolymers containing various slag contents after exposure to elevated temperatures.

[Note: S0 represents 100% fly ash geopolymers].

Figure 14. Volume loss of ambient air-cured geopolymers containing various slag contents after exposure to elevated temperatures.

[Note: S0 represents 100% fly ash geopolymers].

Figure 15. Cracking behaviour of ambient air-cured geopolymers containing various slag contents after exposure to elevated temperatures.

Figure 16. Compressive strength of ambient air-cured geopolymers containing various slag contents before and after exposure to elevated temperatures.

[Note: S0 represents 100% fly ash geopolymers].

Figure 17. Percentage loss of compressive strength of ambient air-cured geopolymers containing various slag contents after exposure to elevated temperatures.

[Note: S0 represents 100% fly ash geopolymers].