Synthesis of geopolymer composites from a mixture of volcanic scoria and metakaolin

Peer review under responsibility of The Ceramic Society of Japan and the Korean Ceramic Society.

Figures & data

Table 1 Chemical composition and physical properties of volcanic scoriae (Z_D, Z_G) and metakaolin (MK).

Oxides	ZD	ZG	MK
SiO2	44.04	41.36	48.31
Al2O3	15.26	15.41	40.48
Fe2O3	12.77	12.88	2.62
TiO2	2.87	3.04	4.45
MnO	0.17	0.2	0.03
MgO	7.00	6.45	0.36
CaO	9.29	7.88	0.04
K2O	1.35	0.90	1.30
Na2O	5.64	2.22	0.15
SO3	0.01	–	–
P2O5	0.53	0.48	0.02
Cr2O3	0.02	0.03	0.02
LOI	1.1	9.31	2.43
Average particles size (d50, μm)	13.01	10.68	9.95
Specific surface area (m^2/g)	2.3	15.7	20.5
SiO2/Al2O3 (molar ratios)	4.90	4.55	1.42
(SiO2 + Al2O3)	59.30	56.77	88.79
Total	100.04	100.10	100

LOI: loss on ignition.

Fig. 1 XRD patterns of volcanic scoria (Z_D and Z_G).

Fig. 2 XRD patterns of kaolin ($\text{M}{{\text{Y}}^{\prime }}_3$) and metakaolin (MK).

Fig. 3 Particle size distribution of Z_D, Z_G and MK (A: density distribution; B: cumulative distribution).

Fig. 4 XRD patterns of geopolymers obtain with blend Z_G–MK. a: Z_G5 (Ms = 1.1); b: Z_G5 (Ms = 1.4); c: Z_G25 (Ms = 1.1) and d: Z_G25 (Ms = 1.4).

Fig. 5 XRD patterns of geopolymers obtain with blend Z_D–MK. a′: Z_D5 (Ms = 1.1); b′: Z_D5 (Ms = 1.4); c′: Z_D25 (Ms = 1.1) and d′: Z_D25 (Ms = 1.4).

Fig. 6 FTIR spectra of Z_G, MK and geopolymers Z_G5 (a: Ms = 1.1 and b: Ms = 1.4).

Fig. 7 FTIR spectra of Z_G, MK and geopolymers Z_G25 (c: Ms = 1.1 and d: Ms = 1.4).

Fig. 8 FTIR spectra of Z_D, MK and geopolymers Z_D5 (a′: Ms = 1.1 and b′: Ms = 1.4).

Fig. 9 FTIR spectra of Z_D, MK and geopolymers Z_D25 (c′: Ms = 1.1 and d′: Ms = 1.4).

Fig. 10 Setting time of geopolymers (a): Z_G/MK and (b): Z_D/MK.

Fig. 11 Compressive strength of geopolymers (a): Z_G/MK and (b): Z_D/MK.

Fig. 12 SEM analysis of geopolymers (a: Z_G5, Ms = 1.1; b: Z_G5, Ms = 1.4; c: Z_G25, Ms = 1.1 and d: Z_G25, Ms = 1.4).

Fig. 13 SEM analysis of geopolymers (a′: Z_D5, Ms = 1.1; b′: Z_D5, Ms = 1.4; c′: Z_D25, Ms = 1.1 and d′: Z_D25, Ms = 1.4).