Palm oil fuel ash based mortar compositions
A mortar composition, which includes (i) a treated palm oil fuel ash, wherein the treated palm oil fuel ash is the only binder present, (ii) a fine aggregate, (iii) an alkali activator containing an aqueous solution of sodium hydroxide and sodium silicate, and (iv) aluminum hydroxide as a strength enhancer. A cured mortar made from the mortar composition is also disclosed with advantageous compressive strength properties.
1. A mortar composition, comprising:
a treated palm oil fuel ash as a binder, wherein the treated palm oil fuel ash is the only binder present;
a fine aggregate;
an alkali activator comprising an aqueous solution of sodium hydroxide and sodium silicate; and
aluminum hydroxide as a strength enhancer.
2. The mortar composition of claim 1 , wherein the treated palm oil fuel ash is present in an amount of 20 to 30 wt. %, based on a total weight of the mortar composition.
3. The mortar composition of claim 1 , wherein the treated palm oil fuel ash is obtained sequentially from drying raw palm oil fuel ash at 80 to 120° C., sieving to a particle size of less than 300 μm, a first mechanical ball milling, calcining at 500 to 600° C., and a second mechanical ball milling.
4. The mortar composition of claim 1 , wherein the treated palm oil fuel ash has a median particle size (d 50 ) of 0.5 to 2.0 μm.
5. The mortar composition of claim 1 , wherein the treated palm oil fuel ash comprises, as constituent oxides, 60 to 72 wt. % SiO 2 , 4 to 8 wt. % Al 2 O 3 , 3 to 7 wt. % Fe 2 O 3 , 3 to 8 wt. % CaO, 1 to 5 wt. % MgO, 3 to 7 wt. % K 2 O, 0.2 to 0.5 wt. % SO 3 , 0.1 to 0.25 wt. % Na 2 O, and 1 to 5 wt. % of P 2 O 3 , each based on a total weight of the treated palm oil fuel ash.
6. The mortar composition of claim 1 , wherein the treated palm oil fuel ash comprises, as constituent oxides, 66 to 68 wt. % SiO 2 , 6 to 7 wt. % Al 2 O 3 , 5 to 6.5 wt. % Fe 2 O 3 , 5 to 6 wt. % CaO, 2.5 to 3.5 wt. % MgO, 4.5 to 6 wt. % K 2 O, 0.3 to 0.35 wt. % SO 3 , 0.18 to 0.2 wt. % Na 2 O, and 3 to 4 wt. % of P 2 O 3 , each based on a total weight of the treated palm oil fuel ash.
7. The mortar composition of claim 1 , wherein the treated palm oil fuel ash has a loss on ignition (LOI) of less 3 wt. %, based on a total weight of the treated palm oil fuel ash, and a specific surface area of 1.4 to 1.6 m 2 /g.
8. The mortar composition of claim 1 , wherein a weight ratio of the fine aggregate to the treated palm oil fuel ash is 1:1 to 2:1.
9. The mortar composition of claim 1 , wherein the fine aggregate has a fineness modulus of 1.8 to 2.1 and a saturated surface dry (SSD) specific gravity of 2.5 to 2.7.
10. The mortar composition of claim 1 , wherein the fine aggregate is dune sand.
11. The mortar composition of claim 1 , wherein a weight ratio of the alkali activator to the treated palm oil fuel ash is 0.3:1 to 0.7:1.
12. The mortar composition of claim 1 , wherein a weight ratio of sodium silicate to sodium hydroxide is 1:1 to 3:1.
13. The mortar composition of claim 1 , wherein the alkali activator is formed from an aqueous solution of sodium hydroxide having a sodium hydroxide concentration of 10 to 12 mol/L.
14. The mortar composition of claim 1 , wherein a weight ratio of the aluminum hydroxide to the treated palm oil fuel ash is 0.01:1 to 0.05:1.
15. The mortar composition of claim 1 , wherein the aluminum hydroxide is the only strength enhancer present.
16. The mortar composition of claim 1 , which has weight ratio of water to the treated palm oil fuel ash of 0.2 to 0.98.
17. The mortar composition of claim 1 , which consists of the treated palm oil fuel ash, the fine aggregate, sodium hydroxide, sodium silicate, aluminum hydroxide, and water.
18. A cured mortar comprising the mortar composition of claim 1 in cured form.
19. The cured mortar of claim 18 , which has a 28 day compressive strength of 25 to 36 MPa.
20. The cured mortar of claim 18 , which has a 28 day compressive strength of 30 to 35.6 MPa.