Alkali activated natural pozzolan based concrete containing ground granulated blast furnace slag

Patent metadata

Field	Value
Publication number	US-2020277230-A1
Application number	US-201916290314-A
Country	US
Kind code	A1
Filing date	Mar 1, 2019
Priority date	Mar 1, 2019
Publication date	Sep 3, 2020
Grant date	—

Abstract

Alkali activated concrete compositions containing natural pozzolan, ground granulated blast furnace slag, alkali activators such as an alkali hydroxide and an alkali silicate, and optionally fine and coarse aggregates. Alkali activated concretes made therefrom and methods of making such concretes are also specified. The inclusion of ground granulated blast furnace slag provides significantly superior mechanical strength (e.g. compressive strength) to the alkali activated concretes within 12-24 hours of curing at 30-60° C.

First claim

1 : An alkali activated concrete composition, comprising:
a natural pozzolan; a ground granulated blast furnace slag; an alkali activator comprising an alkali hydroxide and an alkali silicate, wherein: the natural pozzolan comprises 35-50 wt % of SiO 2 , 10-25 wt % of Fe 2 O 3 , 5-15 wt % of Al 2 O 3 , and 8-15 wt % of CaO, each relative to a total weight of the natural pozzolan; the ground granulated blast furnace slag comprises 30-35 wt % of SiO 2 , 0.5-5 wt % of Fe 2 O 3 , 10-12 wt % of Al 2 O 3 , and 40-50 wt % of CaO, each relative to a total weight of the ground granulated blast furnace slag; a weight ratio of the natural pozzolan to the ground granulated blast furnace slag is in a range of 1:1 to 20:1; a weight ratio of the alkali silicate to the alkali hydroxide is in a range of 2:1 to 3:1; and the alkali activated concrete composition is devoid of fly ash.

2 : The alkali activated concrete composition of claim 1 , wherein the alkali hydroxide is sodium hydroxide.

3 : The alkali activated concrete composition of claim 1 , wherein the alkali silicate is sodium silicate.

4 : The alkali activated concrete composition of claim 1 , further comprising a fine aggregate and a coarse aggregate.

5 : The alkali activated concrete composition of claim 4 , wherein the fine aggregate comprises sand having a specific gravity of 2.2-3.2.

6 : The alkali activated concrete composition of claim 4 , wherein the coarse aggregate comprises crushed limestone having a specific gravity of 2.1-3.0.

7 : The alkali activated concrete composition of claim 1 , wherein the weight ratio of the natural pozzolan to the ground granulated blast furnace slag is in a range of 1:1 to 4:1.

8 : The alkali activated concrete composition of claim 1 , wherein the weight ratio of the alkali silicate to the alkali hydroxide is in a range of 2.4:1 to 2.7:1.

9 : The alkali activated concrete composition of claim 4 , which has a weight percentage of the natural pozzolan ranging from 8-20% relative to a total weight of the alkali activated concrete composition.

10 : The alkali activated concrete composition of claim 4 , which has a weight percentage of the ground granulated blast furnace slag ranging from 0.4-15% relative to a total weight of the alkali activated concrete composition.

11 : The alkali activated concrete composition of claim 4 , which has a weight percentage of the alkali silicate ranging from 5-10% relative to a total weight of the alkali activated concrete composition.

12 : The alkali activated concrete composition of claim 4 , which has a weight percentage of the alkali hydroxide ranging from 1.5-5% relative to a total weight of the alkali activated concrete composition.

13 : The alkali activated concrete composition of claim 4 , wherein a weight ratio of the coarse aggregate to the fine aggregate is in a range of 3:1 to 1:1.

14 : The alkali activated concrete composition of claim 4 , consisting essentially of:
the natural pozzolan; the ground granulated blast furnace slag; the alkali hydroxide; the alkali silicate; the fine aggregate; and the coarse aggregate, wherein: a weight ratio of the natural pozzolan to the ground granulated blast furnace slag is in a range of 1:1 to 20:1; and a weight ratio of the alkali silicate to the alkali hydroxide is in a range of 2:1 to 3:1.

15 : A wet concrete slurry, comprising:
the alkali activated concrete composition of claim 4 ; and water, wherein a weight ratio of the water to the alkali activated concrete composition is in a range of 1:5 to 1:25.

16 : An alkali activated concrete, comprising the wet concrete slurry of claim 15 in a cured form.

17 : The alkali activated concrete of claim 16 , which has a 24-hour unit weight of 2,100-2,400 kg/m 3 as determined by ASTM C138.

18 : The alkali activated concrete of claim 16 , which has a 12-hour compressive strength of 25-70 MPa as determined by ASTM C109 when cured at 30-60° C.

19 : A method of producing the alkali activated concrete of claim 16 , the method comprising:
casting the wet concrete slurry in a mold to form a casted wet concrete; and curing the casted wet concrete for 0.5-30 days thereby forming the alkali activated concrete.

20 : A two-component concrete kit, comprising:
a concrete package comprising:
a natural pozzolan;
a ground granulated blast furnace slag;
a fine aggregate comprising sand; and
a coarse aggregate comprising crushed limestone, and
an alkali package comprising an alkali hydroxide and an alkali silicate, wherein:
the natural pozzolan comprises 35-50 wt % of SiO 2 , 10-25 wt % of Fe 2 O 3 , 5-15 wt % of Al 2 O 3 , and 8-15 wt % of CaO, each relative to a total weight of the natural pozzolan;
the ground granulated blast furnace slag comprises 30-35 wt % of SiO 2 , 0.5-5 wt % of Fe 2 O 3 , 10-12 wt % of Al 2 O 3 and 40-50 wt % of CaO, each relative to a total weight of the ground granulated blast furnace slag;
a weight ratio of the natural pozzolan to the ground granulated blast furnace slag is in a range of 1:1 to 20:1; and
a weight ratio of the alkali silicate to the alkali hydroxide is in a range of 2:1 to 3:1.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Ibrahim Mohammed
• Mohamed Hatim Dafalla
• Barry Mohammed Salihu
• Alhems Luai M

Classifications

• Y02P40/10

  Production of cement, e.g. improving or optimising the production methods; Cement grinding · CPC title

• Y02W30/91

  Use of waste materials as fillers for mortars or concrete · CPC title

• C04B2103/0088

  Compounds chosen for their latent hydraulic characteristics, e.g. pozzuolanes · CPC title

• C04B22/062

  of the alkali or alkaline-earth metals · CPC title

• C04B18/141

  Slags · CPC title