Low density cementitious compositions for use at low and high temperatures

1. A manufactured cementitious binder, comprising:

a hydraulic binder in an amount in the range from 50 to 80% by weight of the cementitious binder;

a first siliceous based material in an amount in the range from 0.5 to 35% by weight of the cementitious binder, the first siliceous based material having a (SiO 2 )/(Al 2 O 3 ) ratio by weight greater than 2.5;

a second siliceous based material in an amount in the range from 10 to 25% by weight of the cementitious binder, the second siliceous based material being different from the first siliceous based material and having (a) a (SiO 2 )/(Al 2 O 3 ) ratio by weight greater than 10 and (b) a BET specific surface area greater than 5 m 2 /g, the second siliceous based material comprising a mixture of silica fume from zirconia production and another siliceous based material that is selected from the group consisting of precipitated silica, rice husk ash, and mixtures thereof;

an aluminum based material in the range greater than 0% by weight of the cementitious binder and less than 7% by weight of the cementitious binder and having a (SiO 2 )/(Al 2 O 3 ) ratio by weight lower than 2.5,

wherein 0.09<Al EFF /(Al EFF +Si EFF )<0.28, where

Al EFF =molar content of aluminum in the hydraulic binder, and

Si EFF =molar content of silica in the first siliceous based material for particles having a size lower than 3 μm+molar content of silica in the second siliceous based material, and

a lightweight additive in an amount less than 50% by weight of the cementitious binder;

wherein the cementitious binder provides a cementitious settable composition, when added with water, having a density less than 14 pounds per gallon (ppg) (1677.6 kg/m 3 ).

2. The manufactured cementitious binder of claim 1 , wherein the first siliceous based material is selected from the group consisting of slag, siliceous pozzolan, silica flour, and mixtures thereof.

3. The manufactured cementitious binder of claim 1 , wherein the aluminum based material is selected from the group consisting of metakaolin, calcined clay, fly ash, aluminum based natural pozzolan and mixtures thereof.

4. The manufactured cementitious binder of claim 1 , wherein the hydraulic binder in an amount in the range from 55 to 78% by weight of the cementitious binder.

5. The manufactured cementitious binder of claim 1 , wherein the first siliceous based material is in an amount in the range from 8 to 30% by weight of the cementitious binder.

6. The manufactured cementitious binder of claim 1 , wherein the second siliceous based material is in an amount in the range from 10 to 20% by weight of the cementitious binder.

7. The manufactured cementitious binder of claim 1 , wherein the hydraulic binder is Portland cement having a Blaine specific surface (BSS) greater than 4,000 m 2 /g.

8. The manufactured cementitious binder of claim 1 , wherein the hydraulic binder is Portland cement having a SO 3 content lower than 6% by weight.

9. The manufactured cementitious binder of claim 1 , wherein the cementitious binder provides a cementitious settable composition when added with water, having a 24 hour compressive strength at 180° F. (83° C.), as hardened, of at least 1500 psi (10.3 MPa).

10. A cementitious settable composition comprising:

water; and

a manufactured cementitious binder of claim 1 , wherein the cementitious settable composition has a density lower than 14 ppg (1677.6 kg/m 3 ).

11. The cementitious settable composition of claim 10 , wherein the cementitious settable composition has a density from 11 ppg (1318 kg/m 3 ) to less than 14 ppg (1677.6 kg/m 3 ).

12. A method of cementing comprising:

providing the cementitious settable composition of claim 10 ; and

introducing the cementitious settable composition into an underground formation.

13. The method of claim 12 , wherein the underground formation is a well bore.