Method of enhancing the latent hydraulic and/or pozzolanic reactivity of materials

Abstract

The present invention relates to a method of enhancing the latent hydraulic and/or pozzolanic reactivity of materials, especially of waste and by-products, comprising the steps: providing a starting material containing sources for CaO and at least one of SiO.sub.2 and AI.sub.2O.sub.3 mixing the starting material with water at a water/solids ratio from 0.1 to 100 hydrothermal treating of the starting material mixed with water in an autoclave at a temperature of 100 to 300 C. and a residence time from 0.1 to 24 hours to provide an autoclaved product suitable as supplementary cementitious material.

Claims

1. A method of enhancing the latent hydraulic and/or pozzolanic reactivity of a material comprising the steps: providing a starting material containing sources for CaO and at least one of SiO.sub.2 and Al.sub.2O.sub.3, mixing the starting material with water at a water/solids ratio from 0.1 to 100, hydrothermal treating of the starting material mixed with water in an autoclave at a temperature of 100 to 300 C. and a residence time from 0.1 to 50 hours to provide an autoclaved product with hydraulic, pozzolanic, or latent hydraulic reactivity, and grinding the autoclaved product to a fineness of 2,000 to 10,000 cm.sup.2/g.

2. The method according to claim 1, wherein the starting material has a molar ratio Ca/(Si+Al+Fe) from 1.5 to 3.

3. The method according to claim 2, wherein the required ratio Ca/(Si+Al+Fe) is adjusted by adding further reactants before treatment begins.

4. The method according to claim 1, wherein the starting material is selected from the group consisting of high calcium fly ash (calcium content of Class C fly ash), low calcium fly ash (calcium content of Class F fly ash), incineration ash from combustion of municipal wastes both solid and liquid, bottom ash, slag, quartz, sand, gravel, used concrete, asbestos, and mixtures thereof.

5. The method according to claim 1, further comprising mechanically treating the starting material to optimize particle size and particle size distribution.

6. The method according to claim 1, wherein further elements or oxides are added in an amount of 0.1 to 30% by weight while mixing the starting materials or in a subsequent step.

7. The method according to claim 6, wherein the further elements are selected from the group consisting of CaSO.sub.4 H.sub.2O, CaSO.sub.4, CaHPP.sub.2 2H.sub.2O, Ca.sub.3P.sub.2O.sub.8, NaOH, KOH, Na.sub.2CO.sub.3, K.sub.2CO.sub.3, MgCO.sub.3,MgSO.sub.4, Na.sub.2Al.sub.2O.sub.4, Na.sub.3PO.sub.4, K.sub.3PO.sub.4, Na.sub.2[B.sub.4O.sub.5(OH).sub.4] 108 8H.sub.2O, CaCl.sub.2, Ca(NO.sub.3).sub.2, MgCl.sub.2, Mg(NO.sub.3).sub.2, AlCl.sub.3, Al(NO.sub.3).sub.3, FeCl.sub.3, Fe(NO.sub.3).sub.3, Ca(CH.sub.3COO).sub.2, Mg(CH.sub.3COO).sub.2, Al(CH.sub.3COO).sub.3, Ca(HCOO).sub.2, Mg(HCOO).sub.2, Al(HCOO).sub.3, and mixtures thereof.

8. The method according to claim 1, wherein the starting material mixture is seeded with seed crystals which contain calcium silicate hydrate, Portland clinker, granulated blast furnace slag, magnesium silicates, calcium sulphate aluminate (belite) cement, sodium silicate, and/or glass powder.

9. The method according to claim 1, wherein hydrothermal treatment in the autoclave is carried out at a temperature from 150 to 250 C.

10. The method according to claim 1, wherein the starting material has a molar ratio Ca/(Si+Al+Fe) from 1.5 to 2.5.

11. The method according to claim 1, wherein hydrothermal treatment in the autoclave is carried out for 16 to 32 hours.

12. The method according to claim 1, where hydrothermal treatment in the autoclave is carried out for 10 to 40 hours.

13. The method according to claim 1, wherein the autoclaved product has enhanced hydraulic, pozzolanic, or latent hydraulic reactivity as compared to the starting material.

14. A method of enhancing the latent hydraulic or pozzolanic reactivity of a material, comprising the steps: providing a starting material containing sources of CaO and at least one of SiO.sub.2 and Al.sub.2O.sub.3, mixing the starting material with water at a water/solids ratio from 0.1 to 100, hydrothermal treating of the starting material mixed with water in an autoclave at a temperature of 100 to 300 C. and a residence time from 0.1 to 50 hours to provide an autoclaved product, tempering the autoclaved product at a temperature ranging from 350 to 600 C. to provide an autoclaved product with pozzolanic or latent hydraulic reactivity, and grinding the autoclaved and tempered product to a fineness of 2,000 to 10,000 cm.sup.2/g.

15. The method according to claim 14, wherein the heating rates are from 10 to 6000 C./minute.

16. The method according to claim 14, wherein the residence time in the tempering step is from 0.01 to 600 minute.

17. The method according to claim 14, wherein an additional holding time of 1 to 120 minutes, during at 400 to 400 C., is performed during the tempering.

18. The method according to claim 14, wherein the starting material is selected from the group consisting of high calcium fly ash (calcium content of Class C fly ash), low calcium fly ash (calcium content of Class F fly ash), incineration ash from combustion of municipal wastes both solid and liquid, bottom ash, slag, quartz, sand, gravel, used concrete, asbestos, and mixtures thereof.

19. The method according to claim 14, wherein the autoclaved product is tempered at a temperature from 400 to 550 C.

20. The method according to claim 11, wherein the autoclaved product is tempered at a temperature from 400 to 495 C.

21. The method according to claim 11, wherein a heating rates are from 20 to 100 C./minute.

22. The method according to claim 11, wherein a residence time in the tempering step is from 1 to 120 minutes.

23. The method according to claim 11, wherein the residence time in the tempering step is from 5 to 60 minutes.

24. The method according to claim 11, wherein an additional holding time of 10 to 60 minutes, during heating at 400 to 440 C., is performed during tempering.

25. The method according to claim 11, wherein the starting material has a molar ratio Ca/(Si+Al+Fe) ranging from 1.5 to 2.5 of about 2.

26. The method according to claim 11, wherein hydrothermal treatment in the autoclave is carried out at a temperature ranging from 150 to 250 C.

27. The method according to claim 14, further comprising mechanically treating the starting material to optimize particle size and particle size distribution.

28. The method according to claim 14, wherein further elements or oxides, sodium, potassium, boron, sulphur, phosphorous, or a combination thereof, are added in an amount of 0.1 to 30% by weight while mixing the starting materials or in a subsequent step.

29. The method according to claim 14, wherein the starting material mixture is seeded with seed crystals which contain calcium silicate hydrate, Portland clinker, granulated blast furnace slag, magnesium silicates, calcium sulphate aluminate (belite) cement, sodium silicate, glass powder, or mixtures thereof.

30. The method according to claim 14, wherein the starting material has a molar ratio Ca/(Si+Al+Fe) from 1.5 to 2.5.

31. The method according to claim 11, wherein hydrothermal treatment in the autoclave is carried out for 16 to 32 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in further detail below on the basis of exemplary embodiments and with reference to the drawings, in which:

(2) FIG. 1a shows measured heat flow according to Example 1,

(3) FIG. 1b shows cumulative heat flow according to Example 1,

(4) FIG. 2a shows measured heat flow according to Example 2,

(5) FIG. 2b shows cumulative heat flow according to Example 2,

(6) FIG. 3a shows measured heat flow according to Example 3,

(7) FIG. 3b shows cumulative heat flow according to Example 3,

(8) FIG. 4a shows measured heat flow according to Example 4,

(9) FIG. 4b shows cumulative heat flow according to Example 4,

(10) FIG. 5a shows measured heat flow according to Example 5,

(11) FIG. 5b shows cumulative heat flow according to Example 5,

(12) FIG. 6a shows measured heat flow according to Example 6,

(13) FIG. 6b shows cumulative heat flow according to Example 6,

(14) FIG. 7a shows measured heat flow according to Example 7,

(15) FIG. 7b shows cumulative heat flow according to Example 7,

(16) FIG. 8a shows measured heat flow according to Example 8,

(17) FIG. 8b shows cumulative heat flow according to Example 8,

(18) FIG. 9a shows measured heat flow according to Example 9,

(19) FIG. 9b shows cumulative heat flow according to Example 9,

(20) FIG. 10a shows measured heat flow according to Example 10,

(21) FIG. 10b shows cumulative heat flow according to Example 10,

(22) FIG. 11a shows measured heat flow according to Example 11, and

(23) FIG. 11b shows cumulative heat flow according to Example 11.

EXAMPLE 1

(24) 10 g of slag were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. and 1.1 MPa for 16 h once or twice in a stainless steel autoclave. 2% NaOH (solid/solid) was added to the solution before each autoclaving step to promote the dissolution of the glassy phases. The products obtained after 16 h and after 32 h autoclaving were tempered for 1 h directly at 500 C.

(25) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used slag designated G is given in table 1. This slag is unsuitable as SCM due to its high content of crystalline phases.

(26) TABLE-US-00001 TABLE 1 Component amount [%] SiO.sub.2 37.67 Al.sub.2O.sub.3 8.76 TiO.sub.2 0.35 MnO 0.41 Fe.sub.2O.sub.3 0.22 CaO 40.52 MgO 7.55 K.sub.2O 0.66 Na.sub.2O 0.45 SO.sub.3 2.18 P.sub.2O.sub.5 0.01 Amorphous 79.24 Free lime 0.00 LOI 0.25

(27) Mixes of 70% OPC and 30% hydrothermally treated slag or of 70% OPC and 30% hydrothermally treated and tempered slag were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden) The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated slag and 70% OPC and 30% quartz. The measured heat flow and the cumulated heat flow are shown in FIGS. 1a and 1b.

(28) The heat evolution curves indicate a significant accelerating effect for blends of OPC and hydrothermally treated material compared to blends of OPC with untreated material. Mixes of OPC with hydrothermally treated slag show a maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. Subsequent tempering further increases the reactivity of the hydrothermally treated product and results in greater maximal values for the main heat peak release. In terms of cumulative heat release, after 8 h the heat output for the blends of OPC with hydrothermally treated and tempered slag are three fold higher compared to blends of OPC with untreated slag. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment and hydrothermal treatment followed by tempering has on the poorly reactive slags.

EXAMPLE 2

(29) 10 g of slag were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. 2% NaOH (solid/solid) was added to the solution before the autoclaving step to promote the dissolution of the glassy phases. The autoclaved product obtained was tempered for 1 h directly at 500 C.

(30) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used slag designated V is given in table 2. This slag has a low reactivity.

(31) TABLE-US-00002 TABLE 2 Component amount [%] SiO.sub.2 38.74 Al.sub.2O.sub.3 11.16 TiO.sub.2 0.49 MnO 1.16 Fe.sub.2O.sub.3 0.58 CaO 35.14 MgO 8.51 K.sub.2O 1.09 Na.sub.2O 0.33 SO.sub.3 1.98 P.sub.2O.sub.5 0.00 Amorphous 89.18 Free lime 0 LOI 1.29

(32) Mixes of 70% OPC and 30% hydrothermally treated slag or of 70% OPC and 30% hydrothermally treated and tempered slag were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated slag and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 2a and 2b.

(33) The heat evolution curves indicate a significant accelerating effect for blends of OPC with treated material compared to blends of OPC with untreated material. Mixes of OPC with hydrothermally treated and tempered slags show a maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. The maximum rate of the heat release shifts to the left with extended duration of the hydrothermal step.

(34) In terms of cumulative heat release, after 8 h the heat output for the blends of OPC with hydrothermally treated and tempered slags are two and three fold higher (three fold higher when the autoclaving step is repeated) compared to blends of OPC with untreated slag. After 16 h autoclaving the heat release values for modified systems are higher by 38% and 75% respectively for mixes of OPC and hydrothermally treated slag with subsequent tempering. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment and hydrothermal treatment followed by tempering has on the poorly reactive slags.

EXAMPLE 3

(35) 10 g of slag were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. 2% water glass (Na.sub.2O.SiO.sub.2) (solid/solid) was added to the solution before the autoclaving step to promote the dissolution of the glassy phases. The autoclaved product obtained was tempered for 1 h directly at 500 C.

(36) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used slag designated E is given in table 3. This slag is a fairly reactive material, but lacks ideal reactivity.

(37) TABLE-US-00003 TABLE 3 Component amount [%] SiO.sub.2 34.97 Al.sub.2O.sub.3 11.42 TiO.sub.2 1.11 MnO 0.27 Fe.sub.2O.sub.3 0.46 CaO 41.64 MgO 5.72 K.sub.2O 0.48 Na.sub.2O 0.08 SO.sub.3 3.04 P.sub.2O.sub.5 0.03 Amorphous 44.6 Free lime 0.00 LOI 1.30

(38) Mixes of 70% OPC and 30% hydrothermally treated and tempered slag were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated slag and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 3a and 3b.

(39) The heat evolution curves indicate a significant accelerating effect compared to blends of OPC with untreated material. Mixes of OPC with hydrothermally treated slag with subsequent tempering show a maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. After 8 h, the cumulative heat output for the blend of OPC with hydrothermally treated and tempered slag is 52% higher compared to the blend of OPC with non-treated slag and by 25% higher at 16 h. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on the fairly reactive slags.

EXAMPLE 4

(40) 10 g of slag were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. 2% NaOH (solid/solid) was added to the solution before the autoclaving step to promote the dissolution of the glassy phases. The autoclaved product obtained was tempered for 1 h directly at 500 C.

(41) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used slag designated M is given in table 4. This slag is a fairly reactive material.

(42) TABLE-US-00004 TABLE 4 Component amount [%] SiO.sub.2 35.84 Al.sub.2O.sub.3 11.06 TiO.sub.2 0.99 MnO 0.34 Fe.sub.2O.sub.3 0.44 CaO 38.99 MgO 8.19 K.sub.2O 0.49 Na.sub.2O 0.15 SO.sub.3 3.18 P.sub.2O.sub.5 0.00 Amorphous 92.6 Free lime 0.00 LOI 1.37

(43) Mixes of 70% OPC and 30% hydrothermally treated and tempered slag were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30 non-treated slag and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow is shown in FIGS. 4a and 4b.

(44) The heat evolution curves indicate a significant accelerating effect for the blend of OPC and treated material compared to the blend of OPC with untreated material. The mix of OPC with hydrothermally treated and tempered slag shows a maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. After 8 h the cumulative heat output for the blend of OPC with hydrothermally treated and tempered slag are 64% higher compared to blends of OPC with non-treated slag and by 27% higher at 16 h. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on fairly reactive slags.

EXAMPLE 5

(45) 10 g of slag were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. and 1.1 MPa in a stainless steel autoclave once or twice for 16 h. 2% NaOH (solid/solid) was added to the solution before each autoclaving step to promote the dissolution of the glassy phases. The autoclaved product obtained was tempered for 1 h directly at 500 C.

(46) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used slag designated I is given in table 5.

(47) TABLE-US-00005 TABLE 5 Component amount [% SiO.sub.2 34.68 Al.sub.2O.sub.3 13.43 TiO.sub.2 0.96 MnO 0.4 Fe.sub.2O.sub.3 0.79 CaO 36.13 MgO 10.03 K.sub.2O 0.41 Na.sub.2O 0.24 SO.sub.3 2.75 P.sub.2O.sub.5 0.01 Amorphous 98.6 Free lime 0.00 LOI 1.53

(48) Mixes of 70% OPC and 30% hydrothermally treated and tempered slag were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated slag and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 5a and 5b.

(49) The heat evolution curves indicate a significant accelerating effect for blends of OPC with autoclaved and tempered material compared to blends of OPC with untreated material. The mixes of OPC with hydrothermally treated slag with subsequent tempering show the maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. After 8 h the cumulative heat output for the blend of OPC with hydrothermally treated and tempered slag are 125% higher compared to blends of OPC with non-treated slag and by 43% higher at 16 h. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on reactive slags.

EXAMPLE 6

(50) 10 g of fly ash were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. and 1.1 MPa in a stainless steel autoclave two times for 16 h. 2% NaOH (solid/solid) was added to the solution before each autoclaving step to promote the dissolution. The autoclaved product obtained was tempered for 1 h directly at 500 C.

(51) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used fly ash designated F is given in table 6. This fly ash has a high free lime content and a high crystalline content so that it is not suitable to be used as SCM.

(52) TABLE-US-00006 TABLE 6 Component amount [%] SiO.sub.2 17.04 Al.sub.2O.sub.3 2.32 TiO.sub.2 0.16 MnO 0.32 Fe.sub.2O.sub.3 13.75 CaO 40.46 MgO 4.56 K.sub.2O 0.31 Na.sub.2O 1.186 SO.sub.3 14.94 P.sub.2O.sub.5 0.017 Amorphous 1.53 Free lime 21.6 LOI 3.17

(53) Blends of 70% OPC and 30% hydrothermally treated fly ash and hydrothermally treated fly ash with subsequent tempering were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated fly ash and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 6a and 6b.

(54) The heat evolution curves indicate an accelerating effect for blends of OPC with treated material compared to blends of OPC with untreated material. The mixes of OPC with hydrothermally treated fly ash show the maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. Subsequent tempering leads to further acceleration compared to OPC. After 8 h the cumulative heat output for the blend of OPC with hydrothermally treated and tempered fly ash are 14% higher compared to blends of OPC with non-treated fly ash. At 16 h the values are 10% higher. The values remain 11% greater after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on the low reactive fly ashes.

EXAMPLE 7

(55) 10 g of fly ash were added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. and 1.1 MPa in a stainless steel autoclave two times for 16 h. 2% NaOH (solid/solid) was added to the solution before each autoclaving step to promote the dissolution. The autoclaved product was tempered for 1 h directly at 500 C.

(56) The chemical composition including the loss on ignition at 1050 C. (LOI) of the used fly ash designated B is given in table 7. This fly ash has a high CaO content rendering its use as SCM problematic.

(57) TABLE-US-00007 TABLE 7 Component amount [%] SiO.sub.2 35.7 Al.sub.2O.sub.3 21.6 TiO.sub.2 1.21 MnO 0.03 Fe.sub.2O.sub.3 6.02 CaO 25.50 MgO 1.34 K.sub.2O 0.13 Na.sub.2O 0.07 SO.sub.3 3.96 P.sub.2O.sub.5 0.15 Amorphous 47.96 Free lime 2.4 LOI 3.48

(58) Blends of 70% OPC and 30% twice hydrothermally treated fly ash and twice hydrothermally treated fly ash with subsequent tempering were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for mixes of 70% OPC and 30% non-treated fly ash and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 7a and 7b.

(59) The heat evolution curves indicate an accelerating effect for blends of OPC and treated material compared to blends of OPC with untreated material. The mixes of OPC with hydrothermally treated fly ash show the maximum rate of the heat release shifted to the left and a faster onset of the acceleration period. Subsequent tempering leads to further acceleration and to an increase in the rate of the maximum heat release compared to OPC. After 8 h the cumulative heat output for the blend of OPC with hydrothermally treated and tempered fly ash are 35% higher compared to blends of OPC with non-treated fly ash. At 16 h the values are 31% higher. The values are not higher after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on the low reactive fly ashes.

EXAMPLE 8

(60) 10 g of a mix of the two fly ashes F and B was added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. 2% NaOH (solid/solid) was added to the solution before the autoclaving step to promote the dissolution. The hydrated product obtained was tempered for 1 h directly at 500 C.

(61) The chemical compositions of fly ashes F and B are presented in table 6 and table 7. The composition of the mixes chosen to be autoclaved is given in table 8.

(62) TABLE-US-00008 TABLE 8 Fly ash + B Fly ash + F Mix 25/75 25% 75% Mix 50/50 50% 50% Mix 75/25 75% 25%

(63) Blends of 70% OPC and 30% hydrothermally treated mixes of fly ashes with subsequent tempering were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The results were compared to the heat flow recorded for blends of 70% OPC and 30% non-treated individual fly ash and 70% OPC and 30% quartz. The measured heat flow and cumulative heat flow are shown in FIGS. 8a and 8b.

(64) The heat evolution curves indicate an accelerating effect for blends of OPC and treated material compared to blends of OPC with untreated material. The mixes of OPC with hydrothermally treated and tempered fly ashes show a higher maximum rate of the heat release which is additionally shifted to the left and a faster onset of the acceleration period. After 8 h the cumulative heat output for the blend of OPC with hydrothermally treated and tempered fly ashes are from 30 to 59% higher compared to blends of OPC with non-treated fly ash. At 16 h the values are 19 to 37% higher. The values remain greater after 7 days. This clearly shows the benefit that hydrothermal treatment followed by tempering has on the low reactive fly ashes.

EXAMPLE 9

(65) A raw meal consisting of 49.97% portlandite, 25.015% slag and 25.015% fly ash was added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. The autoclaved product was tempered for 1 h directly at 500 C.

(66) The chemical compositions and loss on ignition at 1050 C. (LOI) of the fly ash, slag and portlandite are listed in table 9.

(67) TABLE-US-00009 TABLE 9 Portlandite Slag Fly ash Component amount [%] SiO.sub.2 35.84 56.35 Al.sub.2O.sub.3 11.06 21.63 TiO.sub.2 0.99 0.97 MnO 0.34 0.04 Fe.sub.2O.sub.3 0.44 6.95 CaO 75.67 38.99 4.08 MgO 8.19 1.86 K.sub.2O 0.49 1.6 Na.sub.2O 0.15 0.81 SO.sub.3 3.18 0.022 P.sub.2O.sub.5 0.00 0.39 Amorphous 92.6 62.5 Free lime 0.00 0.5 LOI 24.33 1.37 3.87

(68) Mixes of fly ash, slag and portlandite with and without hydrothermal treatment with subsequent tempering were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The measured heat flow and cumulative heat flow are shown in FIGS. 9a and 9b.

(69) The heat development measurements indicate that after hydrothermal treatment followed by tempering the blend of fly ash, slag and portlandite releases substantially higher heat over all the measuring time. This clearly shows that SCMs can benefit from hydrothermal treatment followed by tempering.

EXAMPLE 10

(70) A mix 1 consisting of 30.77% portlandite, 19.18% brucite and 50.06% fly ash was added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. The autoclaved product was tempered for 1 h directly at 500 C.

(71) A mix 2 consisting of 25.87% portlandite and 74.13% fly ash was added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. The autoclaved product was tempered for 1 h directly at 500 C.

(72) The chemical composition and loss on ignition (LOI) at 1050 C. of the starting materials fly ash designated K, brucite and portlandite is listed in table 10.

(73) TABLE-US-00010 TABLE 10 Portlandite Brucite Fly-ash K Component amount [%] SiO.sub.2 42.98 Al.sub.2O.sub.3 19.96 TiO.sub.2 0.66 MnO 0.04 Fe.sub.2O.sub.3 8.41 CaO 75.67 21.4 MgO 68.96 2.24 K.sub.2O 1.47 Na.sub.2O 0.27 SO.sub.3 1.55 P.sub.2O.sub.5 0.25 Amorphous 82.7 Free lime 3.4 LOI 24.33 31.04 0.05

(74) The autoclaved and tempered mixes of fly ash, slag and portlandite were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The measured heat flow and cumulative heat flow are shown in FIGS. 10a and 10b. It can be seen that the autoclaved and tempered products show a high reactivity.

EXAMPLE 11

(75) A raw meal consisting of 44.55% brucite and 55.46% fly ash K was added to water (water-to-solid (w/s) of 10) and hydrothermally treated at 185 C. for 16 h and 1.1 MPa in a stainless steel autoclave. The autoclaved product was tempered for 1 h directly at 500 C. The chemical composition and loss on ignition (LOI) at 1050 C. of the starting materials fly ash and brucite is found in table 10.

(76) Mixes of fly ash and brucite with and without hydrothermal treatment with subsequent tempering were mixed with water (water-to solid ratio of 0.5) and the heat flow development was measured by isothermal calorimetry (TAM Air, TA Instruments, Sweden). The measured heat flow and cumulative heat flow are shown in FIGS. 11a and 11b.

(77) The heat development measurements indicated that, after hydrothermal treatment followed by tempering, the blend of fly ash and brucite releases substantially higher heat over all the measuring time. This clearly shows the enhanced reactivity of SCMs resulting from hydrothermal treatment followed by tempering.