Method for manufacturing binders hardening by hydration and carbonation

Abstract

A method for manufacturing a binder of a hydratable material includes providing a starting material from one or more raw materials convertible by tempering at 600 to 1200° C. into the hydratable material, tempering the starting material to provide the hydratable material containing not more than 10% by weight monocalcium silicate and at least 15% by weight hydratable phases in the form of lime and dicalcium silicate, wherein the residence time and the tempering temperature are adapted to obtain the hydratable material by converting not more than 80% by weight of the starting material, and cooling the hydratable material to provide the binder comprising the hydratable material. The binder can be mixed with water and optionally one or more of aggregate, additives, admixtures to obtain a binder paste that is placed, hydrated and carbonated to produce a building product.

Claims

1. A method for manufacturing a binder comprising a hydratable material comprising the steps: providing a starting material from one or more raw materials convertible by tempering at 600 to 1200° C. into the hydratable material, wherein the starting material has a Ca/Si molar ratio from 0.5 to 1.8 and contains no or up to 30% by weight of other elements than CaO and SiO.sub.2 with regard to the total mass calculated as oxides, tempering the starting material at a temperature in the range from 600 to 1200° C. during a residence time from 1 minute to 5 hours to provide the hydratable material containing crystalline hydratable phases, not more than 10% by weight monocalcium silicate and at least 15% by weight hydratable phases in the form of lime and dicalcium silicate, wherein at least 50% of the crystalline hydratable phases are dicalcium silicate, wherein the residence time and the tempering temperature are adapted to obtain the said hydratable material by converting not more than 80% by weight of the starting material, and cooling the hydratable material to provide the binder comprising the hydratable material.

2. The method according to claim 1, further comprising grinding the binder to a fineness characterized by a particle size distribution and a Rosin-Rammler Parameter (slope) n, wherein according to a determination of the particle size distribution of the binder by laser granulometry the binder has a D.sub.90≤90 μm, whereby the Rosin-Rammler Parameter (slope) n can vary from 0.6-1.4.

3. The method according to claim 1, wherein the hydratable material contains at least 15% by weight dicalcium silicate, less than 10% by weight monocalcium silicate, and from 20 to 80% by weight phases from the raw materials and/or formed during the tempering.

4. The method according to claim 1, wherein the starting material has a Ca/Si molar ratio from 0.6 to 1.2.

5. The method according to claim 3, wherein the tempering temperature ranges from 800 to 1100° C. and the residence time ranges from 5 minutes to 2 hours.

6. The method according to claim 1, wherein the raw materials are selected from the group consisting of concrete fines, overburden from quarries, low quality limestone, marl, and dolomite.

7. The method according to claim 1, wherein the tempering temperature is adjusted to range from 900 to 1100° C. for residence times from 5 minutes to 1 hour.

8. The method according to claim 1, wherein the tempering temperature is adjusted to range from 800 to 1000° C. for residence times from 30 minutes to 2 hours.

9. The method according to claim 3, wherein the starting material has a Ca/Si molar ratio from 0.6 to 1.3.

10. The method according to claim 4, wherein the tempering temperature ranges from 850 to 1050° C. and the residence time ranges from 5 minutes to 2 hours.

11. The method according to claim 4, wherein the tempering temperature is adjusted from 900 to 1100° C. for residence times from 5 minutes to 1 hour or to range from 800 to 1000° C. for residence times from 30 minutes to 2 hours.

12. The method for manufacturing a building element from a binder comprising a hydratable material comprising the steps: providing a starting material from one or more raw materials convertible by tempering at 600 to 1200° C. into the hydratable material, wherein the starting material has a Ca/Si molar ratio from 0.5 to 1.8 and contains no or up to 30% by weight of other elements than Ca and Si with regard to the total mass calculated as oxides, tempering the starting material at a temperature in the range from 600 to 1200° C. during a residence time from 1 minute to 5 hours to provide the hydratable material containing hydratable phases, not more than 10% by weight monocalcium silicate and at least 15% by weight hydratable phases in the form of lime and dicalcium silicate, wherein at least 50% of the hydratable phases are dicalcium silicate, wherein the residence time and the tempering temperature are adapted to obtain the said hydratable material by converting not more than 80% by weight of the starting material, cooling the hydratable material to provide the binder comprising the hydratable material grinding the binder to a fineness characterized by a particle size distribution and a Rosin-Rammler Parameter (slope) n, wherein according to a determination of the particle size distribution of the binder by laser granulometry the binder has a D.sub.90≤90 μm, whereby the Rosin-Rammler Parameter (slope) n can vary from 0.6-1.4 mixing the binder with water to obtain a binder paste placing the binder paste hydrating the binder paste until an amount of bound water is at least 5% of hydraulic phases mass in dry binder and carbonating the binder paste until an amount of additionally bound carbon dioxide is at least 150% of an initially bound water mass or the strength exceeds 2 MPa while still keeping the amount of bound water at at least 50% of the initially bound water mass.

13. The method according to claim 12, wherein the building element is a precast concrete part or concrete good.

14. The method according to claim 12, wherein placing comprises filling the binder paste into a mold or formwork.

15. The method according to claim 12, wherein carbonation is carried out with gaseous carbon dioxide.

16. The method according to claim 15, wherein the gaseous carbon dioxide is supplied with a pressure from atmospheric pressure to 6 bar, with a carbon dioxide concentration of at least 1% by volume.

17. The method according to claim 12, wherein carbonation is carried out with carbon dioxide dissolved during the carbonation process in an aqueous alkaline solution.

18. The method according to claim 17, wherein the solution has initially a pH in the range from 8 to 14 accounting for an activity index of OH.sup.−.

19. The method according to claim 12, wherein carbonation is carried out with carbon dioxide dissolved during the carbonation process in an aqueous solution comprising substances improving dissolution of calcium ions.

20. The method according to claim 12, wherein carbonation is carried out with carbon dioxide dissolved during the carbonation process in an aqueous solution comprising substances improving dissolution of carbonate ions.

21. The method according to claim 12, wherein the fineness of the binder is D.sub.90<μm or the Rosin-Rammler Parameter n varies from 0.7 to 1.2 if the binder is coarser.

22. The method according to claim 16, wherein the gaseous carbon dioxide is supplied with a pressure from 2 to 4 bar with a carbon dioxide concentration of at least 5% by volume.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 presents the dependence of phase composition on temperature for Portland clinker manufacturing.

DETAILED DESCRIPTION OF THE INVENTION

(2) The invention will be illustrated further with reference to the examples that follow, without restricting the scope to the specific embodiments described. If not otherwise specified any amount in % or parts is by weight and in the case of doubt referring to the total weight of the composition/mixture concerned. A characterization as “approx.”, “around” and similar expression in relation to a numerical value means that up to 10% higher and lower values are included, preferably up to 5% higher and lower values, and in any case at least up to 1% higher and lower values, the exact value being the most preferred value or limit. The invention further includes all combinations of described and especially of preferred features that do not exclude each other.

(3) The term “substantially free” means that a particular material is not purposefully added to a composition, and is only present in trace amounts or as an impurity. As used herein, unless indicated otherwise, the term “free from” means that a composition does not comprise a particular material, i.e. the composition comprises 0 weight percent of such material.

Example 1

(4) Recycled concrete fines (RCF) and limestone (L) from HeidelbergCement AG were used as raw materials. The properties of the raw materials are summarized in table 1.

(5) TABLE-US-00001 TABLE 1 Unit RCF L1 Fineness Blaine cm.sup.2/g 5460 3800 Chemical LOI 1050° C. % 17.98 43.25 composition SiO2 % 43.02 0.96 XRF AI2O3 % 6.38 0.25 TiO2 % 0.32 0.01 MnO % 0.069 0.06 Fe2O3 % 3.02 0.22 CaO % 24.39 54.21 MgO % 1.39 0.89 K2O % 0.80 0.03 Na2O % 0.35 0.00 SO3 % 1.21 0.02 P2O5 % 0.18 0.01 Sum % 99.11 99.91

(6) From RCF and L1 two mixtures were made as starting materials:

(7) CS0.6 with molar ratio Ca/Si=0.6 from 100% RCF and

(8) CS1.0 with molar ratio Ca/Si=1.0 from 77% RCF and 23% L1.

(9) The starting materials were made and homogenized in an Eirich mixer and tempered in a laboratory oven at temperatures in the range from 800-1200° C. for either 30 minutes or 60 minutes. The tempered materials were cooled in air down to room temperature. Table 2 lists the phase compositions in % by weight of the obtained binders for the different samples, temperatures, and times. All phase contents in this patent are based on XRD-Rietveld calculations if not stated otherwise. Note that the table contains only selected phases, the remaining content up to 100% is composed by other crystalline and amorphous phases either originally present in the precursor materials or formed during the tempering. The conversion was calculated as the molar amount of CS (wollastonite+pseudowollastonite) in the clinker relative to the moles of calcium oxide in all calcium-silicates and in free lime, i.e. the moles of Ca in C2S+CS+free lime. The calculation is based on the assumption that for the clinker characterized by Ca/Si<1.0 all calcium is bound in CS after complete conversion and hence CS/Ca (moles/moles) should be one for 100% conversion.

(10) TABLE-US-00002 TABLE 2 sample, temperature, dicalcium pseudo- time lime silicate wollastonite wollastonite quartz conversion CS0.6, 800° C., 1 h 1.5 18.9 1.9 33.9 0.09 CS0.6, 900° C., 1 h 3.5 28.3 5.6 2.8 28.8 0.23 CS0.6, 1000° C., 1 h 10.9 13.1 5.5 23.3 0.66 CS0.6, 1100° C., 1 h 1.9 20.0 10.0 21.0 0.92 CS0.6, 1200° C., 1 h 3.1 24.2 6.4 1.00 CS0.6, 900° C., 0.5 h 24.1 4.9 3.4 30.0 0.30 CS0.6, 1000° C., 0.5 h 14.1 9.3 3.6 27.0 0.47 CS0.6, 1100° C., 0.5 h 3.1 18.3 8.8 22.3 0.87 CS1.0, 800° C., 1 h 4.7 21.9 1.0 1.0 26.2 0.10 CS1.0, 900° C., 1 h 10.1 35.4 2.8 1.2 23.8 0.08. CS1.0, 1000° C., 1 h 3.0 43.8 3.1 1.0 18.8 0.08 CS1.0, 1100° C., 1 h 31.9 6.5 4.2 10.8 0.25 CS1.0, 1200° C., 1 h 3.5 27.7 27.7 2.5 0.96 CS1.0, 900° C., 0.5 h 11.6 22.6 2.4 2.4 25.2 0.10 CS1.0, 1000° C., 0.5 h 5.6 34.8 3.3 3.3 23.1 0.12 CS1.0, 1100° C., 0.5 h 44.2 4.9 3.0 16.9 0.14

(11) It can be seen that the desired partial conversion of the starting material took place at appropriate combinations of temperature and residence time. For low Ca/Si ratio lower temperature and longer residence time are needed. With the higher ratio Ca/Si higher temperature and lower time are better. It is also evident that monocalcium silicate comes at the cost of the targeted hydratable phases so that a high amount of CS indicates unsuitable products. It is also visible that hydratable materials produced contain significant amounts of nonhydratable and non-carbonatable phase, i.e. quartz. The targeted composition of the novel partially transformed hydratable material was achieved.

Example 2

(12) Binders were made analogously to example 1 from the low quality raw materials quarry overburden (Le, mainly loess) and limestone (L2), the compositions of which are listed in table 3.

(13) TABLE-US-00003 TABLE 3 Unit Le L2 Chemical LOI 1050° C. % 15.6 36.79 composition SiO2 % 54.49 10.69 XRF AI2O3 % 6.69 3.76 TiO2 % 0.47 0.15 MnO % 0.06 0.05 Fe2O3 % 2.83 1.15 CaO % 15.04 43.07 MgO % 2.84 2.52 K2O % 1.4 1.13 Na2O % 0.98 0.04 SO3 % 0.01 0.6 P2O5 % 0.13 0.04 Sum % 99.94 99.99

(14) The starting material contained either 70.6% quarry overburden and 29.4% limestone (samples CS0.6b, Ca/Si=0.6) or 48.0% quarry overburden and 52.0% limestone (samples CS1.0, Ca/Si=1.0). Tempering of the starting materials took place in a laboratory oven in the temperature range 900-1200° C. for 60 minutes. The tempered materials were cooled in air to room temperature. Table 4 lists the phase composition in % by weight of the obtained binder for the different samples and temperatures. Again, the table gives only selected phases, the remaining content up to 100% is composed by other crystalline and amorphous phases either originally present in the precursor materials or formed during the tempering

(15) TABLE-US-00004 TABLE 4 sample, temperature, dicalcium pseudo- time lime silicate wollastonite wollastonite quartz conversion CS0.6 900° C. 1 h 11.3 13 4.3  1.7 36.2 0.15 CS0.6 1000° C. 1 h 4.2 24.7 5.8  0.8 27.2 0.15 CS0.6 1100° C. 1 h 0.4 21.7 13.7 — 19.8 0.37 CS0.6 1200° C. 1 h 3.4 22.7 5.4 1.00 CS1.0 900° C. 1 h 15.5 21 3.4 — 22.7 0.06 CS1.0 1000° C. 1 h 9.9 31.9 3.4 15.3 0.05 CS1.0 1100° C. 1 h 2.8 44.7 6.1 — 10.9 0.10 CS1.0 1200° C. 1 h 23.4 0.4 11.1 1.4 0.35

(16) It can be seen that the partial conversion provided hydratable material made by suitable combinations of starting material composition, temperature and residence time.

Example 3

(17) Hardening of binders was examined. The clinkers CS0.6a (Ca/Si=0.6, 900° C., 1 h) and CS1.0a (Ca/Si=1.0, 1000° C., 30 minutes) were made like in example 1 and had the following phase compositions:

(18) CS0.6a: 1.4% ferrite; 1.0% maghemite; 1.2% anhydrite; 3.5% lime; 0.5% periclase; 4.1% CA Na orthorhombic; 1.2% C.sub.12A.sub.7 (mayenite); 1.4% C.sub.2S gamma; 14.4% C.sub.2S beta; 8.4% bredigite; 17.0% C.sub.2AS (gehlenite); 0.8% akermanite; 4.3% anorthite; 28.8% quartz; 1.7% rankinite; 5.6% wollastonite 1T; 2.8% pseudo-wollastonite; 1.9% X ray amorphous; and
CS1.0a: 3.2% ferrite; 1.0% maghemite; 1.4% anhydrite; 5.4% lime; 0.7% periclase; 2.9% CA Na orthorhombic; 2.3% C.sub.12A.sub.7 (mayenite); 1.1% C.sub.2S gamma; 31.9% C.sub.2S beta; 5.1% bredigite; 13.8% C.sub.2AS (gehlenite); 1.1% akermanite; 3.6% anorthite; 20.8% quartz; 3.9% wollastonite 1T; 1.5% pseudo-wollastonite; 0.3% X ray amorphous.

(19) The hydratable materials were ground in a laboratory planetary mill to a fineness according to the determination of the particle size distribution by laser granulometry of about D.sub.90˜50 μm and a Rosin-Rammler Parameter (slope) n of ˜0.87. For hydration the binder obtained was mixed with water in a water/binder ratio of 0.5. Hydration took place at 50° C. for 24 h. It was followed by carbonation with ˜100% CO.sub.2 gas at a pressure of 2.5 bar and a temperature of 20° C. for 24 h. Comparison samples were exposed to ˜100% CO.sub.2 gas at a pressure of 2.5 bar and a temperature of 20° C. for 24 h without the initial hydration step.

(20) The hydrated and the hardened products were analysed by thermogravimetry in a Netzsch Jupiter STA 449 device (DTG) and BW and CO.sub.2 bound calculated as described above from the thermogravimetry measurements. Results are summarized in Tables 5 and 6.

(21) TABLE-US-00005 TABLE 5 BW and bound CO2 for C/S = 0.6 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Treatment ation ation ation ation Hydration Carbonation g/100 g hydratable material — 24 hours at — 3 — 10 ~100% CO2 at 2.5 bars, 20° C. 24 hours 24 hours at 2 4 1 12 at 50° C. ~100% CO2 at 2.5 bars, 20° C.

(22) TABLE-US-00006 TABLE 6 BW and bound CO2 for C/S = 1.0 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Treatment ation ation ation ation Hydration Carbonation g/100 g hydratable material — 24 hours at — 3 5 ~100% CO2 at 2.5 bars, 20° C. 24 hours 24 hours at 5 3 1 14 at 50° C. ~100% CO2 at 2.5 bars, 20° C.

(23) Based on the TG results, it can be concluded that both hydratable materials hydrated. Subsequent carbonation led to significant CO.sub.2 uptake and parallel ongoing hydration demonstrated by the presence of BW after the carbonation treatment. It is seen that the combined hydration and carbonation had a synergistic effect enhancing the amount of CO.sub.2 bound and therewith strength under given conditions.

Example 4

(24) The same binder with C/S=0.6 as in example 3 was used. The binder was hydrated identically to example 3, but carbonated immersed in 0.5 M NaOH-solution, all conditions being the same otherwise. The results of an analysis with thermogravimetry are compared in table 7 to results without NaOH-solution.

(25) TABLE-US-00007 TABLE 7 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Treatment ation ation ation ation Hydration Carbonation g/100 g hydratable material 24 hours 24 hours at 2 3 1 11 at 50° C. ~100% C02 at 2.5 bars, 20° C. 24 hours 24 hours at 2 4 1 13 at 50° C. ~100% CO2 at 2.5 bars, 20° C., in 0.5 M NaOH solution

(26) It is seen that the carbonation was further enhanced by the presence of alkali hydroxide in the solution. This effect is associated with the presence of alkalis. Hence, the alkali source is not limited to hydroxides and sodium. Suitable alkali sources comprise soluble alkali-containing salts as well. Additionally, the presence of alkalis enhanced the ongoing hydration demonstrated by the increase of BW.

Example 5

(27) The same binder with C/S=1.0 as in example 3 was used. The binder was hydrated identically to example 3, but carbonated immersed in 0.5 M NaOH-solution, all conditions being the same otherwise. The results of an analysis with thermogravimetry are compared in table 8 to results without NaOH-solution

(28) TABLE-US-00008 TABLE 8 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Treatment ation ation ation ation Hydration Carbonation g/100 g hydratable material 24 hours 24 hours at 5 3 1 14 at 50° C. ~100% CO2 at 2.5 bars, 20° C. 24 hours 24 hours at 5 6 1 16 at 50° C. ~100% CO2 at 2.5 bars, 20° C., in 0.5 M NaOH solution

(29) It is seen that the carbonation was further enhanced by the presence of alkali hydroxide in the solution. This effect is associated with the presence of alkalis. Hence, the alkali source is not limited to hydroxides and sodium. Suitable alkali sources comprise soluble alkali-containing salts as well. Additionally, the presence of alkalis enhanced the ongoing hydration demonstrated by the increase of BW.

Example 6

(30) The same binder with C/S=1.0 as in example 3 was used and mixed with 1% citric acid solution instead of water. Hydration, drying and carbonation took place as in example 3. The results of an analysis with thermogravimetry including those of example 3 are shown in table 9.

(31) TABLE-US-00009 TABLE 9 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Treatment ation ation ation ation Hydration Carbonation g/100 g hydratable material 24 hours 24 hours at 5 3 1  14 at 50° C. ~100% CO2 at 2.5 bars, 20° C. 24 hours 24 hours at 5 6 2* 18 at 50° C. ~100% CO2 in 1% citric acid at 2.5 bars, solution instead 20° C. of mixing water

(32) It can be seen that immersion in citric acid further enhanced the combined hydration-carbonation hardening.

Example 7

(33) Hardening of binders prepared by tempering of a mixture of the natural materials quarry overburden (mainly loess) and limestone was examined. The clinkers CS0.6b (Ca/Si=0.6, 1000° C., 1 h) and CS1.0b (Ca/Si=1.0, 1000° C., 1 h) were made like in example 2 and had the following phase compositions:

(34) CS0.6b: 3.1% ferrite; 0.8% maghemite; 0.7% arcanite; 0.9% Ca-langbeinite; 4.2% lime; 2.0% periclase; 24.7% dicalcium silicate; 7.5% gehlenite; 6.5% akermanite; 2.7% anorthite; 2.5% ortoclas; 2.5% albite; 27.2% quartz; 5.8% wollastonite; 0.8% pseudo-wollastonite; 8.1% X-ray amorphous; and
CS1.0b: 4.6% ferrite; 0.8% hematite; 9.9% lime; 2.4% periclase; 31.9% dicalcium silicate; 0.3% mayenite, 6.3% gehlenite; 4.3% akermanite; 1.9% anorthite; 0.3% crystobalite; 15.3% quartz; 3.4% wollastonite; 18.6% X-ray amorphous.

(35) The hydratable materials were ground in a laboratory planetary mill to a fineness according to the determination of the particle size distribution by laser granulometry of about D.sub.90˜50 μm and the Rosin-Rammler Parameter (slope) n˜0.87. For hydration the binder obtained was mixed with water in a water/binder ratio of 0.5. Hydration took place at 50° C. for 24 h. It was followed by carbonation with ˜100% CO.sub.2 gas at a pressure of 2.5 bar and a temperature of 20° C. for 24 h. The results of an analysis with thermogravimetry including those of example 3 are shown in table 10.

(36) TABLE-US-00010 TABLE 9 BW BW CO2 CO2 before after before after Hydratable carbonation carbonation carbonation carbonation material g/100 g hydratable material CS0.6b 3 3 1 14 CS1.0b 6 4 1 15

(37) Based on the TG results, it can be concluded that both hydratable materials hydrated. Subsequent carbonation led to significant CO.sub.2 uptake and parallel ongoing hydration demonstrated by the presence of BW after the carbonation treatment. It is seen that both materials hardened comparably to materials in example 3 demonstrating that the origin of precursor materials does not play a crucial role and the hydration, carbonation and hardening behavior is related to the phases present after the tempering step.

Example 8

(38) Hardening of binders prepared from identical precursor materials by tempering at different temperatures was examined and compared to pure commercially available wollastonite. Hydratable materials from example 1 with C/S=1.0 tempered for 60 minutes at 800° C. or for 60 minutes at 900° C. or for 60 minutes at 1000° C. or for 60 minutes at 1200° C. were examined. The wollastonite was a commercial product with fineness provided by producer characterized by D90=43 μm, D10=1.5 μm. The chemical composition was provided by the producer as: SiO2 51%; Al2O3 1%; Fe2O3 0.3%; CaO 45%; MgO 1%; Na2O+K2O 0.1%; loss on ignition at 1000° C. 2%.

(39) The hydratable materials were ground in a laboratory planetary mill to a fineness according to the determination of the particle size distribution by laser granulometry of about D.sub.90˜50 μm and the Rosin-Rammler Parameter (slope) n˜0.87. The wollastonite was used as received. For hydration the binder obtained was mixed with water in a water/binder ratio of 0.5. Hydration took place at 60° C. for 12 h. It was followed by carbonation with ˜100% CO.sub.2 gas at a pressure of 4 bar and a temperature of 20° C. for 2 h. Samples were characterized by thermogravimetry and their BW and CO.sub.2 bound calculated as previously described. Results are summarized in table 10.

(40) TABLE-US-00011 TABLE 10 BW BW CO2 CO2 before after before after carbon- carbon- carbon- carbon- Hydratable ation ation ation ation material g/100 g hydratable material CS1.0 tempered for 4 5  7*  14** 60 minutes at 800° C. CS1.0 6 4 1 11 tempered for 60 minutes at 900° C. CS1.0 tempered for 5 6 1 16 60 minutes at 1000° C. CS1.0 tempered for 0 1 0 10 60 minutes at 1200° C. Wollastonite not measured 0   2***  2 *hydratable material contains 16% of calcite and dolomite because of low transformation degree **corresponds to an increase of CO.sub.2 of 7 g /100 g of hydratable material ***calculated from producers data

(41) The results show that the hydratable material tempered for 60 minutes at 1000° C. which has the highest content of lime+dicalcium silicates has the optimal composition among the materials investigated demonstrated by its highest BW after carbonation and the highest CO.sub.2 bound. Increasing the tempering temperature further results in a higher conversion, i.e. degree of transformation out of the optimum range and hence in phases of lower reactivity. Similarly, decreasing the tempering temperature and hence the transformation degree results in lower content of reactive phases and hence in lower BW and CO.sub.2 bound. Wollastonite has neither hydrated nor carbonated under the given conditions which is in accordance with R. Berger and J. F. Young, “Reaction of Calcium Silicates with Carbon Dioxide and Water,” ILLINOIS UNIV AT URBANA-CHAMPAIGN, 1979.