CN1594195A

CN1594195A - Hydrated magnesium silicate system gelling material coagulating and hardening at normal temperature and its preparation method

Info

Publication number: CN1594195A
Application number: CNA2004100487682A
Authority: CN
Inventors: 陈益民; 韦江雄
Original assignee: China Building Materials Academy CBMA
Current assignee: China Building Materials Academy CBMA
Priority date: 2004-06-18
Filing date: 2004-06-18
Publication date: 2005-03-16
Anticipated expiration: 2024-06-18
Also published as: CN1267374C

Abstract

The invention discloses a hydrated magnesium silicate system gelling material coagulating and hardening at normal temperature and its preparation method, wherein the material is prepared from water and magnesia mass material, silicon oxide material, phosphor-containing raw material, calcium oxide and reactive mineral blended material through proportionally mixing.

Description

Hydrated magnesium silicate system gel material solidified and hardened at normal temperature and preparation method thereof

Technical Field

The invention relates to the field of cementing materials and products in the building material industry, in particular to a cementing material taking hydrated magnesium silicate as a main cementing component.

Background

There are three minerals of magnesium silicate (enstatite, clinoptilolite, forsterite) encountered in nature, and eight kinds of hydrated magnesium silicate, such as forsterite, magnesium metasilicate, serpentine, etc. At present, the conditions for artificially synthesizing the magnesium silicate are high temperature and high pressure, such as MgO-SiO under the condition of exceeding the critical temperature of water₂-H₂Various phases in the O system can synthesize magnesium silicate at the temperature range of 200-500 ℃ and the pressure of 14.0-87.0MPa, and the magnesium silicate synthesized by the method has no gelling property. C, Kangai BoreisiBase and M.C. Zabbitz base Mg (OH)₂And silica gel (or quartz sand) are pressed into a test piece, and the test piece is cured under the condition of a normal warm and humid medium, so that hydrous magnesium silicate is found, but the hydrous magnesium silicate does not have the gelling property.

The existing cementing materials mainly comprise the following three types:

(1) magnesium phosphate gelling material: the high-strength magnesium phosphate is prepared from magnesium oxide and phosphoric acid or phosphate, and the reaction product is magnesium phosphate and the like, has the characteristics of quick setting and hardening and high early strength, and can be used in rush repair engineering.

(2) Magnesium oxychloride cement: from MgO, MgCl₂Proportionally mixing it with water, and preparing the product from different double salts, 5Mg (OH)₂.MgCl₂.8H₂O (5.1.8 phase or phase 5 for short), 3Mg (OH)₂.MgCl₂.8H₂O (3.1.8 or 3) and Mg (OH)₂. The cement has better strength performance and light volume weight, and is used for inner partition boards and the like. But poor water resistance, easy halogen return, easy deformation and catalysis, and limit the use and development of the catalyst.

(3) Calcium silicate series cements: currently, a cement containing calcium silicate as a main component, which is called portland cement, is widely used in the market. It is hydrated by adding water, the main gelling component is hydrated calcium silicate, which usually contains a small amount of magnesium oxide, and the hydrated calcium silicate becomes magnesium hydroxide and cannot generate hydrated magnesium silicate. In the preparation process of the Portland cement, cement clinker taking tricalcium silicate as a main component is required to be sintered at a high temperature of more than 1400 ℃, and the cement is prepared by adding gypsum and a mixed material into the cement clinker. The energy consumption is large and the process is complicated.

So far, no normal-temperature synthesized magnesium silicate containing crystal water and hydrated magnesium silicate material with gelling property at normal temperature appear in commercial products and scientific research reports.

Summary of the invention

The invention aims to provide a hydrated magnesium silicate system gel material which is synthesized at normal temperature and has good gelling performance.

The hydrated magnesium silicate system cementing material provided by the invention is prepared from water and powdery solid at a weight ratio of 0.28-1: 1 at normal temperature, wherein the powdery solid comprises the following components in parts by weight:

magnesium oxide material: 15-80 parts of (A) a water-soluble polymer,

silicon oxide material: 85 to 30 portions of

Phosphorus-containing salts: 0.5 to 4 portions of

Active mineral admixture: 0 to 70 portions of

Calcium oxide raw material: 0-4 parts by weight of free calcium oxide and calcium hydroxide contained in the raw material.

Wherein the magnesia material is a magnesia-containing raw material prepared by calcining phosphorite or dolomite; the silicon oxide material is SiO₂One or both of silica fume and fine fly ash as main components, and has specific surface area not less than 400m²Per kg; the phosphorus-containing salt is one of metaphosphate and polyphosphate of sodium and potassium; the calcium oxide raw material is a raw material containing free CaO and is selected from one or more of lime, high-calcium fly ash containing free calcium oxide and calcium hydroxide and steel slag; the active mineral admixture is a powdery mineral admixture used in cement and concrete, is one or a combination of more than one selected from slag powder, fly ash, steel slag powder, phosphorus slag powder, zeolite powder and metakaolin, and has a specific surface area of not less than 400m²/kg。

The hydrated magnesium silicate system cementing material of the invention preferably comprises the following components in percentage by weight:

30-80 parts by weight of a magnesia-containing material prepared by calcining a phosphorus-magnesium ore or dolomite;

SiO-containing composition of one or both of silica fume and fly ash₂20-70 parts of the raw materials;

1-3 parts of a phosphorus-containing salt material of one of metaphosphate and polyphosphate of sodium and potassium.

More preferred powdered solids consist of:

30-80 parts by weight of magnesia material;

5-20 parts of silica fume;

5-15 parts of steel slag powder;

5-50 parts of fine fly ash;

0-50 parts of fly ash as active mineral admixture

0.5-3 parts of sodium metaphosphate.

Another object of the present invention is to provide a method for preparing the above-mentioned hydrous magnesium silicate system gelling material.

The method for preparing the hydrated magnesium silicate system cementing material provided by the invention is to grind various powder solids to a specific surface area of more than or equal to 400m²After the water is mixed with the water according to the weight ratio of 1: 0.28-1, the water is mixed to prepare the water-based paint.

The hydrated magnesium silicate system cementing material which is coagulated and hardened at normal temperature provided by the invention has the following advantages: high strength, light weight per unit volume and low alkalinity. The reason for the light weight is that magnesium oxide itself has a smaller specific gravity than calcium oxide, and the reason for the low basicity is that the magnesium hydroxide saturated aqueous solution is less basic than the calcium hydroxide saturated aqueous solution. The material of the invention is suitable for manufacturing gelled material products, wall materials, grouting materials, glass fiber reinforced cement products and the like. Can replace magnesium oxychloride cement, is suitable for various purposes of magnesium oxychloride cement, and has no adverse effects of chlorine and alkali. Can replace part of the application of silicate series cement to prepare mortar and concrete.

Detailed Description

The present invention is described in detail below in several aspects.

Based on intensive research in the cement industry, the inventor finds that under the action of a certain catalyst, magnesium oxide and silicon oxide can generate hydration reaction at normal temperature to generate hydrated magnesium silicate with gelling property, and the hydrated magnesium silicate can be used as a main cementing component in a cementing material.

The reaction formula is as follows:

wherein x is 0.5-2 and y is 1-7.

Based on the research, the raw materials screened by the invention to form the hydrous magnesium silicate system cementing material are as follows: magnesia raw materials, silica raw materials, phosphorus-containing raw materials, calcium oxide raw materials and active mineral admixtures.

Wherein the magnesia raw material is a magnesia-containing raw material prepared by calcining phosphorite or dolomite; the silicon oxide material is SiO₂The fly ash-containing silica fume-. The magnesium oxide material and the silicon oxide material react with water to produce hydrated magnesium silicate, which is the main cementing component in the material of the invention.

The phosphorus-containing raw materials are metaphosphate and polyphosphate, and the action of the phosphorus-containing raw materials has three aspects: firstly, the dispersion effect improves the fluidity of the system and reduces the water amount required for achieving certain fluidity; a catalyst for hydration reaction between the magnesia raw material and the silica raw material; thirdly, the activity of various raw materials is stimulated.

The calcium oxide material is a material containing free CaO, and comprises lime, high-calcium fly ash containing free calcium oxide and calcium hydroxide and steel slag, and the calcium oxide material has the function of adjusting the setting time of the magnesium silicate system cementing material.

The main gelling component is composed of a magnesia raw material, a silica raw material, a phosphorus raw material and a calcium oxide raw material.

The active mineral admixture is also called as an auxiliary gelling component, is a powdery mineral admixture used in cement and concrete, and comprises slag powder, fly ash, steel slag powder, phosphorus slag powder, zeolite powder, coal gangue powder and metakaolin.

The raw materials are solid raw materials, and are respectively ground until the specific surface area is more than or equal to 200m²Kg of solid powder which is mixed into a gelled material according to a certain proportion, and the solid powder is mixed with water according to a certain proportion to form the inventionThe cementitious material of (1).

The following examples illustrate the invention in more detail.

Example set 1:

in the examples of this group, the raw materials used were silica fume, magnesium oxide, sodium hexametaphosphate (NaPO)₃)₆In the case of cementitious materialsThe solid composition of (A) is composed of (A) silica fume 10-50 wt%, magnesium oxide 50-90 wt%, (NaPO)₃)₆The doping amount of the silicon ash is 0.5-4% of the total weight of the silicon ash and the magnesium oxide. The weight ratio of water to the gelled material solid is 0.40-0.65, and the weight ratio of the gelled material solid to the sand is 1: 2.5. The strength of the hydrated magnesium silicate binder of this group of examples was measured at room temperature (20. + -. 2 ℃ C.) according to the test method specified in national standards for cement, and the raw material composition and measurement results are shown in tables 1 and 2:

TABLE 1

Gel weight (kilogram)			Water/liquor Cementitious material	Sand/liquor Cementitious material	Flexural strength (MPa)		Compressive strength (MPa)
Gel weight (kilogram)					Flexural strength (MPa)		Compressive strength (MPa)		Magnesium oxide	Silica fume	(NaPO₃)₆	3 days	28 days	3 days	28 days
70	30	1.5			1.00	2.5	4.3	8.2	Magnesium oxide	Silica fume	(NaPO₃)₆	3 days	28 days	3 days	28 days	18.8	54.7
70	30	1.5	60	40	1.00	2.5	4.3	8.2	1.5	1.00	2.5	3.8	6.8	16.1	51.6	18.8	54.7
50	50	1.5	60	40	1.00	2.5	3.7	6.3	1.5	1.00	2.5	3.8	6.8	16.1	51.6	17.2	55.9
50	50	1.5	90	10	1.00	2.5	3.7	6.3	2	0.50	2.5	3.1	5.6	17.6	45.2	17.2	55.9
80	20	2	90	10	0.50	2.5	4.4	8.4	2	0.50	2.5	3.1	5.6	17.6	45.2	24.3	56.4
80	20	2	70	30	0.50	2.5	4.4	8.4	2	0.50	2.5	4.6	10.0	20.6	57.4	24.3	56.4
60	40	2	70	30	0.50	2.5	4.0	7.1	2	0.50	2.5	4.6	10.0	20.6	57.4	16.4	53.2
60	40	2	50	50	0.50	2.5	4.0	7.1	2	0.50	2.5	3.9	6.6	18.2	57.2	16.4	53.2
55	45	0.5	50	50	0.65	2.5	3.7	6.5	2	0.50	2.5	3.9	6.6	18.2	57.2	17.5	42.3
55	45	0.5	90	10	0.65	2.5	3.7	6.5	3	0.50	2.5	5.5	6.1	26.1	56.2	17.5	42.3
80	20	3	90	10	0.50	2.5	8.8	10.1	3	0.50	2.5	5.5	6.1	26.1	56.2	24.2	64.5
80	20	3	70	30	0.50	2.5	8.8	10.1	3	0.50	2.5	7.0	9.4	25.9	66.3	24.2	64.5
60	40	3	70	30	0.50	2.5	7.5	8.5	3	0.50	2.5	7.0	9.4	25.9	66.3	27.2	70.0
60	40	3	50	50	0.50	2.5	7.5	8.5	3	0.50	2.5	5.1	9.8	24.3	64.6	27.2	70.0
65	35	4	50	50	0.40	2.5	8.7	11.3	3	0.50	2.5	5.1	9.8	24.3	64.6	48.6	71.5

TABLE 2

Weight ratio of cementing material			Water/liquor Cementitious material	Sand/liquor Cementitious material	Flexural strength (MPa)			Compressive strength (MPa)
Weight ratio of cementing material					Flexural strength (MPa)			Compressive strength (MPa)			Magnesium oxide	Silica fume	(NaPO₃)₆	3 days	7 days	28 days	3 days	7 days	28 days
80	20	2			0.45	2.5	5.4	5.1	5.8	32.4	Magnesium oxide	Silica fume	(NaPO₃)₆	3 days	7 days	28 days	3 days	7 days	28 days	48.4	62.3
80	20	2	70	30	0.45	2.5	5.4	5.1	5.8	32.4	2	0.45	2.5	7.5	5.3	4.6	26.6	50.1	74.6	48.4	62.3
60	40	2	70	30	0.45	2.5	7.4	4.9	5.2	31.0	2	0.45	2.5	7.5	5.3	4.6	26.6	50.1	74.6	54.8	78.6

The strength grades of the ordinary portland cement are 32.5, 42.5 and 52.5, and the compressive strength of 28 of the ordinary portland cement is 32.5-60 MPa. From the data in tables 1 and 2, the weight ratio of magnesia/silica fume is between 90/10 and 50/50, and the gel is formedThe strength of the material is comparable to that of ordinary portland cement, in which oxidation occursThe strength of the magnesium/silicon ash reaches more than 70 MPa when the weight ratio of the magnesium/silicon ash is 60/40, which is higher than that of ordinary portland cement. (NaPO)₃)₆The doping amount of the silicon ash is 2 to 3 percent of the sum of the weight of the silicon ash and the weight of the magnesium oxide, so that good effect can be obtained.

The fluidity of the gelled materials of the examples in this group was tested, and the flowing down time of the gelled materials was measured with a Marshal cylinder as the fluidity index of the slurry. The shorter the time the cement slurry flows down from the Marshal cylinder indicates the better the fluidity of the slurry, and for cements the flow down time is below 120 seconds which is a value suitable for normal use. Table 3 shows the composition and fluidity measurements of the examples of this group of cement materials.

TABLE 3

Gel weight (kilogram)			Water/liquor Cementitious material	Flow-down time (seconds)
Gel weight (kilogram)					Magnesium oxide	Silica fume	(NaPO₃)₆
90	10	1			Magnesium oxide	Silica fume	(NaPO₃)₆	0.8	45
90	10	1	90	10	2	0.8	44	0.8	45
90	10	3	90	10	2	0.8	44	0.8	33
90	10	3	80	20	1	0.8	16	0.8	33
80	20	2	80	20	1	0.8	16	0.8	13
80	20	2	80	20	3	0.8	15	0.8	13
70	30	1	80	20	3	0.8	15	0.8	13
70	30	1	70	30	2	0.8	12	0.8	13
70	30	3	70	30	2	0.8	12	0.8	12
70	30	3	80	20	2	0.5	70	0.8	12
70	30	2	80	20	2	0.5	70	0.5	43
70	30	2	60	40	2	0.5	26	0.5	43
50	50	2	60	40	2	0.5	26	0.5	30

Example set 2:

in the embodiment of the group, the raw materials are silica fume, magnesium oxide, sodium metaphosphate and steel slag powder, the silica fume accounts for 10-30% of the solid composition of the cementing material, the magnesium oxide accounts for 60-70%, the steel slag powder is used as an active mineral admixture, and as free calcium oxide and calcium hydroxide are contained, the steel slag powder is used as a calcium oxide raw material to adjust the setting time, the usage amount of the calcium oxide raw material is 10-20%, and the doping amount of the sodium metaphosphate is 2-3% of the sum of the silica fume, the magnesium oxide and the steel slag powder. The water/cement solids ratio was 0.45 and the cement solids/sand weight ratio was 1: 2.5. The strength of the hydrated magnesium silicate cements was measured at room temperature (20. + -. 2 ℃ C.) according to the test method specified in national standards for cements, and the compositions and the results of the tests of the examples of this group of cements are shown in Table 4.

TABLE 4

Gel weight (kilogram)				Water/liquor Cementitious material	Flexural strength (MPa)			Compressive strength (MPa)
Gel weight (kilogram)					Flexural strength (MPa)			Compressive strength (MPa)			Magnesium oxide	Silica fume	Steel slag powder	Sodium metaphosphate	3 days	7 days	28 days	3 days	7 days	28 days
70	10	20	3		0.45	2.38	4.87	3.45	11.6	21.6	Magnesium oxide	Silica fume	Steel slag powder	Sodium metaphosphate	3 days	7 days	28 days	3 days	7 days	28 days	27.8
70	10	20	3	70	0.45	2.38	4.87	3.45	11.6	21.6	20	10	3	0.45	6.05	11.7	10.6	23.9	45.4	68.7	27.8
60	30	10	3	70	0.45	4.72	10.8	11.7	19.6	49.7	20	10	3	0.45	6.05	11.7	10.6	23.9	45.4	68.7	86.9
60	30	10	3	60	0.45	4.72	10.8	11.7	19.6	49.7	20	20	3	0.45	3.07	5.98	7.54	10.6	25.9	47.7	86.9

From the data in Table 4, it can be seen that when the weight ratio of magnesium oxide/silica fume is 60/30 and steel slag powder is added in an amount of 10 wt%, the strength of the binding material reaches more than 80 MPa, which is higher than the highest strength in Table 2 of example group 1, indicating that a proper amount of steel slag is helpful for improving the strength. For the system with the weight ratio of magnesium oxide/silicon ash being 70/10, the strength of the gelled material is only 27 MPa after 20% of steel slag powder is mixed, and is lower than that when the steel slag powder is not mixed, which indicates that the steel slag powder has a proper mixing amount, mainly related to the content of free calcium oxide and calcium hydroxide in the steel slag powder, and the excessive free calcium oxide and calcium hydroxide can reduce the strength of the hydrated magnesium silicate gelled material.

The water consumption and setting time for the standard consistency of the cementitious materials of the examples were determined by reference to the method of national standard for cement GB 1346. The mixing water quantity is changed, and the water quantity required when the stirred cement paste reaches a specific plastic state is found out. When a standard cone of a certain mass is allowed to freely sink in the net slurry for a prescribed period of time, the magnitude of the consistency (%) of the cement net slurry is reflected in the magnitude of the sinking depth s (mm) of the cone. And taking the consistency of the measured cone sinking net pulp depth as 28 +/-2 mm as the standard consistency, and taking the weight ratio of the water consumption to the cementing material consumption as the water consumption of the standard consistency. The setting time of the cement was determined with a standard consistency paste. Table 5 shows the composition of the cement of example 1 and the results of the measurement. Table 6 shows the composition of the cement of example 2 and the results of the measurement.

TABLE 5

Gel weight (kilogram)			Water consumption for standard consistency (％)	Setting time (hours: minutes)
Gel weight (kilogram)				Setting time (hours: minutes)		Magnesium oxide	Silica fume	(NaPO₃)₆	Initial setting	Final setting
80	20	3		41	8:35	Magnesium oxide	Silica fume	(NaPO₃)₆	Initial setting	Final setting	10:20
80	20	3	70	41	8:35	30	3	36	7:50	9:25	10:20
60	40	3	70	35	7:15	30	3	36	7:50	9:25	8:35

TABLE 6

Gel weight (kilogram)				Water consumption for standard consistency (％)	Setting time (hours: minutes)
Gel weight (kilogram)					Setting time (hours: minutes)		Magnesium oxide	Silica fume	Steel slag powder	Sodium metaphosphate	Initial setting	Final setting
70	10	20	3		43	2:12	Magnesium oxide	Silica fume	Steel slag powder	Sodium metaphosphate	Initial setting	Final setting	3:13

70	20	10	3	38	2:51	3:29
70	20	10	3	38	2:51	3:29	60	30	10	3	36	2:00	2:35
60	20	20	3	40	2:22	2:57	60	30	10	3	36	2:00	2:35

As can be seen from the data in Table 5, in example 1, no calcia-based material was added, and the resulting hydrous magnesium silicate cement had a longer setting time and a setting speed slower than that of portland cement (the setting time of portland cement was defined to be 45 minutes to 6 hours, and the actual setting time of portland cement was usually 1 hour to 4 hours in many cases), but it could also meet the requirements for practical use. As the ratio of magnesium oxide/silica fume is reduced, the water consumption for standard consistency is reduced and the setting time is shortened.

As shown in the data in tables 5 and 6, the addition of the calcia raw material can shorten the setting time of the hydrated magnesium silicate cementing material, achieve the setting time similar to that of ordinary portland cement, and is convenient to use.

Example set 3:

adopts the raw materials of silica fume, magnesium oxide and (NaPO)_a)₆The solid composition of the cementing material comprises 10-30% of silica fume, 60-70% of magnesium oxide material and 10-20% of slag powder (NaPO) which is an active mineral admixture₃)₆The mixing amount of the slag powder is 2-3% of the sum of the silica fume, the magnesium oxide and the slag powder. The water/cement solids ratio was 0.45 and the cement solids/sand weight ratio was 1: 2.5. The strength of the hydrated magnesium silicate cements was tested at room temperature (20. + -. 2 ℃ C.) according to the test methods specified in the national standards for cements, examples of this group of cementsThe composition and the measurement results are shown in Table 7.

TABLE 7

Gel weight (kilogram)				Water/cementitious materials	Flexural strength (MPa)				Compressive strength (MPa)
Gel weight (kilogram)					Flexural strength (MPa)				Compressive strength (MPa)				Magnesium oxide	Silica fume	Slag powder	(NaPO₃)₆	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days
70	10	20	3		0.45	6.3	9.3	7.4	4.4	24.3	37.4	55.2	Magnesium oxide	Silica fume	Slag powder	(NaPO₃)₆	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days	47.6
70	10	20	3	70	0.45	6.3	9.3	7.4	4.4	24.3	37.4	55.2	20	10	2	0.45	6.0	7.9	9.6	7.9	21.3	41.7	72.8	71.4	47.6
60	30	10	3	70	0.45	6.0	8.8	10.3	9.2	22.8	41.7	78.2	20	10	2	0.45	6.0	7.9	9.6	7.9	21.3	41.7	72.8	71.4	83.5
60	30	10	3	60	0.45	6.0	8.8	10.3	9.2	22.8	41.7	78.2	20	20	2	0.45	6.4	9.5	12.8	12.5	23.5	42.0	79.1	90.2	83.5

From the data in Table 7, it can be seen that the strength of the hydrated magnesium silicate cement incorporated with the slag powder is steadily increased. When the weight ratio of the magnesium oxide to the silica fume is not less than 70/20, the compressive strength of the cement is more than 70 MPa in 28 days, which is higher than that of ordinary portland cement. When the weight ratio of the magnesium oxide to the silicon ash is 60/20, the compressive strength of the magnesium oxide to the silicon ash is close to 80 MPa in 28 days, the flexural strength is more than 12 MPa, and the compressive strength of the magnesium oxide to the silicon ash in 90 days is 90 MPa, which is much higher than that of ordinary portland cement.

Example set 4:

the raw materials are silica fume, magnesia material and (NaPO)₃)₆The fly ash is prepared from 10-30% of silica fume, 30-70% of magnesium oxide material and 10-50% of NaPO (sodium oxide powder oxide), wherein the silica fume is 10-30% of the solid composition of the cementing material, the fly ash is a silicon oxide raw material and is required to be low-calcium fly ash, and the low-calcium fly ash is mixed with the silica fume for use₃)₆The mixing amount of the silicon ash, the magnesium oxide and the fly ashAnd 2-3% of the sum. The water/cement solids ratio was 0.45 and the cement solids/sand weight ratio was 1: 2.5. The strength of the hydrated magnesium silicate cements was measured at room temperature (20. + -. 2 ℃ C.) according to the test method specified in national standards for cements, the compositions of the examples of this group of cements and the results of the measurements are shown inTable 8.

TABLE 8

Gel weight (kilogram)				Flexural strength (MPa)				Compressive strength (MPa)
Gel weight (kilogram)				Flexural strength (MPa)				Compressive strength (MPa)				Magnesium oxide	Silica fume	Fly ash	Water/cementitious materials	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days
70	10	20	0.45	7.29	8.25	6.03	6.07	33.8	45.4	64.0	68.0	Magnesium oxide	Silica fume	Fly ash	Water/cementitious materials	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days
70	10	20	0.45	7.29	8.25	6.03	6.07	33.8	45.4	64.0	68.0	70	20	10	0.45	7.08	9.33	8.88	5.72	32.8	55.6	82.7	75.6
60	30	10	0.45	7.34	9.45	8.57	8.71	31.2	58.4	90.3	86.8	70	20	10	0.45	7.08	9.33	8.88	5.72	32.8	55.6	82.7	75.6
60	30	10	0.45	7.34	9.45	8.57	8.71	31.2	58.4	90.3	86.8	60	20	20	0.45	7.98	11.2	9.29	8.23	32.0	55.0	86.0	82.8
60	10	30	0.45	4.78	6.13	6.82	5.83	16.5	32.6	57.8	61.6	60	20	20	0.45	7.98	11.2	9.29	8.23	32.0	55.0	86.0	82.8
60	10	30	0.45	4.78	6.13	6.82	5.83	16.5	32.6	57.8	61.6	50	10	40	0.45	4.63	4.72	6.48	7.0	13	20.7	47.2	62.9
40	10	50	0.45	3.96	5.33	7.49	7.7	11.0	21.6	41.2	52.7	50	10	40	0.45	4.63	4.72	6.48	7.0	13	20.7	47.2	62.9
40	10	50	0.45	3.96	5.33	7.49	7.7	11.0	21.6	41.2	52.7	50	20	30	0.45	5.24	8.64	8.62	7.63	14.7	34.3	63.4	66.0
40	20	40	0.45	3.68	6.83	9.95	9.65	11.7	32.1	59.6	63.5	50	20	30	0.45	5.24	8.64	8.62	7.63	14.7	34.3	63.4	66.0
40	20	40	0.45	3.68	6.83	9.95	9.65	11.7	32.1	59.6	63.5	30	20	50	0.45	3.43	5.21	8.39	8.66	11.7	29.6	58.5	64.6

From the data in Table 8, it is seen that the fly ash, as both an active mineral admixture and a silica-based material, is very advantageous for increasing the rate of increase in the later strength of the cementitious material, maintaining the structural and volume stability of the hardened body, reducing the volume expansion, and avoiding the later strength collapse.

The water consumption for standard consistency and setting time of the cementitious material were determined according to the method of national standard for cement GB1346, and the compositions and results of the measurements of the examples ofthis set of cementitious materials are given in table 9.

TABLE 9

Weight ratio of cementing material				Water consumption for standard consistency (%)	Setting time (hours: minutes)
Weight ratio of cementing material					Setting time (hours: minutes)		Magnesium oxide	Silica fume	Fly ash	(NaPO₃)₆	Initial setting	Final setting
70	10	20	3		0.33	9:30	Magnesium oxide	Silica fume	Fly ash	(NaPO₃)₆	Initial setting	Final setting	10:55
70	10	20	3	70	0.33	9:30	20	10	3	0.33	8:25	10:10	10:55
60	30	10	3	70	0.35	8:20	20	10	3	0.33	8:25	10:10	10:25
60	30	10	3	60	0.35	8:20	20	20	3	0.32	8:35	10:15	10:25

In the table, the standard consistency is determined by referring to the definition and numerical value in the calcium silicate series cement standard (in portland cement, the water consumption of the standard consistency is usually about 0.25-0.30), and represents the water storage capacity when the fluidity of the slurry reaches a certain degree. The lower the water usage for standard consistency, the better the flow ability of the cementitious material. From the data in Table 10, the fly ash has no significant effect on the setting time of the slurry, but the fly ash is beneficial for improving the fluidity of the cement and mortar, a property which is very useful in the practical application of the cement. The better the fluidity of the slurry, the more advantageous the application, and the less the amount of water added, the more likely it is to achieve higher strength. Therefore, the fly ash is adopted as the raw material, which is beneficial to the development of later strength.

Example set 5:

the raw materials are fly ash A, fly ash B, magnesium oxide and sodium hexametaphosphate. Wherein the fly ash A is common fly ash and mainly serves as an active mineral admixture; the specific surfacearea of the fly ash B is 1005m²Ultrafine fly ash/kg, which acts mainly as a siliceous material. In the solid composition of the cementing material, the using amount of the fly ash is 30-50%, the using amount of the magnesium oxide material is 20-50%, the using amount of the slag powder is 0-50%, and the mixing amount of the sodium hexametaphosphate is 1.5% of the sum of the silica fume, the magnesium oxide and the fly ash. The ratio of water/gelled material solids is 0.28-0.40, and the gelled material solids/sand weight ratio is 1: 2.5. The strength of the hydrated magnesium silicate cements was measured at room temperature (20. + -. 2 ℃ C.) according to the test method specified in the national standards for cements, and the compositions and the results of the test of the examples of this group of cements are shown in Table 10:

watch 10

Gel weight (kilogram)					Water/liquor Cementitious material	Flexural strength (MPa)				Compressive strength (MPa)
Gel weight (kilogram)						Flexural strength (MPa)				Compressive strength (MPa)				Magnesium oxide	Fly ash A	Fly ash B	Slag powder	Steel slag powder	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days
50	10	30	10	0		0.28	2.21	3.12	4.47	6.12	6.2	13.7	24.2	Magnesium oxide	Fly ash A	Fly ash B	Slag powder	Steel slag powder	3 days	7 days	28 days	90 days	3 days	7 days	28 days	90 days	35.4
50	10	30	10	0	40	0.28	2.21	3.12	4.47	6.12	6.2	13.7	24.2	15	30	15	0	0.40	2.56	3.73	5.19	6.71	8.0	16.6	29.1	38.2	35.4
50	20	30	0	0	40	0.28	2.34	3.61	5.62	6.63	8.7	14.3	31.7	15	30	15	0	0.40	2.56	3.73	5.19	6.71	8.0	16.6	29.1	38.2	40.8
50	20	30	0	0	40	0.28	2.34	3.61	5.62	6.63	8.7	14.3	31.7	20	20	20	0	0.40	2.58	3.53	5.92	6.66	7.7	13.1	28.6	39.2	40.8
30	20	20	30	0	40	0.40	2.46	3.28	5.69	6.41	7.6	14.6	30.5	20	20	20	0	0.40	2.58	3.53	5.92	6.66	7.7	13.1	28.6	39.2	40.6
30	20	20	30	0	45	0.40	2.46	3.28	5.69	6.41	7.6	14.6	30.5	30	25	0	0	0.40	3.01	4.21	6.25	7.59	9.8	16.3	33.2	42.4	40.6
45	25	20	0	10	45	0.40	3.02	4.34	6.35	7.35	9.3	17.3	34.2	30	25	0	0	0.40	3.01	4.21	6.25	7.59	9.8	16.3	33.2	42.4	41.5

As can be seen from the data in Table 10, the use of ultrafine fly ash instead of silica fume can also obtain a hydrated magnesium silicate cementing material with gelling property, but the early strength development is slower and the later strength growth is faster. Because the price of the ultrafine fly ash is far lower than that of the silica fume, the hydrous magnesium silicate cementing material prepared by using the ultrafine fly ash has good market prospect. Table 11 is the flow and setting time data for each of the samples in table 10.

TABLE 11

Weight ratio of cementing material					Water/liquor Cementitious material	Time of flow down (second)	Standard consistency Amount of water used	Setting time (h: min)
Weight ratio of cementing material										Magnesium oxide	Fly ash A	PowderCoal ash B	Slag powder	Steel slag powder
Initial setting	Initial setting
Initial setting	Initial setting	50	10	30				10	0						0.28	25	0.28	10:30	11:30
40	15	50	10	30	30	15	0	10	0	0.4	14	0.28	10:25	11:25	0.28	25	0.28	10:30	11:30
40	15	50	20	30	30	15	0	0	0	0.4	14	0.28	10:25	11:25	0.28	16	0.28	10:20	11:20
40	20	50	20	30	20	20	0	0	0	0.4	16	0.28	10:35	11:35	0.28	16	0.28	10:20	11:20
40	20	30	20	20	20	20	0	30	0	0.4	16	0.28	10:35	11:35	0.4	17	0.28	10:15	11:25
45	30	30	20	20	25	0	0	30	0	0.4	14	0.28	10:05	11:05	0.4	17	0.28	10:15	11:25
45	30	45	25	20	25	0	0	0	10	0.4	14	0.28	10:05	11:05	0.4	26	0.29	3:35	5:10

Example set 6:

the raw material was dolomite calcined at 800 ℃ with a MgO content of 41%, and the solid compositions of steel slag powder, silica fume, sodium metaphosphate, and a binder were as listed in Table 12. Wherein the ratio of water/cement solids is 0.45 and the weight ratio of cement solids/sand is 1: 2.5. The strength of the hydrated magnesium silicate cements was measured at room temperature (20. + -. 2 ℃ C.) according to the test method specified in the national standards for cements, and the compositions and the measurement results of the examples of this group of cements are shown in Table 12.

TABLE 12

Weight ratio of cementing material					Flexural strength (MPa)			Compressive strength (MPa)
Weight ratio of cementing material					Flexural strength (MPa)			Compressive strength (MPa)			Calcined dolomite	Steel slag powder	Silica fume	Fly ash	Sodium metaphosphate	3d	7d	28d	3d	7d	28d
50	5	10	20	2	2.0	4.6	4.9	8.7	26.3	35.7	Calcined dolomite	Steel slag powder	Silica fume	Fly ash	Sodium metaphosphate	3d	7d	28d	3d	7d	28d
50	5	10	20	2	2.0	4.6	4.9	8.7	26.3	35.7	60	10	20	10	2	2.2	4.8	5.5	9.1	25.6	34.3
70	10	20	0	2	2.1	4.6	4.8	8.1	23.2	31.2	60	10	20	10	2	2.2	4.8	5.5	9.1	25.6	34.3
70	10	20	0	2	2.1	4.6	4.8	8.1	23.2	31.2	60	10	30	0	2	3.2	5.6	6.7	12.1	33.2	41.3

As seen from Table 12, sources of MgO other than those fired from the phosphomagnesium ore, magnesia-containing feedstocks fired from dolomite can be used. The hydrated silicic acid coal cementing material prepared by burning calcined dolomite as a magnesia material also has the strength which can meet the practical application.

Example set 7:

the raw materials are fly ash, magnesium oxide, steel slag powder, silica fume and sodium metaphosphate, wherein the fly ash is ground to have a specific surface area of 820m²In terms of/kg. The proportions of the individual components in the solid composition of the cement are listed in Table 13. Wherein the ratio of water/cement solids is 0.45 and the weight ratio of cement solids/sand is 1: 2.5. National cement standard with reference to cementThe strength of the hydrated magnesium silicate cements was tested at room temperature (20. + -. 2 ℃ C.) according to the test methods specified, and the compositions and the results of the test of the examples of this group of cements are shown in Table 13.

Watch 13

Weight ratio of cementing material						Flexural strength (MPa)				Compressive strength (MPa)
Weight ratio of cementing material						Flexural strength (MPa)				Compressive strength (MPa)				MgO	Steel slag powder	Slag powder	Fly ash	Silica fume	Polyphosphoric acid sodium salt	3d	7d	28d	90d	3d	7d	28d	90d
50	10	20	20	0	2	3.8	5.6	9.5	10.5	12.3	25.5	46.8	66.6	MgO	Steel slag powder	Slag powder	Fly ash	Silica fume	Polyphosphoric acid sodium salt	3d	7d	28d	90d	3d	7d	28d	90d
50	10	20	20	0	2	3.8	5.6	9.5	10.5	12.3	25.5	46.8	66.6	50	10	20	15	5	2	4.1	6.4	9.6	12.0	14.2	23.9	49.4	71.9
50	10	20	10	10	2	4.0	6.0	9.9	11.9	14.0	24.6	59.1	78.8	50	10	20	15	5	2	4.1	6.4	9.6	12.0	14.2	23.9	49.4	71.9
50	10	20	10	10	2	4.0	6.0	9.9	11.9	14.0	24.6	59.1	78.8	50	10	20	5	15	2	3.3	4.8	8.1	10.7	11.6	20.8	55.9	81.8
50	10	20	20	20	2	5.0	6.69	7.9	13.4	16.9	26.4	58.8	89.9	50	10	20	5	15	2	3.3	4.8	8.1	10.7	11.6	20.8	55.9	81.8

From the data in Table 13, it is seen that a hydrated magnesium silicate cement can be prepared by using fly ash as the silica-based material, and the strength of the cement is good. The strength of the cement is gradually increased as the amount of silica fume increases.

Example set 8:

the raw materials are magnesium oxide, silica fume, fly ash, high calcium fly ash, slag powder, phosphorous slag powder, zeolite powder, steel slag powder and metakaolin, which are prepared into gelled materials containing different admixtures according to the proportion in the table 14, and the properties of the gelled materials are measured and listed in the table 14. These data in Table 14 illustrate that various admixtures can be formulated into hydrated magnesium silicate cements having good gelling properties.

TABLE 14

Sample numbering		8-1	8-2	8-3	8-4	8-5
Sample numbering		8-1	8-2	8-3	8-4	8-5	Wood material Material Group of Become into kg	Magnesium oxide	60	45	60	42	30
Silica-based raw material	Silica fume 18	Fly ash 20 Silica fume 5	The amount of the silica fume 10 is such that, fly ash 10	Silica fume 15	Fly ash 30			Magnesium oxide	60	45	60	42	30
Silica-based raw material	Silica fume 18	Fly ash 20 Silica fume 5	The amount of the silica fume 10 is such that, fly ash 10	Silica fume 15	Fly ash 30	Active mineral admixture		Phosphorus slag powder 20	Zeolite powder 20	Metakaolin 19	Zeolite powder 20 Phosphorus slag powder 18	Metakaolin 20 Slag powder 17
Calcareous raw material	High calcium flyash 2	Steel slag powder 10	0	High calcium flyash 5	Lime 2	Active mineral admixture		Phosphorus slag powder 20	Zeolite powder 20	Metakaolin 19	Zeolite powder 20 Phosphorus slag powder 18	Metakaolin 20 Slag powder 17
Calcareous raw material	High calcium flyash 2	Steel slag powder 10	0	High calcium flyash 5	Lime 2	Phosphorus-containing feedstock		Sodium metaphosphate 1	Sodium polyphosphate 3	Potassium polyphosphate 2	Potassium metaphosphate 4	Sodium metaphosphate 1
Property of (2) Can be used for Measuring Test for	28d flexural strength MPa	8.58	7.03	8.21	7.65	Phosphorus-containing feedstock		Sodium metaphosphate 1	Sodium polyphosphate 3	Potassium polyphosphate 2	Potassium metaphosphate 4	Sodium metaphosphate 1	3.47
	28d flexural strength MPa	8.58	7.03	8.21	7.65	28d compressive strength MPa	72.2	65.3	71.3	63.6	35.1		3.47
	Flow-down time (seconds)	19	22	34	12	28d compressive strength MPa	72.2	65.3	71.3	63.6	35.1	16
	Flow-down time (seconds)	19	22	34	12	Water content for standard consistency%	0.30	0.33	0.31	0.32	0.29	16
	Initial setting time h: min	2:30	2:15	7:45	2:45	Water content for standard consistency%	0.30	0.33	0.31	0.32	0.29	3:30
	Initial setting time h: min	2:30	2:15	7:45	2:45	The final setting time h: min	3:25	3:20	9:00	4:15	4:40	3:30

As can be seen from the multiple groups of embodiments, the mortar prepared by the cementing material has a 28-day compressive strength of 20-100 MPa, a 28-day flexural strength of 3-15 MPa, a setting time of 1-15 hours and good durability.

Example set 9:

MgO and silica fume were mixed in the proportions shown in Table 15, and added(NaPO₃)₆Deionized water was added, and the pH of the solution was measured by a pH meter, and the results are shown in Table 15. As can be seen from the data in Table 15, the pH of portland cement is 12.6 or more because the aqueous solution of portland cement is Ca (OH)₂Saturated solution, higher alkalinity. The pH value of the aqueous solution in the magnesium silicate cementing material is lower than that of the aqueous solution of Portland cement, and the alkalinity is lower.

Watch 15

Raw material weight ratio (gram)				pH of the solution
Raw material weight ratio (gram)				pH of the solution				MgO	Silica fume	(NaPO₃)₆	Deionized water	30 minutes	6 hours	3 days	7 days
100	0	0	500	10.82	10.85	10.85	10.85	MgO	Silica fume	(NaPO₃)₆	Deionized water	30 minutes	6 hours	3 days	7 days
100	0	0	500	10.82	10.85	10.85	10.85	70	30	1.5	500	11.78	11.81	11.85	11.81
50	50	1.5	500	11.68	11.69	11.71	11.65	70	30	1.5	500	11.78	11.81	11.85	11.81
50	50	1.5	500	11.68	11.69	11.71	11.65	30	70	1.5	500	12.01	11.82	11.85	11.81
Portland cement 100			500	12.6	12.7	12.7	12.7	30	70	1.5	500	12.01	11.82	11.85	11.81

Claims

1. A hydrated magnesium silicate system cementing material is prepared from water and powdery solid according to the weight ratio of 0.28-1: 1 at normal temperature, wherein the powdery solid comprises the following components in parts by weight:

magnesium oxide material: 15-80 parts of (A) a water-soluble polymer,

silicon oxide material: 85 to 30 portions of

Phosphorus-containing salts: 0.5 to 4 portions of

Active mineral admixture: 0 to 70 portions of

Calcium oxide raw material: 0-4 parts byweight of free calcium oxide and calcium hydroxide contained in the raw material.

2. The hydrous magnesium silicate system cementitious material of claim 1, characterised in that the magnesia material is magnesia-containing raw material made from foscarnite or dolomite by calcination.

3. The hydrous magnesium silicate system cementing material of claim 1, wherein the silica material is SiO₂One or both of silica fume and fine fly ash which are main components are combined, and the specific surface areas of the silica fume and the fine fly ash are not less than 400m²/kg。

4. The hydrous magnesium silicate system cementitious material as claimed in claim 1, characterised in that said phosphorus containing salt is one of metaphosphate and polyphosphate of sodium and potassium.

5. The hydrous magnesium silicate system cementing material of claim 1, wherein the calcium oxide raw material is a raw material containing free CaO, and is selected from one or more of lime, high calcium fly ash containing free calcium oxide and calcium hydroxide, and steel slag.

6. The hydrous magnesium silicate system gelled material of claim 1, wherein the active mineral admixture is a powdery mineral admixture used in cement and concrete and is one or a combination of more than one selected from the group consisting of slag powder, fly ash, steel slag powder, phosphorus slag powder, zeolite powder and metakaolin, and the specific surface area of the active mineral admixture is not less than 400m²/kg。

7. The hydrous magnesium silicate system cementitious material according to any one of claims 1 to 6, characterised in that said pulverulent solid consists of:

8. The hydrous magnesium silicate system cementitious material according to any one of claims 1 to 6, characterised in that said pulverulent solid consists of: