CN111138105A - Method for adjusting β -hemihydrate gypsum setting time - Google Patents

Method for adjusting β -hemihydrate gypsum setting time Download PDF

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CN111138105A
CN111138105A CN202010055329.3A CN202010055329A CN111138105A CN 111138105 A CN111138105 A CN 111138105A CN 202010055329 A CN202010055329 A CN 202010055329A CN 111138105 A CN111138105 A CN 111138105A
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phosphoric acid
setting time
gypsum
waste
hemihydrate gypsum
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CN111138105B (en
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田晓华
赵风清
张宇
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Hebei University of Science and Technology
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039Premixtures of ingredients
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/14Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
    • C04B28/145Calcium sulfate hemi-hydrate with a specific crystal form
    • C04B28/146Calcium sulfate hemi-hydrate with a specific crystal form alpha-hemihydrate

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention provides a method for adjusting β -hemihydrate gypsum setting time, which comprises the steps of crushing waste cement, grinding to obtain waste cement powder, mixing the waste cement powder and a phosphoric acid aqueous solution, reacting for 0.5-60 min, and adding β -hemihydrate gypsum to prepare uniform slurry, wherein the gypsum slurry can be poured to produce a gypsum building material product, and can also be directly poured on site to form a building wall.

Description

Method for adjusting β -hemihydrate gypsum setting time
Technical Field
The invention relates to a method for adjusting β -hemihydrate gypsum setting time by mixing and reacting waste cement and phosphoric acid aqueous solution, which can be used for production and construction of gypsum building materials.
Background
Gypsum building products have the advantages of light weight, fire resistance, heat preservation, sound insulation, certain temperature and humidity regulation and the like, and become green and environment-friendly building materials which are widely accepted and widely used in the world, β -semi-hydrated gypsum has the advantages of fast setting and hardening and short operable time, in practical application, β -semi-hydrated gypsum is adjusted by adding a proper amount of retarder and other additives, the commonly used gypsum retarder mainly comprises organic acids such as citric acid, sodium citrate and the like, soluble salts (phosphates such as sodium hexametaphosphate, sodium polyphosphate and the like) and proteins, and has higher cost, in addition, due to the adoption of industrial byproduct gypsum raw materials, different calcining modes and other reasons, the application of β -semi-hydrated gypsum cannot achieve good retarding effect no matter the conventional retarder such as citric acid, sodium citrate and the like or the method in patent document CN 106866015A, CN 107082587A, namely the applicability of the traditional gypsum retarder to semi-hydrated gypsum is reduced, and the application of industrial byproduct gypsum is greatly limited.
Disclosure of Invention
The invention provides a method for adjusting the setting time of building gypsum by using waste cement and phosphoric acid, which can be applied to the production and engineering construction of gypsum building materials and has low production cost.
A method for adjusting the setting time of β -semi-hydrated gypsum comprises the steps of crushing waste cement, grinding to obtain waste cement powder, mixing the waste cement powder with a phosphoric acid aqueous solution, reacting for 0.5-60 min, adding β -semi-hydrated gypsum to prepare uniform slurry, and pouring the gypsum slurry to produce a gypsum building material product or directly pouring the gypsum slurry on site to form a building wall.
In the method, the waste cement is expired cement, damp-out cement or cement wetted by water, and the waste cement powder accounts for 0.1-2.0% of the β -hemihydrate gypsum by weight.
In the above method, the specific surface area of the waste cement powder is 350 m2/kg~450m2/kg。
In the method, the pH value of the phosphoric acid aqueous solution is 1.2-2.0.
In the above method, the phosphoric acid may be either industrial-grade phosphoric acid or waste phosphoric acid.
The invention has the advantages that the waste cement and the phosphoric acid are used as main modified materials, the reaction time, the feeding amount and the pH value of the phosphoric acid aqueous solution are controlled to react to prepare the gypsum retarder, and the product can effectively regulate and control the setting time of β -hemihydrate gypsum and meet the production and construction requirements of gypsum building materials.
The embodiment shows that the active hydrogen phosphate generated by the reaction of the waste cement and the phosphoric acid aqueous solution is the main reason for regulating and controlling the setting time of β -semi-hydrated gypsum, the setting time of β -semi-hydrated gypsum can be controlled to be 25 min-50 min when the reaction time is within the range of 0.5 min-60 min, the setting time of β -semi-hydrated gypsum can be controlled to be 40 min-65 min when the reaction time is within 5min, and the setting time of β -semi-hydrated gypsum can only be controlled to be about 20min when the waste cement is singly mixed with the phosphoric acid aqueous solution (comparative example 2, attached figure 3) or the waste cement (comparative example 3, attached figure 4).
The method solves the problems of short setting time of the building gypsum and unfavorable production and construction, has simple process and low cost, and provides a new way for resource utilization of the waste cement and the low-concentration waste phosphoric acid.
Drawings
FIG. 1 is a graph showing the effect of the amount of waste cement powder on the setting time of β -hemihydrate.
FIG. 2 is a graph showing the effect of reaction time of waste cement with an aqueous solution of phosphoric acid on the setting time of β -hemihydrate.
FIG. 3 is a graph showing the effect of pH on the setting time of β -hemihydrate.
FIG. 4 is a graph showing the effect of the amount of waste cement powder added on the setting time of β -hemihydrate gypsum.
Detailed Description
The present invention will be described in detail with reference to examples. The inventive and comparative example test methods were carried out according to the standard GB/T17669.4-1999 construction gypsum.
Example one
Water and phosphoric acid were first mixed to prepare an aqueous phosphoric acid solution having a pH of 1.2, and then 0.42 part of waste cement powder (having a specific surface area of 371 m) was added to 113 parts of the aqueous phosphoric acid solution2Kg), stirring and reacting for 1min, then adding 199.58 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used phosphoric acid is industrial grade and has an effective concentration of 85%.
Example two
Water and phosphoric acid were first mixed to prepare an aqueous phosphoric acid solution having a pH of 1.3, and 1 part of waste cement powder (having a specific surface area of 358 m) was added to 113 parts of the aqueous phosphoric acid solution2Kg), stirring and reacting for 2min, then adding 199 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used phosphoric acid is industrial grade and has an effective concentration of 85%.
EXAMPLE III
Water and waste phosphoric acid were first mixed to prepare an aqueous phosphoric acid solution having a pH of 1.5, and then 0.5 part of waste cement powder (specific surface area 407 m) was added to 113 parts of the above aqueous phosphoric acid solution2And/kg), stirring and reacting for 1min, then adding 199.5 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used waste phosphoric acid is waste phosphoric acid etching liquid generated by a photoelectric enterprise, and the content of the phosphoric acid is 37.46 percent.
Example four
Water and waste phosphoric acid were first blended into an aqueous phosphoric acid solution having a pH of 1.6, and then 0.42 part of waste cement powder (specific surface area of 446 m) was added to 113 parts of the above aqueous phosphoric acid solution2Kg), stirring and reacting for 2min, then adding 199.58 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used waste phosphoric acid is waste phosphoric acid etching liquid generated by photoelectric enterprises, and the content of the phosphoric acid is 37.46 percent.
EXAMPLE five
Mixing water and waste phosphoric acid to obtain phosphoric acid aqueous solution with pH of 1.7, adding 0.28 part of waste cement powder (specific surface area of 389 m) into 113 parts of phosphoric acid aqueous solution2Kg), stirring and reacting for 1min, then adding 199.72 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring setting timeAnd (4) determining. The waste phosphoric acid is generated in the synthesis process of the pesticide butachlor, and the content of the phosphoric acid is 32.18 percent.
EXAMPLE six
Mixing water and waste phosphoric acid to obtain phosphoric acid aqueous solution with pH of 2.0, adding 0.1 part of waste cement powder (specific surface area 426 m) into 113 parts of phosphoric acid aqueous solution2Kg), stirring and reacting for 2min, then adding 199.9 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used waste phosphoric acid is the waste phosphoric acid generated in the synthesis process of the pesticide butachlor, and the content of the phosphoric acid is 32.18 percent.
EXAMPLE seven
Water and phosphoric acid were first mixed to prepare an aqueous phosphoric acid solution having a pH of 2.3, and then 2 parts of waste cement powder (specific surface area of 396 m) were added to 113 parts of the above aqueous phosphoric acid solution2Kg), stirring and reacting for 3min, then adding 198 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting time, wherein the used phosphoric acid is industrial grade and has an effective concentration of 85%.
EXAMPLE eight (phosphoric acid aqueous solution pH =1.5, changing the amount of waste cement powder blended)
Mixing water and phosphoric acid to obtain phosphoric acid aqueous solution with pH value of 1.5, and adding 0 part, 0.14 part, 0.28 part, 0.42 part, 0.7 part, 1.0 part, 1.2 parts and 1.4 parts of waste cement powder (specific surface area of 358 m) into 113 parts of phosphoric acid aqueous solution2Kg), stirring and reacting for 1min, adding β -semi-hydrated gypsum (200 parts of waste cement powder and β -semi-hydrated gypsum in total) to prepare uniform slurry, and measuring the setting time, wherein the used phosphoric acid is industrial grade and has an effective concentration of 85 percent, and the test result is shown in figure 1.
EXAMPLE nine (changing the reaction time of the waste Cement powder with the phosphoric acid aqueous solution)
Water and phosphoric acid were first mixed to prepare an aqueous phosphoric acid solution having a pH of 1.5, and then 0.42 part of waste cement powder (specific surface area of 396 m) was added to 113 parts of the aqueous phosphoric acid solution2Kg), controlling the stirring reaction time to be 0.5min, 1min, 3min, 5min, 30min, 45min and 60min respectively, then adding 199.58 parts of β -hemihydrate gypsum to prepare uniform slurry, and measuring the setting timePhosphoric acid is technical grade, and the effective concentration is 85%. The test results are shown in FIG. 2.
COMPARATIVE EXAMPLE 1 (blank)
A homogeneous slurry was prepared by adding 200 parts of β -hemihydrate to 113 parts of water and the setting time was measured.
COMPARATIVE EXAMPLE 2 (phosphoric acid only)
Water and phosphoric acid are mixed to prepare a phosphoric acid aqueous solution with the pH value of 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.9 and 2.0, 200 parts of β -hemihydrate gypsum is added into 113 parts of the phosphoric acid aqueous solution to prepare uniform slurry, the setting time is measured, the used phosphoric acid is industrial grade, the effective concentration is 85 percent, and the test result is shown in figure 3.
COMPARATIVE EXAMPLE 3 (addition of waste Cement powder only)
To 113 parts of water were added 0 part, 0.1 part, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts of waste cement powder (specific surface area 438 m)2Kg) was stirred for 1min, β -hemihydrate gypsum was added to make a homogeneous slurry (200 parts of waste cement powder in total with β -hemihydrate gypsum) and the setting time was measured the test results are shown in figure 4.
Figure DEST_PATH_IMAGE001

Claims (4)

1. A method for adjusting β -hemihydrate gypsum setting time is characterized by crushing waste cement, grinding to obtain waste cement powder, mixing the waste cement powder with a phosphoric acid aqueous solution for reaction for 0.5-60 min, and adding β -hemihydrate gypsum to prepare uniform slurry, wherein the waste cement is expired cement, damp-out cement or cement wetted with water, and the waste cement powder accounts for 0.1-2.0% of the weight of β -hemihydrate gypsum.
2. The method for adjusting β -hemihydrate gypsum setting time according to claim 1, wherein the pH of the phosphoric acid aqueous solution is 1.2-2.0.
3. The method of claim 1A method for adjusting β -hemihydrate gypsum setting time is characterized in that the specific surface area of the waste cement powder is 350 m2/kg~450m2/kg。
4. The method for adjusting β -hemihydrate gypsum setting time of claim 1, wherein the phosphoric acid is industrial grade phosphoric acid or industrial waste phosphoric acid.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1646647A1 (en) * 1967-09-01 1971-08-19 Kloeckner Humboldt Deutz Ag Process for the production of cement
CN101265068A (en) * 2008-04-28 2008-09-17 长沙归一建材科技有限公司 Gelatinization material gypsum-cement and producing method thereof
CN106866015A (en) * 2017-03-15 2017-06-20 河北科技大学 A kind of β semi-hydrated gypsums retarder and preparation method thereof
CN107082587A (en) * 2017-05-18 2017-08-22 河北科技大学 A kind of preparation method of calcium sulphate retarder
CN108558251A (en) * 2018-02-06 2018-09-21 河北科技大学 A method of adjusting gypsum material setting time
CN109678369A (en) * 2018-12-24 2019-04-26 铜陵上峰水泥股份有限公司 A kind of polynary solid waste prepares the production technology and method of cement
CN110104984A (en) * 2019-05-07 2019-08-09 武汉理工大学 A kind of ardealite slag cements early strength coagulant based on modified composite dewatering phase

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1646647A1 (en) * 1967-09-01 1971-08-19 Kloeckner Humboldt Deutz Ag Process for the production of cement
CN101265068A (en) * 2008-04-28 2008-09-17 长沙归一建材科技有限公司 Gelatinization material gypsum-cement and producing method thereof
CN106866015A (en) * 2017-03-15 2017-06-20 河北科技大学 A kind of β semi-hydrated gypsums retarder and preparation method thereof
CN107082587A (en) * 2017-05-18 2017-08-22 河北科技大学 A kind of preparation method of calcium sulphate retarder
CN108558251A (en) * 2018-02-06 2018-09-21 河北科技大学 A method of adjusting gypsum material setting time
CN109678369A (en) * 2018-12-24 2019-04-26 铜陵上峰水泥股份有限公司 A kind of polynary solid waste prepares the production technology and method of cement
CN110104984A (en) * 2019-05-07 2019-08-09 武汉理工大学 A kind of ardealite slag cements early strength coagulant based on modified composite dewatering phase

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
铁道部华北铁路工程局: "《混凝土工》", 31 December 1966, 人民铁道出版社 *

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