Phosphogypsum-based bottom formwork-free steel truss floor slab and manufacturing method thereof

Abstract

The present application relates to the technical field of solid waste resource utilization, and specifically discloses a phosphogypsum-based bottom mold-free steel truss floor and a manufacturing method thereof, comprising the following steps: step 1: adding a modifier to modify β-phosphogypsum to obtain modified β-phosphogypsum; step 2: adding a foaming agent to the modified β-phosphogypsum; step 3: adjusting the pH value of the modified β-phosphogypsum so that the pH value of the modified β-phosphogypsum is ≥ 10; step 4: adding short fibers and sawdust to the modified β-phosphogypsum; step 5: adding the modified β-phosphogypsum obtained in step 4 to a mold to make a floor. The purpose of this patent is to solve the problems of low strength and poor weather resistance of existing β-phosphogypsum products, as well as the inconvenience of using existing steel truss floor slabs and the easy rust and fall-off of the welding between the galvanized iron sheet and the steel truss.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste resource utilization, and in particular to a phosphogypsum-based bottom formwork-free steel truss floor slab and a manufacturing method thereof. Background Art

[0002] In recent years, the comprehensive utilization of phosphogypsum resources has been achieved to consume a large amount of phosphogypsum stockpiles. At the same time, phosphogypsum has been rapidly developed in the fields of building materials such as gypsum boards, gypsum lines, gypsum plaster mortar, and gypsum blocks. The industrial chain of comprehensive utilization of phosphogypsum resources has been initially formed, which has greatly improved the scale of comprehensive utilization of phosphogypsum resources. However, the hydration product of β-phosphogypsum is cubic crystal, which has insufficient structural tightness and poor stability, resulting in low strength and poor weather resistance of the product.

[0003] At present, the steel truss floor slabs on the market are generally made of galvanized iron sheets welded on the steel trusses. The main disadvantage is that the welding points between the galvanized iron sheets and the steel trusses are prone to rust and fall off. Secondly, since the galvanized iron sheets cannot be bonded with the plaster mortar, this layer of iron sheets must be torn off after the construction is completed, and the plaster mortar must be in contact with the concrete base surface before the mortar can be applied for decoration. In order to overcome the above defects, cement fiber boards have been used to replace galvanized iron sheets; they have now been widely used in Shenzhen, Shandong, Zhejiang and other places in my country, but cement fiber boards also have many shortcomings; first, the capacity is relatively large, reaching 2000kg / m 3 , which increases the transportation cost; secondly, it is relatively brittle and has poor flexibility; it is easy to knock off the corners during transportation and construction, making it difficult to repair.

[0004] β-phosphogypsum is semi-hydrated gypsum, and its hydration product is dihydrated gypsum. The flexural strength of the product made of dihydrated gypsum is 1-3MPa and the compressive strength is 3-6MPa one day after molding; this performance does not meet the requirements of steel truss floor slabs. Therefore, in order to solve the problems of low strength and poor weather resistance of existing β-phosphogypsum products, inconvenient use of existing steel truss floor slabs, and easy rust and fall off at the welding point between galvanized iron sheet and steel truss, it is urgent to study a method for modifying β-phosphogypsum and then applying it to building materials. Summary of the invention

[0005] In view of the deficiencies in the prior art, the technical problem solved by the present invention is to provide a phosphogypsum-based steel truss floor slab that does not require removal of the bottom formwork and a manufacturing method thereof, so as to solve the problems that the existing β-phosphogypsum products have low strength and poor weather resistance, the existing steel truss floor slabs are inconvenient to use, and the welding points between the galvanized iron sheet and the steel truss are prone to rust and fall off.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is: a method for manufacturing a phosphogypsum-based bottom formwork-free steel truss floor, comprising the following steps: step 1: adding a modifier to modify β-phosphogypsum to obtain modified β-phosphogypsum; step 2: adding a foaming agent to the modified β-phosphogypsum; step 3: adjusting the pH value of the modified β-phosphogypsum so that the pH value of the modified β-phosphogypsum is ≥10; step 4: adding short fibers and sawdust to the modified β-phosphogypsum; step 5: adding the modified β-phosphogypsum obtained in step 4 into a mold to make a floor.

[0007] The beneficial effects of this solution are: 1. By modifying β-phosphogypsum, the compressive strength and flexural strength of the modified β-phosphogypsum are improved, basically reaching the PC32.5 cement index; 2. By adding an appropriate amount of short fibers and wood chips, the flexibility and nail holding force of the floor slab are increased, achieving the effect of not being easy to collide and fall off the corners, and at the same time increasing the nail holding force of the floor slab. After testing, the nail holding force of the floor slab is greater than 2000N; 3. By using a foaming agent, the bulk density of the floor slab is effectively reduced, so that the bulk density of the floor slab is 1100-1200Kg / m 3 ; 4. Adjust the pH value of phosphogypsum to be greater than 10. In this alkaline environment, the steel bars are prone to passivation, and a passivation film is produced on the surface of the steel bars, which can prevent the steel bars covered by phosphogypsum from rusting, thereby controlling the corrosion of the steel bars.

[0008] Furthermore, the modifier in step 1 is composed of the following components in a mass ratio: ultrafine sub-nano material: crystal inversion agent: surfactant: retarder = 1:1:0.3:0.03-4:2:0.7:0.08. The modified β-phosphogypsum modified by the above modifier has a compressive strength index of 1d≥25MPa; 3d≥35MPa; and a flexural strength index of 1d≥4.0MPa; 3d≥5MPa.

[0009] Furthermore, the ultrafine sub-nano material is at least one of silicon powder, heavy calcium powder and kaolin powder.

[0010] Furthermore, the crystal-changing agent is one or two of sulphoaluminate cement clinker powder and α-type hemihydrate gypsum.

[0011] Furthermore, in step 1, the amount of modifier added is 3%-4% by mass; the amount of β-phosphogypsum added is 96%-97% by mass.

[0012] Furthermore, the retarder is at least one of an inorganic salt or a protein.

[0013] Furthermore, the short fibers are added in an amount of 0.2-0.3% by mass, the sawdust is added in an amount of 5-20% by mass, and the length of the short fibers is 9-13 mm. The use of short fibers of this length range can improve the toughness of the manufactured floor slab and facilitate the mixing of the short fibers with the modified-β phosphogypsum.

[0014] Furthermore, the foaming agent is one or more of K12, air entraining agent, hydrogen peroxide and foam stabilizer.

[0015] Furthermore, in step 3, the pH value is adjusted by adding 1-2% of an alkaline compound, and the alkaline compound is one or more of calcium hydroxide, calcium oxide, and sodium hydroxide.

[0016] Furthermore, a floor slab is manufactured using the manufacturing method described in claim 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of the manufacturing method of Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The following is further described in detail through specific implementation methods:

[0019] Example 1 This is as attached Figure 1 As shown: A method for manufacturing a phosphogypsum-based bottom formwork-free steel truss floor slab comprises the following steps;

[0020] Step 1: Add 3.02% of the modifier to 96.98% of the β-phosphogypsum and mix evenly, add 38% of the total amount of water and stir evenly to obtain modified β-phosphogypsum; the modifier is composed of the following components in a mass ratio, ultrafine sub-nano material: crystal transfer agent: surfactant: retarder = 1.5:1:0.5:0.02; the ultrafine sub-nano material is selected from silicon powder, the crystal transfer agent is selected from sulphoaluminate cement clinker powder, the surfactant can be selected from at least one of hydrolyzed resin, polyamide, polycarboxylic acid water reducer, melamine, and naphthalene-based water reducer. In this embodiment, the preferred surfactant is polyamide, and the retarder is an inorganic salt.

[0021] Step 2: Add 0.07% foaming agent to the modified β-phosphogypsum; make the bulk density of the board 1080kg / m 3 ; The foaming agent is K12.

[0022] Step 3: adding 1.5% calcium hydroxide to adjust the pH value of the modified β-phosphogypsum to 10.7;

[0023] Step 4: Add 0.2% short fiber and 15% sawdust to the modified β-phosphogypsum;

[0024] Step 5: Add the modified β-phosphogypsum obtained in step 4 into the mold, and add 150g of alkali-resistant fiber mesh cloth to the bottom of the mold to make a 1000*400*20mm floor slab.

[0025] The difference between Example 2 and Example 1 is that: a method for manufacturing a phosphogypsum-based bottom formwork-free steel truss floor slab comprises the following steps:

[0026] Step 1: Add 3.64% of the modifier to 96.36% of the β-phosphogypsum and mix evenly, add 38% of the total amount of water and stir evenly to obtain modified β-phosphogypsum; the modifier is composed of the following components in a mass ratio, ultrafine sub-nano material: crystallization agent: surfactant: retarder = 2:1:0.6:0.04; the ultrafine sub-nano material is a 1:1 mixture of silicon powder and heavy calcium powder, the crystallization agent is α-type hemihydrate gypsum, the surfactant is a hydrolyzed resin and a polycarboxylic acid water reducer, and the retarder is an inorganic salt.

[0027] Step 2: Add 0.075% foaming agent to the modified β-phosphogypsum; make the bulk density of the board 1050kg / m 3 ; The foaming agents are K12 and hydrogen peroxide.

[0028] Step 3: adding 1.2% calcium hydroxide to adjust the pH value of the modified β-phosphogypsum so that the pH value of the modified β-phosphogypsum is 10.5;

[0029] Step 4: Add 0.3% short fiber and 10% sawdust to the modified β-phosphogypsum;

[0030] Step 5: Add the modified β-phosphogypsum obtained in step 4 into the mold, and add 100g of alkali-resistant fiber mesh cloth to the bottom of the mold to make a 1000*400*20mm floor slab.

[0031] The difference between Example 3 and Example 1 and Example 2 is that: a method for manufacturing a phosphogypsum-based bottom formwork-free steel truss floor slab comprises the following steps:

[0032] Step 1: Add 3.13% of the modifier to 96.87% of the β-phosphogypsum and mix evenly, add 38% of the total amount of water and stir evenly to obtain modified β-phosphogypsum; the modifier is composed of the following components in a mass ratio, ultrafine sub-nano material: crystal-changing agent: surfactant: retarder = 2:1:0.6:0.04; the ultrafine sub-nano material is a 1:1 mixture of silicon powder and heavy calcium powder, the crystal-changing agent is α-type hemihydrate gypsum, the surfactant is a hydrolyzed resin and a polycarboxylic acid water reducer, and the retarder is an inorganic salt.

[0033] Step 2: Add 0.075% foaming agent to the modified β-phosphogypsum; make the bulk density of the board 1060kg / m 3; The foaming agent is selected from air entraining agent and foam stabilizer.

[0034] Step 3: adding 1.2% calcium hydroxide to adjust the pH value of the modified β-phosphogypsum to a pH value of 10.5;

[0035] Step 4: Add 0.25% short fiber and 8% wood chips to the modified β-phosphogypsum;

[0036] Step 5: Add the modified β-phosphogypsum obtained in step 4 into the mold, and add 80g of alkali-resistant fiber mesh cloth to the bottom of the mold to make a 1000*400*20mm floor slab.

[0037] The modified β-phosphogypsum of Examples 1 to 3 were respectively poured into a 4*4*16 cm mold to test the performance. The test results are shown in Table 1:

[0038] Table 1 Performance test table of modified β-phosphogypsum

[0039]

[0040] After the modified β-phosphogypsum is placed at room temperature for 365 days, the strength of the modified β-phosphogypsum is increased relative to that of the β-phosphogypsum; the flexural strength of the modified β-phosphogypsum is increased by 2-4 MPa, and the compressive strength is increased by 8-12 MPa.

[0041] The following method is used for the phosphogypsum bottom formwork-free steel truss floor slab made in Examples 1-3. The two ends of the phosphogypsum bottom formwork-free steel truss floor slab are respectively placed on wooden blocks with a height of 100 mm. After gravity is added to the middle of the floor slab, the floor slab can be bent until it touches the ground without breaking. After the gravity is removed, the floor slab can be restored to its original state without any cracks.

[0042] A 2.5*40 wood screw was screwed into the floor slab with a screwdriver, and the floor slab's nail holding force was tested to be greater than 2000N; a 60Kg weight was hung on the wood screw, and the board was intact and the wood screw did not fall off. This shows that the floor slab made with this solution has extremely strong toughness and extremely high holding force; it can not only avoid collision and falling edges and corners during transportation and hoisting, but also fasten the steel truss in the floor slab.

[0043] The floor slabs prepared by the steps of Example 1 to Example 3 were tested, and the test results are shown in Table 2;

[0044] Table 2 Floor performance test table

[0045]

[0046] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for manufacturing a phosphogypsum-based bottom formwork-free steel truss floor, characterized in that: The method comprises the following steps: step 1: adding a modifier to modify β-phosphogypsum to obtain modified β-phosphogypsum; step 2: adding a foaming agent to the modified β-phosphogypsum; step 3: adjusting the pH value of the modified β-phosphogypsum so that the pH value of the modified β-phosphogypsum is ≥10; step 4: adding short fibers and sawdust to the modified β-phosphogypsum and mixing them evenly; step 5: adding the modified β-phosphogypsum obtained in step 4 into a mold to form a floor slab; In step 1, the modifier is composed of the following components in a mass ratio: ultrafine sub-nano material: crystal-changing agent: surfactant: retarder = 1.5:1:0.5:0.02, or ultrafine sub-nano material: crystal-changing agent: surfactant: retarder = 2:1:0.6:0.04; in step 1, the amount of modifier added is 3%-4% by mass percentage; the amount of β-phosphogypsum added is 96%-97%; The ultrafine sub-nano material is at least one of silicon powder, heavy calcium powder and kaolin powder; the crystal-changing agent is one or two of sulphoaluminate cement clinker powder and α-type hemihydrate gypsum.

2. The method for manufacturing the phosphogypsum-based bottom formwork-free steel truss floor according to claim 1, characterized in that: The retarder is at least one of inorganic salts or proteins.

3. The method for manufacturing the phosphogypsum-based bottom formwork-free steel truss floor according to claim 1, characterized in that: The short fibers are added in an amount of 0.2-0.3% by mass, the wood chips are added in an amount of 5-20% by mass, and the length of the short fibers is 9-13 mm.

4. The method for manufacturing the phosphogypsum-based bottom formwork-free steel truss floor according to claim 1, characterized in that: The foaming agent is added in an amount of 0.06%-0.08% by mass; the foaming agent is one or more of K12 and hydrogen peroxide.

5. The method for manufacturing the phosphogypsum-based bottom formwork-free steel truss floor according to claim 1, characterized in that: In step 3, the pH value is adjusted by adding 1-2% of an alkaline compound, wherein the alkaline compound is one or more of calcium hydroxide, calcium oxide, and sodium hydroxide.

6. A phosphogypsum-based steel truss floor slab without dismantling bottom formwork, characterized in that: A floor slab manufactured using the manufacturing method described in claim 1.

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