Low-cost delayed coagulation type concrete and preparation method thereof

Abstract

The invention relates to low-cost retarded concrete and a preparation method thereof. The low-cost retarded concrete comprises the following components in parts by weight: 24-27 parts of cement, 6-8 parts of blast furnace slag powder, 5-8 parts of fly ash, 70-90 parts of fine aggregate, 2-7 parts of sludge incineration ash, 93-100 parts of coarse aggregate, 0.4-0.6 part of a water reducing agent, 0-0.25 part of a retarder and 12-21 parts of water. When the temperature of the production environment is lower than 30 DEG C, the retarder comprises sodium gluconate; when the temperature of the production environment is higher than or equal to 30 DEG C, the retarder further comprises white sugar. According to the invention, the sludge incineration ash is recycled, phosphate radicals dissolved in the sludge incineration ash are combined with calcium ions generated by cement hydration, and the calcium ions coat the surfaces of cement particles to hinder further hydration of cement, so that the purpose of retarding is achieved, and the cement can be retarded by increasing the mixing amount of the sludge incineration ash and the retarder. The retarded concrete meeting different setting time requirements can be prepared; other components in the sludge incineration ash can be subjected to secondary hydration reaction with calcium hydroxide generated by cement hydration, so that the durability of the concrete can be improved.

Description

Technical Field

[0001] The invention relates to the field of building concrete, and in particular to a low-cost slow-setting concrete and a preparation method thereof. Background Art

[0002] Slow-setting concrete is a type of concrete with a relatively long setting time. It is mainly used in special working conditions such as long transportation time, large pouring volume, high temperature in summer, underwater pouring, etc. At present, the preparation of slow-setting concrete is mainly obtained by adulterating chemical admixtures with a slow-setting effect, while mineral slow-setting admixtures are less used.

[0003] Incineration is one of the common sludge reduction measures used by urban sewage treatment plants. Incineration will produce a large amount of sludge incineration ash, and the cost of sludge incineration ash treatment is relatively high. Therefore, if the sludge incineration ash produced by incineration can be reused, it can not only solve the treatment cost of sludge incineration ash, but also make full use of resources.

[0004] The prior art, such as a retarding enhancer, retarding cement for roads and a preparation method thereof, is disclosed in the patent application publication document with publication number CN116553852A. The retarding enhancer comprises 40-70 parts of sludge incineration ash, 10-20 parts of steel slag powder, 5-15 parts of silica ash and 10-20 parts of desulfurization ash. The retarding enhancer is used to achieve the time delay requirement of the retarding cement for the road base, thereby ensuring the strength of the retarding cement for the road base.

[0005] However, the retarding effect of sludge incineration ash as a retarding enhancer is limited. The longest setting time in the above patent disclosure is 513 minutes, and the retarding effect is limited; and the increase in the addition of sludge incineration ash may affect the strength of concrete. Summary of the invention

[0006] In order to improve the retarding effect and avoid reducing the strength of concrete due to the addition of sludge incineration ash, the present invention provides a low-cost retarding concrete and a preparation method thereof. By compounding sludge incineration ash and a retarder, the retarding effect is improved while ensuring the strength of the concrete.

[0007] The technical objectives of the present invention are achieved through the following technical solutions:

[0008] A low-cost slow-setting concrete, comprising, by weight:

[0009] 24-27 parts of cement, 6-8 parts of blast furnace slag powder, 5-8 parts of fly ash, 70-90 parts of fine aggregate, 2-7 parts of sludge incineration ash, 93-100 parts of coarse aggregate, 0.4-0.6 parts of water reducer, 0-0.25 parts of retarder, 12-21 parts of water; when the production environment temperature is lower than 30°C, the retarder includes sodium gluconate; when the production environment temperature is greater than or equal to 30°C, the retarding effect of sodium gluconate decreases, and the retarder also includes white sugar, and the retarding effect of the retarder is improved by adding white sugar.

[0010] Furthermore, the sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, and 28d strength activity index ≥70%.

[0011] Furthermore, the water reducing agent is a polycarboxylic acid water reducing agent or a naphthalene water reducing agent, and the water reducing rate is ≥14%.

[0012] Furthermore, the specific surface area of ​​the blast furnace slag powder is ≥400 m2 / kg, and the 28d activity index is ≥95%.

[0013] Furthermore, the 45 μm sieve residue of the fly ash is ≤45%, and the 28d strength activity index is ≥70%.

[0014] Furthermore, the cement is P.O42.5 Portland cement.

[0015] Furthermore, the particle size of the coarse aggregate is 5-25 mm.

[0016] The present invention also provides a method for preparing low-cost slow-setting concrete, which is characterized by comprising:

[0017] Step 1, mix 24-27 parts of cement, 6-8 parts of blast furnace slag powder, 5-8 parts of fly ash, 70-90 parts of fine aggregate, 2-7 parts of sludge incineration ash, and 93-100 parts of coarse aggregate in proportion so that the powder is evenly mixed with the coarse aggregate and the fine aggregate;

[0018] Step 2, add 0-0.25 parts of retarder and 0.4-0.6 parts of water reducer to 12-21 parts of water and stir to dissolve the coagulant and water reducer in the water;

[0019] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir evenly to obtain slow-setting concrete slurry.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention reuses the sludge incineration ash, utilizes the dissolved phosphate in the sludge incineration ash to combine with the calcium ions generated by cement hydration, and coats the cement particle surface to hinder the further hydration of cement, thereby achieving the purpose of slow setting.

[0022] 2. In the present invention, in addition to the soluble phosphates in the sludge incineration ash having a retarding effect, other components can undergo a secondary hydration reaction with the calcium hydroxide produced by cement hydration, which is beneficial to improving the durability of concrete.

[0023] 3. The present invention uses sludge incineration ash and a retarder in combination, and can significantly improve the retarding effect by increasing the dosage of sludge incineration ash and the dosage of the retarder, so as to prepare retarded concrete that meets different setting time requirements.

[0024] 4. The present invention uses sludge incineration ash to reduce the cost of treating sludge incineration ash. Sodium gluconate and white sugar are used as retarders in small amounts and at relatively low costs, thereby making the preparation cost of the retarded concrete of the present invention relatively low. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0026] Example 1

[0027] A low-cost slow-setting concrete, comprising, by weight:

[0028] 25.6 parts of cement, 6 parts of blast furnace slag powder, 4 parts of fly ash, 82.4 parts of fine aggregate, 3.6 parts of sludge incineration ash, 96 parts of coarse aggregate, 0.59 parts of water reducer, and 21 parts of water.

[0029] The sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, usually P2O5 content does not exceed 15%, and 28d strength activity index ≥70%; the water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer, and the water reduction rate is ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400㎡ / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, coarse aggregate is such as crushed stone, and fine aggregate is such as river sand.

[0030] When preparing:

[0031] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate, sludge incineration ash, and 93-100 parts of coarse aggregate in proportion so that the powder, coarse aggregate, and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0032] Step 2, adding the water reducer and stirring to dissolve the water reducer in the water;

[0033] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir in a mixer for 3 minutes to obtain a slow-setting concrete slurry.

[0034] Example 2

[0035] A low-cost slow-setting concrete, comprising, by weight:

[0036] 25.6 parts of cement, 6 parts of blast furnace slag powder, 4 parts of fly ash, 82.4 parts of fine aggregate, 3.6 parts of sludge incineration ash, 96 parts of coarse aggregate, 0.59 parts of water reducer, 0.04 parts of sodium gluconate, and 21 parts of water.

[0037] The sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, and 28d strength activity index ≥70%; the water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer, and the water reduction rate is ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400㎡ / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, the coarse aggregate is such as crushed stone, and the fine aggregate is such as river sand.

[0038] When preparing:

[0039] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate, sludge incineration ash, and 93-100 parts of coarse aggregate in proportion so that the powder, coarse aggregate, and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0040] Step 2, adding a water reducer and sodium gluconate and stirring to dissolve the water reducer and sodium gluconate in water;

[0041] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir in a mixer for 3 minutes to obtain a slow-setting concrete slurry.

[0042] Example 3

[0043] A low-cost slow-setting concrete, comprising, by weight:

[0044] 25.6 parts of cement, 6 parts of blast furnace slag powder, 4 parts of fly ash, 82.4 parts of fine aggregate, 3.6 parts of sludge incineration ash, 96 parts of coarse aggregate, 0.59 parts of water reducer, 0.02 parts of sodium gluconate, 0.02 parts of white sugar, and 21 parts of water.

[0045] The sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, and 28d strength activity index ≥70%; the water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer, and the water reduction rate is ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400㎡ / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, the coarse aggregate is such as crushed stone, and the fine aggregate is such as river sand.

[0046] When preparing:

[0047] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate, sludge incineration ash, and 93-100 parts of coarse aggregate in proportion so that the powder, coarse aggregate, and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0048] Step 2, adding water reducing agent, sodium gluconate and white sugar and stirring to dissolve the retarder and water reducing agent in water;

[0049] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir in a mixer for 3 minutes to obtain a slow-setting concrete slurry.

[0050] Example 4

[0051] A low-cost slow-setting concrete, comprising, by weight:

[0052] 25.6 parts of cement, 4 parts of blast furnace slag powder, 3 parts of fly ash, 82.4 parts of fine aggregate, 6.6 parts of sludge incineration ash, 96 parts of coarse aggregate, 0.59 parts of water reducer, 0.02 parts of sodium gluconate, 0.02 parts of white sugar, and 21 parts of water.

[0053] The sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, and 28d strength activity index ≥70%; the water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer, and the water reduction rate is ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400㎡ / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, the coarse aggregate is such as crushed stone, and the fine aggregate is such as river sand.

[0054] When preparing:

[0055] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate, sludge incineration ash, and 93-100 parts of coarse aggregate in proportion so that the powder, coarse aggregate, and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0056] Step 2, adding water reducing agent, sodium gluconate and white sugar and stirring to dissolve the retarder and water reducing agent in water;

[0057] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1, stir in a mixer for 3 minutes to obtain a slow-setting concrete slurry.

[0058] Comparative Example 1

[0059] A low-cost slow-setting concrete, comprising, by weight:

[0060] 23 parts of cement, 8 parts of blast furnace slag powder, 5 parts of fly ash, 80 parts of fine aggregate, 102 parts of coarse aggregate, 0.43 parts of water reducer, 0.002 parts of sodium gluconate, and 17 parts of water.

[0061] The sewage water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer with a water reduction rate of ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400㎡ / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, such as crushed stone, and fine aggregate is such as river sand.

[0062] When preparing:

[0063] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate and coarse aggregate in proportion so that the powder, coarse aggregate and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0064] Step 2, adding water reducing agent and sodium gluconate and stirring to dissolve the retarder and water reducing agent in water;

[0065] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1, stir in a mixer for 3 minutes to obtain a slow-setting concrete slurry.

[0066] Comparative Example 2

[0067] A low-cost slow-setting concrete, comprising, by weight:

[0068] 25.6 parts of cement, 7.7 parts of blast furnace slag powder, 5.9 parts of fly ash, 82.4 parts of fine aggregate, 96 parts of coarse aggregate, 0.59 parts of water reducer, and 19 parts of water.

[0069] The water reducer is a polycarboxylic acid water reducer or a naphthalene water reducer with a water reduction rate of ≥14%; the specific surface area of ​​blast furnace slag powder is ≥400 m2 / kg, and the 28d activity index is ≥95%; the 45μm sieve residue of fly ash is ≤45%, and the 28d strength activity index is ≥70%; the cement is P.O42.5 silicate cement; the particle size of coarse aggregate is 5-25mm, such as crushed stone, and fine aggregate is such as river sand.

[0070] When preparing:

[0071] Step 1: Mix cement, blast furnace slag powder, fly ash, fine aggregate and coarse aggregate in proportion so that the powder, coarse aggregate and fine aggregate are evenly mixed. The mixing time is 1 minute.

[0072] Step 2, adding the water reducer and stirring to dissolve the water reducer in the water;

[0073] Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir in a mixer for 3 minutes to obtain concrete slurry.

[0074] The chemical composition of the sludge incineration fly ash in the above Examples 1-4 is shown in the following table:

[0075]

[0076] According to 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", the setting time of concrete was measured: the slow setting concrete slurries obtained in Examples 1 to 4 and the concrete slurries obtained in Comparative Examples 1 and 2 were sieved through a 5 mm sieve, and then the mortar was poured into a bucket, and the penetration resistance at different hydration ages was measured, and the initial setting time, final setting time and compressive strength of the concrete were calculated, as shown in the following table:

[0077]

[0078]

[0079] It can be seen from the above test results that the retarding effect of the compounding of retarder and sludge incineration ash is significantly improved compared with the single addition of sludge incineration ash and general concrete (comparative example).

[0080] This embodiment is only a further explanation of the present invention, not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it will be protected by the patent law.

Claims

1. A low-cost slow-setting concrete, characterized in that: In terms of weight ratio, it includes: 24-27 parts of cement, 6-8 parts of blast furnace slag powder, 5-8 parts of fly ash, 70-90 parts of fine aggregate, 2-7 parts of sludge incineration ash, 93-100 parts of coarse aggregate, 0.4-0.6 parts of water reducer, 0-0.25 parts of retarder, 12-21 parts of water; when the production environment temperature is lower than 30°C, the retarder includes sodium gluconate; when the production environment temperature is greater than or equal to 30°C, the retarder also includes white sugar.

2. A low-cost slow-setting concrete according to claim 1, characterized in that: The sludge incineration ash is sludge incineration fly ash, with 80μm sieve residue ≤20%, P2O5 content ≥10%, and 28d strength activity index ≥70%.

3. The low-cost slow-setting concrete according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid water reducing agent or a naphthalene water reducing agent, and the water reducing rate is ≥14%.

4. The low-cost slow-setting concrete according to claim 1, characterized in that: The specific surface area of ​​the blast furnace slag powder is ≥400 m2 / kg, and the 28d activity index is ≥95%.

5. The low-cost slow-setting concrete according to claim 1, characterized in that: The fly ash has a 45 μm sieve residue of ≤45%, and a 28d strength activity index of ≥70%.

6. The low-cost slow-setting concrete according to claim 1, characterized in that: The cement is P.O42.5 silicate cement.

7. The low-cost slow-setting concrete according to claim 1, characterized in that: The particle size of the coarse aggregate is 5-25 mm.

8. A method for preparing low-cost slow-setting concrete according to any one of claims 1 to 7, characterized in that: include: Step 1, mixing cement, blast furnace slag powder, fly ash, fine aggregate, sludge incineration ash, and coarse aggregate according to proportions so that the powder, coarse aggregate, and fine aggregate are evenly mixed; Step 2, adding the retarder and the water reducer into the water and stirring so that the coagulant and the water reducer are dissolved in the water; Step 3: Add the water obtained in step 2 to the dry material mixed in step 1 and stir evenly to obtain slow-setting concrete slurry.

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