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CN-121974608-A - Underwater early-strength micro-expansion self-compaction concrete and preparation method thereof

CN121974608ACN 121974608 ACN121974608 ACN 121974608ACN-121974608-A

Abstract

The invention belongs to the technical field of concrete, and particularly relates to underwater early-strength micro-expansion self-compaction concrete and a preparation method thereof. The concrete provided by the invention has higher self-sealing performance, early strength, micro-expansion and concrete self-protection performance, is easy to use in sealing the bottom of an underwater deep foundation pit water-flooding section, plugging a dewatering well and the like, can reduce the separation of cement paste and aggregate in the underwater pouring process, effectively inhibits the seepage of underground water, and improves the compactness and strength of the concrete. Meanwhile, the underwater early-strength micro-expansion self-compaction provided by the invention has excellent sulfate erosion resistance, crack resistance and the like, and can further expand the use scene and improve the durability.

Inventors

  • YANG LIN
  • SU DINGFENG
  • SHEN JUN
  • GUO XIAOWEI
  • LIAO JIAONING
  • TANG HAIQING
  • ZHAO ZHIFA
  • LIANG JINXIAN
  • CAO JIACHANG
  • YU HAIRUO
  • XIONG FENG

Assignees

  • 川铁国际经济技术合作有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. The underwater early-strength micro-expansion self-compaction concrete is characterized in that each cubic meter of concrete comprises the following components: 395-4478 kg of cement, 79-132 kg of limestone powder 740-780 kg of fine aggregate, 920-960 kg of coarse aggregate 160-170 kg of water, 3.6-5.3 kg of expanding agent 5.3-6.7 kg of early strength water reducer 2.3-2.7 kg of non-dispersant; The cement has the mortar strength of 23-28 MPa for 2 days and 45-52 MPa for 28 days, and the cement has the setting time of 100-135 min for initial setting and 170-190 min for final setting; The 7-day compressive strength of the expanding agent is 24-30 MPa, and the limiting expansion rate in 7-day water is 0.025-0.040%; The water reducing rate of the early strength water reducer is more than or equal to 25%, and the compression strength ratio in 1 day is more than or equal to 180%; The cement loss amount of the non-dispersant agent is 1-15%, the suspension content is less than 150mg/L, and the water-land strength ratio is 7 days to 60% and 28 days to 70%.
  2. 2. The underwater early-strength micro-expansion self-compaction concrete according to claim 1, wherein the content of calcium carbonate in limestone powder is more than or equal to 75wt%; The 7d activity index of the limestone powder is more than or equal to 78%, and the 28d activity index is more than or equal to 82%; The fineness of the limestone powder is that the screen residue of a square hole screen with the diameter of 45 mu m is less than or equal to 15 percent; the fluidity ratio of the limestone powder is more than or equal to 100 percent.
  3. 3. The underwater early strength micro-expansive self-compacting concrete of claim 1, wherein the cement is sulfate-resistant early strength cement SRC (R) 42.5; The weight percentage of MgO in the cement is not more than 5.0%, the weight percentage of tricalcium aluminate is not more than 3.5%, and the weight percentage of SO 3 is not more than 2.5%; The specific surface area of the cement is 3200-3400 cm 2 /g, the stability is 0.7-0.9 mm, and the loss on ignition is 2.34%.
  4. 4. The underwater early-strength micro-expansive self-compacting concrete according to claim 1, wherein the fine aggregate has a natural sand fineness modulus of 2.3-3.2, a mud content of 1.6-2.6%, a light matter content of 0.2-0.4%, a water absorption of 1.0-1.6%, a firmness of 4-8% and a sand equivalent of 84-87%.
  5. 5. The underwater early-strength micro-expansive self-compacting concrete of claim 1, wherein the coarse aggregate is 5-20 mm continuous graded broken stone.
  6. 6. The underwater early-strength micro-expansive self-compacting concrete according to claim 1, wherein the setting time of the expansive agent is 45-60 min, and the final setting time is 160-250 min; the fineness of the expanding agent is 0% based on a screen with the aperture of 1.18 mm; the 28-day compressive strength of the expanding agent is 40-45 MPa.
  7. 7. The underwater early-strength micro-expansive self-compacting concrete of claim 1, wherein the early-strength water reducer is an early-strength polycarboxylate water reducer; the bleeding rate ratio of the early-strength water reducer is not more than 50%, the air content is not more than 2.5%, and the shrinkage ratio in 28 days is less than 110; the compression strength ratio of the early strength water reducer is more than or equal to 170% in 3 days, more than or equal to 145% in 7 days and more than or equal to 130% in 28 days.
  8. 8. The underwater early-strength micro-expansive self-compacting concrete according to claim 1, wherein the bleeding rate of the non-dispersant agent is 0%, the air content is 2-4%, the 1h expansion degree is 500-550 mm, and the pH value is less than 12; The setting time of the non-dispersant agent is 6-9 min, and the final setting time is 10-12 min.
  9. 9. The method for preparing the underwater early-strength micro-expansive self-compaction concrete according to any one of claims 1 to 8, which is characterized by comprising the following steps: and stirring and mixing the components included in the underwater early-strength micro-expansion self-compaction concrete to obtain the underwater early-strength micro-expansion self-compaction concrete.
  10. 10. The preparation method according to claim 9, wherein the stirring and mixing speed is 1300-1580 rpm, the temperature is 25-30 ℃ and the time is 120-180 s.

Description

Underwater early-strength micro-expansion self-compaction concrete and preparation method thereof Technical Field The invention belongs to the technical field of concrete, and particularly relates to underwater early-strength micro-expansion self-compaction concrete and a preparation method thereof. Background The underwater self-compacting concrete has self-leveling property, and can realize the compaction by self-weight during underwater pouring. The underwater self-compacting concrete has higher requirements on workability and durability and very strict requirements on raw materials and mix proportion, the mix proportion design needs to fully consider the interrelationship and contradiction among the fluidity, segregation resistance, self-filling property, slurry consumption and volume stability of the self-compacting concrete, and also needs to consider the considerations of underwater non-dispersion, rapid increase of early strength and expansion rate. The existing underwater self-compacting concrete mainly adopts fly ash and mineral powder as admixture, and adopts additives such as non-dispersing agent and the like, so that the concrete is not dispersed rapidly under water, and the characteristics of early strength, micro expansion and the like under water are not achieved. At the same time, the defects of low expansion degree and relatively poor sulfate erosion resistance are also present. Disclosure of Invention The invention aims to provide underwater early-strength micro-expansion self-compaction concrete and a preparation method thereof. In order to achieve the above object, the present invention provides the following technical solutions: the invention provides underwater early-strength micro-expansion self-compaction concrete, which comprises the following components in per cubic meter: 395-4478 kg of cement, 79-132 kg of limestone powder 740-780 kg of fine aggregate, 920-960 kg of coarse aggregate 160-170 kg of water, 3.6-5.3 kg of expanding agent 5.3-6.7 kg of early strength water reducer 2.3-2.7 kg of non-dispersant; The cement has the mortar strength of 23-28 MPa for 2 days and 45-52 MPa for 28 days, and the cement has the setting time of 100-135 min for initial setting and 170-190 min for final setting; The 7-day compressive strength of the expanding agent is 24-30 MPa, and the limiting expansion rate in 7-day water is 0.025-0.040%; The water reducing rate of the early strength water reducer is more than or equal to 25%, and the compression strength ratio in 1 day is more than or equal to 180%; The cement loss amount of the non-dispersant agent is 1-15%, the suspension content is less than 150mg/L, and the water-land strength ratio is 7 days to 60% and 28 days to 70%. Preferably, the content of calcium carbonate in the limestone powder is more than or equal to 75wt%; The 7d activity index of the limestone powder is more than or equal to 78%, and the 28d activity index is more than or equal to 82%; The fineness of the limestone powder is that the screen residue of a square hole screen with the diameter of 45 mu m is less than or equal to 15 percent; the fluidity ratio of the limestone powder is more than or equal to 100 percent. Preferably, the cement is sulfate-resistant early strength cement SRC (R) 42.5; The weight percentage of MgO in the cement is not more than 5.0%, the weight percentage of tricalcium aluminate is not more than 3.5%, and the weight percentage of SO 3 is not more than 2.5%; The specific surface area of the cement is 3200-3400 cm 2/g, the stability is 0.7-0.9 mm, and the loss on ignition is 2.34%. Preferably, the fineness modulus of the natural sand of the fine aggregate is 2.3-3.2, the mud content is 1.6-2.6%, the light matter content is 0.2-0.4%, the water absorption is 1.0-1.6%, the firmness is 4-8%, and the sand equivalent is 84-87%. Preferably, the coarse aggregate is 5-20 mm continuous graded broken stone. Preferably, the setting time of the expanding agent is 45-60 min, and the final setting time is 160-250 min; the fineness of the expanding agent is 0% based on a screen with the aperture of 1.18 mm; the 28-day compressive strength of the expanding agent is 40-45 MPa. Preferably, the early strength water reducer is an early strength polycarboxylate water reducer; the bleeding rate ratio of the early-strength water reducer is not more than 50%, the air content is not more than 2.5%, and the shrinkage ratio in 28 days is less than 110; the compression strength ratio of the early strength water reducer is more than or equal to 170% in 3 days, more than or equal to 145% in 7 days and more than or equal to 130% in 28 days. Preferably, the bleeding rate of the non-dispersant agent is 0%, the air content is 2-4%, the 1h expansion degree is 500-550 mm, and the pH value is less than 12; The setting time of the non-dispersant agent is 6-9 min, and the final setting time is 10-12 min. The invention also provides a preparation method of the underwater early-strength micro-ex