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CN-121974611-A - Low-hydration-heat large-volume concrete and preparation method thereof

CN121974611ACN 121974611 ACN121974611 ACN 121974611ACN-121974611-A

Abstract

The invention discloses a low-hydration heat large-volume concrete and a preparation method thereof. Relates to the technical field of concrete. The concrete is prepared from 380-450 parts of cementing material, 140-160 parts of water, 1000-1150 parts of coarse aggregate, 700-800 parts of fine aggregate, 2-6 parts of water reducer, 0.5-2 parts of retarder, 20-40 parts of expanding agent, 3-10 parts of internal curing agent and 0.5-3 parts of hydration heat regulator, wherein the cementing material consists of cement and mineral admixture, and the mineral admixture accounts for 40-60% of the total mass of the cementing material.

Inventors

  • LIANG XIAO
  • WANG XINGHAO
  • LI LIN

Assignees

  • 曙光装配式建筑科技（浙江）有限公司

Dates

Publication Date
20260505
Application Date
20251112

Claims (10)

  1. 1. A low heat of hydration mass concrete, characterized in that it is made from raw materials comprising, per cubic meter of concrete: 380-450 parts of cementing material; 140-160 parts of water; 1000-1150 parts of coarse aggregate; 700-800 parts of fine aggregate; 2-6 parts of water reducer; 0.5-2 parts of retarder; 20-40 parts of an expanding agent; 3-10 parts of internal curing agent; 0.5-3 parts of hydration heat regulator; The cementing material consists of cement and mineral admixture, wherein the mineral admixture accounts for 40-60% of the total mass of the cementing material.
  2. 2. The low heat of hydration mass concrete according to claim 1, wherein said internal curing agent is at least one of pre-saturated lightweight porous ceramic sand, expanded vermiculite or diatomaceous earth, having a particle size in the range of 0.1-2mm, and a water absorption of not less than 20% for 1 hour.
  3. 3. The low heat of hydration mass concrete according to claim 1, wherein said heat of hydration control agent is a complex of a nucleating agent and a lithium salt, preferably said nucleating agent is surface treated nano calcium carbonate and said lithium salt is lithium hydroxide or lithium carbonate.
  4. 4. The low hydration heat mass concrete according to claim 1, wherein the mineral admixture is at least one of fly ash, slag powder and silica fume, and preferably, the mineral admixture is formed by compounding the fly ash and the slag powder according to the mass ratio of (1:1) - (1:2).
  5. 5. The low heat of hydration mass concrete according to claim 1 or 4, wherein said cement is p.o42.5 or p.il42.5 grade portland cement, said fly ash is class F class I or class II fly ash, and said slag powder is class S95 or class S105 slag micropowder.
  6. 6. The low hydration heat mass concrete according to claim 1, wherein said coarse aggregate is continuous graded crushed stone with a particle size of 5-25mm, the mud content is not more than 1.0%, said fine aggregate is medium sand with a fineness modulus of 2.3-2.8, and the mud content is not more than 2.0%.
  7. 7. The low hydration heat mass concrete according to claim 1, wherein the water reducing agent is a polycarboxylic acid high-performance water reducing agent, the water reducing rate is not lower than 25%, the retarder is sodium gluconate, calcium sucrose or phosphate retarder, and the expansion agent is calcium sulfoaluminate or calcium oxide concrete expansion agent.
  8. 8. The low heat of hydration mass concrete according to any one of claims 1-7, wherein said concrete has a3 day heat of hydration of not more than 210 kJ/kg and a 7 day heat of hydration of not more than 250 kJ/kg.
  9. 9. A method of preparing a low heat of hydration high volume concrete according to any one of claims 1 to 8, comprising the steps of: (1) Soaking the internal curing agent in water until the internal curing agent is saturated, and filtering out redundant water for standby; (2) Adding coarse aggregate, fine aggregate, pretreated internal curing agent and half of mixing water into a stirrer, and pre-stirring for 30-60 seconds; (3) Adding the cementing material and the hydration heat regulator into the stirrer, and continuously stirring for 60-90 seconds; (4) Dissolving a water reducing agent, a retarder and an expanding agent in the residual mixing water to form an additive solution, and then adding the solution into a stirrer; (5) And after all materials are added, stirring is continued for 90-120 seconds, and the low hydration heat mass concrete is obtained.
  10. 10. The method of low hydration heat mass concrete according to claim 9, wherein the outlet temperature of the concrete mix is controlled to be not higher than 25 ℃ throughout the preparation process, preferably by using cooling water as mixing water and/or by spray cooling the aggregate.

Description

Low-hydration-heat large-volume concrete and preparation method thereof Technical Field The invention relates to the technical field of concrete, in particular to low-hydration heat large-volume concrete and a preparation method thereof. Background The large-volume concrete has increasingly wide application in engineering construction due to thick structure and large volume, such as large equipment foundation, dam, pier, thick and large bottom plate of super high-rise building, etc. However, in the hardening process of the mass concrete core, a large amount of heat is released by the cement hydration reaction, and the heat dissipation property is poor, so that the temperature in the structure is rapidly increased, and a huge temperature gradient is formed with the surface. The temperature difference between the inside and the outside can lead the concrete to generate obvious temperature tensile stress, and when the tensile stress exceeds the early tensile limit of the concrete, the structure can generate harmful temperature cracks, thereby seriously threatening the integrity, the durability and the safety of the building. In order to control hydration heat and temperature cracks of mass concrete, the traditional technical means mainly comprise the steps of adopting low-heat or medium-heat silicate cement, mixing a large amount of mineral admixture such as fly ash or mineral powder and the like to partially replace cement, embedding a cooling water pipe for forced cooling, layering and block pouring and the like. Although these methods can reduce the temperature rise to some extent, they have significant limitations. For example, overreliance on mineral admixtures can severely delay early strength development, affect construction progress, make cooling water pipes complex in construction, high in cost and risk uneven maintenance, while conventional retarders can delay hydration exothermic peaks, but do not fundamentally reduce total exothermic amount. It is particularly notable that shrinkage of concrete, especially early self-shrinkage and drying shrinkage, is superimposed on each other with thermal stress caused by hydration heat, further exacerbating the cracking risk. The prior art is often focused on single temperature control or post-compensation shrinkage, and lacks a cooperative solution capable of carrying out peak clipping and valley filling from a hydration process source and synchronously realizing internal curing to inhibit shrinkage. Therefore, developing a novel mass concrete which can intelligently regulate and control the hydration process, remarkably reduce the exothermic peak value, accurately compensate shrinkage and give consideration to the early-stage and later-stage mechanical properties has become a key technical problem to be solved in the field. Disclosure of Invention The invention mainly aims to provide a low-hydration heat large-volume concrete and a preparation method thereof. Aims at solving the technical problems of temperature cracking, shrinkage cracking, slow early strength development and the like caused by hydration heat of the traditional mass concrete. In order to achieve the above object, in a first aspect, the present invention provides a low heat of hydration mass concrete made from raw materials comprising: 380-450 parts of cementing material; 140-160 parts of water; 1000-1150 parts of coarse aggregate; 700-800 parts of fine aggregate; 2-6 parts of water reducer; 0.5-2 parts of retarder; 20-40 parts of an expanding agent; 3-10 parts of internal curing agent; 0.5-3 parts of hydration heat regulator; The cementing material consists of cement and mineral admixture, wherein the mineral admixture accounts for 40-60% of the total mass of the cementing material. By adopting the technical scheme, the invention constructs a system with the synergistic effect of all the components, and systematically solves the technical problems of temperature cracks, shrinkage cracks, slow early strength development and the like of mass concrete caused by hydration heat. The technical effects of the components are related to each other, so that the comprehensive technical effects of the invention are realized together: The high-proportion mineral admixture (40% -60%) is the basis for reducing the total hydration heat of a system, the generation source of the hydration heat is fundamentally reduced, under the premise, the internal curing agent directly inhibits the self-drying shrinkage possibly caused by the later continuous hydration of the mineral admixture through an internal water supply mechanism, moisture guarantee is provided for the deep hydration of the mineral admixture, so that the long-term compactness is improved, the shrinkage cracking resistance is enhanced, the hydration heat regulator aims at the defect of slow development of the early strength of the high admixture system, the early strength is compensated by exciting the activity of the mineral admixture, the nucleation