Concrete additive and preparation method thereof

Abstract

The invention provides a concrete additive and a preparation method of the concrete additive. The concrete additive comprises the following components in parts by weight: 10-14 parts of a water-reducing agent, 77-82 parts of early strength agent and 8-13 parts of a retarder. The preparation method comprises the step of mixing three materials uniformly. The concrete additive is mainly applied to construction of cast-in-place large-volume concrete in the building fields of hydraulic engineerings and marine traffic engineering and the like, and has the advantages that the problem of cold joints between layers in the casting process of large-volume concrete can be solved, and the problem of temperature cracks caused by excessively-concentrated hydration heat in the casting process of the large-volume concrete is relieved; after final setting, the strength is rapidly improved, the mold-dissasembling time is shortened, and the use efficiency of a template is improved; no influence is caused on later strength of the concrete, and the phenomenon of strength reduction can not occur.

Description

technical field [0001] The invention relates to an engineering material and a preparation method thereof, in particular to a concrete admixture and a preparation method of the admixture. Background technique [0002] At present, with the increase of large-scale projects, cast-in-place large-volume concrete is becoming more and more common in water conservancy projects and water transportation projects. The following problems often occur in the construction of cast-in-place mass concrete: [0003] 1. Due to the loose control of concrete setting time and construction speed, cold joints appear between layers of cast-in-place concrete, which reduces the bonding force between layers, especially for concrete buildings with water-retaining functions. This caused serious water leakage between layers and lost the water retention function of the building; for example, the cold seam of No. 4 unit of the main workshop of Yantan Hydropower Station in Guangxi was caused by the inconsiste...

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Problems solved by technology

[0005] 3. During the mass concrete pouring process, in order to reduce the heat of hydration of the cementitious material, a large amount of fly ash is generally mixed into the cementitious material. For example, the amount of fly ash in the Three Gorges Dam is up to 35%. %, the maximum amount of fly ash in the Xiaowan arch dam is 50%, and the activity of fly ash is much lower than that of cement, which results in slower development of concrete early strength and longer formwork removal time, which affects construction speed and formwork utilization efficiency, increasing engineering cost

[0007] 1. On the project site, the water reducing agent and the retarder are mixed in the concrete alone. This method is currently the most common method used on the construction site during the mass concrete pouring process, but the disadvantage of this single mixing method is that it increases the pouring time. The workload, and the amount of retarder is very low, the amount of addition is easy to make mistakes, resulting in project quality problems

[0008] 2. In the process of mass concrete pouring, there are also admixtures compounded with retarding superplasticizers. The compounding of such admixtures still cannot solve the problem of low early strength and affect the later construction speed.

[0009] 3. In order to improve the early strength of concrete, some projects add early strength agents to the concrete. Although some early strength agents can improve the early strength of concrete, the later strength will shrink, which will bring hidden dangers to the safety of the project.

[0010] 4. In the mass concrete pouring process of water conservancy projects and water transportation projects, no admixtures combined with water reducers, early strength agents, and retarders have been found to be used in mass concrete

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