how to use concrete admixtures
3 Application Note Concrete Admixture
Despite the incorporation of admixtures in concrete can significantly improve many physical and mechanical properties of concrete made significant technical and economic effect. However, if the selection and use of improper quality of the project will cause some problems in the selection and use of additives should note the following:
3.1 The selection of suitable concrete admixture
Many kinds of additives, different effects should be a reasonable choice. First of all levels should be based on the strength of concrete, fresh concrete durability indicators and work requirements; secondly to understand
Based on the principle role of concrete admixtures, targeted selection of concrete admixtures, to give full play to their economic and technical advantages. Such as increasing the impermeability of concrete admixtures option 3, with water reducer, water repellent, expansive agent.
Choose which of three kinds of additives, should first understand the three kinds of works of concrete admixtures, waterproofing agents (such as latex) mainly in the capillary to form a hydrophobic polymer membrane, thus enhancing the impermeability of concrete . Expansive agent is usually by sulphoaluminate in cement hydration generated Ca (OH) 2 at high alkalinity, into high-sulfur-based sulphoaluminate that AFt, volume expansion and filling the pores in concrete block channel and porosity, which improves the impermeability of concrete. According to three kinds of concrete admixtures action principle, the choice of indicators to meet the impermeability of concrete admixtures for the purpose, they should have moisture requirements, or concrete strength grade is not high, but require a higher level of permeability, the water should be preferred agent; If the concrete strength grade is not high, permeability is not high grade, should be selected superplasticizer; when the concrete strength grade higher (C40 and above), the permeability level was also higher (P10 or more), then select the water reduction agents, waterproofing agents, expansive agent can.
At present more concrete admixtures to compound development, although it extends the use of certain additives, but it is not economical and technical characteristics of outstanding. Therefore chosen to take into account the design requirements of concrete admixtures and economy have to do this, we must first understand the characteristics of concrete admixture products, then according to the strength grade of concrete, fresh concrete durability indicators and work requirements, in the understanding of concrete plus based on the principle agent role, targeted selection of concrete admixtures, to give full play to their economic and technical advantages.
3.2 rationally determine the content of concrete admixtures and mixed method
Concrete admixtures, as a product of its content in the product description is often only a range. To science, the correct technical play of concrete admixtures, economy, the need for concrete specimens with in order to determine the content of concrete admixtures, admixtures for concrete, whether organic, inorganic, or composite, and its content and blending effects are related with the concrete composition of the raw materials. Species such as cement, mineral composition, fineness and alkalinity; mixed material variety, fineness; sand gradation, fineness modulus; coarse aggregate species, grading situations, all affect the content of concrete admixtures. Additive mixed concrete mixture in the methods, after a first mixed method and mixed method, to achieve the same effect, after the mixed method of the content is often smaller.
3.3 reasonable detection performance concrete admixtures
As a concrete admixture products, has achieved commercial production, product performance and stability. Product testing, Natural Phenomena, like cement to form a detection system, rather than the current practice of concrete admixtures only 1 or 2 years a time of product testing and certification testing, this is not conducive to ensuring the quality of concrete admixtures. In addition to the construction site of the additive construction specifications should be strictly enforced, do first products will be seized and conventional projects, while strengthening the performance of the construction site inspection of concrete mixed with additives. Concrete mixture to ensure homogeneity, the quality control of concrete structures entities. Uneven concrete admixture content, especially in small dosage (such as air-entraining agent) should be encrypted homogeneous concrete mixture, the work of the test mixture.Sodium Naphthalene Formaldehyde
Only guarantee the quality of concrete admixtures to play the role of concrete mixed with additives to promote application and development of concrete admixtures.
3.4 environmentally friendlyPolycarboxylate superplasticizer
Some of the material composition of the additives are industrial by-products may be toxic or may pollute the environment, endanger human health. Therefore, the prohibited use of the human body and harm the environment polluting additives.water reducer
As China's construction industry and technological development, on the concrete strength and durability of our energy requirements will be higher. The concrete strength and durability of the improvement, can not do without concrete admixtures. Therefore, in the near future, we will usher in a new era of application of concrete admixtures.