High-calcium fly ash concrete

Abstract

The invention belongs to the technical field of building materials, particularly relating to high-calcium fly ash concrete. The high-calcium fly ash concrete comprises the following raw materials by weight in per cubic meter of concrete: 144-175 kg of mixing water, 224-480 kg of cement, 35-135 kg of high-calcium fly ash, 1007-1120 kg of gravels, 671-804 kg of sand, 1.7-9 kg of water reducing agents, 0-110 kg of low-calcium fly ash and 0-110 kg of slag powder, wherein the mixing water is temporary hardwater, and the concentration of HCO3<-> in the mixing water is greater than 300 mg / L. The concrete has the characteristics of easy production and high operability, the high-calcium fly ash resource can be fully utilized, and the poor stability is eliminated.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a high-calcium fly ash concrete. Background technique [0002] Fly ash is a kind of industrial waste from thermal power plants. It is the waste residue discharged from the flue after the combustion of finely ground coal, commonly known as "fly ash". Fly ash is an artificial pozzolanic material, and the current classification methods in my country are not uniform. In the "Technical Specifications for the Application of Fly Ash Concrete" (GBJ 146-90), fly ash is divided into three grades: I, II, and III from the indicators of fineness, ignition loss, water demand ratio, and sulfur trioxide content; Fly ash used in cement and concrete" (GB / T 1596-2005) divides fly ash into F and C according to coal types. F fly ash is collected from anthracite calcination, and C Fly ash is coal ash collected by calcining lignite or sub-bituminous coal, and its calcium oxide ...

AI Technical Summary

Problems solved by technology

[0006] 1) Aging water spraying, this method utilizes CO in the air through long-term aging 2 React with moisture and f-CaO in high calcium fly ash to reduce or eliminate f-CaO to achieve the purpose of reducing or eliminating stability. However, this method takes a long time and is not suitable for ready-mixed concrete production enterprises. In other words, the powder is stored in a closed barrel, so the operability is not strong. In addition, because the high-calcium ash is self-hardening, the high-calcium ash processed by this method is easy to form agglomerates, and it is not suitable for use as a concrete admixture. ;

[0007] 2) chemical excitation, which is to excite an activator (such as an alkaline substance: NaOH, Ca(OH) 2 , alkali metal salt: Na 2 CO 3 、Na 2 SO 4 , CaSO 4 etc.) After being added to cement concrete, the chemical activity of high-calcium fly ash is improved and the stability of high-calcium fly ash is reduced through the "variety effect" and "excitation effect". However, a large amount of alkali metal ions introduced by it Or sulfate ions, will increase the alkali metal content in the prepared cement concrete, thereby increasing the risk of steel corrosion, alkali aggregate reaction or sulfate attack in cement concrete;

[0008] 3) Mechanical activation. In this method, the high-calcium fly ash is ground, so that part of the f-CaO enriched in the coarse-grained high-calcium fly ash is activated into active CaO, and the CaO activity in the fine ash is also obtained. Excited, it is easier to participate in hydration, so that the stability is improved, but this method consumes more energy;

[0009] 4) mixing other mineral admixtures, as Chinese patent 03102238.3 discloses a kind of composite admixture that uses high-calcium fly ash, its composition includes the high-calcium fly ash of 70~90% by weight, 5~15% by weight of Pozzolanic materials, 3-12% by weight of sulfoaluminate and 2-13% by weight of clay mineral materials, however, the composition of the above-mentioned composite admixture is too complicated, which is not conducive to its popularization and application in ready-mixed concrete, and the above-mentioned The clay mineral materials added in the composite admixture have almost no hydration activity, which is detrimental to the compressive strength of concrete

[0010] In summary, the above-mentioned traditional methods of harmless treatment of high-calcium fly ash may take a long time, are not operable, or consume a lot of energy, or have adverse effects on some properties of concrete, which is not conducive to high-calcium fly ash. Popularization and Application of Ash in Concrete Mixing

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