Special double-toothed phosphonic acid-based water reducing agent for medium and low slump concrete and preparation method thereof

Abstract

The invention discloses a special double-toothed phosphonic acid-based water reducing agent for the medium and low slump concrete. The structure of the water reducing agent is as follows: one end is abis-phosphorous acid or bis-phosphite G linked by the N atom which is called as the terminal end double-toothed adsorption group, the other end is a polyether chain P prepared by carrying out the alkoxylation reaction of an initiating agent of a C1-C12 saturated alkyl or unsaturated alkyl and ethylene oxide or propylene oxide, the two ends are connected by a connecting arm L, and the connecting arm L is an aliphatic or aromatic group of C1-C10. According to the special double-toothed phosphonic acid-based water reducing agent for the medium and low slump concrete, the long-term stable slump retention of the medium and low slump concrete can be achieved, the workability is improved, and the mechanical properties and durability of the concrete are improved, so that the water reducing agentis suitable for special projects such as nuclear power, hydropower, super-high-rise buildings, super-long-span bridges and the like.

Description

technical field [0001] The invention belongs to the technical field of concrete water reducers, and in particular relates to a double-dentate phosphonic acid-based water reducer for medium and low slump concrete and a preparation method thereof. Background technique [0002] Concrete water reducer is a carboxyl or sulfonic acid grafted polymer that reduces the amount of mixing water, regulates the flow properties of concrete, and improves the mechanical properties and durability of concrete. It can be classified as an anionic surfactant. With the development of industries such as ultra-long-span bridges, ultra-large-volume concrete, and super-high-rise buildings, higher requirements are placed on the strength and durability of concrete. Sulfonate water reducers such as water agents and naphthalene-based water reducers have been developed into a new generation of high-performance polycarboxylate water reducers. [0003] With the reduction of high-quality sand and gravel aggr...

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Problems solved by technology

[0009] The water-reducing mechanism of the phosphate-modified water reducer described in patent CN 105271887 A is still electrostatic repulsion, the force is weak, and a higher dosage is required. In the concrete test, the slump loss is still serious; patent CN 105713151 A , CN106008853 A and CN 105713150 A report that the phosphoric acid-containing comb polymer by free radical polymerization has good water reduction and slump retention properties, but the phosphonic acid-based monomer has a chain transfer effect. In the radical reaction, there are problems such as difficult to control the molecular weight, wide molecular weight distribution and difficult to increase the molecular weight, and the phosphonic acid monomer is not commercialized, and there are difficulties in the source of raw materials. A composite soil adsorbent reported by Wan Tianming is also limited to the compound use of traditional carboxyl polymers, and it is difficult to achieve a fundamental improvement in the performance of the water reducer

[0010] In short, today's construction raw materials are mostly low-quality aggregates and low-activity industrial waste residues. In the case of high mud content in sand and gravel, water reducers can improve the workability of fresh concrete and meet the requirements of strength and durability of hardened concrete. Often contradictory; when encountering a cement system containing calcium ions, there is a sensitivity problem; when encountering a cement system containing fly ash, mineral powder, stone powder or clay, there is a compatibility problem; especially in the face of For the high temperature and dry construction environment, the water reducing agent has poor adaptability

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