Modified superabsorbent polymer, preparation method thereof and application thereof to cement-based material

Abstract

The invention discloses a preparation method of a modified superabsorbent polymer. The preparation method comprises a step of preparing an SAP (superabsorbent polymer) microemulsion under the action of ultrasonic to finally obtain a superabsorbent polymer product and a step of modifying the surface of the superabsorbent polymer by using a silane coupling agent to obtain the modified superabsorbent polymer. The invention further discloses the modified superabsorbent polymer prepared by the preparation method and application of the modified superabsorbent polymer to a cement-based material. When the modified superabsorbent polymer prepared by the preparation method is applied to the cement-based composite material, water-proof and anti-permeability characteristics of a concrete structure can be improved; the modified superabsorbent polymer has excellent water retention and quite high gel strength, so that even though the concrete structure is pressed, water is unlikely to be squeezed out and pores of the cement-based material are further blocked, so that the purposes of stopping water by using water as well as saving water are achieved; and after a long-time water-absorbing and water-releasing circulation, the durability of the concrete structure can still be ensured.

Description

technical field [0001] The invention relates to the technical field of cement-based materials, in particular to a modified superabsorbent polymer, a preparation method thereof and an application in cement-based materials. Background technique [0002] High-performance cement-based materials (HPC) are usually obtained by low water-cement ratio technology. Therefore, it is easy to produce large autogenous shrinkage and cause structural cracking. At the same time, the hydration of incompletely hydrated cement in the later stage will also cause wet expansion and cracking. The key to solving the above problems is to increase the relative humidity inside the HPC to promote cement hydration. However, HPC usually has a dense structure, and it is difficult to introduce curing water from the outside by conventional curing methods. Therefore, some scholars proposed to directly introduce water into HPC for self-curing. Among them, superabsorbent polymer (SAP) is a commonly used intern...

AI Technical Summary

Problems solved by technology

However, the traditional SAP preparation of rigid cement-based waterproof materials has the following problems: 1) the traditional SAP has a high liquid absorption rate in distilled water, but in salt water (such as NaCl solution, CaCl 2 solution), the water absorption rate will be greatly reduced, making it poor in salt tolerance, and the water absorption rate will be significantly reduced in the ion-containing solution. In the actual application process, this type of water-absorbing resin mainly absorbs water containing electrolytes.

Especially when it is applied to offshore structures, the use effect will be greatly affected

2) Although general superabsorbent materials have a significant impact on the working performance of cement-based materials, it is difficult to obtain ideal high-performance waterproof cement-based materials due to large water-absorbing particles and irregular and uniform particle shapes.

3) Under the action of long-term water absorption expansion, water release or water pressure of SAP, the interface between SAP and cement substrate will be damaged, which will affect the waterproof, impervious and other durable properties of cement structures.

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