Additive capable of improving bending strength and tensile strength of cement base material and its preparation method

Abstract

The invention discloses an additive capable of improving bending strength and tensile strength of a cement base material. The additive is an aqueous dispersion of organic-inorganic hybrid particles with core-shell structures. Each organic-inorganic hybrid particle is composed of inner and outer layers, wherein the inner layer is an organic polymer core; the outer layer is an inorganic composite oxide or an inorganic composite oxide covalently connected with an organic functional group; the inorganic composite oxide is a silicon-calcium composite oxide or a silicon-magnesium composite oxide or a silicon-calcium-magnesium composite oxide; and the outer layer is in covalent connection with an electronegative organic polyelectrolyte internally. Compared to the mixing amount of a polymer or polymer fiber in a pure polymer-modified cement base material or a polymer fiber-modified cement base material, the mixing amount of the additive in the cement base material can be greatly reduced; and the additive can more obviously improve the splitting tensile and bending resistant performances of the cement base material in comparison with a traditional polymer emulsion in the same mixing amount. Therefore, the additive overcomes the disadvantage that the high polymer mixing amount of the traditional polymer modified cement base material affects the compressive strength of the cement base material, and can effectively improve the bending strength and tensile strength (or splitting tensile strength) of the cement base material.

Description

technical field [0001] The invention relates to the field of admixtures used for modifying cement-based materials, in particular to an admixture capable of improving the flexural and tensile strength of cement-based materials. Background technique [0002] As used herein, the term "concrete" generally refers indiscriminately to cementitious materials such as concrete, mortar or grout, and this applies elsewhere herein as well. [0003] Ordinary cement concrete is a typical brittle material with high compressive strength but obviously insufficient bending and tensile strength. In actual use, it is easy to produce various cracks or damage due to stress concentration or uneven force, making it durable. For example, when it is applied to cement pavement, it is easy to cause premature plate fracture and surface structure damage, which limits its application in high-grade highways. [0004] People have carried out a lot of research on improving the brittleness of concrete, especi...

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Problems solved by technology

[0010] (2) The amount of polymer in polymer modified concrete is too high

[0013] In addition, patents CN103130436A and CN101239800B respectively report the use of graphene (graphene oxide) and carbon nanotubes to modify cement-based materials to improve compressive, tensile, and flexural strength, but the cost is too high

EP2695850A1 discloses a method for in-situ nucleation and growth of calcium silicate (wollastonite) nanocrystals in cement-based materials for toughening, which requires specific conditions such as temperature and pressure, which brings difficulties to the preparation

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