Method for characterizing dispersion effect of silica fume in cement-based material with extremely low water-binder ratio

Abstract

The invention discloses a characterization method for the dispersion effect of silica fume in a cement-based material with an extremely low water-binder ratio. The characterization method comprises the following steps: firstly, effectively stripping a clinker intermediate phase from other silicon-containing mineral phases based on a chemical extraction method, and meanwhile, replacing other mineral admixtures with an inert filler to ensure that no other silicon source components exist in a cementing material system of an obtained test block except silica fume to be tested; and finally, carrying out surface scanning test analysis by utilizing an environmental scanning electron microscope energy spectrometer to obtain the distribution condition of section elements of the test block, and analyzing and comparing a distribution diagram of each element to realize the characterization of the dispersion effect of the silica fume in the hardened body of the cement-based material with the extremely low water-binder ratio. According to the detection method, the dispersion effects of silica fume with different qualities in the cement-based material with the extremely low water-binder ratio can be compared in parallel, and the method is used for evaluating the quality difference of the silica fume; and the optimal silica fume mixing amount suitable for a system with an extremely low water-binder ratio can be determined by evaluating the dispersibility of the silica fume, so that the silica fume is fully dispersed, and the effective utilization rate of the silica fume is improved.

Description

technical field [0001] The invention belongs to the technical field of performance testing of building materials, and in particular relates to a method for characterizing the dispersion effect of silica fume in a cement-based material with a very low water-to-binder ratio. Background technique [0002] Ultra-High Performance Concrete (UHPC), usually refers to a water-to-binder ratio of less than 0.25, a compressive strength of more than 150 MPa, a tensile strength of more than 7 MPa, and has ultra-high mechanical properties, ultra-high toughness, and ultra-long durability. The fiber-reinforced cement-based composite material with obvious strain hardening behavior belongs to the cement-based material system with a very low water-to-binder ratio. According to the theory of maximum density, the particle gradation of raw materials is optimized by introducing ultra-fine powder, so that the internal defects of the material are minimized. Due to its excellent properties such as li...

AI Technical Summary

Problems solved by technology

However, the dispersion of nanomaterials is one of the key issues in the nano-modification technology of cement-based materials. The easy agglomeration of nanomaterials in cement-based materials not only deteriorates the fluidity of the slurry, but also affects the mechanical properties and durability of the materials.

[0004] At present, the commonly used dispersion methods for micro-nano materials such as silica fume include functional group treatment, surfactant encapsulation, polymer encapsulation, ultrasonic dispersion and mechanical stirring dispersion, etc. There is no effective means of characterizing the dispersion effect in slurry

On the one hand, the dispersion effect after silica fume modification can only be reflected indirectly through the evaluation of slurry fluidity changes; Affect the dispersion of silica fume in the cement-based material slurry, and then affect the rheological properties, mechanical properties and durability of the slurry

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