Abstract
This paper presents the experimental results of the production of Nano-SiO2 (NS) from rice husk ash (RHA) and the engineering properties of High Strength Concrete (HSC) containing various NS contents. Firstly, the mesoporous silica nanoparticles were effectively modulated from RHA using NaOH solution, and subsequently precipitated with HCl solution until the pH value reached 3. The optimum synthesis for the manufacture of SiO2 nanoparticles in the weight ratio of RHA/NaOH was 1:2.4, and the product was calcined at 550 °C for 2 h. The EDX, XRD, SEM, TEM, FT-IR, and BET techniques were used to characterize the NS products. Results revealed that the characteristics of the obtained NS were satisfactory for civil engineering materials. Secondly, the HSC was manufactured with the aforementioned NS contents. NS particles were added to HSC at various replacements of 0, 0.5, 1.0, 1.5, 2.0, and 2.5% by the mass of the binder. The water-to-binder ratio was remained at 0.3 for all mixes. The specimens were cured for 3, 7, 28, 25 days under 25 ± 2 °C and a relative humidity of 95% before testing compressive and flexural strengths. Chloride ion permeability was investigated at 28 and 56 days. Results indicated that the addition of NS dramatically enhanced compressive strength, flexural strength, chloride ion resistance, and reduced chloride ion permeability compared to control concrete. The optimal NS content was found at 1.5%, which yielded the highest strength and lowest chloride ion permeability. Next, the development of flexural and compressive strengths with an age curing of 3–28 days can be analytically described by a logarithmic equation with R2 ≥ 0.74. The ACI code was used, and the compressive strength at t-day was determined based on 28 days with R2 ≥ 0.95. The study is expected to solve the redundancy of waste RHA in southern Vietnam by making RHA a helpful additive when producing high-strength concrete and contributing meaningfully to a sustainable environment.
Highlights
Nano SiO2 (NS) is well-known for its many uses in the past two decades, including in catalytic materials, dielectric materials, gas adsorbents, heavy metal ion adsorption, and inorganic carriers [1]
Based on the literature reviews mentioned earlier, the objective of this paper focused on producing NS from waste rice husk ash (RHA), obtained in Southern Vietnam
The results indicated that the NS particles were composed of Si and O, with 28.78%
Summary
Nano SiO2 (NS) is well-known for its many uses in the past two decades, including in catalytic materials, dielectric materials, gas adsorbents, heavy metal ion adsorption, and inorganic carriers [1]. Nazari and Riahi [24] used NS particles as a fractional replacement for cement They suggested that an NS content of less than 4%, by weight, could improve the formation of C–S–H gel and refine the pore structure of the concrete; with a further increase in NS content of more than 4%, the strength of concrete reduced due to uneven nanoparticle dispersion. Certain studies discovered that adding 0 ÷ 1.5% nano-silica particles to reinforced concrete containing polyvinyl alcohol fibers improved compressive strength, flexural strength, and fracture energies. NS particles were added to concrete at various contents, of 1%, 2%, 3%, 4%, and 5%, according to binder weight, and it was concluded that the compressive, flexural, and splitting tensile strengths were enhanced by 15.5%, 27.3%, and 19%, respectively. The results should help to use waste material in construction materials, enriching the source of building materials and contributing to protecting the environment
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