Research on the Mechanical Strengths and the Following Corrosion Resistance of Inner Steel Bars of RPC with Rice Husk Ash and Waste Fly Ash

Lili Cui,Hui Wang

doi:10.3390/coatings11121480

Lili Cui, Hui Wang

Open Access

https://doi.org/10.3390/coatings11121480

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Journal: Coatings	Publication Date: Dec 1, 2021
Citations: 13	License type: CC BY 4.0

Affiliation: Harbin University of Commerce, Ningbo University

Abstract

In this paper, the slump flow and mechanical strengths (compressive and flexural strengths) of the reactive powder concrete (RPC) with rice husk ash (RHA) and waste fly ash (WFA) were investigated. The following corrosion resistance of steel bars-reinforced specimens was researched. The ultrasonic sound, the mass loss rate, the electrical resistance, and the electrical resistance time history curves were determined to reflect the corrosion resistance of steel bars. The influence of NaCl freeze–thaw cycles and dry–wet alternations was considered. Results showed that the addition of RHA and WFA demonstrated a negative effect on the fluidity of fresh RPC. The fluidity of fresh RPC with WFA was lower. Moreover, RHA and WFA could effectively improve the mechanical strengths of hardened RPC, and the enhancing effect of RHA was higher. The increasing dosage of RHA could improve the corrosion resistance of steel bars in RPC when the specimens were exposed to the environment of NaCl freeze–thaw cycles and dry–wet alternations. However, when WFA was added, the effect was the opposite. The steel bars in RPC corroded more seriously when the specimens were exposed to the environment of NaCl dry–wet alternations than the environment of NaCl freeze–thaw cycles.

Highlights

Billions of tons of waste fly ash and rice husk ash are produced due to the generation of domestic refuse and agricultural production
The slump flow of fresh reactive powder concrete (RPC) paste decreased with the increasing dosages of rice husk ash and waste fly ash. This was attributed to the fact that the particle diameters of rice husk ash and waste fly ash were smaller than that of cement particles, resulting in increasing the surface area of cementitious material, leading eventually to adsorbing free water of fresh RPC and decreasing the slump flow
It can be concluded from this research that the addition of rice husk ash was advantageous to the corrosion resistance of steel bars in RPC

Summary

Introduction

Billions of tons of waste fly ash and rice husk ash are produced due to the generation of domestic refuse and agricultural production. Prior research pointed out that the addition of the rice husk ash was able to improve the corrosion resistance of steel bars in the cement concrete [11]. Cement concrete with a low dosage (mass loss ratio by total binder materials lower than 10%) of rice husk ash could decrease the water permeability and freeze–thaw damage. The research on the corrosion of steel bars’ inner reactive powder concrete with waste fly ash and rice husk ash is a novel topic and is discussed in this study. The ultrasonic velocity, mass loss, and electrical parameters (electrical resistivity and electrical resistance time history curves) were determined to reflect the corrosion resistance of specimens This thought of the thesis will provide a view of the application of rice husk ash and waste fly ash in the future

Raw Materials

Specimen Preparation and Measurement Methods

Slump Flow of Fresh RPC Paste

The Mechanical Strengths

The Corrosion Resistance of Steel Bars in RPC

Conclusions