Rice Husk Ash Incorporation in Calcium Aluminate Cement Concrete: Life Cycle Assessment, Hydration and Strength Development

Amirmohamad Abolhasani,Fatemeh Aslani,Bijan Samali

doi:10.3390/su14021012

Amirmohamad Abolhasani, Fatemeh Aslani + Show 1 more

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https://doi.org/10.3390/su14021012

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Abstract

In this research effect of rice husk ash (RHA), as silicate impurities, on the hydration reaction and mechanical strength of calcium aluminate cement (CAC) concrete, as one of the most important non-Portland cements, was investigated. Furthermore, in order to evaluate the environmental performance of mixtures, a lifecycle assessment was performed using the recipe midpoint and endpoint method. Compressive and tensile strength tests were conducted at the ages of 7, 28, and 90 days on specimens containing different contents of RHA (0, 2.5, 5, 7.5, and 10%) substituting for cement at the water-cement ratio of 0.4. Moreover, in order to calculate the hydration reaction of the specimens, thermogravimetric analysis (TGA) was performed at a rate of 10 °C/min to up to 1000 °C. The results revealed that the use of rice husk ash as a partial replacement at a concentration of 5% could reduce CO2 emission and ozone depletion by 18.75% and 31%, respectively. The findings indicate that, at 90 days, the mechanical strength of the mixes containing RHA were higher than those of the control mix, with the maximum improvement occurring at the substitution percentage of 5%. In accordance with TGA analysis the substitution of 5% RHA in CAC concrete led to a higher hydration level, which in turn improved the mechanical properties relative to the specimen without RHA at 90 days.

Highlights

Calcium aluminate cement (CAC) is employed as the main binding agent in the cementitious matrix to produce a High-Performance Concrete (HPC) type known as Calcium aluminate cement concrete (CACC) [1,2,3,4,5]
Blaine (XRF) method was employed to obtain the physicochemical features of rice husk ash (RHA) Ig
The thermal performance of the CACC for exposure temperatures of the ambient temperature to 1000 ◦ C was obtained using the thermogravimetric analysis (TGA) performed at a fixed heating rate of 10 ◦ C/min in vacuum with a TA-Q600 device

Summary

Introduction

Calcium aluminate cement (CAC) is employed as the main binding agent in the cementitious matrix to produce a High-Performance Concrete (HPC) type known as Calcium aluminate cement concrete (CACC) [1,2,3,4,5]. CAC has superior features such as a fast development of strength and high resistance to fire, leading to applications in places where refractoriness and resistance to chemical attack are required [6,7,8]. One effective way to improve fire-resistance is to use CAC. Multiple factors such as the concrete constituent features, exposure duration and temperature, and cooling manner affect the concrete performance when exposed to heat. As reported in a paper addressing the post-fire performance of CACC, the decline that occurred in the strength was less than that of the normal OPC concrete; this observation was ascribed to the existence of alumina phases as a binder [9]. CAC hydration compounds, CAH10 and C2 AH8 , are strongly affected by the temperature, such that, the conversion of these compounds into

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