Multi-Objective Optimization of Nano-Silica Modified Cement-Based Materials Mixed With Supplementary Cementitious Materials Based on Response Surface Method

Xiuzhi Zhang,Mengdi Bi,Hailong Sun,Ru Mu,Liming Lin,Qinfei Li,Heng Chen

doi:10.3389/fmats.2021.712551

Xiuzhi Zhang, Mengdi Bi + Show 5 more

Open Access

https://doi.org/10.3389/fmats.2021.712551

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Abstract

This paper investigates the effect of supplementary cementitious materials (SCMs) on the fresh and mechanical properties of nano-silica modified cement-based materials (NSMCBM) based on the response surface method (RSM). Fly ash (FA), ground granulated blast-furnace slag (GGBFS), and silica fume (SF) were selected and the Box-Behnken design (BBD) method was used to design mix proportion. Besides, the quadratic term model was used to describe the relationship between independent variables and responses including fluidity, yield stress, plastic viscosity, thixotropy, and 3, 7, 28, and 56 d compressive strength. Based on the quadratic term model, the response surface of each response was drawn to understand the influence of SCMs. Results showed that FA had significant effect on fluidity and thixotropy while three kinds of SCMs had extremely significant effect on plastic viscosity. Response surface plot showed that NS could increase the plastic viscosity of NSMCBM to 1.445 Pa•s (M16). However, the addition of FA and GGBFS decreased the plastic viscosity to 0.9 Pa•s, which was comparable with the reference sample (M17). Such value was 37.7% lower than that of M16. Meanwhile, NS complemented the reduction of compressive strength caused by SCMs. Thus, the synergy effect of SCMs and NS could improve both fresh and mechanical properties. At last, multi-objective optimization was utilized to optimize the proportion of SCMs considering the interaction between SCMs to achieve desirable parameters.

Highlights

With the development of concrete technology, supplementary cementitious materials (SCMs) have grown up to be indispensable components in concrete
Nano-Silica Modified Cement-Based Materials though adding accelerators such as calcium chloride (Riding et al, 2010), triethanolamine (Yan-Rong et al, 2016), and nitrate (Pizoń et al, 2016) can compensate for the adverse effects caused by the large amount of SCMs, but the improvement of early strength is limited and some accelerators lead to the reduction of long term mechanical properties of concrete (Pizoń, 2017)
Based on the discussion above, conclusions can be drawn that silica fume (SF) needs to be mixed with Fly ash (FA) or ground granulated blast-furnace slag (GGBFS) to reduce the yield stress

Summary

Introduction

With the development of concrete technology, supplementary cementitious materials (SCMs) have grown up to be indispensable components in concrete. It reduces cost and improves the workability and durability of concrete (Cheng et al, 2018; Dhanya et al, 2018). Nano-Silica Modified Cement-Based Materials though adding accelerators such as calcium chloride (Riding et al, 2010), triethanolamine (Yan-Rong et al, 2016), and nitrate (Pizoń et al, 2016) can compensate for the adverse effects caused by the large amount of SCMs, but the improvement of early strength is limited and some accelerators lead to the reduction of long term mechanical properties of concrete (Pizoń, 2017). The proportion of SCMs should be optimized to obtain satisfying properties

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Results

Conclusion