Effect of pre-saturated lightweight sand on material properties of eco-friendly lightweight cementitious composites

Abstract

In this study, eco-friendly lightweight high-strength engineered cementitious composites (ELHECC) were developed using lightweight sand fines (LSF) and fly ash cenospheres. The effects of LSF content and pretreatment methods on mechanical properties, shrinkage and micro-mechanism of ELHECCs were investigated. Two pretreatment methods—normal pressure immersion and vacuum saturation—were employed. The internal curing effects of treated and untreated LSF were compared. The results showed that increasing the content of LSF slightly reduced compressive strength but improved the tensile properties and ductility of ELHECCs. Vacuum-saturated LSF improved the mechanical properties of ELHECCs more than normal pressure-immersed LSF. In addition, increasing the substitution amount of LSF increased the corresponding internal relative humidity, extended the duration of saturated humidity, and subsequently reduced the autogenous shrinkage of ELHECC. The reduction effect of autogenous shrinkage and drying shrinkage after LSF pre-saturation was much greater than without saturation. Moreover, LSF significantly delayed the hydration process and reduced the hydration heat rate and hydration heat, and the content of Ca(OH)₂ in ELHECCs decreased with increased LSF substitution rate. The effect of vacuum saturation for LSF in reducing the porosity of ELHECC was greater than that of normal pressure saturation. Furthermore, LSF had superior bonding with the ELHECC matrix, forming a well-integrated sand–matrix interface. The experimental results provide inspiration for green applications in bridge bearing structure, building structure reinforcement and repair in terms of impressive tensile properties, low shrinkage, light weight, and waste utilization.

Keywords:

• Lightweight high-strength ECC
• lightweight sand fines
• waste utilization
• shrinkage
• micro-mechanism

Acknowledgement

Financial support of this research is provided by Department of Infrastructure Engineering, University of Melbourne; College of Materials science and Engineering, Tongji University; China Scholarship Council and Shanghai Construction Building Materials Technology Group Co., Ltd.

Author contributions

Hongxiang Gou: Methodology, Data curation, Writing, Original draft preparation. Massoud Sofi: Supervision, Conceptualization, Writing, Review. Nilüfer Özyurt: Conceptualization, review and editing. Zhiuyan, Zhou: Conceptualization, review and editing. Hongbo Zhu: Investigation, Validation, Formal analysis. Priyan Mendis: Conceptualization, Supervision, Validation, Formal analysis.

Disclosure Statement

The authors declare that there’s no financial/personal interest or belief that could affect their objectivity. The authors confirm explicitly that no conflicts of interest exist.