Microstructure and Nanomechanical Characteristics of Hardened Cement Paste Containing High-Volume Desert Sand Powder

• Published in: Buildings (Basel) Vol. 14; no. 6; p. 1873
• Main Authors: Liu, Hongxin, Wang, Jian, Yao, Zhihui, Li, Zijun, He, Zhihai
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-06-2024
• Subjects: Cement; Cement paste; Compressive strength; Concrete; Construction industry; Density; desert sand powder; Deserts; Environmental impact; heat evolution; high volume; Hydration; Mechanical properties; Microstructure; nanomechanical properties; Particle size; Pores; Porosity; Powders; Raw materials; Sand; Sand & gravel; China; United Kingdom > UK; United States > US
• ISSN: 2075-5309; 2075-5309
• DOI: 10.3390/buildings14061873

Desert areas contain abundant desert sand (DS) resources, and high-volume recycling of DS resources as components of cement-based materials can achieve high-value applications. In this paper, DS was processed into desert sand powder (DSP) and replaced with cement in high volumes (20 wt.%–60 wt.%) to produce cement pastes. The mechanical properties, heat evolution, nanomechanical characteristics, microstructure, and economic and environmental impact of cement pastes were studied. The results show that adding 20 wt.% DSP increases the compressive strength of pastes and accelerates cement hydration, compared with the control group (0 wt.% DSP). Meanwhile, incorporating an appropriate amount of DSP (20 wt.%) effectively reduces porosity, increases the proportion of harmless and less harmful pores, and reduces the proportion of more harmful pores. From the perspective of nanoscopic properties, the addition of 20 wt.% DSP increases the C-S-H volume fraction, especially enhancing the transformation of low-density C-S-H to high-density C-S-H. Notably, the sample incorporating 60 wt.% DSP exhibits the lowest values for CI coefficients (13.02 kg/MPa·m3) and Cp coefficients (2.29 USD/MPa·m3), thereby validating the application of high-volume DSP feasibility in cement-based materials.