Effects of intense ultraviolet irradiation on drying shrinkage and microstructural characteristics of cement mortar. (12th September 2022)

• Record Type: Journal Article
• Authors: Wang, Haixu; Long, Guangcheng; Xie, Youjun; Zeng, Xiaohui; Ma, Kunlin; Dong, Rongzhen; Tang, Zhuo; Xiao, Qiyuan
• Is Part Of: Construction & building materials. Volume 347(2022)
• Publication Date: 2022-09-12
• Subjects: UV irradiation environment -- Cement-mineral admixtures mortar -- Mass loss -- Drying shrinkage -- Microstructure -- Phase composition; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.128513
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The physical effect of intense UV radiation accelerates the mass loss of the cement mortar. The chemical effect of the intense UV radiation exacerbates the carbonation of the cement mortar. FA and GGBS have the effect of reducing drying shrinkage under conditions of intense UV radiation. The incorporation of FA and GGBS weakens the carbonation resistance of the cement mortar. Abstract: The intense UV irradiation factor in the plateau area is easy to ignore, but it may have adverse effects on the microstructure and properties of concrete. Theredore, to clarify the evolution characteristics and the corresponding mechanism of the drying shrinkage of cement-based materials under intense UV irradiation environments at high altitudes cement mortars incorporating three types of mineral admixture were prepared to investigate the drying shrinkage, mass loss and microstructure, respectively. The hydration process and microstructure of samples were discussed in detail by microscopic experiments including TG-DTG, MIP, XRD, and IR patterns analysis. The results show that the mass loss and drying shrinkage of the cement-mineral admixture mortar exposed to intense UV irradiation were higher than those under the standard environment. Under intense UV radiation environment, the total porosity, mesoporosity (<50 nm), and carbonization degree of each group of samples increased. However, UV irradiation did not change the phase composition, chemical bond type, and polymerization degree of the CSH gel of the cement-based material. The incorporation of fly ash and slag resulted in the reduction of drying shrinkage of mortars, an increase in carbonation degree, and decreasing the hydration degree.