Air-void structure, strength, and permeability of wet-mix shotcrete before and after shotcreting Operation: The influences of silica fume and air-entraining agent

作者：Choi Pangil; Yeon Jung Heum^*; Yun Kyong Ku

来源：CEMENT & CONCRETE COMPOSITES, 2016, 70: 69-77.

DOI：10.1016/j.cemconcomp.2016.03.012

• Wet-mix shotcrete
• Air-void structure
• Strength
• Permeability
• Silica fume
• Air-entraining agent

It is well known that the air-void structure of hardened concrete has substantial effects on the mechanical properties and durability of concrete. In this study, laboratory evaluations were conducted to quantify the effects of air-entraining agent (AEA) and silica fume on the air-void characteristics of wet mix shotcrete (WMS) before and after shotcreting process. For this purpose, a high-resolution image analyzer capturing elaborate graphical layouts of air-void structure using the linear transverse method was employed. Also, this study examined the effects of air-void characteristics, such as air content and spacing factor, on the strength and permeability of WMS. Based on the findings of this study, it can be concluded that: (1) shotcreting process considerably reduces overall air contents in WMS; (2) incorporating AEA with a 4.5% silica fume replacement ensures both satisfactory spacing factor and good retention of small entrained air bubbles even after shotcreting, which may improve the freeze-thaw and scaling resistance; (3) the compressive and flexural strengths of WMS were reduced as the air content increased and average spacing factor decreased; and (4) the air content affected the permeability of WMS, but no consistent correlation was found between spacing factor and permeability.

• 出版日期2016-7