Role of sizing agent on the microstructure morphology and mechanical properties of mineral-impregnated carbon-fiber (MCF) reinforcement made with geopolymers

Temperature-Dependent Pullout Behavior of Geopolymer Concrete Reinforced with Polymer- or Mineral-Impregnated Carbon Fiber Composites: An Experimental and Numerical Study

“…The significantly increased porosity at 200 °C measured via MIP confirmed this pronounced dehydration. The pore structure can be defined in four categories: nanopores (3–10 nm), mesopores (10–50 nm), macropores (50–200 nm), and pores >200 nm, following the methodology in past work . Nanopores are mainly associated with the intrinsic microstructure of the formation of GP gel, while mesopores, macropores, and pores larger than 200 nm correspond to dehydration and microstructural damages .…”

“…The pore structure can be defined in four categories: nanopores (3−10 nm), mesopores (10−50 nm), macropores (50−200 nm), and pores >200 nm, following the methodology in past work. 41 Nanopores are mainly associated with the intrinsic microstructure of the formation of GP gel, while mesopores, macropores, and pores larger than 200 nm correspond to dehydration and microstructural damages. 51 After exposure to elevated temperatures, the specific pore volume of all size ranges increased considerably, causing a loosely bound microstructure and eventual premature failure under loading.…”

“…Further data can be found in Table . The GP mixture design was developed by a combination of sufficient flowability for an automated pultrusion process and good mechanical performance after hardening, following the special method developed for the mineral impregnation technique in previous studies by the authors, see refs and . A slump flow of 250 mm and a flow time of 15 s were determined using a small V-funnel having a volume of 150 mL and an opening diameter of 7 mm, while 28 days’ flexural and compressive strengths, tested on prism specimens with dimensions of 10 × 10 × 60 mm 3 , were 8 and 37 MPa, respectively.…”

“…In fabrication, a continuous, automated processing line based on in situ pultrusion consisting of a five-roller-foulard system and additional equipment was applied, as detailed in previous investigations by the authors of refs and . In the first step, the unidirectional CF tow with a width of ∼19 mm was pulled by winding it onto a motor-driven wheel under constant tension, leveled, guided via a kiss-coater and suspension bath, and then shaped by a plastic, funnel-like nozzle with an opening diameter of 4.1 mm.…”

Influence of Roller Configuration on the Fiber–Matrix Distribution and Mechanical Properties of Continuously Produced, Mineral-Impregnated Carbon Fibers (MCFs)

“…Even with particle sizes in the range of the filament diameter (~7-9 µm) or even smaller, it is still challenging to realize the complete homogenous impregnation of entire CF yarns with up to 50,000 (50 K) filaments each [17], acting as a kind of filter and thus hindering the penetration of mineral fines into the yarn core. Although the wettability of CF can be improved by different surface treatments [27][28][29][30][31][32], capillary forces alone cannot provide the required quality of the traditional composite industry without applying mechanical pressure to the rovings [33][34][35].…”