Concrete by Preplaced Aggregate Method Using Silica Fume and Polypropylene Fibres

Area of Science:

• Materials Science
• Civil Engineering
• Construction Materials

Background:

• Preplaced Aggregate Concrete (PAC) is a two-step concrete construction method.
• Supplementary Cementitious Materials (SCMs) like silica fume enhance concrete properties and reduce CO2 emissions from Ordinary Portland Cement (OPC).
• Polypropylene fibers can improve concrete performance.

Purpose of the Study:

• To investigate the impact of adding macro polypropylene fibers to PAC with silica fume as an SCM (FRPAC).
• To evaluate the mechanical properties and high-temperature performance of FRPAC compared to control mixes.

Main Methods:

• Casting 100 mm × 200 mm PAC cylinders with 10% cement replaced by silica fume and 1.5% macro polypropylene fibers.
• Conducting compressive strength, splitting tensile strength, mass loss at 250 °C, and compressive strength at 250 °C tests.
• Comparing results of fiber-reinforced PAC with silica fume (FRPAC) against silica fume PAC (SPAC) and non-fiber PAC (NPAC).

Main Results:

• FRPAC exhibited lower compressive strength than SPAC.
• FRPAC demonstrated higher tensile strength compared to NPAC and SPAC.
• SPAC experienced greater mass loss at 250 °C than FRPAC.
• FRPAC showed significantly greater compressive strength loss at 250 °C than SPAC.
• FRPAC displayed increased ductility and strain capacity.

Conclusions:

• The addition of polypropylene fibers to silica fume PAC affects its mechanical properties, notably reducing compressive strength but enhancing tensile strength and ductility.
• FRPAC shows improved resistance to mass loss at high temperatures, though compressive strength degradation is more pronounced.
• Further research may optimize fiber content for enhanced high-temperature performance and overall structural integrity.