An Initial Study of Ultra High Performance Concrete as Reusable Mold Material for Aluminum Casting

Area of Science:

• Materials Science
• Manufacturing Engineering
• Concrete Technology

Background:

• Reusable molds are crucial for efficient casting processes.
• Traditional mold materials face limitations in durability and cost.
• Ultra-high performance concrete (UHPC) offers potential for advanced mold applications.

Purpose of the Study:

• To evaluate the feasibility of UHPC for reusable aluminum casting molds.
• To compare the performance of ordinary Portland cement (OPC)-based UHPC and alkali-activated material (AAM)-based UHPC.
• To assess the surface integrity and thermal durability of UHPC molds through repeated casting cycles.

Main Methods:

• Fabrication of UHPC molds using OPC and AAM formulations.
• Surface roughness measurements and repeated casting cycle testing.
• Thermal stability analysis via thermogravimetric analysis, mercury intrusion porosimetry, microscopy, and crack segmentation.

Main Results:

• AAM-UHPC molds demonstrated superior performance, withstanding up to ten casting cycles with minimal degradation.
• OPC-UHPC molds showed faster degradation compared to AAM-UHPC molds.
• UHPC molds produced aluminum castings with comparable grain size to steel molds, indicating high casting quality.

Conclusions:

• Alkali-activated UHPC is a viable material for reusable casting molds, offering enhanced durability and surface quality.
• UHPC molds exhibit low adhesion and minimal defect formation when interacting with molten aluminum.
• UHPC materials, especially AAM formulations, present a promising avenue for improving casting efficiency and quality in low-pressure environments.