Investigation on the safety concrete for highway crash barrier

• We prepare a no-fine concrete with AAS for highway safety barrier.
• Optimum aggregate gradation ensures the concrete high strength and fragmentability.
• This concrete has strength around 20 MPa and high energy absorption ability.
• High energy absorption results from the micro-crack and low specific surface area.

A new type of concrete named “safety concrete” for traffic safety is developed. A no-fine concrete solidified by Alkali Activated Slag (AAS) can form a network of micro-cracks throughout the concrete to ensure its good energy absorption under the sudden and severe loading, the mixture design and microstructure of this new concrete is studied. Results indicated that, the optimum aggregate gradation with 2.36 mm passing ratio around 20% and around 5% of particles bigger than 4.75 mm ensure this concrete reach compressive strength of 20 MPa and fragmentability of 90%, the micro-cracks generate in different scales in the paste of this concrete, there are much more micro-cracks generated in AAS than in OPC paste, laboratory manufactured no-fine safety concrete blocks are broken into fragments smaller than 4.75 mm when they are dropped from 7th floor (18 m), safety concrete can serve as frontier guard railing or crash barrier installed for highway traffic safety.

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