Table 2.

Summary of proposed solutions to mitigate durability problems when using RA in alkali-activated concretes.

Durability Index	Proposed Solutions	References
Water absorption, porosity, sorptivity	The moisture state of RA should be approximately 80% or pre-saturated	[42,69]
	Staged mixing approach could be used	[111]
	Limit RA content	[98]
	Use small size RA	[98]
	Use reactive additive to enhance binder properties	[113]
Chloride and sulfate diffusion	Use of 25–75 wt % of RA	[69]
	Increasing sodium silicate to sodium hydroxide ratio	[72]
Acid resistance	Using recycled bricks instead of crushed old OPC concretes as RA	[122]
	Use reactive additive to enhance binder properties	[113]
Freeze and thaw resistance	Using crushed old OPC concretes instead of recycled bricks as RA	[124]