Low-Alkali, Ambient-Cured One-Part Alkali-Activated Concrete: A Critical Review of Mix Design, Reaction, Performance and Durability

One-part alkali-activated concrete avoids corrosive activator solutions, but its solid activators are still strongly alkaline. Lowering the dose and curing at ambient temperature both slow the reaction, so the two aims conflict. This critical review examines how far activator-derived alkali can be reduced in one-part, ambient-cured concrete. It draws on 66 primary studies, of which 37 used one-part mixes and only 8 tested concrete. Low alkali is defined as at most 5% Na₂O-eq by mass of precursor. Doses are expressed per unit precursor and per cubic metre, concrete results are kept separate from paste and mortar results, and an alkali intensity index (kg Na₂O-eq m⁻³ per MPa) is introduced. Within the low-alkali range, mixes reached 25 MPa only with slag-rich precursors, mostly with a calcium co-activator, and all the concretes tested were silicate-activated. Curing at 24 °C and 50% RH reduced the 28-day strength of such slag concrete by 34–36% and its elastic modulus to 30–35% of the ACI 318 prediction. Moist-cured slag concrete at low water–binder ratio had the lowest alkali intensity (0.40–0.50 kg m⁻³ MPa⁻¹); high-dose concretes had 0.57–1.02. A lower dose reduced efflorescence and expansion from alkali–silica reaction (ASR) but not drying shrinkage, and its effect on chloride ingress and carbonation-induced corrosion has not been tested in one-part concrete. A conditional mix-selection framework, a minimum reporting checklist and research priorities are proposed.