This　paper　presents　systematic　experimental　investigations　on　the　combined　influences　of　loading　strain　rate　and　structural　size　on　uniaxial-compression　failure　characteristics　of　LAC　and　basalt　fiber-reinforced　lightweight　aggregate　concrete　(BFLAC),　in　terms　of　workability,　failure　morphology,　deformation　curve,　failure　strength,　elastic　modulus　and　energy　absorption,　with　a　special　focus　on　the　size-dependence　of　strain　rate　effect.　Results　indicate　that　the　uniaxial-compression　strength,　elastic　modulus,　compression　toughness　as　well　as　specific　toughness　are　increased　when　the　basalt　fibers　with　0.3%　volume　content　is　added　in　LAC,　which　can　be　ascribed　to　the　synergistic　effect　of　three　working　modes　of　basalt　fibers　in　restricting　the　crack　propagation　and　fracture　failure.　As　the　strain　rate　increases,　specimens　with　larger　size　perform　a　stronger　strain　rate　effect,　resulting　in　that　the　influence　of　structural　size　on　uniaxial-compression　failures　is　weakened.　The　addition　of　basalt　fibers　can　also　weaken　the　size-dependence　on　uniaxial-compression　strength,　compression　toughness　and　specific　toughness,　which　contributes　to　the　promotion　and　application　of　basalt　fibers　in　LAC,　especially　for　large-scale　engineering　structures.　The　dynamic　increase　factor　(DIF)　empirical　formulas　of　LAC　and　BFLAC　with　various　structural　sizes　have　been　obtained,　which　can　provide　a　reasonable　reference　for　structure　safety　design　and　numerical　computation　of　LAC　and　BFLAC.　©　2023　Elsevier　Ltd