The　incorporation　of　basalt　fibres　in　lightweight　aggregate　concrete　(LAC)　is　a　potentially　effective　approach　to　ameliorate　failure　strength　and　ductility,　which　has　been　extensively　applied　in　concrete　structures.　This　paper　investigates　the　comprehensive　effects　of　strain-rate　(ranging　from　10−5　to　10−2s−1)　and　structure　size　(ranging　from　70　to　300　mm)　on　splitting-tension　fracture　failures　of　LAC　and　basalt　fibre-reinforced　lightweight　aggregate　concrete　(BFRLAC)　via　a　systematic　experiment,　in　terms　of　failure　modes,　deformation　curves,　peak　fracture　strengths　and　microstructure　mechanisms.　Results　indicated　that　the　incorporation　of　basalt　fibres　with　0.30%　volume　fraction　in　LAC　enhanced　the　splitting-tension　strength　by　27.3–38.0%　at　quasi-static　strain-rate　while　it　increased　to　42.3–53.4%　at　low　strain-rate　rising　to　10−2s−1,　which　can　be　attributed　to　the　change　of　dominated　action　mode　of　basalt　fibres　in　bridging　and　toughening　effect　and　the　superior　tensile　properties　of　basalt　fibres　being　made　the　best　use.　Both　LAC　and　BFRLAC　with　larger　structure　sizes　performed　higher　dynamic　increase　factors　(DIFs),　showing　a　stronger　strain-rate　effect.　LAC　and　BFRLAC　performed　a　dropping　trend　in　splitting-tension　strength　with　the　growing　structure　size　but　the　drop　was　reduced　as　strain-rate　rose.　The　incorporation　of　basalt　fibres　could　reduce　the　sensitivity　of　splitting-tension　strength　to　structure　size,　which　caused　13.3%　reduction　in　size　effect　at　quasi-static　strain-rate　while　up　to　51.7%　reduction　at　strain-rate　rising　to　10−2s−1.　The　DIF　equations　captured　through　regressive　analysis　on　test　results　could　reasonably　describe　the　strain-rate　effect　of　LAC　and　BFRLAC　considering　the　influence　of　structure　size　and　offer　a　valuable　guidance　for　optimal　structure　designs　and　simulation　calculations.　©　2023　Elsevier　Ltd