This　study　investigates　the　cracking　scale　and　main　fracture　precursor　characteristics　of　polypropylene　fiber　(PPF)-reinforced　recycled　aggregate　concrete　(RAC).　A　total　of　30　test　groups　were　prepared,　utilizing　coarse　aggregate　substitution　rates　of　0%　and　25%　across　varying　coarse　aggregate　ratios.　The　energy　and　dominant　frequency　of　acoustic　emission　(AE)　signals　from　the　PPF-reinforced　RAC　were　recorded　during　uniaxial　compression　testing.　The　K-means　clustering　method　was　employed　for　two-dimensional　clustering　analysis　to　differentiate　between　large-scale　and　small-scale　cracking.　Subsequently,　a　support　vector　machine　(SVM)　was　utilized　to　delineate　the　boundary　between　these　two　types　of　cracking.　The　effectiveness　of　single-blend　and　double-blend　micro-　and　macro-PPF　in　mitigating　cracking　was　examined　by　analyzing　the　frequency　of　large-scale　cracking　signals　and　the　evolution　characteristics　of　the　AE　b-value.　An　assessment　of　the　evolution　of　AE　signals　during　the　rupture　process　of　PPF-reinforced　RAC　revealed　significant　trends:　a　decrease　in　the　AE　b-value,　an　increase　in　large-scale　cracking　signals,　and　the　disappearance　of　low-energy　small-scale　cracking　signals.　A　precursor　response　coefficient　was　introduced,　highlighting　that　the　precursor　response　ability　concerning　the　disappearance　of　low-energy　small-scale　cracking　signals　proved　to　be　a　significant　characteristic,　thereby　offering　insights　for　predicting　main　fractures　in　PPF-reinforced　RAC.　©　King　Fahd　University　of　Petroleum　&　Minerals　2024.