An　innovative　microbial　remediation　protocol　is　proposed　to　overcome　critical　limitations　of　conventional　microbial-induced　carbonate　precipitation　(MICP)　for　concrete　crack　repair.　The　method　integrates　pH　preconditioning　of　Sporosarcina　pasteurii　with　a　bioadditive-assisted　crystallization　strategy　to　address　microbial　inactivation　under　highly　alkaline　conditions,　inefficient　calcium　utilization,　and　structural　instability　caused　by　metastable　vaterite　formation.　Acidification　to　pH　5.5　preserved　78　%　of　urease　activity　at　pH　12.5　by　stabilizing　bacterial　zeta　potential,　while　a　composite　bioadditive　composed　of　polyvinyl　alcohol,　sodium　alginate,　and　colloidal　silica　nanoparticles　reduced　the　critical　nucleation　radius　by　29　%,　enhancing　calcite　crystal　formation.　Mechanical　testing　showed　a　26.8　%　increase　in　flexural　strength　and　an　88.7　%　calcium　utilization　rate,　with　durability　evaluations　confirming　stable　crack　sealing　over　180　thermal-humidity　cycles.　Field-scale　application　to　a　deteriorated　underground　garage　demonstrated　92　%　void-filling　efficiency　and　compressive　strength　recovery　from　28.5　MPa　to　41.2　MPa.　The　developed　protocol　eliminates　the　need　for　carrier　materials　and　reduces　carbon　emissions,　establishing　a　scalable　and　sustainable　framework　for　infrastructure　rehabilitation.　These　results　highlight　the　potential　of　synergistic　biological　and　material　strategies　for　advancing　next-generation　selfhealing　concrete　technologies.