Limestone　powder　(LS)　has　been　widely　used　in　cement-based　materials;　and　reportedly,　can　influence　their　properties　by　filler,　nucleation,　dilution　and　chemical　effects.　The　action　mechanism　of　LS　mainly　depends　on　its　particle　size　and　amount.　The　filler　effect　of　LS　refines　the　microstructure　and　reduces　the　porosity　of　cement-based　materials.　Its　nucleation　effect　accelerates　the　hydration　of　C3S,　increases　the　amount　of　hydration　products　and　reduces　the　porosity　of　cement-based　materials　at　early　ages.　Its　dilution　effect　reduces　the　hydration　peak　of　C3S,　decreases　the　amount　of　hydration　products　and　increases　the　porosity　of　cement-based　materials.　Its　chemical　effect　promotes　the　appearance　of　third　hydration　peak,　forms　carboaluminate　and　reduces　the　porosity　of　cement-based　materials.　©　2018