Isophorone　diisocyanate　(IPDI)　was　encapsulated　successfully　within　double-layered　shells,　and　final　microcapsules　showed　outstanding　self-healing　functions　in　cement　paste.　The　well-dispersed　microcapsules　had　a　diameter　of　347.0　+/-　103.4　mu　m,　shell　thickness　of　3.1　+/-　0.4　mu　m,　and　core　fraction　around　74.8%　+/-　1.9%　by　weight.　The　diameters　of　microcapsules　were　adjustable　by　varying　agitation　rates.　The　beginning　weight-loss　temperature　of　microcapsules　was　200　degrees　C,　implying　good　thermal　stability.　The　final　microcapsules　affected　slightly　the　workability　and　setting　time　of　fresh　self-healing　cement　paste.　Although　the　mechanical　strength　of　hardened　self-healing　cement　paste　was　decreased　with　the　increase　of　microcapsule　concentrations,　the　open　porosity　was　improved　obviously　from　33.5%　(control　samples)　to　31.8%　when　5.0%　by　weight　of　microcapsules　was　introduced.　The　interfaces　of　microcapsules　were　compatible　enough　with　cement　paste　without　obvious　delamination.　Especially,　the　self-healing　cement　paste　showed　outstanding　self-healing　functions　in　open　air　when　10.0%　by　weight　of　microcapsules　was　introduced.　(C)　2021　American　Society　of　Civil　Engineers.