A　comparison　study　is　made　between　the　dynamic　properties　of　an　argillaceous　siltstone　and　its　grouting-reinforced　body.　The　purpose　is　to　investigate　how　grout　injection　can　help　repair　broken　soft　rocks.　A　slightly　weathered　argillaceous　siltstone　is　selected,　and　part　of　the　siltstone　is　mechanically　crushed　and　cemented　with　Portland　cement　to　simulate　the　grouting-reinforced　body.　Core　specimens　with　the　size　of　50　mm　×　38　mm　are　prepared　from　the　original　rock　and　the　grouting-reinforced　body.　Impact　tests　on　these　samples　are　then　carried　out　using　a　Split　Hopkinson　Pressure　Bar　(SHPB)　apparatus.　Failure　patterns　are　analyzed　and　geotechnical　parameters　of　the　specimens　are　estimated.　Based　on　the　experimental　results,　for　the　grouting-reinforced　body,　its　shock　resistance　is　poorer　than　that　of　the　original　rock,　and　most　cracks　happen　in　the　cementation　boundaries　between　the　cement　mortar　and　the　original　rock　particles.　It　was　observed　that　the　grouting-reinforced　body　ends　up　with　more　fragmented　residues,　most　of　them　have　larger　fractal　dimensions,　and　its　dynamic　strength　is　generally　lower.　The　mass　ratio　of　broken　rocks　to　cement　has　a　significant　effect　on　its　dynamic　properties　and　there　is　an　optimal　ratio　that　the　maximum　dynamic　peak　strength　can　be　achieved.　The　dynamic　strain-softening　behavior　of　the　grouting-reinforced　body　is　more　significant　compared　with　that　of　the　original　rock.　Both　the　time　dependent　damage　model　and　the　modified　overstress　damage　model　are　equally　applicable　to　the　original　rock,　but　the　former　performs　much　better　compared　with　the　latter　for　the　grouting-reinforced　body.　In　addition,　it　was　also　shown　that　water　content　and　impact　velocity　both　have　significant　effect　on　dynamic　properties　of　the　original　rock　and　its　grouting-reinforced　body.　Higher　water　content　leads　to　more　small　broken　rock　pieces,　larger　fractal　dimensions,　lower　dynamic　peak　strength　and　smaller　elastic　modulus.　However,　the　water　content　plays　a　minor　role　in　fractal　dimensions　when　the　impact　velocity　is　beyond　a　certain　value.　Higher　impact　loading　rate　leads　to　higher　degree　of　fragmentation　and　larger　fractal　dimensions　both　in　argillaceous　siltstone　and　its　grouting-reinforced　body.　These　results　provide　a　sound　basis　for　the　quantitative　evaluation　on　how　cement　grouting　can　contribute　to　the　repair　of　broken　soft　rocks.　©　2017　Techno-Press,　Ltd.