Like the body,when cement composites are“hurt”,they try to find a way to fix themselves.This is known as the self-healing phenomenon.This self-healing concept is one of great importance as it gives structures a measure of self-reliance.The precast grouted sleeve connection is a cement composite entrapped in a steel enclosure.This connection is useful in its joining of precast elements to ensure a monolithic structure.This research investigates a newly formulated grout,to ascertain its mechanical properties.This study also investigates the self-healing phenomenon of this research grout（W）and a commercial grout（C）.The two grouts were tested with and without the addition of Calcium Sulphur-Aluminate（CSA）based expansive agent for self-healing.The samples were then cured in water and saturated lime water（Ca（OH）2）solution for20 and 35 days.The research grout was then tested in a sleeve tensile test to check the self-healing phenomenon in grouted sleeves.Ultra-Sonic Pulse Velocity（UPV）test,Scanning Electron Microscope（SEM）and X-Ray Diffusion（XRD）analysis was done to ascertain the self-healing and its subsequent products.The results showed that the research had a maximum flexural strength of 12.40MPa.The average compressive strength of research grout increase was at a constant rate of close to 10MPa every 7 days.For the sleeve tensile test,the ultimate tensile force was116.352k N,with the desired failure mode of rebar fracture which shows that the research grout can successfully be used in the precast sleeve connection.The research grout grouted sleeves underwent near-complete self-healing,with self-healing ratios of 99%and 98%.A“compression effect”phenomenon was noticed in the UPV test and some basic guidelines were put forward for the testing of self-healing phenomenon of sleeve’s grout.For strength regain after self-healing,tested in compression,both commercial and research grout specimen without CSA performed better when cured in water than when cured in saturated lime solution.For specimens with CSA,at 20 days post cracking,the average self-healing efficiency of the research specimen cured in saturated lime water was higher than the commercial specimen.The research grout had an average self-healing efficiency 129.6%.and the commercial grout had a self-healing efficiency of 123.5%.The SEM and XRD results showed that the specimens with CSA had more of the production of ettringite as the primary source of self-healing,whereas the specimen without CSA had hydration products and some ettringite as their self-healing products.This led not only to the reduction in crack width,but also to the bridging of cracks