Prediction Of Strength And Temperature Stress Of Self-Compacting Concrete For PC Artifacts

Fabricated building was more and more applied recently in precast concrete artifacts,due to the short work period,long service life,excellent performance,controllable quality,environmental protection,which accelerates the modernization process of construction industry.Because of the special requirements of shape of artifacts,there are lots of problems such as the poor concrete mobility,fillibility and difficult to artificial vibration caused by dense arrangement of bar or lack of thickness.It has become a important subject of construction industry how to apply self-compacting concrete on production of precast concrete artifact.On the basis of present situation of concrete application at home and abroad summarized,research on strength,temperature field,temperature stress of SCC cube and influence factors was carried out systematically from engineering application,providing scientific foundation for reliability design of self-compacting concrete and application promotion.Through the optimization of fixed sand volume method and overall calculation method,27 sets of C30 self-compacting concrete mix proportions were designed,by which concrete test cubes were made to test kilned and 28d strength curing in steam method.The optimum mix proportion was found and analyse the influences of different parameters to concrete strength.Self-compacting concrete mix proportion-strength mathematical model was established by artificial neural network,deriving the functional relation of different parameters in mix proportion(cement content,water-binder ratio,sand ratio)and strength.Compared the predicted strength value with the actual value,there was a maximum error of 4.51%,fully proving the availability of applying this model in trial work.In view of phenomenon that it is easy to shrinkage cracking of concrete in the hardening process,the main cause and main influencing factors were analyzed.On the basis of thermal elastoplastic theory,the method of computation and analysis of self-compacting concrete temperature field in the influence of concrete creep were found.Further more,self-compacting concrete thermal elastoplastic constitutive relation was found.Using COMSOL software simulating the self-compacting concrete model,regular patterns of temperature field,stress and strain were found,and influence of mix proportion and curing condition to temperature field,stress distribution and deformation distribution was analyzed.The results show that the difference between the capability of self-compacting concrete cube surface heat radiation and cement hydration heat causes a temperature gradient.The temperature gradient causes the differences between temperature stress,strain of surface and interior,then the cracking appears at some deformation value.