Keywords : Compressive strength
Effect of thermal insulation on compressive strength of concrete exposed to high temperature by using ansys software.
journal of kerbala university,
Volume 10, Issue 2, Pages 211-221
The concrete construction suffer from the loss of a lot of mechanical properties (compressive strength) when exposed to fire because of the dehydration of cement paste which causes to lose of its adhesive property. The study has been carried out to establish the mathematical equation between the compressive strength of concrete and firing temperature at varying times depending on the experimental data of firing concrete obtained from previous studies .Result of mathematical equation gave good agreement
Depending on the thermal properties of concrete got a relationships as mathematical equations to explain the temperatures distribution and time on firing specimen of transient heat by using the ansys software 14, also the study included the effect of adding a Calcium Silicate as insulation on those variable. Compressive strength was calculated from ansys results with and without insulator depend on the earlier mathematical equation. Results showed the influence of adding insulation material to reduce the fire effect's on the residual compressive strength of fired specimen's.
Finally, it can refer to the the possibility of the use the research equations to give first prediction of the amount of damage caused by the fire in the concrete constructions after knowing the fire temperature and the type , thickness of the insulators.
journal of kerbala university,
Volume 6, Issue 3, Pages 87-100
Self-compacting concrete (SCC) is a very important advance in the concrete technology in recent time. It is a new type of high performance concrete with the ability of flowing under its own weight and without the need of vibrations. Due to its specific properties, SCC may contribute to a significant improvement of the quality of concrete structures and open up new field for the application of concrete. This study aims to check whether the fresh properties of self compacting concrete mixed by the Nan Su et al.,  method and using limestone filler comply with the requirements specified by the ACI Committee 237. In this study, four values of cement content 200, 250, 300 350 kg/m3 are used. The maximum aggregate size of 20 mm was used. The contents of limestone powder for each cement content were 165, 139, 116, and 96 kg/m3 respectively. Fresh performance of self compacting concrete was determined by slump flow, J-ring and column segregation. The results showed that the workability of all studied mixes is good, with slump flow diameter range between 570 to 630 mm. The difference between slump flow diameter and J-ring diameter is not exceed 50 mm, while the segregation resistance range between 10 and 15%. These results showed that the self compacting concrete used was complied with the requirements specified by the ACI Committee 237. The results also showed that the volume of coarse aggregate, paste fraction, mortar fraction and powder content were 0.294 m3/m3, 0.32 m3/m3, 0.69 m3/m3 and 446 kg/m3 respectively, which meet the lower limits requirements of ACI Committee 237. Further, to obtain self compacting concrete with 15 to 30 MPa compressive strength, the content of cement required is only 200 to 350 kg/m3.