Self-Compacting Concrete mixes (SCC) is increasingly being used in many application some of which are susceptible to an Aggressive Environment such as sulfuric acid solution. In this study SCC incorporating silica fume, chalk powder and hybrid fibers were used in casting twelve specimens with a dimensions of (1000× 200× 100) mm , in three groups. The specimens in the first group were cured in normal environment for 28 days, while those in the second and third groups were subjected to sulfuric acid solution of 0.5% for six and ten months, respectively. The flexural tests of the specimens were evaluated by testing the specimens under two-concentrated point loading until failure. The experimental results show that after chemical exposure for ten months, using of chalk powder or hybrid fibers enhances the resistance to sulfuric solution
Self-consolidating concrete (SCC) is increasingly used in a number of concrete applications, some of which are highly susceptible to attack by sulfuric acid. This work aimed to study the resistance of a wide range of different SCCs to sulfuric attack. The main variables studied included binder material type (highly reactive materials), limestone powder, and hybrid fibers in this work, compaction, L-box, and V-hopper were performed for the new mixtures. In this study, the specimens were immersed in a solution of sulfuric acid at a concentration (0.5%) for up to 289 days after normal curing for 28 days. Laboratory results show that concrete containing pozzolanic material has reduced mechanical properties compared to a mixture containing only limestone powder. The study also showed that there was an improvement in the resistance of concrete to acid solutions when hybrid fibers were added to the concrete mix. From the stress graph, the strain at given axial stress will be less than once the failure becomes more severe, it will become less rigid than immersing the specimen for six months.
Existing concrete structures may, for a variety of reasons, be found to be unsatisfactory. This could manifest itself by poor performance under service loading in the form of excessive deflections, cracking or inadequate ultimate strength and changing the main function. In such circumstances, there are two possible solutions i.e. demolish and rebuild or carryout a program of repair and strengthening. In this investigation, the structural evaluation and suggested repairing works were studied for Iraqi Ministry of Trade building, the building was exposed to fire, vandalism and looting during the war on Iraq at 2003. The building consists of twelve stories, ten stories have area about 1428m2 and about 1150 m2 area of middle and basement stories. Each story has height of 3.5m. The structure of building consists of one way ribbed slab with 900mm slab thickness and 0.15×0.7m rib sectional dimensions. The columns have dimensions 0.6×1.2m and height 3.5m. The girders, ribs, floors and columns were peeled and decayed, there are a several cracks wider than 0.4mm distributed on the beams and floors and several columns, the concrete floors were destroyed and that caused appearance of steel reinforcement, parts of concrete of column at the second floor were destroyed and the longitudinal reinforcement steel buckled outside dragging the transverse reinforcement, a high possibility of reduction in concrete strength caused by the fire effects happened during 2003 war but the steel dose not affected by the fire because of the concrete cover which protected reinforcement. From this investigation, there is no serious damage in the sense that it is imperative to demolish the building and re-create. The damage in the building, as indicated in this study require some repairs, known in the field of rehabilitation through chemical additives and steel structures are additional materials available in local markets. It necessary to minimize the additional dead loads and the use of Limestone partitions in their implementation Gypsum Board partitions or imported light partitions.
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