Engineering and Technology Journal

The main aim of this research is to study the effect of using hooked end steel fiber on the fresh and hardened properties of self-consolidating concrete. The experimental work includes two stages. First stage involved conducting several trial mixes and then choosing the one that conform tothe international standards in terms of fresh properties. Second stage concerned on the compressive, flexural tensile and splitting tensile strengths evaluationof the selected mixes, at 28 and 90 days.Four concrete mixes were obtained and evaluated. They were similar in mix proportions and differ only in volume fractions of steel fibers incorporated: 0%, 0.5%, 1%, and 1.5%.
Results showed that adding hooked steel fibers adversely affect SCC workability and thus more dosage of SP should be added to stay within the standard limits. Similar to conventional HPC, the presence of steel fibers with SCC provide slight increase in compressive strength at 28 days, (up to 11%), while significant enhancement in tensile properties were observed (up to 68% and 80% for splitting and flexural strength respectively). Flexural strength (i.e. modulus of rapture) was generally still higher than splitting testing results in a decreasing order. This order is still applicable in SCC even with the presence of steel fibers.

This research has studied the possibility of optimizing some of the properties of the precast concrete flags by using by-products of steel fragments from the CNC machines and local slag, the combined influence of these materials
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with the water reducing agent. The local slag is produced by the blast furnace from the scrap as a raw material, which is called (steel slag). The local slag has a low activity as a cementicious material due to low content of glass since it has not been treated, and contains high ferrous ratio. The study includes the results of compressive and strength as well as transverse loading tests. Also, it includes the measurements of absorption on different curing durations of the reference concrete samples and concrete contains the metal and chemical additives, reinforced by steel fibers. This study has taken place by replacing the slag instead of fine aggregate, using ratios of (0, 10, 20, 30%) by weight of sand with the influence of steel fibers from the CNC by-products, using ratios of (0.5, 1.0, 1.5 %) by volume of the concrete mix with the influence of super plasticizer of (1.5%) ratio by weight of cement. The results had shown that the concrete compressive strength had increased with using (30%) of slag and (1%) of steel fibers of the CNC machine by- product, with (1.5%) of the super plasticizer, compared with the reference mixes. The results had shown also, that the concrete containing super plasticizer with slag (20%) and (1.0%) of the steel fibers had shown better flexural strength compared with the reference mixes at ages (7, 28 days). The results had also shown increasing in the transverse loading test of the pre cast concrete flags, especially when using slag of (30%) and steel fibers of (1%) and super plasticizer, compared with the reference mixes at ages (7, 28 days). The results had shown clear reduction of the absorption at slag ratio (30%) and (1.0%) of steel fibers with the super plasticizer, compared with the reference mixes at age (28 days).