|
چکیده
|
This study program deals with investigating the applicability of using crumb rubber (CR) as a replacement for fine aggregate in developing a new concrete type suitable for structural applications, especially when normal rubberized reinforced concrete is used. This study deal with shear behavior of rubberized reinforced concrete beam and Some extensive experimental studies have been carried out on both small-and large-scale concrete specimens to accomplish the research objective, in these studies, we were caste (16) large-scale reinforced concrete beams to be tested shear, another some mixtures on normal rubberized concrete were developed for mechanical properties of the developed mixtures were evaluated using small-scale specimens (cubic, cylinder, and prism). On the other hand, the evaluation of mechanical properties such as compressive strength(Fcu), splitting tensile strength (Fct), flexural strength (Fr), modulus of elasticity (Ec), Poisson’s ratio was done, the reinforced concrete beams dimensions (120*150*100) mm, (120*150*1240) mm and (120*150*1480) mm, four beams made with crumb rubber from 0% to 40%, with improved lower self-weight, and toughness and decrease the angle of failure but increase the crack width and number of cracks. three beams with the shear span to depth ratio a/d (2.5, 3.5, 4.5) with 30% crumb rubber decrease the cruck width, angle of failure but increase the number of cracks and high toughness. 0.4% and 0.80% of large steel fiber, polypropylene fiber, and small steel fiber were used for six beams, the result showed that the increase of 1st diagonal crack, ultimate shear capacity, post diagonal cracking, high energy absorption and decrease the crack width, but the large steel fiber has the best result compared form other fibers, three beams shear span to depth ratio a/d (2.5, 3.5, 4.5) with 30% crumb rubber and 0.8% polypropylene fiber were conducted the result shows that decrease the crack width and the number of cracks. after that final studies were fixed large steel fiber for three beams by 0.80% but varied crumb rubber from (15%, 30% to 40%), the result showed that the 15% crumb rubber (CR) with 0.8% large steel fiber (LSF) was more toughness, shear caTpacity, and post diagonal cracking. in the end, the results showed that using CR in normal reinforced concrete helped to develop mixtures with improved lower self-weight, toughness, reduce the cruck width, number of crucks, reduce ultimate shear capacity by about 30%. but mechanical properties explained above were decreased. However, using a higher amount of three types of fibers allowed high percentages of CR to be used, successfully. Although using fibers in normal reinforced concrete mixtures, they proved to have a significant enhancement on the mixtures’ strengths, especially compressive strength (Fcu), split tensile strength (Fct), flexural strength (Fr), modulus of elasticity (Ec), and Poisson’s ratio. improve ultimate shear capacity by 40%, reduce the number of crucks, cruck width and post diagonal cruck. it was possible to develop mixtures with a higher percentage of CR with fibers. This high combination of CR and fibers provides a new concrete composite with further Improvement in toughness and with further reduction in self-weight, reduction in the crack and width of the crack, better shear capacity.
|