scholarly journals PERILAKU GESER BALOK BETON BERTULANG MUTU TINGGI DENGAN VARIASI FLY ASH BATU BARA, PASIR POZZOLAN DAN BONGKAHAN CANGKANG SAWIT

2020 ◽  
Vol 3 (4) ◽  
pp. 268-277
Author(s):  
Cut Fatmawati ◽  
Teuku Budi Aulia ◽  
Muttaqin Muttaqin

The utilization of high strength concrete particularly on construction is an option in structural elements. High Strength Concrete (BMT) is a compressive strength exceeding 6000 psi or 41 MPa. High quality concrete can be obtained by mixing superplasticizers (high range water reducers) and cementitious mineral additives in the form of fly ash, pozzofume (super fly ash), and microscopy (silicafume). In this study, it will used the substitution of cement material using coal fly ash, fly ash pozzolan sand and palm shell ash fly ash, fine aggregates using pozzolan sand, coarse aggregates palm shell. The aim of this study is to compare the shear behavior of normal high quality reinforced concrete beams and beams with the addition of material substitution. The high quality reinforced concrete beam specimens were designed to experience shear failure by strengthening the bending area. Reinforced concrete beam specimens of beam size 150 mm x 300 mm x 2200 mm with shear reinforcement diameter 6 mm (fy) 423.46 MPa, compressive reinforcement 16 mm (fy) 412.39 MPa and tensile reinforcement 19 mm (fy) 462, 24 MPa. The beam specimen is pure flexural tensile strength with a size of 150 mm x 150 mm x 600 mm and a cylindrical specimen with a diameter of 150 mm x 300 mm in height. The magnitude of the flexural tensile strength for BMT-N with f cc = 44.4 MPa is 4.5, and for BMT-FBPP with f cc = 51.04 MPa which is 5.35 with FAS 0.3. The results of the two beams experienced shear failure, with a comparison of laboratory and theoretical shear capacity of 2,292 BMT-N with a maximum load of 27,200 MPa, BMT-FBPP 1,720 with a maximum load of 21,410 MPa. The values of deflection and ductility tend to decrease in BMT-FBPP beams which are equal to 19.780% and 6%.

2014 ◽  
Vol 629-630 ◽  
pp. 544-550
Author(s):  
Nuri Mohamed Elbasha

The primary long and short term advantages of high strength concrete are, low creep and shrinkage, higher stiffness, higher elastic modulus, higher tensile strength, higher durability (resistance to chemical attacks) and higher shear resistance. In addition, high strength concrete reduces the size of the member, which in turn reduces the form size, concrete volume, construction time, labor costs and dead load. Reducing the dead load reduces the number and size of the beams, columns and foundations. Thus there is a positive impact on reduction of maintenance and repair costs and an increase in rentable space. Other, yet to be discovered advantages may also exist. High strength concrete has definite advantages over normal strength concrete. The ductility of over reinforced HSC beams is enhanced through the application of helical reinforcement located in the compression region. The pitch of helix is an important parameter controlling the level of strength and ductility enhancement. This paper presents an experimental investigation of the effect of helices on the behavior of over reinforced high strength concrete beams through testing ten helically confined full scale beams. The helix pitches were 25, 50, 75, 100 and 160 mm. Beams’ cross section was 200×300 mm, and with a length of 4 m and a clear span of 3.6 m subjected to four point loading. The main results indicate that helix effectiveness is negligible when the helical pitch is 160 mm (helix diameter). The experimental program in this study proved that the HSC, HSS and helical confinement construct a reinforced concrete beam. This beam has the ability to resist weathering action and chemical attack while maintaining its desired engineering properties. In near future Reinforced High Strength Concrete Beam with Helical Confinement will be considered as a durable and sustainable Reinforced Concrete Beam.


2011 ◽  
Vol 243-249 ◽  
pp. 415-418
Author(s):  
Chun Min Dong ◽  
Ke Dong Guo ◽  
Jia Jia Sun

With the application of high strength concrete and rebar, the influence of concrete strength on cracking width of reinforced concrete beam with high strength rebar is becoming more and more important. To investigate the effect of concrete strength on cracking width of reinforced concrete beam with high strength rebar, the experiment including 6 simply supported T-beams with high-strength rebar and 2 beams with ordinary-strength rebar have been made. Then the relevant specifications advised in Code for Design of Concreter Structure (GB50010-2002) are revised according to the experiment results so as to considering the influence of concrete on cracking width. A new cracking width method considering the influence of concrete strength on cracking width for reinforced concrete beam with high strength rebar is proposed. Finally, the comparisons between predictions and experiment results have been conducted, which shown that the proposed new cracking width method agreed with experiment results well.


2014 ◽  
Vol 92 ◽  
pp. 74-83 ◽  
Author(s):  
Wanchai Yodsudjai

The applications of using fly ash-based geopolymer as a structural member and a repair materials in reinforced concrete structure was conducted. The optimum mix proportion of fly ash-based geopolymer concrete using for structural beam and fly ash-based geopolymer mortar using for repair material were developed. The flexural behavior of fly ash-based geopolymer reinforced concrete and the durability aspect namely the corrosion of steel reinforcement were investigated using the electrical acceleration. For the repair purpose, the fundamental properties; that is, compressive strength, flexural strength, bonding strength between fly ash-based geopolymer mortar and mortar substrate, setting time and chloride penetration were investigated. Also, the durability of conventional reinforced concrete beam repaired by the fly ash-based geopolymer mortar comparing with the comercial repair mortar was investigated. The behavior of the fly ash-based geopolymer reinforced concrete beam was similar to that of the conventional reinforced concrete beam; however, the corrosion of the steel reinforcement of the fly ash-based geopolymer reinforced concrete beam was higher than that of the conventional reinforced concrete beam. The fundamental properties of the fly ash-based geopolymer mortar were not different from that of the commercial repair materials; however, the durability of the reinforced concrete beam repaired by the fly ash-based geopolymer mortars performed a little lower than that of repaired with the commercial repair motar and also the control reinforced concrete with no repair. As a result, even there will be still a need of improvement there was a good tendency for using the fly ash-based geopolymer as the structural member and the repair materials.


2017 ◽  
Vol 737 ◽  
pp. 441-447 ◽  
Author(s):  
Stefanus Kristiawan ◽  
Agus Supriyadi ◽  
Senot Sangadji ◽  
Hapsara Brian Wicaksono

Degradation of reinforced concrete (RC) element could lead to a reduction of its strength and serviceability. The degradation may be identified in the form of spalling of concrete cover. For the case of RC beam, spalling of concrete cover could occur at the web of the shear span due to corrosion of the web reinfocements. The shear strength of the damaged-RC beam possibly will become less conservative compared to the corresponding flexural strength with a risk of brittle failure. Patch repair could be a choice to recover the size and strength of the damaged-RC beam. This research investigates the shear failure of patched RC beam without web reinforcements with a particular interest to compare the shear failure behaviour of patched RC beam and normal RC beam. The patch repair material used in this research was unsaturated polyester resin (UPR) mortar. The results indicate that the initial diagonal cracks leading to shear failure of patched RC beam occur at a lower level of loading. However, the patched RC beam could carry a greater load before the diagonal crack propagates in length and width causing the beam to fail in shear.


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