scholarly journals The Fire Exposure Effect on Hybrid Reinforced Reactive Powder Concrete Columns

2020 ◽  
Vol 6 (2) ◽  
pp. 363-374 ◽  
Author(s):  
Hasanain A. Shubbar ◽  
Nameer A. Alwash
Keyword(s):  
Cross Section ◽  
Steel Fiber ◽  
Polypropylene Fiber ◽  
Concrete Columns ◽  
Concrete Cover ◽  
Reactive Powder Concrete ◽  
Eccentric Load ◽  
Concrete Core ◽  
Reactive Powder ◽  
Hybrid Cross

This paper offers an experimental investigation of the fiber reinforced reactive powder concrete columns' behavior after exposure to fire and improvements made to improve column resistance against fire. This study is mainly aimed to study the experimental behavior of hybrid reinforced columns produced by reactive concrete powder (RPC) and exposure to the flame of fire at one side and subjected to eccentric load. The experimental methodology consists of sixteen RC columns that organized into four groups based on the variables used in this research: (SF) steel fibers, (PP) polypropylene fibers, (HB) hybrid fibers, (PPC-SF) hybrid cross-section (steel fiber reactive powder concrete core with polypropylene fiber reactive powder concrete cover). All columns were tested under 60 mm eccentric load and the burn columns were exposed to fire for different duration (1, 1.5 and 2) hours. The results indicated that (SF-RPC, PP-RPC, HB-RPC, PPC-SFRPC) columns exposed to a fire flame for the period 2 hours, lost from their load capacity by about (54.39, 40.03, 34.69 and 30.68) % respectively. The main conclusion of this paper is that the best fire resistance of the column obtained when using a hybrid cross-section (steel fiber reactive powder concrete core with polypropylene fiber reactive powder concrete cover).

Study on the compression performance of steel reactive powder concrete columns

2020 ◽  
Vol 23 (10) ◽  
pp. 2018-2029
Author(s):  
Hongbing Li ◽  
Fangbo Wu ◽  
Liangtao Bu ◽  
Yong Liu ◽  
Jiang Yao
Keyword(s):  
Failure Mode ◽  
Axial Compression ◽  
Ductile Failure ◽  
Concrete Columns ◽  
Compression Testing ◽  
Reactive Powder Concrete ◽  
Sudden Increase ◽  
Eccentric Load ◽  
Eccentric Compression ◽  
Reactive Powder

In this study, the mechanical properties and failure characteristics of steel reactive powder concrete columns with different strength grades were investigated through compression testing. Six steel reactive powder concrete columns were tested; three columns underwent axial compression testing and three columns underwent eccentric compression testing. The results of the axial compression testing showed that steel and reactive powder concrete could work cooperatively at the initial stage, and the final column failure mode was primarily splitting failure at the end of the column, with the formation of a main crack in the longitudinal direction extending to the middle of the column. The results of the eccentric compression testing showed that the eccentrically loaded steel reactive powder concrete columns had comparatively strong deformability. The columns presented ductile failure mode under the eccentric load with 0.2 eccentricity. The final failure of the column involved a sudden increase in the horizontal crack width on the tension side, the steel flange on the tension side reached the yield state, the reactive powder concrete in the middle of the compressive side was crushed, and the reactive powder concrete surface layer burst open and partially spalled off. According to the test results and with reference to the relevant standards, equations for calculating the approximate ultimate bearing capacities of axially and eccentrically compressed reactive powder concrete columns were proposed.

Abrasion of Reactive Powder Concrete under Direct Water Impact

2020 ◽  
Vol 897 ◽  
pp. 41-48 ◽  
Author(s):  
Munther L. Abdul Hussein ◽  
Sallal R. Abid ◽  
Sajjad H. Ali
Keyword(s):  
Steel Fiber ◽  
Fiber Type ◽  
Polypropylene Fiber ◽  
Experimental Program ◽  
Reactive Powder Concrete ◽  
Fiber Distribution ◽  
Hybrid Fiber ◽  
Normal Concrete ◽  
Weight Losses ◽  
Reactive Powder

An experimental program was directed in this study to evaluate the abrasion resistance of reactive powder concrete (RPC) under direct normal impact of water jet. Abrasion and compressive strength specimens were cast from six RPC mixtures using different single and hybrid distributions of 6 mm-length and 15 mm-length micros-steel fibers and 18 mm-length polypropylene fiber. Fixed mix proportions were used for the six RPC mixtures and with fixed total volumetric fiber content of 2.5%. In addition to the RPC mixtures, a normal concrete mixture was prepared for comparison purposes. All specimens were cured in the same conditions and tested at an age of 28 days. The test results showed that abrasion weight losses increase with time at rates that are independent of fiber type and fiber distribution. The results also showed that all RPC mixtures exhibited significantly lower abrasion losses than normal concrete. The lowest percentage abrasion weight losses were recorded for the mixture with pure 15 mm micro-steel, where after 12 testing hours, it was 0.41% of the total weight before testing. On the other hand, the mixture with pure 6 mm micro-steel fiber exhibited the highest percentage abrasion weight loss (0.98%) among the six RPC mixtures. Another conclusion is that the inclusion of polypropylene fiber to compose hybrid fiber distribution with micro-steel fiber led mostly to lower abrasion losses.

scholarly journals Experimental Investigation of Short Square Normal and Hybrid Fiber Reactive Powder Concrete Columns Subjected to Chloride Solution Attack

2018 ◽  
Vol 24 (7) ◽  
pp. 75
Author(s):  
Mohammed Mosleh Salman ◽  
Husain Khalaf Jarallah ◽  
Raed Satar Al-Behadili
Keyword(s):  
Tap Water ◽  
Load Capacity ◽  
Concrete Columns ◽  
Experimental Program ◽  
Reactive Powder Concrete ◽  
Normal Concrete ◽  
Ultimate Load Capacity ◽  
Eccentric Load ◽  
Chloride Water ◽  
Reactive Powder

In this research, the structural behavior of reinforced concrete columns made of normal and hybrid reactive powder concrete (hybrid by steel and polypropylene fibers) subjected to chloride salts with concentration was 8341.6 mg/l. The study consists of two parts, the first one is experimental study and the second one is theoretical analysis.  Three main variables were adopted in the experimental program; concrete type, curing type and loading arrangement. Twenty (120x120x1200) mm columns were cast and tested depending on these variables. The samples were reinforced using two different bars; Ø8 for ties and Ø12 with minimum longitudinal reinforcement (0.01Ag). The specimens were divided into two main groups based on curing type: The first group consists of casting and testing of ten columns that cured in tap water for 28 days with two types of concrete (normal and hybrid), five columns for each type. While the second group consists of ten columns that direct cured and fully immersed in chloride water (8341.6 mg/l) 6 months with two types of concrete (normal and hybrid), five columns for each type. The specimens were tested under three types of loading, the first one is axial load, the second one is eccentric load with three different eccentricities (50,100 and 150) mm and where (e/h) are (0.42, 0.83 and 1.25) respectively from the center of column while the third type of loading is tested the specimens as beam. The experimental results showed an increase in ultimate load capacity and higher chlorides resisting for hybrid reactive powder concrete in comparison with normal concrete in both types of curing (tap and chloride water) through studying strain profile. Interaction diagram charts were obtained from different types of loading for each specimen. These charts showed high values for hybrid reactive powder concrete in comparison with normal concrete.  

Behavior of Reactive Powder Concrete Columns Under Eccentric Compression Loading

2014 ◽  
Vol 7 (3) ◽  
pp. 45-64
Author(s):  
Yaarub G. Abtan
Keyword(s):  
Failure Modes ◽  
Lateral Displacement ◽  
Concrete Columns ◽  
High Ratio ◽  
Concrete Cover ◽  
Steel Fibers ◽  
Reactive Powder Concrete ◽  
Substantial Variation ◽  
Concrete Type ◽  
Reactive Powder

The strength of concrete columns is controlled by the strength of the material and the geometry of the cross section. The use of Reactive Powder Concrete RPC technology has proven most popular with superior strength, stiffness and durability being the major advantages. An experimental investigation was carried into the behavior of RPC columns subjected to axial load with initial eccentricity. Twelve columns were prepared with 120mm square section at the midsection and were hunched at the ends to apply eccentric loading. The specimens were tested up to failure to evaluate the effects of the variation of the concrete type (normal or RPC), presence of steel fibers and longitudinal steel ratio. Experimental data on strength, lateral displacement and failure mode was obtained for each test. The comparative analysis of the experimental results showed that the use of RPC caused substantial variation in the ultimate strength and failure modes. Also, inclusion of steel fibers in RPC was an effective way to prevent spalling of the concrete cover and increase the ductility, as well as, high ratio of longitudinal reinforcement delays the buckling of the columns and increases strength.

scholarly journals Experimental Research on Fire Resistance of Reactive Powder Concrete

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Gai-Fei Peng ◽  
Yi-Rong Kang ◽  
Yan-Zhu Huang ◽  
Xiao-Ping Liu ◽  
Qiang Chen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fire Resistance ◽  
Steel Fiber ◽  
Polypropylene Fiber ◽  
Reactive Powder Concrete ◽  
Explosive Spalling ◽  
Residual Mechanical Properties ◽  
Tensile Splitting Strength ◽  
Reactive Powder

An experimental investigation was conducted on fire resistance of reactive powder concrete (RPC), mainly on explosive spalling occurrence and residual mechanical properties exposed to high temperature. The residual mechanical properties measured include compressive strength, tensile splitting strength, and fracture energy. RPC was prepared using cement, sand, silica fume, steel fiber, and polypropylene fiber. After subjected to high temperatures from 200 to 600°C, the residual mechanical properties were determined. RPC spalled considerably under high temperature. After exposure to high temperatures from 200 to 400°C, mechanical properties were enhanced more or less, which can be attributed to further hydration of cementitious materials activated by elevated temperature. Compressive strength started to decrease after exposure to 400°C, but tensile splitting strength and fracture energy started to decrease after exposure to 200°C. Incorporating hybrid fiber (polypropylene fiber and steel fiber) is a promising way to enhance resistance of RPC to explosive spalling, which should be a main objective for improving its fire resistance.

scholarly journals Bond Stresses between Reinforcing Bar and Reactive Powder Concrete

2018 ◽  
Vol 24 (11) ◽  
pp. 84
Author(s):  
Hussein Al-Quraishi ◽  
Nada Sahmi ◽  
Maha Ghalib
Keyword(s):  
Steel Fiber ◽  
Limit State ◽  
Concrete Cover ◽  
Bond Stress ◽  
Reactive Powder Concrete ◽  
Reinforcing Bar ◽  
Nominal Diameter ◽  
Compressive Strength Of Concrete ◽  
Reactive Powder ◽  
Push Out

A good performance of reinforced concrete structures is ensured by the bond between steel and concrete, which makes the materials work together, forming a part of solidarity. The behavior of the bond between the reinforcing bar and the surrounding concrete is significant to evaluate the cracking control in serviceability limit state and load capacity in the ultimate limit state. In this investigation, the bond stresses between reinforcing bar and reactive powder concrete (RPC) was considered to compare it with that of normal strength concrete (NSC). The push-out test with short embedment length is considered in this study to evaluate the bond strength, bond stress-slip relationship, and bond stress-crack width relationship for reactive powder concrete members. The compressive strength of concrete, the nominal diameter of reinforcement, concrete cover, and amount of steel fibers and embedded length of reinforcement were considered as variables in this study. The test results show that the ultimate bond stress increased with increasing of the compressive strength of concrete, decreasing the nominal diameter of the reinforcing bar, increasing the concrete cover and increasing steel fiber content. In a bond stress-slip relationship, the NSC specimen shows a very short softening zone after reaching the peak point in comparisons with RPC specimen. In RPC, bond stress-slip relationship shows stiffer behavior when the steel fiber content was increased. RPC shows stepper softening zone due to the presence of steel fiber, and the absence of steel fiber cause push-out failure without descending part after peak point. Using NSC instead of RPC in anchorage between reinforcement and concrete, decrease the crack width produced due to radial tensile stresses through the push-out of reinforcing bar. In RPC, the absence of steel fiber, decrease the nominal diameter of the reinforcing bar, increase the concrete cover, decrease the embedded length of reinforcing bar cause push-out failure and vice versa cause splitting failure.  

Tests on Mechanical Properties and Anti-Penetration Performance of Steel-Fiber Reactive Powder Concrete

2013 ◽  
Vol 671-674 ◽  
pp. 1761-1765
Author(s):  
Yong Liu ◽  
Chun Ming Song ◽  
Song Lin Yue
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Reactive Powder Concrete ◽  
Calculation Results ◽  
Reactive Powder ◽  
Penetration Tests

In order to get mechanical properties ,some RPC samples with 5% steel fiber are tested, many groups data were obtained such as compressive strength, shear strength and fracture toughness. And a group of tests on RPC with 5% steel-fiber under penetration were also conducted to validate the performance to impact. The penetration tests are carried out by the semi-AP projectiles with the diameter of 57 mm and earth penetrators with the diameter of 80 mm, and velocities of the two kinds of projectiles are 300～600 m/s and 800～900 m/s, respectively. By contrast between the experimental data and the calculation results of C30 reinforced concrete by using experiential formula under penetration, it shows that the resistance of steel-fiber RPC to penetration is 3 times as that of general C30 reinforced concrete.

scholarly journals A Study on Optimum Mixture Ratio of Reactive Powder Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Mingyang Chen ◽  
Wenzhong Zheng
Keyword(s):  
Compressive Strength ◽  
Steel Fiber ◽  
Raw Materials ◽  
Reactive Powder Concrete ◽  
Mixture Ratio ◽  
Curing Methods ◽  
Main Components ◽  
Cement Strength ◽  
Reactive Powder ◽  
Design Factors

To optimize the main components of reactive powder concrete (RPC) for various curing methods, based on the fluidity and compressive strength, an inclusive experimental research is conducted on 58 different mixture ratios. The results indicate that owing to the increase of the cement strength, the RPC fluidity decreases and the cement strength is not proportional to the compressive strength. The addition of the fly ash and the nano-microbead is an effective way to improve the fluidity, and it is required at the low W/B ratio. However, the influence of the SF grade on the strength and fluidity is almost negligible. By considering the fluidity, strength, and economy of RPC as crucial design factors, SF90 is suggested. The contribution of the steel fiber to the compressive strength cannot be ignored. The upper envelope value of the steel fibers is required for the structure to resist appropriately against the fire. According to the test results, the mixture ratio formula is proposed through considering the characters of different compositions and curing methods. The strength coefficient k1 is introduced to verify the influence of the steel fiber content, and the parameters fb, αa, and αb in the formula are reevaluated. A reasonably good agreement between the calculated strength and those obtained from the tests is reported, except for the case of W/B = 0.16 with P.O.52.5 cement. The basic steps for preparations of different RPC strengths are given, which provide a valuable reference to choose appropriate raw materials and mixture ratio design for different strength values.

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