Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Reactive powder concrete


Experimental Research on Tension Lap Splice in Reactive Powder Concrete Beams Exposed to Repeated Loading

Q.A-M. Hassan; H.M. AlHassani; F.F. Saleem

Engineering and Technology Journal, 2017, Volume 35, Issue 5, Pages 479-484

This research is a part of an experimental study to examine the effect of lap splicing tension steel bars reactive powder concrete (RPC) beams under repeated loads. Eight RPCbeams whose tension steel bars were spliced at mid-span for a length equals 20 times the bar diameter and one RPC beam without lap splice were casted and tested. These beams were simply supported and tested up to failure under the action of two point repeated loads. The studied parameters were: the steel fiber volumetric ratio (1.5%,1.75% and2%), diameter of tension steel bars (12mm, 16mm and 20mm) and the repeated loading regime in which three types of loading were used depending on the minimum to maximum ratio of the applied load. The first loading regime with ratio of 0% with 0 kN for the minimum load while the maximum was the load beyond that causes yielding of steel bars and this is determined from the previous monotonic load test. The second type with 27% ratio (30 kN for the minimum and 105-110 kN for the maximum). The last type was with 20% ratio (the minimum12 kN and the maximum 60 kN).It should be mentioned that 10mm bar diameter was used to the top reinforcement and stirrups for all beams. The mid-span deflection as well as cracks propagation were recorded for each beam throughout the test. The main results showed that the adopted spliced length of tension steel bars was sufficient in monotonic load but insufficient under the action of high number of cycles of the repeated load. In addition, there were beams of splice failure that having low steel fiber ratio or larger diameter of tension steel bars.

Behavior of Reinforced RPC Beams Strengthened by External CFRP in Flexure

Kaiss F. Sarsam; Raid I. Khalel; Falah Jarass Aied

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1537-1554

This study is an attempt to provide experimental test data for reactive powder concrete (RPC) beams strengthened by externally bonded carbon fiber reinforced polymer (CFRP) in flexure.
The mixing procedure used in this work presents a successful wayto produce RPC with a (cylinder 100 x 200 mm) compressive strength exceeding 110 MPa using heat curing.
Seven singly reinforced RPC beams were investigated, one was the control beam (no CFRP was applied) and six were externally strengthened by CFRP. All beams were of the same cross section, length, internal reinforcement, and of the same concrete mix design and were cured in the same way. The experimental variables considered in the test program include, number of CFRP strip layers (1 layer or 2 layers) and the width of CFRP strip, with and without using external anchorages. The experimental results showed that the ultimate loads are increased up to 64.29 % for the beams strengthened with bonded CFRP sheets and external anchorage with respect to the unstrengthened reinforced concrete beam (control beam). Also, these strengthened beams showed an increase in the first cracking load up to 100 %.On the other hand, there is a lower deflection at corresponding loads than the unstrengthened reinforced concrete beam.

Prediction of the Nominal Bending Moment Capacity for Plain and Singly Reinforced Rectangular RPC Beam Sections

Hisham M. Al-Hassani; Wasan I. Khalil; Lubna S. Danha

Engineering and Technology Journal, 2015, Volume 33, Issue 5, Pages 1113-1130

A new generation of Ultra High Performance Concrete (UHPC) named Reactive Powder Concrete (RPC) was developed in the last decades, which offers, superior strength, durability and ductility. One of the main differences between other concretes and RPC is that the latter requires mechanical models capable of taking tensile behavior into account for structural application to enable the material to be fully exploited. The complete stress-strain relationship under direct tensile test and uniaxial compressionof differentRPC mixes was experimentally investigated. Nonlinear equations are suggested to model the complete tensile and compressive stress-strain relationship for all the RPC mixes studied. In this research an analytical study is devoted to establish a simple equation for predicting the nominal bending moment capacity Mn of plain and singly reinforced rectangular RPC beam sections. The equation derived showed good agreement with all the flexural test results performed in previous researches and some other investigations on reactive powder concrete beams.

Experimental Study of Reactive Powder Reinforced Concrete Beams Strengthened with CFRP for Critical Shear Zones

Alaa M. Al-Habbobi; Shakir .A. Al-Mishhadani; Kaiss F. Sarsam

Engineering and Technology Journal, 2015, Volume 33, Issue 1, Pages 1-11

The behavior and shear strength characteristics of eight SFRHSC beams strengthened with CFRP strips subjected to combined bending and shear are studied in the present research (in addition to a 9th control beam without CFRP strengthening). The studied variables were shear span to effective depth ratio (a/d) and the deep beam effect, the effect of end anchorage of the CFRP strips with the beams, and effect of the amount of wrapping (width and spacing of the CFRP strips).Tests show that the presence of end anchorage for the strips increases the shear capacity of the beams by 12%for beams with the same properties regardless to the compressive strength.

Mechanical Properties of Reactive Powder Concrete (RPC) with Various Steel Fiber and Silica Fume Contents

Lubna S. Danha; Wasan Ismail Khalil; Hisham M. Al-Hassani

Engineering and Technology Journal, 2013, Volume 31, Issue 16, Pages 3090-3108

An experimental work was carried out to investigate some mechanical properties
of Reactive Powder Concrete (RPC) which are particularly required as input data for
structural design. These properties include compressive strength, tensile strength
(direct, splitting and flexural), flexural toughness, load-deflection capacity and static
modulus of elasticity. The effects of three variable parameters on these properties were
carefully studied which are, the silica fume content SF (0%, 10%, 15%, 20%, 25%, and
30%) as a partial replacement by weight of cement, hooked macro steel fibers volume
fraction Vf (0%, 1%, 2% and 3%) and superplasticizertype(Sikament®-163N and
PC200).The diameter of the steel fiber is 0.5mm and its length is 30mm with aspect
ratio 60.The experimental results showed that as the silica fume content (SF) increases
from 0% to 30% the compressive strength significantly increases, while the increase in
tensile strength is relatively lower. The inclusion of steel fibers leads to a considerable
increase intensile strength, while the addition of steel fibers causes a slight increase in
compressive strength of RPC as fiber volume fraction increases from 0% to 3%.The
increase in the steel fibers volume fraction and silica fume content improved the loaddeflection
behavior and consequently gave higher ductility and fracture toughness of
RPC.

Nonlinear Finite Element Analysis of RPC Beams Failing in Shear

Kaiss F. Sarsam; Ihsan A.S. Al-Shaarbaf; Maha M. S. Ridha

Engineering and Technology Journal, 2011, Volume 29, Issue 11, Pages 2175-2188

Reactive powder concrete (RPC) is a new type of ultra-high strength and high ductility concrete first developed in the 1990's in France. It is recognized as a revolutionary material that provides a combination of ductility, durability, and high strength. In this research work the nonlinear f ini t e element investigation on the behavior of RPC
beams is presented. This investigation is carried out in order to get a better understanding of their behavior throughout the entire loading history. Also, a numerical parametric study was carried out on the RPC beams to investigate the influence of fibrous concrete compressive strength ( ) cf f ¢ , tensile reinforcement ratio ( ) w r , fiber content ( Vf ) and shear span to effective depth ratio (a/d) on the shear behavior and ultimate load capacity of these beams.
The three- dimensional 20-node brick elements are used to model the concrete, while the reinforcing bars are modeled as axial members embedded within the concrete brick elements. The compressive behavior of concrete is simulated by an elastic-plastic work-hardening model followed by a perfectly plastic response, which terminated at the onset of crushing. In tension, a fixed smeared crack model has been
used.

A Proposed Equation for the Evaluation of the Nominal Ultimate Bending Moment Capacity of Rectangular Singly Reinforced RPC Sections

Suaad Kh. Ibraheem; Hisham M. Al Hassani

Engineering and Technology Journal, 2011, Volume 29, Issue 5, Pages 925-934

Based on compressive stress – compressive strain curves of Reactive Powder
Concrete (RPC) which have been established recently in a Ph.D thesis(1), an
equivalent bi-linear compressive stress block for RPC sections under pure
bending moment is proposed and used to derive an equation for calculating the
nominal ultimate bending moment capacity (Mn) of rectangular singly reinforced
RPC sections. The accuracy of the derived equation of Mn is examined by
comparison with the results of existing experimental tests.