Behavior Of Reactive Powder Concrete Research Articles

Effects of high temperatures on the behavior of reactive powder concrete based on recycled brick powder

Effects of high temperatures on the behavior of reactive powder concrete based on recycled brick powder

Behavior of Reactive Powder Concrete reinforced with Hybrid Fibers containing Sustainable Materials

Behavior of Reactive Powder Concrete reinforced with Hybrid Fibers containing Sustainable Materials

Performing laboratory study of the behavior of reactive powder concrete on the shear of RC deep beams by the drilling core test

Abstract In the past decade, it has been observed that the applications of modern materials have developed a lot, especially effective reactive powder concrete (RPC), due to its superior performance properties. As a result of the superior resistance of RPC, it will give a longer construction life with less maintenance and more resistance to various environmental conditions and exhibits high-performance features such as high porosity, very high strength, and excellent corrosion resistance. The parameters studied in the present research were used to investigate the effect of maximum load, deflection, tensile and strain of concrete, first shear crack, crack pattern, and crack width. Considering the aforesaid cause and objective, one specimen of RPC RC deep beams has a rectangular cross-section of 150 mm in width, 500 mm in depth, and a total length of 1.2 m. One control specimen was tested for comparison. Moreover, 12 control specimens including cylinders and cubes were cast and tested to obtain the mechanical properties of the normal and RPC deep beams. Following the specimens’ processing, they were subjected to two concentrated load pressure tests through a hydraulic jack. Based on the results, the ultimate strength, deflection, and first shear crack capacity for the reactive powder concrete deep beam (RPCDB) have increased by 68, 10.5, and 62.5%, respectively, compared with concrete deep beam (CDB). Moreover, with respect to the width, the delay in the appearance of the first shear crack was reduced by 11 and 78%, respectively, compared with CDB at 65% of the final shear load. In addition, regarding the stress-strain results, RPCDB has increased by 118% at the maximum stress compared with CDB and in contrast, the strain scores for CDB increased by 22.5% at maximum stress compared to RPCDB.

Nonlinear-finite-element analysis of reactive powder concrete columns subjected to eccentric compressive load

AbstractStudies on the behavior of reactive powder concrete (RPC) columns under eccentric loading are limited. The effect of materials used in manufacturing these RPC columns has not yet been investigated. This research aimed to perform a nonlinear-finite-element analysis to determine the load-carrying capacity and displacement of RPC columns made of different RPC mixes and subjected to various loading eccentricities. This research investigates two types of parameters. The first parameter is the column’s geometric parameters (the heightLand the load eccentricity distancee). The second is the RPC material parameter (regarding the silica fume or fly ash used as pozzolanic material and the type of fibers used, whether steel or glass fiber). Results indicate that eccentric-loaded slender columns exhibit much less load-carrying capacity than the corresponding short columns. The 2 m-long columns with eccentricity ratioe/t= 0.2 resulted in a 65% average reduction in the ultimate load (Pu) compared to the corresponding 1 m-long columns. Using fly ash as a pozzolanic material instead of silica fume reduces the ultimate load (Pu) of an RPC column by an average of 60%. Using glass fibers instead of steel fibers also reduced Pu by 50%. The average percentage increase in the maximum vertical deflection (Δymax) of the short column (L= 1 m) is found in the range of 18–31% for eccentricity ratioe/t= 0.1 but 45–69% fore/t= 0.2. In contrast, for a slender column (L= 2 m), the percentage increase in Δymaxis in the range of 10–30% for bothe/t= 0.1 and 0.2.

Structural Behavior of Reactive Powder Concrete under Harmonic Loading

Industrial buildings usually are designed to sustain several types of load systems, such as dead, live, and dynamic loads (especially the harmonic load produced by rotary motors). In general, these buildings require high-strength structural elements to carry the applied loads. Moreover, Reactive Powder Concrete (RPC) has been used for this purpose because of its excellent mechanical strength and endurance. Therefore, this study provides an experimental analysis of the structural behaviors of reinforced RPC beams under harmonic loads. The experimental program consisted of testing six simply supported RPC beams with lengths of 1500 mm, widths of 150 mm, and thicknesses of 200 mm under harmonic loading with varied frequencies between 10 and 20 Hz. Different steel fiber ratios of 0%, 0.5%, 0.75%, 1.0%, 1.5%, and 1.75% were provided in the concrete mixes to explore the effect of steel fibers on the dynamic behavior of these beams. Except for the steel fiber volume fraction, all of the examined specimens shared the same material attributes and reinforcing details. The outcomes proved the positive effect of adding steel fibers on the dynamic response under the effect of harmonic loading. The optimum volume fraction of steel fibers was characterized by a percentage of 1.5%. Moreover, the vibration amplitude was more affected by the steel fibers than the support reactions. The inertial force increased as the harmonic loading duration increased. This increase in the inertial force by the load duration was enhanced after adding the steel fibers. However, this enhancement started to decline after increasing the steel fiber content to 1.75%.

Compression behavior of reactive powder concrete confined with high‐strength spiral stirrups

AbstractThe lateral confinement of stirrups can improve the load‐bearing capacity and ductility of reactive powder concrete (RPC) columns. To explore the compression behavior of RPC confined with high‐strength stirrups, 45 specimens were prepared and tested under axial compression. The concrete strength was in the range of 99.86–138.24 MPa, the tensile strength of stirrups was Grade 800, Grade 970, and Grade 1270, and the volumetric ratios of stirrups were in the range of 0.9%–2.0%. The results showed that the failure modes of RPC confined with stirrups were shear expansion failure. The compressive strength and ductility of confined RPC were improved with the increase of stirrups volumetric ratios, while stirrups strength slightly affected the compressive strength and ductility. In addition, the peak stress, peak strain, and residual stress prediction models were proposed. Furthermore, the ductility index prediction models were proposed, which can be applied to determine the volumetric ratio of stirrups in stirrups confined concrete columns.

Experiment study on reactive powder concrete beams using spirals reinforcement under torsion

This paper investigates the torsional behavior of reactive powder concrete (RPC) beams using spiral reinforcement. The influences of parameters, including different spiral reinforcement configuration, spiral reinforcement ratio, and the steel fiber content on the torsional performance of the nine RPC beams, were investigated and discussed. The experimental results showed that the failure mode, ultimate torque, torsional stiffness, and energy dissipation of the RPC beams were not affected by longitudinal reinforcement alone, but it improved the ductility. Compared to commonly used stirrups, the locked spiral reinforcement exhibits more torsional ductility, stiffness, and ultimate torque of the RPC beams. But the torsional ductility, stiffness, and ultimate torque decreased when the spiral reinforcement was unlocked. The cracking torque and pre-cracking torsional stiffness of beams were less affected by the locking and unlocking of spiral reinforcement. Greater steel fiber content and spiral reinforcement ratio resulted in higher torsional ductility, torsional stiffness, energy dissipation and ultimate torque of the locked spiral reinforcement reinforced beams. The pre-yielding torsional stiffness and plastic dissipation capacity were strongly influenced by spiral reinforcement states and spiral reinforcement ratio. The pre-cracking torsional stiffness and energy dissipation of RPC beam were determined by the steel fiber content. Considering the torsional contribution of steel fiber and concrete tensile strength, a new formula for calculating the ultimate torque of RPC beam was proposed, and the calculated value was closer to the experimental value.

Experimental investigation on flexural strength behaviour of reactive powder concrete

The performance of a composite conventional beam and a reactive powder concrete beam with various forms of reinforcement, such as PVC tubes, stainless steel tubes, and normal reinforcement, is compared in this project through an experimental comparison. In this study, experimental research on four specimens of conventional concrete beams and four specimens of reactive powder concrete beams was conducted using the two point loading test method, and mechanical properties such as flexural strength of composite beams were tested for M20 grade of conventional concrete beams and reactive powder concrete beams. The flexural strength of reactive powder concrete beams combined with conventional composite beams. Comparing the composite Reactive powder concrete beam with normal reinforcement to the composite concrete beam with normal reinforcement, the flexural strength is enhanced by 8.78%. Comparing the composite Reactive powder concrete beam with stainless steel reinforcement to the composite concrete beam with stainless steel reinforcement, the flexural strength is increased by 7.58%. When compared to composite concrete with PVC reinforcement, the composite Reactive powder concrete beam has a 5.6% higher flexural strength.

Performance of polypropelene and polyester fibres-reinforced reactive powder concretes at elevated temperatures

Reactive Powder Concrete (RPC) is an emerging class of special concrete that falls under the category of ultra-high-performance concrete. RPC offers very superior mechanical properties as compared to conventional concretes. The application of RPC is limited to some of the restricted applications such as, construction of nuclear power plants, precast bridges and girders. The generalized application of RPC is restricted due to the unknown behavior of RPC, when it is exposed to fire load. The dense and fine microstructure of RPC is prone to spalling under elevated temperatures. To combat spalling, RPC is produced with suitable fibres. In this study RPC is prepared with addition of polypropelene and polyester fibres with different fibre dosages like 0.1, 0.5 and 0.9% by weight of cement. The residual mechanical and durability properties of fibre-based RPC are evaluated at elevated temperatures ranging from 200 to 800 °C. Results indicate that the combined effect of polypropelene and polyester fibre-based RPC, possess good spalling resistance with 0.1% fibre content. Fibre dosage of 0.5% has shown superior residual mechanical and durability properties of RPC at elevated temperatures. Formation of pores, cracks and evaporation of fibres due to elevated temperatures is also investigated based on microstructure examination for all RPC mixes.

Mechanical properties of ultra-high performance concrete based on reactive powder concrete: Effect of sand-to-cement ratio, adding glass fiber and calcium carbonate

Reactive Powder Concrete (RPC) contains high amounts of cement. This high ratio increases causing issues such as a high hydration temperature and concrete shrinkage. The present investigation is an attempt to study the effect of Sand-Cement ratio, substitution of calcium carbonate with part of Silica sand and adding glass fiber, on the properties of RPC. The study also deals with the microstructure investigation and Thermo-Gravimetric Analysis of RPC. Results indicate that increasing the S/C ratio up to 1.2 can improved the properties of RPC by reducing the amount of cement used. On the other hand, substitution 40%-50% of the silica sand with calcium carbonate can improved the microstructure of RPC. Moreover, the tensile behavior of RPC must be improved using another material due to the limit on the largest grain size in it. Adding glass fibers equivalent to 8%-10% of the cement weight to the mix design of RPC (containing 40%-50% silica sand that was replaced with calcium carbonate) improves the mechanical and durability behavior of RPC.

Seismic behavior of reactive powder concrete (RPC) interior beam–to-column joints under reversed cyclic loading

Not all precast concrete structures show performance that can be obtained by experiment. Finite element analysis also plays a vital role in the study of structural performance. In this paper, a steel hysteretic is employed to reproduce the experimental response of a steel strand anchored precast concrete frame joints exposed to reversed cyclic load tests. The ultimate load and ultimate displacement obtained by finite element calculation are not more than 1% different from the experimental values. By employing the proposed model, the hysteretic curve, energy dissipation capacity, stiffness degradation, and displacement ductility of the reactive powder concrete (RPC) interior beam–column joints were analyzed. According to the analysis, in the case of the failure morphology of RPC beam-to-column joints with friction dampers, it is evident that the plastic hinge at the end of beam had shifted outward. In addition, both the energy dissipation capacity and the ultimate bearing capacity of the RPC interior beam–column joints have been improved, the ultimate load of PC2 is 28.8% higher than that of PC1. According to the aforementioned results, the parametric analysis of the RPC interior beam–column joint was performed. Subsequently, by varying the friction coefficient of the friction damper, the stirrup spacing in the panel zone and the different axial compression ratios, the influence of a number of different parameters on the mechanical properties of the joint was obtained.

The Influence of Hybrid Fibers and Nanomaterials (Nano Glass with Nano Slag) on the Behavior of Reactive Powder Concrete

The new production ofReactive Powder Concrete (RPC) has become an interesting topic due to the dramatic properties that such materials can give. Thus, this study has been prepared to observe the properties of RPC mixes reinforced with micro steel fibers (MSF) by the order of 2% volumetric fractions (vol.). As well, hybrid fibers from MSF, sisal fiber (SIF), and also human hair fibers (HHF) have been included in the RPC mix in the order of 1.5% MSF plus 0.5% SIF, 1.5% MSF plus 0.5% HHF, and 1.5% MSF plus 0.25% SIF plus 0.25% HHF, respectively. Besides, the inclusion of two different nanomaterials combination by 2.5% Nano glass powder (NG) and 2.5% Nano Iron slag powder (NS) was performed into that reinforced RPC. The preparation of these different RPC mixes was followed by testing them to investigate the performance of such RPC based on the properties of flowability, compressive strength, tensile strength, flexural strength, flexural toughness, and static modulus of elasticity. The results showed that the incorporation of 2%MSF increases the compressive strength, tensile strength, and flexural strength by 6.76%, 12.45%, and 14.34%, respectively, at 90 days. Whereas, the reinforcing of RPC by 1.5% micro steel fibers (MSF) with 0.25% sisal fibers (SIF) and 0.25% human hair fibers (HHF) rises the values of compressive strength, tensile strength, and flexural strength by 5.38%, 11.59%, and 14.05%, respectively, at age of 90 days. Moreover, the uses of nanoparticles as 2.5%NG with 2.5%NS in addition to 2%MSF increase the compressive strength, tensile strength, and flexural strength by 33.09%, 36.05%, and 43.68% at age of 90 days, respectively. The use of 1.5% MSF plus 0.25% SIF plus 0.25% HHF with the mentioned nanoparticles (2.5%NG and 2.5% NS) boosts the best performance by converting such concrete from brittle material to ductile material.

Behavior of reactive powder concrete containing recycled glass powder reinforced by steel fiber

AbstractEnvironmental sustainability is described as one that avoids the depletion or deterioration of natural resources, while also allowing for the preservation of long-term environmental quality. By practicing environmental sustainability, we may assist to guarantee that the requirements of today’s population are satisfied without risking the capacity of future generations to meet their own needs in the future. Engineers in the field of concrete production are becoming increasingly interested in sustainable development, which includes the utilization of the locally available materials in addition to using the agricultural and industrial waste in construction industry as one of the possible solutions to the environmental and economic issues. This study investigated the effect of partial substitution of cement with recycled glass powder (0, 15, 20, and 25%) by weight of cement at various ages (on compressive strength) after determining the optimal ratio of replacement. This optimal ratio is used to study its effect on some mechanical properties (such as flexural strength, absorption, and dry density) of reactive powder concrete containing 1% micro steel fiber (SRPC), and furthermore, utilizing steam curing for 5 h at 90°C after hardening the sample directly. Reactive powder concrete (RPC) has been designed with the use of the local cement, silica fume, and super plasticizer with a water/cement ratio of 0.20 in order to achieve a compressive strength of 137.09 MPa at the age of 28 days. When recycled glass powder replacement (20%) was utilized, the findings revealed that the compressive strength of RPC improved by 4.2%, the flexural strength increased by 15.3%, the dry density increased by 0.61%, and the absorption was reduced by 32% at 28 days after the test results were compared to the reference mix.

Entropy based model for the creep behavior of reactive powder concrete at high temperature

Creep of concrete has certain impact on its mechanical properties and can seriously affect the structural safety. At high-temperature or under fire attack, the basic creep strain develops rapidly in a few hours in concrete and cannot be ignored. In the current study, a new entropy based basic creep model for concrete at high-temperature is proposed based on the thermodynamic principle and entropy increasing theory. The relationship between entropy increase rate and time is developed. The influence of key engineering parameters for basic creep of concrete at different temperatures is investigated. Predictions of the developed model are compared with the experimental data and show good accuracy.

Stress-Strain Characteristics of Reactive Powder Concrete Under Cyclic Loading

Reactive powder concrete (RPC) is a type of ultra-high strength cement composite material. It has advanced mechanical properties and shows high ductility characteristics. Many researches have shown that normal and high strength concrete fails under cyclic stresses at load level below its static capacity. In the present study, the mix design guidelines to produce high strength RPC is provided. RPC with compressive strength of 120, 130 and 140MPa was produced. The mechanical properties are obtained for hardened concrete. The present study focuses on the investigation of reactive powder concrete under uniaxial compressive cyclic loading. The investigation was carried out on cubical and cylindrical specimens. The behaviour of RPC under cylic loads is studied by obtaining the stress-strain characteristics under monotonic loading and cyclic loading. Three main types of tests were performed. Stress-strain envelope curve, common point curve and stability point curves were established under repeated load cycles. The limiting stress values required for design are provided. It was concluded that peak stress of the stability point curve could be regarded as the maximum permissible stress. A nonlinear analytical expression was proposed for the normalised stresses and strain which shows a precise fit with the experimental data. The expression will assist in predicting the cyclic response of concrete required for constructional applications.

Mechanical Behavior of Reactive Powder Concrete Subjected to Biaxial Loading

To investigate the biaxial mechanical characteristics of reactive powder concrete (RPC), RPC plate specimens and bone‐shaped specimens were tested under compression‐compression and compression‐tension loadings, respectively. The strengths and strains of the specimens were recorded, and the crack patterns and failure modes in various stress states were examined. Based on the test data, the characteristics of biaxial strength were analyzed, and a biaxial failure criterion was established. The characteristics of major stress‐strain curves and failure modes in different biaxial stress states were determined. The results show that the ratio between the biaxial compression strength and the uniaxial compression strength was 1.44–1.58 for RPC. When the stress ratio under compression‐tension was −0.05, the tensile strength decreased by 48%. Under compression‐compression, the proportional limit of RPC was about 95%, and its peak strain was high. Under compression‐tension, as the compressive stress increased, the elastic modulus decreased, and the peak strain in the tensile direction increased. When the RPC specimens were under compression‐compression, the failure mode of RPC was splitting failure. Under compression‐tension, the failure mode changed from single‐crack tensile failure to multicrack compressive failure with increasing confining stress.

Effect of production technology on high strain rate characteristics of Reactive Powder Concrete

This paper presents an experimental study evaluating the effect of mixing technology and curing conditions on the high strain rate compressive behavior of Reactive Powder Concrete (RPC). Nine sets of specimens were prepared with identical composition, based on Aalborg Portland cement 52.5 R, fine sand, silica fume, micronized quartz, superplasticizer and water. Three different production methods were tested: 1) mixing under ambient pressure+ standard moulding without additional pressure, 2) vacuum mixing+ standard moulding without additional pressure, 3) mixing under ambient pressure+ moulding with subsequent 5 MPa pressure during the setting time. Three curing conditions were adopted: 1) Curing in water at an ambient temperature, 2) Curing under hydrothermal conditions at 190°C for 40 hours, 3) Curing under hydrothermal conditions at 180°C for 8 hours, Quasi-static compressive and flexural strength tests were performed and bulk density was determined. Split Hopkinson pressure bar (SHPB) equipment was used to determine the RPC behaviour at high strain rates. It was observed that vacuum mixing reduces the pore content in the composite, which is accompanied by a significant increase in peak stress values of water cured RPC at both quasistatic and high strain rate regimes (about 20% increase). Further increase in peak stress values is then achieved by hydrothermal treatment, with higher values connected with higher temperature and dwell time. The pressure developed at the first stage of the curing period does not provide a significant benefit in the form of an increase in mechanical parameters. The presented research is a part of the development process of high-performance ballistic resistant composites. The results will be used for the design of the composite panels for protection against ballistic load in the A2-A4 level according to STANAG 2280 standard.

Utilization of granite powder and glass powder in reactive powder concrete: assessment of strength and long-term durability properties

This paper aims to assess the mechanical and long-term durability performance of reactive powder concrete (RPC) containing granite powder (GrP) as cement replacement and waste glass powder (GP) as quartz sand replacement. The workability and mechanical behaviour of RPC containing various proportions of GrP and GP are assessed for different water/binder (w/b) ratios (0.3, 0.35, 0.4, and 0.45). The water resistance and tightness of RPC are measured by monitoring the electrical resistivity, water absorption, sorptivity, and chloride migration over a one-year period. Results reveal that substitution of GrP and GP at optimum levels of 15% and 30% respectively enhances the performance of RPC with the achievement of satisfiable workability at a 0.35 w/b ratio. A significant increase in the resistance towards chloride penetration and electrical resistivity was also observed with increasing ages. Thus, glass powder and granite powder can be considered as alternative construction materials providing economical and ecological efficiency.

Study of the Influence of the Aggressive Environment on the Behavior of Reactive Powder Concrete

Reactive Powder Concrete (RPC) currently represents the family of cementitious matrix materials with properties the most exceptional mechanics and durability. This study aims to investigate the physico-mechanical properties, and the durability in a sulphated environment of a reactive powder concrete using materials available in our region, we have integrated materials rich in silica (slag, silica fume and crushed quartz) in Portland cement with 15, 23 and 25%, respectively. After The remove of the specimens from the mold and place the RPC in the curing box under steam curing conditions of 90 ° C for 72h, let them cool naturally for 24 h, the test pieces are immersed in water at 20 ° C, the specimens are broken in flexion and compression. From this study we can make the following conclusions: The incorporation of additions increases the compressive and flexural tensile strengths, which gives an improvement in the compactness of the mixtures by the pozzolanic effect of these last, by removing the particle size phase in the RPC and the affluence of dune sand (southern Algeria) and slag (industrial waste from the iron ore blast furnace), because Na2SO4 has a major effect on the compressive strength notably for non-fibrous formulations. NaOH improve the compressive strength for all formulation.

The mechanical behavior of RPC under combined shear and compressive loads

In this study, the shear behavior of reactive powder concrete (RPC) in terms of shear strength and shear slip was studied by direct shear tests on cubic specimens and the influences of water-binder ratio, steel fiber volume ratio and normal compressive stress ratio were investigated. The test results indicated that using a low water-binder ratio and a reasonable fiber content could enhance the shear strength of RPC specimens. The RPC specimen containing steel fiber will not be severed into two individual parts due to the connection of steel fiber. Moreover, the normal stress was the key contribution to the shear strength, and the residual shear capacity was mainly provided by the friction of the shear surface. The cracking of the specimens became more severe but the shear strength in the cyclic horizontal test did not decrease obviously compared with that in the monotonic horizontal test. Applying the twin-shear unified strength theory to the test data, it was indicated that the elliptic curve showed a good agreement. Therefore, the unified twin shear strength theory could predict the proper RPC strength envelope curve under combined compressive-shear stress states.