Reactive Powder Concrete Mixes Research Articles

Experimental Study on The Effect of Size, Type, and Replacement Ratio of Recycled Aggregate on The Mechanical Properties of Reactive Powder Concrete

This paper presents an experimental investigation of the mechanical characteristics of Reactive Powder Concrete (RPC) and Recycled Aggregate Reactive Powder Concrete (RPC-RA), utilizing two types of recycled aggregate (RA), recycled concrete aggregate (RCA), and recycled concrete brick aggregate (RCBA) as alternative aggregates. A series of sixteen RPC and RPC-RA mixes were prepared and tested. A reference RPC mix without RA was tested to determine the maximum compressive strength of 128.17 MPa, the tensile strength of 15.56 MPa, and the flexural strength of 25.90 MPa. Then, the study examines twelve different mixes of RPC-RA, each with RCA with maximum particle sizes of 0.6, 1.18, 2.36, and 4.75 mm and replacement ratios of 20%, 40%, and 60%, to study the effects of varying replacement ratios of the RCA and various maximum particle sizes. Additionally, three mixes of RPC-RA are investigated using RCBA with a maximum particle size of 0.6 mm and replacement ratios of 20%, 40%, and 60%. The use of RA resulted in various percentages of reduction in compressive, splitting, and flexural strength, as shown in the results of the study.

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.

Determination of Optimized Mix Design of Reactive Powder Concrete

There are different types of reactive powder concrete (RPC) and researchers continue to develop better-quality mix designs. This research presents an integrated approach for RPC mix design. For this purpose, 13 RPC mix designs were collected according to expert opinion and laboratory samples and were tested in this study for validation of the characteristics of compressive strength and water absorption. The samples were then ranked using the simple additive weighting (SAW) method, and three highest-quality RPCs were selected for the Taguchi method. These RPCs were used to prepare 27 experimental RPC mix designs applying the Taguchi method. From the experimental results, compressive strength with 0.38–0.76% and water absorption with 0.50–0.99% differences were more appropriate in compliance with the collected data. Also, results from the 27 mix designs investigated by the Taguchi method revealed the optimized mix design for the maximum compressive strength with 146.7 MPa and the optimized mix design for the minimum water absorption with 0.89%. The results showed that our approach was consistent with the results of classic methods that require a large number of samples. This suggests that integrating the SAW and Taguchi methods is an appropriate approach for screening and optimizing RPC mix design.

Elevated Temperatures Impact on the Mechanical Behavior of Reactive Powder Concrete Containing Hybrid Fibers

Reactive Powder Concrete (RPC) is a combined material that will allow the concrete industry to enhance material consumption, produce economic benefits, be more durable, and be more environmentally friendly. Due to the highly dense microstructure of RPC, it performs poorly at high temperatures due to the formation of high pore pressure, which causes material breakdown. This paper demonstrates the outcomes of an investigational study of the behavior of six RPC mixes incorporating hybrid steel and plastic waste (polypropylene) fibers after being subjected to high temperatures of up to 500 ºC. Residual compressive strength, residual splitting strength, and density were performed for all the RPC mixes. The results demonstrate that the drop in the compressive strength of RPC is greater than the reduction in their corresponding splitting strength. Furthermore, within a temperature range of about 500 ºC, this mechanical strength showed a noticeable decrease. The decrement of splitting strength ranged between about 8% to 33% . Steel and polypropylene fibers also improve the residual strength of RPC samples. On the basis of these results, a mix containing mixed fibers (25 % steel and 75 % polypropylene) is recommended as appropriate for extreme temperature applications.

Recent advances in the heating resistance, thermal gravimetric analysis, and microstructure of green concrete incorporating palm-leaf and cotton-stalk nanoparticles

Environmental pollution reduction is becoming increasingly crucial, especially in concrete production. In this regard, green concrete (GC) may help reduce the environmental impact of cement concrete by replacing ordinary Portland cement (OPC) with waste agricultural cotton stalk and palm leaf nanoparticles (NC and NP) or reusing crushed granite (G) as coarse aggregate. Nine green concrete mixes containing total binder material (B.M = 436 km/m3) were created by using OPC alone (MO) or partially substituting with 9% silica-fume alone (MSF) or with various percentages (2%, 3%, and 5%) of NC (MC2, MC3, and MC5) or NP (MP2, MP3, and MP5) or with (3% NC + 3% NP) (MC3P3). Also, the outcomes of the two reactive powder concrete (RPC) mixes (MRC3 and MRP3) incorporating 1090 km/m3 of B.M with 3% NC and 3% NP were compared with the previous GC mixes. Experiments on the compressive, splitting tensile, and water permeability of the used mixes were conducted. Temperatures of up to 800 °C were also an issue. Thermal gravimetric analysis (TGA) and scanning electron microscopy of the specimens were performed, and the results were studied. This research reveals that adding NC and NP to GC improves the mechanical properties and durability. Therefore, using crushed granite and agricultural waste nanoparticles to make eco-friendly, high-strength GC mixes is technically and ecologically feasible. The mechanical properties and durability of green mixes specially (MC3P3, MC5 and MP5) are better than those of RPC mixes. Furthermore, the specimens fractured when subjected to 800 °C and water pressure. Finally, the MC3P3 blend has the best mechanical qualities and heat resistance up to 400 °C. MC3 has nearly the same mechanical and thermal qualities as the MC3P3 and MC5 mixes, but it is the most potent up to 800 °C. The TGA of MC3 is better at all temperatures up to 1000 °C.

Development of fibre-reinforced concrete mix for manufacturing non-prestressed concrete sleepers

In this paper, an optimal ultra-high performance fibre-reinforced concrete (UHP-FRC), which is also known as reactive powder concrete (RPC), with high flexural strength was developed to satisfy the demands for manufacturing non-prestressed concrete sleepers. First, a preliminary analysis is performed to estimate the maximum flexural stresses developed within sleepers with typical dimensions under typical train axle loads of 25 and 40 tonnes. After determining the required flexural strength, the optimum mix proportions of the RPC is obtained using the Taguchi method. The effects of four important parameters, i.e., silica fume to cement ratio (SF/C), sand to cement ratio (Sand/C), superplasticizer to cement ratio (SP/C), and water to binder ratio (W/Binder) are investigated. It is found that an optimum RPC mix with maximum flexural strength can be developed using the SF/C ratio of 0.3, Sand/C ratio of 1.2, SP/C ratio of 0.4, and W/B of 0.2. Subsequently, it is proved that the UHP-FRC with 2% of fibres (by volume) satisfies the flexural strength demand determined by the preliminary track analysis. Finally, two different configurations of the non-prestressed concrete sleepers are proposed for two different target tonne axle loads (TALs), 25 TAL and 40 TAL.

Mechanical Behavior of Modified Reactive Powder Concrete with Waste Materials Powder Replacement

Across the world, a huge amount of waste materials is deposited from different industrial or construction activities. Out of this massive waste quantity, a petite is recycled and remaining is dumped in vulnerable lands. This paper deals with the potential utilization of solid waste in reactive powder concrete, practically powdered glass originating from waste glass bottles and powdered ceramics tile from waste of construction process. First, the optimum ratio of waste pozzolanic material (ceramics to glass ratio) was obtained by pozzolinic activity test. Then, the optimal waste pozzolanic material was incorporated in reactive powder concrete at several substitution levels. The waste pozzolanic material in 5 %, 10 %, 15 %, 20 %, and 25 % were added in the reactive powder concrete mixes as fractional supplement of silica fume. Strength and water absorption of the modified reactive powder concrete were evaluated. A significant enhancement was observed in mechanical behavior of modified reactive powder concrete containing 15 % waste pozzolanic material. Results directed irrelevant raise in water absorption as increasing the waste replacement material.

The effects of using magnetized water in reactive powder concrete with different curing methods

The effects of using magnetized water in reactive powder concrete (RPC) under various curing procedures was investigated. The RPC samples were separated into four groups, cured with three different curing methods compared to normal curing (lab conditions) as a reference procedure, these methods were; autogenous curing, submersion in warm water (35 °C) and curing by applying high temperature (70 °C) cycles. A magnetic water device was used to produce magnetic water for use in the RPC mix. Where, the intended water was moving with flow rate equal to 0.1 m3/hr. passing through a magnetic field with an intensity of 0.9 Tesla. This circulation process was used for 60 minutes to produce the magnetized water utilised in this study. Test results showed some improvements in the compressive, flexural and splitting tensile strength for RPCs cured with different curing methods The percentage increases for compressive strength for RPC mixes containing magnetic water. Where, the enhancing percentage reached 7.66, 8.43, 8.86, and 9.15% for normal curing, autogenous curing, warm-water, and high temperature curing respectively at 28 days. The high temperature curing method showed the maximum improvement in compressive strength, with up to 34.4, 30.6, and 28.52% increases at 7, 28, and 90 days, respectively.

Direct Shear Strength of RPC Member

In this research paper, results are obtained from Reactive Powder Concrete (RPC) push-off specimens - double L shape subjected to direct shear loading. Different parameters considered are compressive strength, percentages of steel fiber, presence of aggregate and shear reinforcement. The results show that increasing in steel fiber content starting from 0.0% and ending with 1.5% leads to increases in the shear strength by (261%) and attempt to decrease its brittleness. The presence of steel fiber content enhances and improves the tensile strength and the shear strength. Using RPC in constructing the specimens enhances the shear strength by 29.6% compared with NSC specimen. Shear strength increased by 25% when the compressive strength increased from 75 to 90MPa. The presence of transverse steel rebar in the direction of shear line increased the shear strength by (108.3%) as compare with the specimen without shear rebar. The presence of small aggregate in RPC mix creates an increase in the shear strength by (9.1%).

Experimental study on the effect of macro and microfibers on the mechanical properties of reactive powder concrete

AbstractDue to the outstanding mechanical properties of the reactive powder concrete (RPC), it has attracted a great deal of attention. In which, incorporating fibers can improve its behavior and properties. The main objectives of this study were to consider different mixing methods and the effect of fiber content and type on the mechanical properties of RPC. The best mix proportion was selected for the final tests among 13 initial mix designs based on the 7‐day compressive strength and flow value of the fresh concrete. Different macro and microfibers (including steel, polyvinyl alcohol, glass, carbon, and basalt fibers) with volume fractions of 0.5% and 1.5% were added to the final RPC mix by two different mixing methods, and mechanical properties such as compressive, tensile, and flexural strengths and energy absorption capability were investigated. Based on the results of experiments, the addition of 1.5% hybrid (macro and micro) steel fibers had the most positive effect on increasing the mechanical properties of RPC compared to other fibers. The hybrid fibers increased the compressive, tensile, and flexural strengths and flexural toughness of the specimens by 42.5%, 26.9%, 87.6%, and 396%, respectively. According to the results, the addition of 0.5% fibers to RPC did not significantly enhance the mechanical properties of the concrete.

A probabilistic approach to the design of reactive powder concrete mixes modified using slag

Abstract Reactive Powder Concretes (RPC) are well known for their strength, durability, and sensitivity to the environment. RPCs are composed of very fine powders such as Ordinary Portland Cement (OPC), Silica Fume (SF), Quartz Powder (QP), etc. Aiming to develop sustainable RPC, in this study, the cement used is partially replaced with Ground Granulated Blast-furnace Slag (GGBS). The replacement was done at different levels, such as 0%, 10%, 20%, 30%, and 40% of cement by mass. Further, QP is replaced with Rice Husk Ash (RHA) at three different levels, such as 0%, 50%, 100%. 2% of crimped steel fibers by volume of concrete were used to reinforce the matrix. As there are no comprehensive design approaches for Reactive Powder Concretes (RPC), many trials are required to optimize the fresh and hardened properties of mixes. The workability for different mixes was evaluated in terms of flow percentage. Hardened properties such as compressive strength and split tensile strength after 28 days of standard water curing were evaluated. Also, this paper describes a factorial design approach to the optimization of flow and maximization of compressive strength and split tensile strength of RPC mixes. It was observed that the flow was increasing with an increasing amount of GGBFS in the mix and decreasing due to the addition of RHA. It was also observed that the strength results were progressively improving up to 20% replacement of cement with GGBS and was getting deteriorated for further replacement. The full replacement of QP with RHA also helped in the betterment of strength. The numerical models developed were competent to predict and optimize the results.

Properties of slag based geopolymer reactive powder concrete

Reactive Powder Concrete (RPC) is a high strength concrete with excellent engineering properties. High cement content is one of the important key parameters in the development of RPC. Production of cement considered a non-sustainable eco-friendly process. Hence, it is needed to replace the usage of cement with environmental friendly materials in the production of RPC. Geopolymer concrete is a new technology that can totally replace the cement in concrete. The main objective of this study is to produce Geopolymer RPC and evaluate its mechanical and durability properties under different curing techniques. The engineering properties like compressive strength, sorptivity and elastic modulus are studied to investigate the performance of Geopolymer RPC. To study the concrete microstructure, SEM analysis were carried out in this investigation. It was concluded that thermal curing has shown a good impact in the performance of all RPC mixes. Geopolymer RPC can be successfully developed and hence satisfying engineering properties can be achieved under microwave curing. Also it was deduced that in Geopolymer RPC, the workability issue should be solved with parameter other than water, i.e. superplasticiczers.

Mechanical Testing of Composite Steel and Reactive Powder Concrete Structural Element.

Reactive powder concrete (RPC), typically with higher compressive strength, is particularly attractive to structural engineers to apply them in infrastructures for enhancing their resistance under severe environments and loads. The main objective of the initial study presented in the paper was to investigate the behavior of two types of these new cementitious materials differing in the nature of microfibers. The RPC mixes were reinforced with steel and then with basalt microfibers. To evaluate the structural performance of developed unconventional materials, properties were investigated experimentally and compared with the control normal concrete mix. Mechanical tests indicated that dispersing fine fibers for making RPC, a mean compressive strength of 198.3 MPa and flexural strength 52.6 MPa or 23.2 MPa, respectively, were developed after 28 days of standard curing at ambient temperatures. In composite structures consisting of steel girders and a concrete slab, it is necessary to prevent the relative slip at the steel and concrete interface using shear connectors. The very high RPC strength enabled a material saving, weight-reduced application of precast construction, and particularly effective joint to steel beams. The investigation of such shear connection efficiency, in the case of the higher strength concrete deck, using standard push-out test specimens was executed. Finite element numerical models were developed. The outputs of the studies are presented in the paper.

Performance of green RPC containing nanoparticles and reinforced with hybrid fibers used for repairing damaged concrete

Recently, there is an increased research awareness towards the use of high strength cementitious matrices like reactive powder concrete (RPC) for rehabilitation and repairing damaged structures in addition to their use in the maintenance of concrete structures. Therefore, this research has been conducted to present some RPC mixes prepared from various percentages of cement replacement, nanoparticles materials, and reinforced with three different types of fibers.The green RPC mixes were prepared with a total 30 % replacement of cement by silica fume, slag powder, and glass powder. Then, the addition of Nanoparticles combination as 2.5 % Nano glass powder (NG) plus 2.5 % Nano Iron slag powder (NS) was performed. Besides, the uses of mono micro steel fibers and hybridization of micro steel fibers (MSF), sisal fibers (SIF), and human hair fibers (HHF) were achieved. The combined systems of substrate concrete and such different green RPC mixes which were proposed here as repair materials besides epoxy were tested in bi-surface shear, oblique shear, flexural bond strength, splitting bond strength, and Pull-out.The results showed that the reinforcing of green RPC with hybrid nanoparticles (2.5 %NG + 2.5 %NS) and hybrid fibers (1.5 %MSF with 0.25 %SIF and 0.25 %HHF) boosted the best performances among green RPC mixes in bi-surface shear, oblique shear and Pull-out tests. Also, the said mix gives higher bond strengths between RPC with substrate concrete than that of epoxy by 2.273 %, 3.663 %, 6.168 % and 10 % through bi-surface shear, oblique shear, splitting strength and flexural strength, respectively.

Reactive Powder Concrete Containing Basalt Fibers: Strength, Abrasion and Porosity.

The paper presents the test results of basalt fiber impact on a compressive and flexural strength, resistance to abrasion and porosity of Reactive Powder Concrete (RPC). The reasons for testing were interesting mechanical properties of basalt fibers, the significant tensile strength and flexural strength, and in particular the resistance to high temperatures, as well as a relatively small number of RPC tests performed with those fibers and different opinions regarding the impact of those fibers on concrete strength. The composition of the concrete mix was optimized to obtain the highest packing density of particles in the composite, based on the optimum particle size distribution curve acc. to Funk. Admixture of basalt fibers was used in quantity 2, 3, 6, 8 and 10 kg/m3, length 12 mm and diameter 18 µm. A low water-to-binder ratio, i.e., from 0.24, was obtained through application of a polycarboxylate-based superplasticizer. The introduction of up to 10 kg/m3 of basalt fibers to RPC mix was proved to be possible, while keeping the same w/c ratio equal to 0.24, with a slight loss of workability of the concrete mix as the content of fibers increased. It was found that the increase of the fiber content in RPC to 10 kg/m3, despite the w/c ratio was kept the same, caused reduction of the concrete compressive strength by 18.2%, 7.8% and 13.6%, after 2, 7, and 28 days respectively. Whereas, the flexural strength of RPC increased gradually (maximum by 15.9%), along with the fiber quantity increase up to 6 kg/m3, and then it reduced (maximum by 17.7%), as the fiber content in the concrete was further increased. The reduction of RPC compressive strength, along with the increase in basalt fibers content, leads to the increase of the total porosity, as well as the change in pore volume distribution. The reduction of RPC abrasion resistance was demonstrated along with the increase of basalt fibers content, which was explained by the compressive strength reduction of that concrete. A linear relation between the RPC abrasion resistance and the compressive strength involves a high determination coefficient equal to 0.97.

Behavior of RPC based Alkali Activated Material Compared with Conventional RPC

Reactive Powder Concrete (RPC) is a type of high strength concrete that is characterized by its excellent engineering properties. Inclusion of high silica fume contents and high cement demand are the most essential parameters in the development of RPC. Silica fume is a highly cost and unavailable material in many countries. Cement industry is not a sustainable eco-friendly process. High heat of hydration and many shrinkage cracks are also the most shortcomings obtained from cement utilization. Therefore, it’s urgently required to replace the utilization of silica fume and cement with partially or totally environmental friendly materials in the production of RPC. Metakaoline (MK) is a low cost, available and high pozzolanic material that can substitute silica fume in concrete. Alkali Activated Materials (AAM) binders are new technology that can totally replace the cement in concrete. The main objective of this study is to evaluate the performance of RPC based cement developed by MK and the performance of RPC based AAM under different curing conditions. Slag and MK are the used AAM in this research which are eco-friendly, sustainable and quite available materials in Egypt. The engineering properties like compressive strength and sorptivity are studied to investigate the behavior of RPC. It was concluded that thermal curing has shown a good impact in the performance of all RPC mixes. MK has shown satisfied results in the behavior of RPC based AAM under thermal curing. Slag shows better mechanical and durability properties that resemble the behavior of the conventional RPC based cement.

Environmental protection based sustainable development by utilization of granite waste in Reactive Powder Concrete

Stone cutting processes generate waste in large volumes that are often buried and cause polluting the environment. Aside from preventing environmental degradation, using of these wastes for different applications, including in the concrete industry, helps reduce the depletion of mineral resources, offering an excellent opportunity for sustainable development. The present study is an investigation into the use of stone cutting waste in the production of Reactive Powder Concrete (RPC). For this purpose, ninety RPC mix designs, with three water-to-binder ratios (w/B = 0.14, 0.17, and 0.2), three silica-fume-to-binder ratios (SF/B = 0.15, 0.2, and 0.25), two binder (cement + silica fume) contents (1200 and 1500 kg/m3), and five replacement ratios of silica sand by granite waste (GW/Agg = 0, 10, 20, 30, and 40%) were prepared. Superplasticizer content was adjusted in the concrete mixes to achieve a 200 mm spreading diameter in the mini-slump test. Compressive strength, flexural strength, and water absorption tests were conducted on specimens of all concrete mixes. The results were suggestive of improvements in the mechanical properties of the concrete by incorporating up to 30% granite waste in the RPC to the replace silica sand. At GW/Agg = 30%, the compressive and flexural strengths were enhanced by 78 and 60%, while reducing the water absorption of the concrete by 75%. The results also show that by making 1 m3 of RPC with GW/Agg = 30%, 120–300 kg of granite production wastes can be used up.

RPC Effect of Crude Oil Products on the Mechanical Characteristics of Reactive-Powder and Normal-Strength Concrete

This study includes detailed information on the mechanical characteristics of the hardened concrete mix for normal concrete (NSC) and reactive powder concrete (RPC) after exposure to crude oil products. Two types of crude oil products (kerosene and gas oil) were investigated after exposure for a period of 180 days. The experimental program consisted of three sets of NSC and RPC specimens; after curing all concrete specimens for 28 days and 2 days to dry in the air, the first set of specimens was immersed in kerosene for 180 days and the second set was immersed in gas oil for the same age, while the third set was left in the air as a reference set (cured normally for 28 days and tested at the age of 180 days). The results showed that the mechanical characteristics of the RPC mix were not highly affected after exposure to each type of crude oil products, where it lost about (3.41–6.32 %) compared with reference RPC mix. While the NSC mix lost about (13.82–21.95 %) of its mechanical characteristics compared with reference NSC mix after exposure to crude oil products for the same period.

Influence of mixing method, speed and duration on the fresh and hardened properties of Reactive Powder Concrete

Production methodology of Reactive Powder Concrete (RPC) is not clearly established yet, as several parameters have a varied influence on the resulting fresh and hardened properties of RPC. Even for the same composition, the fresh and hardened properties differ significantly by changing mixing method, mixing speed and mixing time/duration. The present investigation is an attempt to study the effect of mixing method, speed and duration, on the fresh and hardened properties of RPC. The study also deals with the microstructure investigation of RPC mixes. Results indicate that improved mixing techniques prove beneficial in enhancing fresh and hardened properties of RPC. Mixing speed and duration also have significant effect on the fresh and hardened properties of RPC. Higher mixing speed and longer mixing duration decreases flow and strength characteristics of RPC. Microstructure analysis reveals that higher mixing speed and longer mixing duration increases percentage of pores in RPC, leading to reduced fresh and hardened properties.

Estimation of Strength of Reactive Powder Concrete using Artificial Neural Network

Objective: Attempt is made to estimate the compressive strength of Reactive Powder Concrete (RPC) by developing Artificial Neural Network model. Methods/Analysis: RPC is a complex composite material made using a combination of constituent materials viz. fine quartz, silica fume and cement to form a cementitious matrix. Mix design for RPC is more complicated as it excludes the coarse aggregates and a low water/cement ratio is maintained. The mix proportioning methods applicable to normal concrete cannot be applied readily to RPC. The complexity in behavior of concrete with special constituents makes the mix design complicated. Artificial neural network (ANN) techniques can capture complex relations among input/output variables in a given system and this method has been implemented in Reactive Powder Concrete mix proportion design, for predicting its strength. Findings: This paper presents the development and application of ANN for predicting the strength of RPC using data related to 112 mix proportions and the results of the model are checked experimentally. Compressive strength of concrete is chosen as a function of the 'Water/Cement' ratio (w/c), 'Silica Fume/Cement' ratio (sf/c), and 'Quartz Sand/Cement' ratio (qs/c). The ANN model developed is tested for the 12 mix proportions randomly selected from experimental data for which the experimental compressive strengths were available. The compressive strength given by the model when compared with the experimental values showed an average error of only 3.99 %. Novelty/Improvement: The model developed has coefficient of determination R² equal to 0.9066 which indicates a significant enough correlation.