High Strength Self-consolidating Concrete Research Articles

Experimental investigation on mechanical properties of HSSCC containing waste steel fibers obtained from end-of-life tires

In this study, use of end-of-life tires (ELTs) in self-consolidating concretes (SCC), which enable higher rates of fiber use than conventional concrete due to its superior flow properties, for the elimination of the environmental negative impacts and recycling of them were aimed. Besides, it is aimed to investigate the behavior of waste steel wires with different aspect ratio obtained from different types of tires, contrary to what is mostly researched in the literature. Therefore, bead, cord and base wires, obtained from tires, were used in high-strength self-consolidating concrete (HSSCC) production as fiber reinforcement. Fresh and hardened state properties of the waste wire-reinforced (1-2-3%) samples of different sizes that were produced, were compared with industrial steel-reinforced and non-fibrous samples. In this regard, slump flow and T50 durations were determined, compression and bending tests were performed. Significant improvements in the mechanical properties of conventional concretes were observed with the use of waste wire. Using the optimum ratio of waste wire, an increase of approximately 102% in flexural strength and 14% in compressive strength was observed compared to the reference specimen. Aspect ratio was recognized as one of the most effective factor on optimum fiber content. Moreover, experimental results were analyzed with "paired sample t-test", and it was seen that there were no considerable differences in the mechanical properties of the samples in which industrial fiber and waste-wire had been used. Besides, cost analysis was carried out to assess the economic benefits of the use of waste tire wires in the concrete industry.

Shear Behaviour of High-Strength Self-Compacting Concrete (HSSCC) RC Beam with 12.5% Metakaolin and Variations of Silica Fume

High-Strength Self-Consolidating Concrete (HSSCC) is a type of concrete that possesses superior mechanical properties and can self-settle without the need for vibration assistance. Numerous advancements have been implemented to enhance the properties of HSSCC. In prior experimental work, the authors investigated the mechanical characteristics of HSCC with 12.5% metakaolin and 0-15% silica fume as a partial cement substitute. Since metakaolin and silica fume have smaller particle sizes than cement, they can fill voids between aggregate and enhance the concrete’s compactness. Further structural study is necessary to provide a more complete knowledge of the impact of partially substituting cement with metakaolin and silica fume. Using the Response 2000 program, this investigation analyzes the shear behavior of reinforced HSSCC beams. Laboratory-determined material mechanical properties were utilized as simulation input data. In this investigation, the maximum strength, deflection, and crack development of five beam models produced with varying material mechanical properties were investigated and compared.

Strength and Durability of Sustainable Self-Consolidating Concrete with High Levels of Supplementary Cementitious Materials.

Self-consolidating concrete (SCC) has been used extensively in the construction industry because of its advanced characteristics of a highly flowable mixture and the ability to be consolidated under its own weight. One of the main challenges is the high content of OPC used in the production process. This research focuses on developing sustainable, high-strength self-consolidating concrete (SCC) by incorporating high levels of supplementary cementitious materials. The overarching purpose of this study is to replace OPC partially by up to 71% by using fly ash, GGBS, and microsilica to produce high-strength and durable SCC. Two groups of mixtures were designed to replace OPC. The first group contained 14%, 23.4%, and 32.77% fly ash and 6.4% microsilica. The second group contained 32.77%, 46.81%, and 65.5% GGBS and 6.4% microsilica. The fresh properties were investigated using the slump, V-funnel, L-box, and J-ring tests. The hardened properties were assessed using a compressive strength test, while water permeability, water absorption, and rapid chloride penetration tests were used to evaluate the durability. The innovation of this experimental work was introducing SCC with an unconventional mixture that can achieve highly durable and high-strength concrete. The results showed the feasibility of SCC by incorporating high volumes of fly ash and GGBS without compromising compressive strength and durability.

Comparison of experimental approaches for seismic performance evaluation of bridge piers with high strength self-consolidating concrete towards practical engineering application

In this study, three different types of experimental approaches are carried out for the seismic evaluation of high strength self-consolidating concrete bridge columns in high seismic zone, including unidirectional quasi-static, bidirectional quasi-static and shake table tests. The 1/4-scale bridge column specimens are based on the practical engineering application of urban viaduct in high seismic region of northern China. The use of high strength self-consolidating concrete is to fulfill the demand of short construction time, high seismic resistance and harsh weather durability in the area. Based on the experimental results, it is found that similar damage progression is observed from all the tested specimens with concrete crush and longitudinal rebar buckling. Quasi-static cyclic tests tend to be more conservative but to overestimate the energy dissipation capacity and ductility, and the coupling effect from bidirectional loading cannot be ignored. In addition, nonlinear numerical models with improved bond-slip modeling approach are developed and calibrated by OpenSEES with the experimental data, where good agreement is achieved especially at early loading stage.

Mechanical and abrasion resistance performance of silica fume, marble slurry powder, and fly ash amalgamated high strength self-consolidating concrete

An experimental program was conducted to evaluate the impact of silica fume (SF), marble slurry powder (MSP), and fly ash (FA) on the mechanical properties and abrasion resistance of high strength self-consolidating concrete (HSSCC). For this, Ordinary Portland Cement (OPC) was replaced by SF, MSP, and FA in various proportions in individual and simultaneous manner. Altogether sixteen numbers of concrete mixes were prepared. The mechanical properties were evaluated by performing compressive strength, split tensile strength, flexural tensile strength, pull-off strength tests. The microstructural analysis was also carried out using field emission scanning electron microscope (FESEM) and Energy-dispersive X-ray spectroscopy (EDS) techniques. Amalgamation of MSP and FA in HSSCC resulted in better mechanical performance. The combined use of SF, MSP, and FA in HSSCC at 5%, 10%, and 15%, respectively has produced the best results in terms of mechanical performance. The EDS analysis showed the effect of Ca to Si ratio in strength development and this ratio found to be crucial. A statistical approach also shows the significance of the SF, MSP, and FA on the test results.

An experimental study on transfer length of prestressing strand in self-consolidating concrete

Due to its economic advantages, the use of self-consolidating concrete (SCC) has increased rapidly in recent years. However, because SCC mixes typically have decreased amounts of coarse aggregate and high amounts of admixtures, industry members have expressed concerns that the bond of prestressing strand in SCC may be compromised.Therefore, the objective of this research program was to investigate the transfer lengths of prestressing strand in SCC. Transfer lengths of 12.5 mm diameter (0.5-in.), Grade 270 prestressing strand were evaluated using rectangular beams constructed from normal and high strength conventional concrete and SCC mixes. Strain readings over 56 days were used to calculate transfer lengths of beams. Results indicated that bond performance of SCC is superior to conventional concrete and that AASHTO and ACI equations for transfer length were generally conservative.

Test Methods for the Characterization of Polypropylene Fiber Reinforced Concrete: A Comparative Analysis

Fiber reinforced concrete (FRC) has been used for many different construction applications and many testing protocols have been developed to determine their mechanical behavior. The present paper focus on the comparisons between four major mechanical tests used for FRC: EN 14651, ASTM 1609, ASTM 1550 and EN 14488. Polypropylene fibers were used as reinforcement in volume ratios of 3 kg/m3, 6 kg/m3 and 10 kg/m3 in a self-consolidating high-strength concrete. The flexural beam tests according to ASTM 1609 and EN 14651 standards were carried on through a closed loop type of control. Comparisons include crack post-peak strength and energy absorption values. The EN 14651 showed to be more precise for low ductile concretes (i.e., low fiber volume fractions). This is due to the notch in the EN standard and different methods used for instrumenting the specimen. The EN 14488 due to its boundary conditions showed much higher results with a deflection-hardening type of behavior. Since the EN 14488’s frame comes into full contact with the specimen, that creates a more rigid material response. This response differs from the other three tests since their support conditions allow rotations and induces cracks to appear in determined locations.

Development length of prestressing strand in self-consolidating concrete vs. conventional concrete: Experimental study

An experimental investigation was conducted to compare the development lengths of prestressing strand in self-consolidating concrete (SCC) and conventional concrete (CC). Development lengths and bond performance of 12.5 mm diameter, Grade 270 prestressing strand were evaluated using rectangular beams and the North American Strand Producers (NASP) test for both normal and high strength CC and SCC mixes. (The NASP test has now been formally adopted as ASTM A1081.) Results indicate that the current AASHTO and ACI equations for development length are conservative for both SCC and CC mixes. All development length test beams failed in flexure due to concrete crushing and exceeded the calculated nominal moment by 10–15%. Furthermore, all the SCC and CC beams showed negligible strand end slip during testing. Overall, SCC and CC appeared to exhibit comparable development lengths.

Sorptivity characteristics of high strength self-consolidating concrete produced by marble waste powder, fly ash, and micro silica

The performance of concrete structures is largely affected by the susceptibility of the concrete to the penetration of water. Ingress of moisture or other aggressive liquids through the interconnected pores reaches to the inner part of the concrete structures and causes deterioration. A study has thus been carried out to find the surface water absorption characteristics of high strength self-consolidating concrete (HSSCC). A total of sixteen HSSCC mixes were prepared to investigate the effect of marble waste powder (MWP), Fly Ash (FA), and micro-silica (MS) as a partial replacement of cement on surface water absorption characteristics. Surface water absorption was evaluated using the sorptivity test after 28 days curing period. The initial and secondary rate of absorption was calculated for each HSSCC mix. Sorptivity test results indicated that the incorporation of supplementary cementitious materials in HSSCC resulted in increased resistance against surface water absorption. Incorporation of 5% MS in HSSCC resulted in reduced water absorption through the exposed surface. All the ternary mixes (made with Cement + MS + FA and Cement + MS + MWP) and quaternary mixes (made with Cement + MS + FA + WMP) showed higher resistance against surface water absorption than the reference mixture. However, the highest surface water absorption resistance was found for a ternary mix made with 5% and 35% substitution of cement with MS and FA respectively.

Optimization of high-strength self-consolidating concrete mix design using an improved Taguchi optimization method

Since many parameters are involved in the concrete mix design, finding the optimal mixing design has always been a problem for concrete engineers. In this research, the Taguchi optimization method is improved to model to optimum mix design of the high strength self-consolidating concrete (HSSCC). For this purpose, at first different quality criteria and the parameters influencing them were defined based on the available literature. The Taguchi approach was then utilized to generate an the orthogonal array of the parameters. The experimental tests were then conducted according to the suggested design array in order to obtain the experimental data for each and every single scenario. The Best-Worst method is then adopted for pairwise comparisons of the quality criteria and experiments as such to obtain the overall weights of experiments with respect to each quality characteristics. Analysis of variance was also utilized to appraise the effective factors and the optimal mixture design. It was found that the proposed method was efficient in obtaining the optimal mixture design of the manufacturing process according to decision makers’ preferences. The experimental results indicated a significant improvement in the total quality of concrete compared to the decision maker’s estimated mixture design. The cement amount, water to cementitious ratio and mixing time are the most significant parameters affecting the concrete mix design.

Bond performance of prestressing strand in self-consolidating concrete

An experimental investigation was conducted to study the bond of prestressing strand in self-consolidating concrete (SCC). The bond of 12.5-mm-diameter (0.5 in.), Grade 270 prestressing strand was evaluated using both the large block pullout test (LBPT) and the North American Strand Producers (NASP) test for both normal and high strength conventional concrete (CC) and SCC mixes. (The NASP test has now been formally adopted as ASTM A1081.) Results indicated that there was a strong correlation between the NASP and LBPT pullout loads in this study (R2 = 0.93). Furthermore, the NASP and LBPT pullout loads can be considered fairly accurate with respect to relative bond between strands, but in terms of absolute bond and rejecting or accepting strand based on set limits, the NASP test passed all three types while the LBPT only passed one out of the three. In addition, the statistical data analysis (both parametric and nonparametric) confirmed that SCC mixes had higher bond strength than the CC mixes.

Strength Properties of Fibre-Reinforced Self-Consolidating Concrete with Foundry Waste Sand

This study presents a comprehensive overview of replacing natural river sand (FA) with foundry waste sand (FWS) in fibre-reinforced high strength self-consolidating concrete (SCC). Fine aggregate (FA) was replaced with FWS, proportions varying from 0% to 70%. To maintain workability in the SCC mix, chemical admixtures were added. During fresh state, properties of SCC like filling and passing ability, segregation resistance were studied. Assessment results indicated a moderate reduction in workability, slump flow decreased by 4% over control mix, for 70% replacement of FA with FWS. SCC mixes were prepared with different FWS contents and evaluated for density, modulus of elasticity, compressive, flexural and split tensile strengths. The compressive strength increased by 6% to 8%, flexural strength by 2% to 4% and split tensile strength by 2% to 3% when the FA was partially replaced by 20% with FWS. Density of SCC increased by 6.5% and modulus of elasticity decreased by 10% for 70% replacement of FA with FWS. From the assessment outcome, it can be resolved that FWS could form a dependable alternative source for natural river sand replacement in high strength SCC.

Load Distribution of a Prestressed Self-Consolidating Concrete Bridge

Bridge A7957 is the first Missouri Department of Transportation (MoDOT) large-scale project using self-consolidating concrete (SCC) and high-strength self-consolidating concrete (HS-SCC). The objective of this research was to monitor the initial in-service behavior of the precast-prestressed concrete primary elements of Bridge A7957 and to obtain the load distribution of the bridge using field and finite element models (FEM) data. An initial series of diagnostic load tests was conducted on the bridge superstructure. Embedded sensors recorded strain variations at different section of the instrumented girders for different load configurations. An automated total station (ATS) collected the vertical deflection of the girders at several locations during the application of different test loads. The load distribution for moment was obtained experimentally (using deflection and strain data), FEMs, and using the AASHTO LRFD Bridge Design Specifications. The distribution factors for moment estimated with the AASHTO LRFD equations resulted in larger values compared to field test and FEM results. No difference was observed between the response of the SCC and conventional concrete members during the first series of field load tests.

Pore pressure and spalling in fire-exposed high-strength self-consolidating concrete reinforced with hybrid fibres

This work investigates the influence of different fibres (steel fibre, micro polypropylene (PP) fibre and macro PP fibre) on the build-ups of pore pressure of fibre reinforced high-strength self-consolidating concrete (FRHSSCC). The results showed that the introduction of fibres prolongs the occurrence time of maximum pore pressure. Micro PP fibre plays a dominant role in reducing pore pressure of HSSCC. The active zone of steel fibre is the deeper regions, while the macro PP fibre exerts a better effect in shallow regions for the tested HSSCC specimen. The combination of steel and micro or macro PP fibres further mitigate the maximum pore pressure of HSSCC. However, the pronounced positive hybrid effect is only found in the shallow regions near the fire. Compared to the combination of steel fibre and micro PP fibre, the use of steel fibre and macro PP fibre has a better positive hybrid effect on reducing the pore pressure of HSSCC. Prediction for the pore pressure of HSSCC and FRHSSCC using a thermo-hygral method was carried out. The prediction results are acceptable, thus the thermo-hygral method used in this paper can be simply employed to analyse the pore pressure build-ups and spalling of HSSCC and FRHSSCC.

Experimental investigation on effects of hybrid fibers on rheological, mechanical, and durability properties of high-strength SCC

The aim of the present study is to investigate the effects of using hybrid fibers on rheological, mechanical and durability properties of the high-strength self-consolidating concrete (SCC). For this purpose, two types of fibers including hooked-end steel fibers and polypropylene fibers were used. In this study, a total of eleven mixtures were used: one as a control mix, one containing 0.5% steel fibers, four containing 0.5% hybrid fibers (steel and polypropylene), one containing 1.0% steel fibers and the four containing 1.0% hybrid fibers (steel and polypropylene). For investigating the rheological properties, slump flow, J-ring and V-funnel tests were performed. Mechanical properties were studied by conducting compressive strength, splitting tensile strength, modulus of rupture and flexural toughness tests. Moreover, ultrasonic pulse velocity conducted as a non-destructive test to assess the quality and integrity of the concrete. Durability properties of this type of concrete were evaluated by electrical resistivity tests. Effects of fibers in rheological and mechanical properties have been studied and compared.

Evaluating the early-age behaviour of full-scale prestressed concrete beams using distributed and discrete fibre optic sensors

This paper evaluates the results of a monitoring study that captures the early age behaviour of four 11.9m prestressed concrete bridge beams utilising both distributed and discrete fibre optic sensor (FOS) arrays. The performance of the beams is evaluated before they are placed in-service as part of new concrete railway bridges in the Midlands in the UK. Two types of prestressed beams were monitored, two TY7 internal beams and two TYE7 edge beams. The beams incorporated high strength (up to 90.7MPa) self-consolidating concrete. The entire manufacturing process which included early-age curing and the detensioning process was captured in great detail using the installed FOS system. An analysis of the curing strains within the beams revealed the significant effect that ambient temperature, curing duration, and formwork restraint has on the development of prestress losses prior to detensioning. Based on the distributed FOS readings, it was observed that the strain remained uniform along the length of the beams during the various beam monitoring stages. The measured strain data was then used to calculate prestress losses in the first six months after casting (prior to casting of the in-situ concrete bridge deck). The TY7 and TYE7 beams experienced losses that were 79% and 72% of the ultimate losses predicted using Eurocode 2 equations, respectively. Distributed strain measurements were used to provide estimates of the change in beam camber with time. The pre-camber values calculated using the recorded FOS strain data at the time of detensioning closely match the theoretically calculated values. However, camber values increased by up to 1.7 times in the first six months compared with the post-detensioning values and deviated significantly from the theoretically calculated values. The future aim of this research is to establish integrated FOS systems as viable tools for monitoring strain evolution in concrete bridges in order to establish comprehensive baselines to facilitate long term data-driven bridge monitoring programmes.

Modeling of Compressive Strength for Self-Consolidating High-Strength Concrete Incorporating Palm Oil Fuel Ash.

Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable mathematical models for the prediction of compressive strength of different concretes, but not for self-consolidating high-strength concrete (SCHSC) containing palm oil fuel ash (POFA). The present study has used artificial neural networks (ANN) to predict the compressive strength of SCHSC incorporating POFA. The ANN model has been developed and validated in this research using the mix proportioning and experimental strength data of 20 different SCHSC mixes. Seventy percent (70%) of the data were used to carry out the training of the ANN model. The remaining 30% of the data were used for testing the model. The training of the ANN model was stopped when the root mean square error (RMSE) and the percentage of good patterns was 0.001 and ≈100%, respectively. The predicted compressive strength values obtained from the trained ANN model were much closer to the experimental values of compressive strength. The coefficient of determination (R2) for the relationship between the predicted and experimental compressive strengths was 0.9486, which shows the higher degree of accuracy of the network pattern. Furthermore, the predicted compressive strength was found very close to the experimental compressive strength during the testing process of the ANN model. The absolute and percentage relative errors in the testing process were significantly low with a mean value of 1.74 MPa and 3.13%, respectively, which indicated that the compressive strength of SCHSC including POFA can be efficiently predicted by the ANN.

Shear Behavior of High-Strength Self-Consolidating Concrete in Nebraska University Bridge Girders

Shear Behavior of High-Strength Self-Consolidating Concrete in Nebraska University Bridge Girders

Development of Self-Consolidating High Strength Concrete Incorporating Treated Palm Oil Fuel Ash

Palm oil fuel ash (POFA) has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC). POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties.

Monitoring and theoretical losses of post-tensioned indeterminate I-beams

Self-consolidating concrete is a desirable achievement in reinforced concrete structures. This non-vibrating concrete has had a significant impact on the prestressed concrete industry because it increases productivity in the casting of durable prestressed or precast members without mechanical vibration. In the design of prestressed concrete structures, the immediate and time-dependent losses in tendon stresses are important. The main objective of this study is to investigate the losses in tendon stresses of indeterminate (continuous) post-tensioned unbonded beams consisting of two different types of concrete (high-strength self-consolidating concrete (HSSCC) and high-strength normal concrete (HSNC)). Six continuous, unbounded, post-tensioned I-beams in two groups were cast and monitored by electrical strain gauges for a duration of 60 d and the losses were measured. Results were compared with the Association of State Highway and Transportation Officials (Aashto) third and fourth edition methods, the Precast/Prestressed Concrete Institute (PCI) method and the Eurocode 2 model. It was found that the Aashto third edition, PCI and Eurocode 2 methods were conservative and the Aashto fourth edition method was non-conservative for estimating time-dependent losses in post-tensioned beams cast with high-strength concretes. The amount of experimental time-dependent losses in beams consisting of HSSCC was slightly lower than that of beams prepared using HSNC with almost the same concrete strength.