Self-consolidating Concrete Research Articles

Assessing the Impact of Recycled Concrete Aggregates on the Fresh and Hardened Properties of Self-Consolidating Concrete for Structural Precast Applications

This study explores the influence of different concentrations of recycled concrete aggregate (RCA) on the fresh and hardened properties of self-consolidating concrete (SCC) in order to assess the structural suitability of the use of RCA in a precast concrete plant. The study particularly emphasizes the early strength of the produced concrete. The RCA was sourced from crushed concrete used in roadway applications and was sieved to replicate the characteristics of natural aggregate. Five different SCC mixes were produced, with RCA substituting 0%, 10%, 30%, 50%, and 70% of the natural coarse aggregate (NCA) by weight. For each different mix design, the hardened properties tested were the compressive strength and tensile strength. The fresh properties investigated were the passing and filling ability. Additionally, aggregate properties including grain size distribution and absorption of coarse aggregate were studied. The selected mix design follows a typical well-graded self-consolidating concrete mix with 28-day strength of 8000 psi (55.16 MPa). It was found that replacing up to 50% of the NCA with RCA improves the early strength of concrete without a significant impact on the fresh and hardened concrete properties.

Rice husk ash blended self-consolidating concrete for application in rigid pavements: transforming agro-industrial waste into environment-friendly and sustainable material

Rice husk ash blended self-consolidating concrete for application in rigid pavements: transforming agro-industrial waste into environment-friendly and sustainable material

Prediction of the Lateral Pressure of Self-Consolidating Concrete on Construction Formwork Systems Using Machine-Learning Algorithms

Prediction of the Lateral Pressure of Self-Consolidating Concrete on Construction Formwork Systems Using Machine-Learning Algorithms

Experimental study of bond-slip relationships in high-performance self-consolidating concrete with plain steel bars

Self-consolidating concrete is being used more frequently in structures with high density of reinforcement bars or prestressing strands therefore, it is important to carefully consider whether bond stress-slip relations defined for normal strength concrete can be safely applied to high-strength and self-consolidating concrete. This paper aims to investigate the bond behaviour between plain steel bars and high-performance self-consolidating concrete, with a focus on studying the effect of embedment length and concrete compressive strength on bonding performance. The main parameters that were tested are the active bonded length and the compressive strength of the concrete. The value of adhesive bond stress is discussed, as a factor in determining whether the bar slips against the adhering concrete. Based on the results, it can be observed that the maximum bond stress tends to increase with higher concrete compressive strength, while it decreases with longer embedment length of plain steel bar. Conversely, the adhesive bond tends to increase with longer embedment length and higher concrete compressive strength. The experimental investigations indicate that the bond strength increases proportionally to the square root of the compressive strength of concrete, regardless of the concrete compressive strength. Furthermore, a new bond stress-slip model has been analyzed, which takes into account the initial bond strength (adhesive bond) and the lower convex property to predict the post-peak branch. The model has been compared to the test results, and good agreement has been achieved.

Influence of Admixture Source on Fresh Properties of Self-Consolidating Concrete.

The study presented herein was intended to (1) compare the optimum (minimum) dosage requirements of four different sources of polycarboxylate-based high-range water-reducing admixtures (HRWRAs) and viscosity-modifying admixtures (VMAs) in attaining slump flows of 508 mm, 635 mm, and 711 mm, and a visual stability index (VSI) of 0 (highly stable concrete) or 1 (stable concrete), and (2) assess the flowability/viscosity, stability, passing ability, and filling ability of the resulting self-consolidating concretes. The test results showed that the optimum dosage requirements to obtain a uniform slump flow and visual stability index varied among the four selected admixture sources. The required dosage amount for HRWRAs was highest for the polycarboxylate-ester (PCE) type and lowest for the polycarboxylate-acid (PCA) type. Acceptable flowability plastic viscosity dynamic and static stability, passing ability, and filling ability of self-consolidating concrete can be achieved with the proper dosing of the four studied admixture sources.

Synergistic effects of nano and micro silica on fresh and hardened properties of self-consolidating concrete

The escalating demand for methods to diminish cement usage without compromising the strength and durability of concrete mixtures has led to an intensified exploration of alternative mixture ingredients. Nano silica has emerged as a prominent supplementary cementitious material, recognized for its capability to partially substitute cement. Despite this potential, there was a gap in the literature on the effects of nano silica on the concrete’s fresh and hardened properties, particularly when used in conjunction with silica fume. This gap motivated the current investigation, aiming to capture and compare the effects of incrementally substituting silica fume with nano silica in self-consolidating concrete (SCC). For this purpose, four nano silica dosages—1%, 2%, 3%, and 5%— were considered as replacements for silica fume. A range of experiments, including slump flow, T50 time, and L-box tests, were conducted to assess the workability of the developed SCC mixtures. Subsequent analyses focused on key mechanical attributes, including the static modulus of elasticity, compressive strength, and tensile strength. The research further encompassed water absorption, penetration depth, and electrical resistivity evaluations to understand the durability characteristics of the developed mixtures. The scanning electron microscopy (SEM) analyses complemented these tests, offering a microstructural perspective to further explain the outcomes. This investigation’s findings offer novel insights into leveraging nano silica’s distinctive properties to achieve the desired SCC properties while reducing the environmental impact of this class of mixtures.

Limestone filler as a mineral additive on the compressive strength and durability of self-compacting concrete with limestone manufactured sand

Using limestone filler (LF) as a mineral additive of concrete with manufactured sand (MS) raises concerns about the long-term performance because of the high LF content in mixtures, particularly in high-binder content self-consolidating concrete (SCC). Herein, this paper evaluates the effects of LF as a mineral additive on the compressive strength and durability of SCC incorporating manufactured sand (MS_SCC). Results indicate that LF decreases the compressive strength of MS-SCC akin to that observed with FA, albeit with a more moderate decrease observed at a lower w/b ratio. Both LF and FA contribute to decreasing carbonation resistances, while MS_SCC with LF exhibits a gradual reduction in carbonation rate over time. Furthermore, LF reduces the chloride migration resistance of MS-SCC, unlike FA. However, LF improves the drying shrinkage of MS_SCC, particularly notable at a lower w/b ratio. Microstructure analysis indicates that LF induces a coarsening effect on the pore structure of MS_SCC, with a moderate influence observed for mixtures characterized by a lower w/b ratio.

AN EXPERIMENTAL STUDY ON SELF COMPACTING CONCRETE

This paper gives a review on Self Compacting Concrete (SCC) to be made using various Mineral Admixtures and Fibers. In current scenario of construction industries due to demand in the construction of large and complex structures, which often leads to difficult conditions. When large quantity of heavy reinforcement is to be placed in reinforced concrete (RC) member, it is difficult ensure fully compacted without voids or honeycombs. Compaction by manual or by mechanical vibrators is very difficult in this situation. That leads to the invention of new type of concrete named as self-compacting concrete (SCC). This type of concrete flows easily around the reinforcement and into all corners of the formwork Self- compacting concrete describe a concrete with the ability to compact itself only by means of its own weight without the requirement of vibration. Self-compacting concrete also known as Self-consolidating Concrete or Self Compacting High- Performance Concrete. It is very fluid and can pass around abstractions and fill all the nooks and corners without the risk of either mortar or other ingredients of concrete separating out, at same time there a are no entrapped air or rock pockets. This type of concrete mixture does not require any compaction and is saves time, labour and energy. This review paper explains the utilization of fibers and various mineral admixtures in the properties of Self Compacting Concrete. Key Words: Self Compacting Concrete, Mix design, Mineral Admixtures, Fibers, Durability, Workability.

Reinforced ECC-UHPC-SCC composite modular framed shear wall systems under lateral cyclic loading

The shear strength and deformability of high performance reinforced composite framed shear wall systems made of Engineered Cementitious Composite (ECC), Ultra-High-Performance Concrete (UHPC) and Self-Consolidating Concrete (SCC) subjected to lateral cyclic shear loading to failure were investigated. A total of seven framed shear wall specimens were constructed using combinations of ECC or SCC wall, SCC frame and ECC or UHPC frame joints. The performance of such novel modular forms of walling systems were compared based on experimental results in terms of cracking, failure mode, hysteretic shear load-deformation response, shear load capacity, ductility, bearing capacity degradation, stiffness degradation, dissipated energy, viscous damping capacity, induced wall shear stresses and strain development characteristics. ECC walling system exhibited better structural performance compared to their SCC counterparts showing up to 40% higher load capacity forming significantly higher number of closely spaced diagonal cracks with up to 72% lower crack shear stress, 14% to 21% higher ductility, up to 2 times higher energy dissipation capacity and lower rate of stiffness/bearing capacity degradation through both hysteretic and damping actions. The incorporation of ECC and ECC or UHPC joint in frame significantly improved shear strength capacity of infill wall and overall framed shear wall system. ECC incorporated framed shear walls even with frames made of SCC and UHPC joints also exhibited superior performance. This study confirmed the superior performance of ECC material for the construction of reinforced framed shear wall with boundary frame made of ECC/SCC/UHPC combinations for better seismic resistance.

An Experimental Analysis on Self Compacting Concrete with Different Grades

Abstract: Self-compacting concrete (SCC), moreover called self-consolidating concrete. It is able to stream beneath its possess weight to totally fill the formwork and accomplish total compaction, indeed within the case of over-burden fortification. Solidified concrete is thick, homogeneous and has at slightest the same specialized properties and toughness as conventional vibrated concrete. scc can be made utilizing the same fixings as customary concrete. In any case, a more tightly resistance is required to guarantee tight control of processability characteristics. The dosing of self-compacting blend is much more logical than that of standard concrete blends. SCC blend requires tall powder substance, less coarse total, exceedingly viable superplasticizer and VMA (viscosity modifying agent) to provide concrete blends soundness and fluidity. Workability of SCC could be a adjust of ease, deformability, fill capacity and isolation resistance.

Prediction of self-consolidating concrete properties using XGBoost machine learning algorithm: Rheological properties

Rheological properties are critical for assessing self-consolidating concrete (SCC)’s performance and application. However, predicting these properties accurately, specifically plastic viscosity and yield stress, faces challenges due to inconsistent data, small sample sizes, and measurement inaccuracies, with the type of rheometer significantly impacting results. This study meticulously analyzes 348 mixtures from 19 peer-reviewed sources, focusing on experiments that detail rheometer types to understand variability in rheological properties. Twelve variables, including cement content and water-to-powder ratio, were identified as key to SCC's rheology. Utilizing these, an XGBoost model demonstrated exceptional accuracy (R2 of 0.99), markedly better than traditional methods. This advance not only aids in SCC design but also showcases the potential of machine learning in construction materials research, suggesting a new direction for material property prediction and innovation in construction.

Hardened property changes due to the pumping process of self-consolidating concrete

Pumping of self-consolidating concrete (SCC) is a vital construction technique. Curiosities are aroused by the effect of this intense physical process on the hardened properties of SCC. To examine this issue, a total of seven SCC mixtures are pumped at constant flow rates in pipelines with lengths of 324, 600, and 912 m. Parameters related to the hydration stages, air-void system, compressive strength, elastic modulus, and shrinkage at early ages are tested on specimens made of concrete before and after pumping. Results of tested samples find that the spacing factor grows, but the specific surface lessens after pumping. Also, in most cases, the compressive strength and elastic modulus decrease due to the pumping. The variations of these two factors are linearly related to the pumping distance in most cases. Additionally, the variations in the early age of shrinkage cracking show a dependency on the concrete compositions, temperature, and pumping characteristics.

Durability, mechanical, workability, and environmental assessment of self-consolidating concrete containing blast furnace slag and natural zeolite

This study aims to investigate the possibility of using industrial and natural supplementary cementitious materials (SCMs) in self-consolidating concrete (SCC) with lower embodied carbon. Binary and ternary blends of ground granulated blast furnace slag (GGBFS) and natural zeolite (NZ) at higher range replacements of up to 50 wt% of Portland cement (PC) were used. Ten SCC mixtures with various binder compositions were evaluated for workability, compressive strength, and durability properties, as well as corresponding environmental impacts based on life cycle assessment (LCA). A new approach for LCA's functional unit which specifies the required concrete cover and effective height for a beam section was used to include structural design and durability in environmental assessment. Utilizing GGBFS and NZ presents a positive synergistic effect resulting in improved water impermeability, electrical resistivity, and resistance to chloride migration compared to binary blends of GGBFS + PC or NZ + PC. LCA for a service life of 100 years showed the ternary SCC mixture with PC replacements of 10% NZ, and 40% GGBFS could reduce global warming potential by up to 38% compared to the control mixture without SCM. This study concludes that a cleaner SCC with enhanced properties and reduced environmental footprint can be achieved by replacing PC with blends of GGBFS and NZ up to 50 wt%.

Investigating the applicability of deep learning and machine learning models in predicting the structural performance of V-shaped RC folded plates

Reinforced concrete folded plates (RC-FPs), which are a special class of shell structures, have recently become very popular in modern architectural and engineering applications because of the need for lightweight and aesthetic structures to cover large areas. However, it is known that studies on the structural performance of RC-FPs are insufficient. Therefore, this article presents a study on the development and comparison of different deep learning (DL) and machine learning (ML) models for the prediction of the structural performance of full-scale V-shaped RC-FPs produced from hybrid fiber-reinforced self-consolidating concrete (HFR-SCC) having different plate thicknesses (50, 60, 70, and 80 mm), fiber volumes (1.00% and 1.25%), and combinations (single, binary, and ternary). While vanilla long short-term memory (VLSTM) and bidirectional long short-term memory (BILSTM) are used as DL models, random forest (RF), extremely randomized trees (ERT), and adaptive boosting (AdaBoost) are preferred for ML models. To construct the models, the structural performance results of a total of 44 full-scale V-shaped RC-FPs subjected to four-point bending loading were adopted as the database. In addition to all these, the AdaBoost model is used to determine the relative feature importance of the input parameters. Based on the results, among the DL models, the BILSTM has the best ability to predict the structural performance values of V-shaped RC-FPs (such as R-squared values for maximum load-bearing capacity, cracking load, toughness, and deflection ductility are 0.934, 0.987, 0.972, and 0.812, respectively), while in ML models, this is valid for the ERT (such as R-square values are 0.917 for maximum load-bearing capacity, 0.936 for cracking load, 0.947 for toughness and 0.825 for deflection ductility). On the other hand, DL models predicted all other structural performance values better than ML models, except for deflection ductility. Besides, the most relative important input features for maximum load-bearing capacity and toughness values is plate thickness, whereas for cracking load and deflection ductility values compressive strength is important. In conclusion, it can be emphasized that the use of DL models can provide significant advantages in engineering applications, such as predicting the structural performance of V-shaped RC-FPs.

Use of hybrid fibers and shrinkage mitigating materials in SCC for repair applications

Self-consolidating concrete (SCC) is used to repair structural elements with congested reinforcement or restricted access to placement and consolidation. In addition to adequate flowability, passing ability, filling capacity, and stability, adequate bonding to the substrate and reinforcing bars, low shrinkage and cracking resistance are required for successful repair. This study employs various shrinkage mitigating materials, including expansive agent (EA), coupled use of EA with shrinkage reducing admixture (SRA), and EA with pre-saturated lightweight sand (LWS) to fulfill these requirements. The effect of these materials on the performance of SCC made with a hybrid synthetic (PP) fiber and a hybrid steel-synthetic (STPP) fiber is investigated. The investigation included key fresh and hardened concrete properties and flexural performance of composite beams repaired using these materials. Test results show that the investigated fiber-reinforced self-consolidating concrete (FRSCC) mixtures can secure adequate workability and mechanical properties and low shrinkage, limited to 600 µstrain after 224 days. High EA content (10% by mass of binder) can lead to excessive expansion at early ages resulting in microcracking and drop in mechanical properties. The FRSCC made with 5% EA and 0.5% SRA, by mass of binder (5EA0.5SRA mixture), had superior mechanical properties (50 MPa compressive strength and 36 GPa modulus of elasticity). The cracking potential due to restrained shrinkage of this mixture is very low. The 5EA0.5SRA mixture made with hybrid synthetic fibers is successfully used to repair reinforced concrete beams prepared with various reinforcement ratios in the tension zone. The results indicate a 48% increase in first crack load, 4% gain in peak load, and 33% increase in flexural toughness compared to the monolithic beam cast with the conventional concrete. A comparison between the cracking load and ultimate flexural capacity of the repaired beams with estimated values by ACI 544 reveals the estimated to experimental ratio of 0.36–0.70 for cracking load and 0.56–0.74 for the flexural capacity. This can stem from the promotion of FRSCC concrete by the effect of hybrid synthetic fibers and the development of internally induced stress in the presence of shrinkage mitigating materials and fibers that led to higher mechanical properties and enhanced performance of FRSCC for repair. Reinforced beams repaired using FRSCC made with 0.5% hybrid synthetic fibers and combination of EA-SRA can reduce the steel reinforcement ratio by 21% to 27%, depending on the primary steel reinforcement.

Investigation on Mechanical Properties of Self-Consolidating Concrete containing Slag Aggregate

This paper presents the investigation results on self-consolidating concrete (SCC) produced with slag aggregate (SA). The characteristics of materials, sieve distribution of aggregates, design of self-consolidating concrete mixture and its fresh concrete properties test such as slump flow test, V-funnel, U-funnel and L-box are analyzed. The mechanical properties of SCC are with two different grades slag aggregate is tested for compressive strength (f’c), split tensile strength (fst), young’s modulus (Ec) and durability test. The investigation result on concrete mechanical properties shows that mix with larger aggregate exhibits higher values than the companion mix with smaller aggregate. Although it exhibits fairly optimum strength characteristics with slag aggregate substitution but the higher percentage of replacement affects the durability properties. This study leaves a positive way of application of slag aggregate in concrete.

Effect of Elevated Temperature on the Lightweight Aggregate Fibre Reinforced Self-Consolidating Concrete

This study comprehensively investigates fiber-reinforced self-compacting concrete (FRSCC) behavior across multiple grade variations, namely M20, M30, and M40. The study encompasses substituting conventional natural aggregate with sintered fly ash, exploring replacement percentages of 10%, 20%, and 30%. The primary objective of this study is to identify the optimum Strength achieved through a 20% replacement ratio. The assessment of fresh properties of FRSCC was undertaken through rigorous testing protocols involving the L box, J ring, and V funnel tests, following the guidelines stipulated by the European Guidelines for Self-Compacting Concrete (EFNARC). Furthermore, the research extensively analyzed vital mechanical properties, including compressive Strength, split tensile Strength, and flexural Strength. These evaluations provided insights into the influence of sintered fly ash incorporation on the structural performance of FRSCC. The investigation extended to a post-curing temperature study, subjecting the concrete specimens to varying temperatures of 100 °C, 300 °C, 600 °C, and 900 °C, followed by exposure to a 1000 °C heating furnace for 3 hours at each designated temperature. The outcomes of this research yield valuable insights into the potential improvements in the mechanical and thermal properties of FRSCC by integrating sintered fly ash. This study is pertinent for professionals and researchers engaged in optimizing the formulation and utilization of fiber-reinforced self-compacting concrete, with implications for sustainable construction practices and enhanced resilience in diverse thermal conditions. Index Terms: Fibre reinforced lightweight self-compacting concrete, Fly Ash, Sintered fly ash Aggregate, Lightweight Sintered fly ash aggregate concrete, lightweight self-consolidating concrete, Crimped steel fiber.

Development of self-consolidating concretes based on recycled aggregates: Effect of parent concrete strength

Self-consolidating concrete is a recent type of highly fluid concrete. The high paste concentration ensures excellent rheological behavior. Concrete includes can be selected with durability aims in mind, considering the severe conditions to which the concrete will be exposed. However, the irregularity of recycled aggregates (initial properties unknown from the old concrete) leads to a need for more knowledge of durability indicators. This research is an experimental evaluation of the characteristics of SCC made with recycled aggregates and sand whose initial parent concrete strength was specified. Three ranges of parent concrete strength were chosen (20 to 30 MPa, 35 to 45 MPa, and above 50 MPa). The main objective is to study the effect of introducing recycled concrete aggregates on the mechanical behavior and durability of SCC (total immersion in water and capillary absorption). The test specimens were analyzed after 28 days of curing. The findings demonstrate increased durability and mechanical behavior were achieved using recycled aggregates with high strength in the parent concrete. However, the mechanical strength and durability of SCCs are reduced when recycled concrete aggregates with low parent concrete strength (20 to 30 MPa) are used in the mix.

Aloe Vera-Based Concrete Superplasticizer for Enhanced Consolidation with Limestone Calcined Clay Cement

Self-consolidating concrete (SCC) is renowned for its outstanding workability and ability to seamlessly flow into intricate structures with minimal vibrations, achieved through the incorporation of chemical admixtures. This study pioneers an innovative approach by exploring the use of the cost-effective and readily available plant extract aloe vera mucilage (AVM) as a bio-admixture for SCC. The primary objective is to assess the impact of AVM on SCC formulations, including those comprising ordinary Portland cement (OPC) and blended cement LC3 (clinker 50%, calcined waste clay 30%, limestone 15%, gypsum 5%). AVM is applied at varying dosages at up to 10%. Findings reveal that LC3 exhibits lower consistency, reduced slump values, and extended initial and final setting times compared to OPC. With increasing plasticizer dosage, V-funnel and L-box values decrease. Notably, OPC samples with both plasticizers outperform LC3 in compressive strength at 7, 14, and 28 days. Significantly, a 2.5% AVM dosage demonstrates enhanced compressive strength in both OPC and LC3 samples. In summary, this research positions AVM as an innovative and comparable alternative to commercial plasticizers, contributing to reduced yield stress and increased slump flow in SCC.

Pressure-based analysis of rheological equilibrium distances of pumped self-consolidating concrete (SCC)

The influence of pumping on the rheological properties of self-consolidating concrete (SCC) is widely recognized, but there is still limited understanding of its behavior within the pipeline. In this study, we propose a novel approach using equilibrium distances to investigate the evolution of rheological properties along the pipeline. Full-scale horizontal pumping circuits spanning 328 m were established to assess the axial development of SCC's rheological properties. Thirteen mixtures, with water-to-cement (w/c) ratios ranging from 0.22 to 0.27, were pumped at discharge rates varying from 5.77 to 12.69 L/s. Our findings show that for pumping setups and material studied, both the w/c ratio of SCC and the discharge rate significantly affected the influence of rheological equilibrium distances on pressure loss gradient changes. In all tested samples, viscosity values required the entire length of the pipeline to reach post-pumping levels, while yield stress values rapidly achieved their fully developed state upon entering the pipeline. Importantly, the predicted pressure loss displayed a strong correlation with experimental measurements, with an accuracy of 89.42% across all tested mixtures. Our predictive model showed an average improvement of 4.6% in accuracy compared to the linear approach, with the most significant enhancement observed in samples with higher w/c ratios. This research sheds new light on the behavior of SCC during pumping and provides valuable insights for optimizing the pumping process.