High Strength Self-compacting Concrete Research Articles

Effect of high-strength SCC with and without steel fibres on the shear behaviour of dry joints in PCSBs

The structural behaviour of precast concrete segmental bridges (PCSBs) heavily relies on the strength of the joints between segments. Multi-keyed dry joints are currently the most commonly used solution in these discontinuity zones. Employing high-strength concrete is becoming increasingly common in civil engineering given its higher strength and improved durability. It specifically allows higher prestressing levels in PCSBs. Using self-compacting concrete enhances workability and adding steel fibres improves mechanical properties. The existing scientific literature includes experimental tests to analyse the shear behaviour of castellated dry joints in different concrete types. However, no experimental tests appear specifically for the castellated dry joints made with high-strength self-compacting concrete (HS-SCC) with and without steel fibres. Therefore, this experimental study conducted 31 push-off-type tests to analyse the behaviour and shear capacity of dry joints made of HS-SCC by investigating the influence of adding steel fibres to the concrete mix. The study examined crack patterns, load-displacement behaviour, failure modes and different (cracking, ultimate and residual) loads. The addition of steel fibres improved joints’ shear capacity. However, brittle behaviour was observed after reaching ultimate load when using HS-SCC, even when steel fibres were added to the concrete mix. Finally, the adequacy of existing formulations was analysed. Standard AASHTO proved to be on the unsafe side for the castellated dry joints specimens made of HS-SCC without steel fibres, and provided a good approximation for the specimens with steel fibres.

High-Strength Self-Compacting Concrete Production Incorporating Supplementary Cementitious Materials: Experimental Evaluations and Machine Learning Modelling

AbstractThis study investigates mechanical properties, durability performance, non-destructive testing (NDT) characteristics, environmental impact evaluation, and advanced machine learning (ML) modelling techniques employed in the analysis of high-strength self-compacting concrete (HSSCC) incorporating varying supplementary cementitious materials (SCMs) to develop sustainable building construction. The findings from the fresh characteristics test indicate that mixes’ optimal flowability and passing qualities can be achieved using different concentrations of marble powder (MP) alongside a consistent amount of silica fume (SF) and fly ash (FA). Moreover, the incorporation of 10% MP along with 10% FA and 20% SF in HSSCC significantly improved the compressive strength by 14.68%, while the splitting tensile strength increased by 15.59% compared to the reference mix at 56 days. While random forest (RF), gradient boosting (GB), and their ensemble models exhibit strong coefficient correlation (R2) values, the GB model demonstrates more precision, indicating reliable predicted outcomes of the mechanical properties. Following subsequent testing, it has been demonstrated that incorporating SCMs improves the NDT properties of HSSCC and enhances its durability. The finer MP, SF, and FA particles enhanced microstructural performance by minimizing voids and cracks while improving the C–H–S bond. As noticed by its lower CO2-eq per MPa for SCMs, the HSSCC mix with up to 15% MP inclusion increased mechanical strength while reducing the environmental footprint, making it an eco-friendly concrete alternative.

Characteristics of self-compacting green concrete

Locally, conventional concrete is still created utilizing river sand and crushed stone as filer materials. The massive quarry dust by-product remain untapped in the production of concrete. The coal-fired power station produce significant quantities of Type F fly ash. Self-compacting concrete (SCC) provides many advantages for creating high-quality concrete. Consequently, the main objective of this research is to create a mix design for high-strength SCC utilizing a binary blends, hybrid fibers and fine aggregates that meet both hardened and fresh concrete characteristics. The study is conducted in amendment of w/b ratio, superplasticizer, proportion of fine aggregate to coarse aggregate, optimumal cement replacing by fly ash, dosage of low macro fibre and micro fibre. Mix-50c-X is the best mix design that was produced. The mix quantity for 1m3 concrete was 315 kg Class F fly ash, 315 kg OPC, 630 kg quarry dust, 508 kg river sand, 400 kg coarse aggregate, 0.7% superplasticizer,0.32% w/b, 0.10% macro fiber, and 0.01% micro fiber. This SCC mixture showed fresh characteristics as well as compressive strengths of more than 22 MPa and 62 MPa after 1 day and 28 days, respectively. The results of high-strength SCC demonstrated the enormous potential for the local construction, especially precast product.

Performance of self-compacting concrete with treated rice husk ash at different curing temperatures

Self-compacting concrete (SCC) is currently gaining traction as a replacement to conventional vibrated concrete. Its distinct microstructure leads to varied mechanical behaviour under different curing temperatures. In the past various supplementary cementitious materials (SCMs) were used in SCC to investigate their respective effects on the performance. However, there has been no systematic studies conducted to determine the effect of different curing temperature on the sensitivity reaction of rice husk ash (RHA) in SCC. This research focuses on high-strength SCC with SCMs such as RHA, silica fume (SF), fly ash (FA), and ground granulated blast-furnace slag (GGBS), exploring their applicability for concrete structures under varying curing temperatures. Heat of hydration, compressive strength and open porosity of SCC specimens were assessed at various temperature. Results indicate high curing temperatures expedite the hydration and pozzolanic reaction, refining the microstructure and increasing the early-age concrete strength, but compromising the long-term performance, potentially mitigated by the use of SCMs. Conversely, lower curing temperature, impedes hydration leading to gradual strength gain, particularly with SCMs, yet yielding significant strength increases at later concrete age. SCMs presence and curing temperature significantly influence maturity function-based strength predictions, impacting strength trends in the samples studied.

Performance evaluation of indented macro synthetic polypropylene fibers in high strength self-compacting concrete (SCC)

Concrete is used worldwide as a construction material in many projects. It exhibits a brittle nature, and fibers' addition to it improves its mechanical properties. Polypropylene (PP) fibers stand out as widely employed fibers in concrete. However, conventional micro-PP fibers pose challenges due to their smooth texture, affecting bonding within concrete and their propensity to clump during mixing due to their thin and soft nature. Addressing these concerns, a novel type of PP fiber is proposed by gluing thin fibers jointly and incorporating surface indentations to enhance mechanical anchorage. This study investigates the incorporation of macro-PP fibers into high-strength concrete, examining its fresh and mechanical properties. Three different concrete strengths 40 MPa, 45 MPa, and 50 MPa, were studied with fiber content of 0–1.5% v/f. ASTM specifications were utilized to test the fresh and mechanical properties, while the RILEM specifications were adopted to test the bond of bar reinforcements in concrete. Test results indicate a decrease in workability, increased air content, and no substantial shift in fresh concrete density. Hardened concrete tests, adding macro-PP fibers, show a significant increase in splitting tensile strength, bond strength, and flexural strength with a maximum increase of 34.5%, 35%, and 100%, respectively. Concrete exhibits strain-hardening behavior with 1% and 1.5% fiber content, and the flexural toughness increases remarkably from 2.2 to 47.1. Thus, macro PP fibers can effectively improve concrete's mechanical properties and resistance against crack initiation and spread.

Microstructure and durability properties of high strength self-compacting concrete using micro silica and nano silica

Microstructure and durability properties of high strength self-compacting concrete using micro silica and nano silica

High Strength Self-Compacting Concrete's (HSSCC) Fluidity and Mechanical Properties: An Experimental Study

High Strength Self-Compacting Concrete's (HSSCC) Fluidity and Mechanical Properties: An Experimental Study

High-strength self-compacting concrete produced with recycled clay brick powders: Rheological, mechanical and microstructural properties

High-strength self-compacting concrete (HSSCC), which has superior workability and filling ability compared to conventional concrete, is increasingly used in modern densely reinforced structures in the construction industry. However, HSSCC is more costly to produce than conventional concrete and can result in higher carbon emissions due to higher cement usage. On 6 February 2023, the devastating Kahramanmaraş earthquakes in Türkiye created a serious environmental problem. In this context, recycling and utilizing construction demolition waste (CDW), which creates a serious environmental problem after devastating earthquakes and urban transformations, can contribute to the economy of countries and environmental waste problems. In this study, to produce HSSCC more economically, sustainably, and environmentally, HSSCC series were produced using fly ash (FA) and recycled clay brick powders (RCBP) obtained from CDWs in certain proportions by weight instead of cement. For this purpose, seven different series of HSSCC were produced. FA and RCBP were used separately in the mixtures at 0% (control), 10%, 15%, and 20% by weight instead of cement. The fresh HSSCC series were then subjected to workability tests and cured for 28, 56, and 90 days. At the end of the curing period, physical and mechanical property tests and internal structure analyses by scanning electron microscopy (SEM) were performed on the HSSCC series. In addition, sensitivity analysis was performed using multiple linear model analysis to determine which parameters affect which properties in HSSCC designs. Although the highest workability loss in fresh HSSCCs was in the blend series where 20% RCBP was used, all of the blends provided fresh SCC properties by the standards. In general, the increase in FA and RCBP used in the HSSCC series decreased the 28-day compressive strengths (except RCBP10), while the strength losses gradually decreased as the curing age increased and at the end of 90 days; the compressive strengths of FA10 (71.9 MPa with 1.6% increase), RCBP10 (74.8 MPa with 5.6% increase) and RCBP15 (71.5 MPa with 1% increase) series were obtained above the control series (70.8 MPa). SEM analyses performed at the end of the study showed that HSSCC specimens with 10% RCBP replacement contained more intense hydration products and fewer pores than the other series.

Influence of Glass Microfibers on the Control of Autogenous Shrinkage in Very High Strength Self-Compacting Concretes (VHSSCC)

High-performance concrete (HPC) is widely used in infrastructure for its durability and sustainability benefits. However, it faces challenges like autogenous shrinkage, leading to potential cracking and reduced durability. Fiber reinforcement offers a solution by mitigating shrinkage-induced stresses and enhancing concrete durability. In this sense, this study investigates the use of glass microfibers to mitigate autogenous shrinkage and early-age cracking in high-strength self-compacting concrete. Samples were prepared with two water-to-binder ratios (w/b): 0.25 and 0.32; and three glass microfiber contents: 0.20%, 0.25%, and 0.30 vol.%. The concrete mixtures were characterized in the fresh state for slump flow and in the hardened state for compressive strength, static, and dynamic Young’s modulus. Unrestrained and restrained shrinkage tests were also conducted in the seven days-age. The findings revealed that glass microfibers reduced the workability in mixtures with lower slump flow values (w/b of 0.25), while less viscous mixtures (w/b of 0.32) exhibited a slight improvement. Compressive strength showed a proportional enhancement with increasing fiber contents in concretes with a w/b ratio of 0.32. A contrasting trend emerged in concretes with a w/b ratio of 0.25, wherein strength diminished as fiber additions increased. The modulus of elasticity improved with fiber additions only in the matrix with a w/b ratio of 0.25, showing no correlation with compressive strength results. In shrinkage tests, the addition of glass microfibers up to specific limits (0.20% for a w/b ratio of 0.25 and 0.25% for w/b of 0.32) demonstrated improvements in controlling concrete deformation in unrestrained shrinkage analyses. Concerning cracking reduction in restrained concrete specimens, the mixtures did not exhibit significant improvements in crack prevention.

Influence of coatings on residual strength of geopolymer concrete columns subjected to fire exposure: An experimental investigation

Fires occurring within buildings present a grave concern, as they entail substantial risks to human lives, property, and the environment. Implementing appropriate fire safety measures becomes imperative to mitigate the occurrence of fires and ensure efficient response in the event of an incident. The primary aim of the study is to examine the performance of various coatings on the residual strengths of the reinforced normal strength self-compacting geopolymer concrete (NSGC) and high strength self-compacting geopolymer concrete (HSGC) columns subjected to standard temperature exposure in accordance with ISO 834 guidelines. The design compressive strength of the concretes was 36.12, 57.06 and 52.8 MPa. Two types of coating were employed in the present investigation namely ceramic wool wrapping and high alumina cement. A computerized electric furnace is used to heat the column specimens. Amongst the forty-two columns developed, six specimens tested without temperature exposure and protective coating as a reference specimen. Twelve specimens were heated as per ISO fire curve and tested to assess the residual axial strength performance and twenty-four specimens were coated with protective layers, then heated and tested to assess the post fire performance. It is exemplified that the composite protective coating offers effective resistance to concrete, gaining optimum axial strength performance. The findings show that these fire protecting composites have a high potential for utilizing as new strengthening techniques for reinforced concrete (RC) columns.

Experimental study on the effect of colloidal nano silica in high strength self-compacting concrete containing ground granulated blast furnace slag

Self-compacting concrete (SCC) is profusely utilized in building construction due to its unique design and mechanism of flow without segregation by occupying the corners and preventing the voids to achieve better compaction and mechanical strength. This work addresses the effect of colloidal nano-silica (NS) of size 5-40nm with an active nano solids content of 32% on the high-strength SCC containing Ground Granulated Blast Furnace Slag (GGBFS) and Ordinary Portland Cement as binders in addition to NS. The liquid content of 68% in NS was added to the water content in the mix. The ratios of NS were evaluated at 0%,0.5%,1%,1.5%, 2% and GGBFS as 20% by weight of binder in concrete. The water to binder ratio was 0.33 with a water and binder content of 184kg/m3 and 557.58 kg/m3. The optimum mix was 1.5% NS based on the concrete’s slump and compressive strength at 28 days. The slump was reduced with a rise in NS beyond 1.5% due to the accumulation of NS particles causing the reduction in flowability. The density of SCC for all the mixes was satisfactory. The compressive strength of optimum SCC, M21.5NS20G was decreased by 5.88% and increased by 0.49% and 2.45% at 7, 28 and 91 days to that of the reference mix whereas its split tensile strength was risen by 31.13%, 9.27%, and 12.41% and flexural strength was risen by 5.8% and reduced by 8.17% and 4.06% to that of the reference mix at aforementioned durations. The SEM and XRD analyses were conducted on the optimum hardened SCC mix at 28 days in which the presence of Calcium silicate hydrate compounds of different crystalline structures, viz., Ettringite, and Portlandite were observed. The SCC designed in the work can be used for structural applications such as beam-column joints.

Influence of GGBFS and Silica Fume on the Properties of High-Strength Self-Compacting Concrete

When the compaction of concrete becomes challenging to carry out, Self-Compacting Concrete (SCC) is considered as an alternative to ordinary concrete. The aim of the present work is to obtain high-strength SCC by substituting Ground Granulated Blast Furnace Slag (GGBFS) and Silica Fume (SF) for cement. GGBFS and SF have been extensively employed as admixtures in recent years to produce high-strength concrete. SCC was created as a reference mix without any mineral admixtures, whereas the other mixes had varying amounts of GGBS and SF. The remaining six mixtures contained various concentrations of GGBFS from 10 to 30 percent with variations of 10% and silica fume from 5 to 15 percent with variations of 5 percentile. As workability is the primary attribute of SCC, various flowability features, including the Slump test, V funnel, and L box test were recognized. Studies on mechanical performance and durability properties were conducted. At 28 days, a ternary combination of 30% GGBS and 5% SF reaches its maximum compressive strength of 70.12 MPa. Also, when SF is replaced with 5% and GGBFS with 30% by weight of cement, the results showed better improvement in durability.

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Designing sustainable high-strength self-compacting concrete with high content of supplementary cementitious materials

A sustainable and green approach to concrete mix design is fundamental for the construction sector in terms of reducing carbon dioxide ( CO 2 ) emissions and conserving non-renewable natural resources. This article proposes a novel mix design method for sustainable high-strength self-compacting concrete (HSSCC) based on rheological and mechanical properties with the aim of reducing cement content in such mixes. HSSCC mixes were designed using ground granulated blast furnace slag (GGBS) and fly ash to replace up to 40% of the cement content and tested for target compressive strengths ranging between 70 and 100 MPa. The proposed design method was numerically programmed to provide straightforward and realistic guidance in the form of design charts and verified through the design and production of sixteen HSSCC mixes consisting of varying sand-to-aggregate ratios (S/A). All mixes satisfied the self-compacting concrete criteria in the fresh state and achieved the targeted viscosity and compressive strength values. The effects of S/A and paste-to-solid (P/S) ratios on the rheological properties were evaluated. The experimental results demonstrated that the proposed mix design method could produce HSSCC with excellent fresh and mechanical characteristics while being eco-efficient with respect to CO 2 emissions and cement consumption.

Flexural Behavior of Normal and High Strength Self-Curing Self- Compacted Concrete Beams of Local Materials

In some construction industries, there are difficulties in achieving the required concrete compaction, Self-compaction is an alternative option. Working with self-compaction self-curing concrete requires a unique approach. This study aims to examine the possibility of producing self-compacting concrete with normal and high self-cure rates. This research observed how both the self-curing and self-compacting concrete behaved under normal and high-strength conditions. Two stages were prepared for this investigation. The first stage of this research studied the effect of a curing agent on the fundamental characteristics of both normal-strength and high-strength self-compacting concrete, with the aim of achieving self-curing self-compacting concrete. The primary variables of this study include the grade of concrete, the type of curing agent, the reinforcing bars, and the dosage of these variables. In the second stage, reinforced concrete beams were cast with one of the two proposed concrete types, and their behavior was studied. The findings were analyzed in terms of the beginning cracking loads, the ultimate loads, and the crack patterns of the testing beams. According to the results, both the normal-strength and the high-strength varieties of self-curing self-compacting concrete are effective in providing structural features, which are absent from the processes of curing and compacting. Curing chemicals are utilized to mitigate the process of water evaporation in self-compacting concrete, hence enhancing the water retention capabilities of self-compacting concretes that possess enough hardened concrete characteristics.

Effect of Agricultural Phragmites, Rice Straw, Rice Husk, and Sugarcane Bagasse Ashes on the Properties and Microstructure of High-Strength Self-Compacted Self-Curing Concrete

Each year, billions of tons of agricultural waste are generated globally. Egypt, being an agriculturally centered nation, faces significant challenges in disposing of this waste and coping with self-germinating plants that negatively impact agriculture. The common practice among farmers is to burn the waste, which exacerbates environmental concerns. With the global shift towards eco-friendly concrete, this study explores the utilization of agricultural waste ashes, particularly those abundant in Egypt and numerous other countries worldwide. Among the researched waste ashes are Phragmites ash (PGA), sugarcane bagasse ash (SBA), rice husk ash (RHA), and rice straw ash (RSA). This investigation examines the impact of partially substituting cement with varying ash percentages from these wastes on the characteristics and properties of fresh and hardened high-strength self-compacting self-curing concrete (HSSCSCC). The findings indicate the potential applicability of these ashes in producing HSSCSCC, specifically highlighting the promising outcome of PG ash, which exhibited favorable results as a new type of natural ash suitable for the concrete industry.

Mechanical and shrinkage performance of steel fiber reinforced high strength self-compacting lightweight concrete

This study investigated the effects of mixture proportion on the mechanical and shrinkage behaviors of steel fiber reinforced high strength self-compacting lightweight concrete (SHSLC) mixtures incorporating bottom ash aggregates for internal curing. In this study, different types of fine aggregates, fine aggregate ratios, supplementary materials such as silica fume (SF) and colloidal nano-silica (CNS), and four types of steel fibers were considered to develop SHSLC. The self-compacting characteristics of concrete were evaluated by means of slump flow, J-ring flow, and V-funnel tests. The test results indicate that incorporation of SF and CNS had a positive effect on the mechanical properties, but 4% incorporation of CNS decreased workability and strength due to the agglomeration of mixture. The addition of steel fibers improved compressive strength, and flexural toughness of SHSLC, but reduced the flowability and passing ability with increased fiber contents. Due to the internal curing from coarse bottom ash, significant reduction of autogenous shrinkage up to 33% was observed, whereas 7% for drying shrinkage. The incorporation of fibers reduced the autogenous and drying shrinkage up to 31% and 22% compared with non-fiber reinforced concrete, respectively. Finally, the autogenous shrinkage behavior was simulated with several models in the literature, and a model for high strength self-compacting lightweight concrete with and without fibers considering equivalent age was proposed.

Parametric Sensitivity Analysis of High-Strength Self-compacting Alkali-Activated Slag Concrete for Enhanced Microstructural and Mechanical Performance

Parametric Sensitivity Analysis of High-Strength Self-compacting Alkali-Activated Slag Concrete for Enhanced Microstructural and Mechanical Performance

Effect of fibre diameter and tensile strength on the mechanical, fracture, and fibre distribution properties of eco-friendly high-strength self-compacting concrete

The development of Steel Fibre-Reinforced Self-Compacting Concrete (SFR-SCC) is a complex task with significant practical implications for the construction industry. However, the absence of established design guidelines and recommendations, and the limited availability of design methodologies, present a significant challenge. Achieving the targeted rheological and mechanical properties while simultaneously minimising production costs requires a comprehensive understanding of the optimal blend of fibre type and quantity and the coarse aggregate content. This paper addresses the impact of steel fibre properties on the rheological and fundamental mechanical properties of eco-friendly high-strength self-compacting concrete (HSSCC), using 40% ground granulated blast furnace slag (GGBS) as a cement replacement. The research focused on 30 mm long hooked-end steel fibres with tensile strengths of 1345 MPa and 3070 MPa, and diameters of 0.55 mm and 0.38 mm, respectively. In addition, the study investigated the combined effect of coarse aggregate content and steel fibre type on the performance of eco-friendly HSSCC. The fresh properties of eco-friendly HSSCC were assessed using the slump flow and J-ring tests. Furthermore, mechanical and fracture properties such as compressive strength, splitting tensile strength, elastic modulus, four-point flexural strength, and three-point flexural strength on notched prisms were also evaluated. The distribution and alignment of steel fibres in the HSSCC were assessed using image analysis techniques, which showed that the steel fibre diameters were a crucial factor in the fibre dispersion. The results demonstrated that using steel fibres with higher tensile strength and smaller diameter significantly enhanced the splitting tensile strength, flexural strength, and fracture energy, compared to steel fibres with larger diameters and lower tensile strengths. Additionally, the study indicated that the elastic modulus and fracture energy of eco-friendly HSSCC reinforced with both types of steel fibre are highly dependent on the content of coarse aggregate used. The study highlighted that the coarse aggregate proportion and the steel fibre characteristics were two vital factors that influenced the rheological and mechanical properties of HSSCC and must be considered during the mix design process to optimise the desired properties while also minimising production costs.

Feasibility of waste foundry sand in high-strength self-compacting concrete and the effects of elevated temperatures

The disposal and recycling of waste foundry sand (WFS) as industrial solid waste can effectively solve potential environmental pollution problems. This paper conducted an experimental investigation on the effects of elevated temperatures on mechanical properties and microstructural characteristics of high-strength self-compacting concrete (HSSCC) incorporating WFS for substituting river sand with different contents (i.e., 0%, 25%, 50%, 75% and 100% by weight). The workability of fresh concrete including slump flow, J-ring, T500, and V-tunnel box tests were first measured. A series of tests including ultrasound pulse velocity (UPV), residual compressive strength and the behavior of capillary water absorption were conducted before and after different temperatures (100 °C, 200 °C, 300 °C, 400 °C) following an air-cooling time. Further, the thermal analysis and microstructural observation were conducted for the evaluation of high-temperature damage evolution by using thermogravimetry (TG), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). The test results showed that the specimens obtained excellent self-compaction performance at 50% WFS replacement rate. The coupling effect of WFS substitution rate and temperature level has a large effect on the mechanical properties and thermal resistance. Compared with the control group, the 28-day compressive strength of HSSCC-WFS50 was increased by 8.2%. In addition, thermal analysis tests (TG/DTG/DSC) and SEM also elucidated the changes of HSSCC-WFS products and microstructures at high temperature from a fine microscopic perspective to reveal the deterioration mechanism of HSSCC-WFS durability after high temperature damage.