High Strength Self-compacting Concrete Research Articles

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.

Experimental and theoretical investigation for shielding efficiency of self-compacted concrete containing lead smelting waste for gamma ray

Lead smelter waste is considered as one of the most hazardous waste that pollute the environment by releasing hazardous effluents, a lot of particle matter, and other different solid wastes. In this research lead smelter waste is used as a concrete additive and fine aggregate constituent in self-compacted concrete casting to be used as a gamma ray shield. Three types of traditionally used coarse aggregate (basalt, crushed dolomite, and gravel) were used in casting normal and high strength self-compacted concrete. The fresh and hardened concrete properties were investigated. The cast samples were tested for 137Cs and 60Co gamma rays with energies 0.662 and 1.25 Mev. The mass attenuation coefficients (µ/ρ) and linear attenuation (µ) were measured and calculated using WinXCom program for gamma rays. The experimental measurements and the used theoretical calculation method were highly compatible. The usage of lead smelter waste in concrete casting improved the concrete gamma rays shielding.

Fresh, mechanical and microstructural behaviour of high-strength self-compacting concrete using supplementary cementitious materials

Sustainable practices in the construction sector have become a major issue due to the overuse of natural raw materials. Industrial by-products like fly ash (FA), silica fume (SF), and marble powder (MP) incorporation in concrete production will be assessed in this paper in terms of fresh, mechanical, and microstructural states. Consequently, this study proposes an in-depth investigation of SCMs applied with varied substitute cement amounts, looking at components like MP, SF, and FA. The impacts on fresh characteristics of HSSCC were assessed using slump flow, V-funnel time, T50 time, L-box ratio, and J-ring slump flow. Compressive, flexural, and splitting tensile strength tests were performed to analyze the mechanical properties. Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM) techniques were used for the microstructural examination of HSSCC. It has been found that SCMs, including MP, FA, and SF, may enhance the characteristics of concrete. The slump flow values, which indicate the flowability and filling ability of HSSCC, were improved by a maximum of 9.6 % for 20 % SF and 10 % for both FA and MP replacement. The most promising outcomes on the basis of mechanical operation were gained by using SF, MP, and FA in HSSCC at respective percentages of 20 %, 10 %, and 10 %. This mixture revealed an increase in compressive strength of a maximum of 15 % at 56 days compared to the control mixture, which contained 10 % MP. However, the excessive addition of MP negatively impacted the strength of the concrete. The EDS examination illustrated that the ‘Ca’ to ‘Si’ proportion in HSSCC significantly affects the emergence of strength. This study will enlighten users during the preparation of high-strength self-compacting concrete (HSSCC) by replacing ordinary Portland cement (OPC) with different available supplementary cementitious material (SCM) combinations.

Axial compressive behaviour and physical characteristics of high strength self-compacting geopolymer concrete (HSGC) columns exposed to elevated temperature

The growing demand in the utilization of the cement has increased carbon emissions, necessitating the adoption of new technologies that are eco-friendly. Geopolymer concrete (GC) is a viable alternative to traditional cement-based concrete, with superior mechanical properties and sustainable performance. However, research on the elevated temperature exposure of geopolymer paste, mortar, and concrete is limited, particularly with respect to high-strength and self-compacting geopolymer concrete. This study aims to investigate the performance of high-strength self-compacting geopolymer concrete (HSGC) at room temperature and elevated temperatures up to 1029 ℃. The investigation is carried out consisting of two strength grades: normal strength GC and HSGC. Tests are conducted on both HSGC cube and column specimens to examine the residual compressive strength (CS) and axial compression performance of the concrete before and after exposure to elevated temperature. The fresh physical characteristics of HSGC are examined following EFNARC guidelines. Post-fire performance is analysed through physical observation, surface modification, crack pattern, weight loss (WL), and residual CS of HSGC samples. Load-Moment (P-M) interaction curves are developed to predict the ultimate load and ultimate moment capacity of the HSGC columns before and after exposure to elevated temperature. The ductility of heated and unheated HSGC columns is found to be almost same. Microstructural analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are performed to examine the internal morphology of the HSGC samples before and after exposure to elevated temperature. Furthermore, a life-cycle assessment (LCA) is conducted to compare the cost of HSGC production with conventional cement-based concrete. The analysis indicates that HSGC emits 6.15% less CO2-e than its counterpart cement-based concrete.

Self-Compacting High-Strength Textile-Reinforced Concrete Using Sea Sand and Sea Water.

In this study, a self-compacting high-strength concrete based on ordinary and sulfate-resistant cements was developed for use in textile-reinforced structural elements. The control concrete was made from quartz sand and tap water, and the sea concrete was made from sea water and sea sand for the purpose of applying local building materials to construction sites in the coastal area. The properties of a self-compacting concrete mixture, as well as concrete and textile-reinforced concrete based on it, were determined. It was found that at the age of 28 days, the compressive strength of the sea concrete was 72 MPa, and the flexural strength was 9.2 MPa. The compressive strength of the control concrete was 69.4 MPa at the age of 28 days, and the flexural strength was 11.1 MPa. The drying shrinkage of the sea concrete at 28 days exceeded the drying shrinkage of the control concrete by 18%. The uniaxial tensile test showed the same behavior of the control and marine textile-reinforced concrete; after the formation of five cracks, only the carbon textile reinforcement came into operation. Accordingly, the use of sea water and sea sand in combination with a cement with reduced CO2 emissions and textile reinforcement for load-bearing concrete structures is a promising, sustainable approach.

Impact and durability properties of alccofine-based hybrid fibre-reinforced self-compacting concrete

Many research works have already been made and are still in progress on metallic fibres, as their incorporation reduces the brittleness of the concrete and improves its resistance to the impact and crack propagation. But the use of such non-metallic fibres may induce corrosion which is a major problem to be addressed from the durability aspect. To overcome this problem, in the present research work, a non-metallic hybrid fibre combination was investigated with synthetic fibres like polypropylene and abaca fibres. Also, rather than using conventional cementitious materials such as silica fume, fly ash, and ground granulated blast furnace slag, a new generation of ultra-fine material namely alccofine was used as a partial replacement for the cement by 15%. Abaca fibre was utilised in a constant addition of 0.5% and blended with polypropylene fibre in a range varying from 0% to 2% with an increment of 0.5%. The fresh properties of self-compacting concrete (SCC) in mono and hybrid fibres combinations were assessed through slump flow, J-ring, and V-funnel tests. Water absorption and sorptivity tests were conducted to ensure the durability of the prepared mix. Further, impact tests were carried out on the prepared cylinder specimens to check the capability of the mix with the non-metallic hybrid combination. The main objective here was to check whether a high-strength durable SCC could be achieved using non-metallic fibres and natural fibres. From the obtained experimental results, it was observed that 15% alccofine as a partial substitute to the cement with the addition of 0.5% of abaca fibre and 2% of polypropylene fibre to SCC performed better than the control SCC.

Deep learning based concrete compressive strength prediction model with hybrid meta-heuristic approach

In concrete design, the compressive strength of the concrete is the critical parameter that defines the quality of concrete. Determination of the compressive strength of concrete by laboratory testing is the conventional way, however, with the help of advancements in technology, the development of an exact predicting technique for the compressive strength of concrete will reduce time as well as cost to a greater extent. There are various types of concrete, as concrete is the most used material and has wide applications in the construction sector and hence huge article is being done to increase the performance of concrete. In this paper, the compressive strength of High-Performance Concrete and Fiber Reinforced High Strength Self-Compacting Concrete is predicted by next three main stages, namely (a) pre-processing, (b) feature extraction, and (c) prediction of concrete compressive strength. Initially, in the data pre-processing phase, duplicate data samples are removed. Subsequently, various features like statistical features, symmetrical uncertainty-based features, higher order statistical features, ReliefF feature, and are derived from the pre-processed data. In the prediction phase of concrete compressive strength, a hybrid algorithm is designed by mingling the concepts of Deep Belief Network and Long Short-Term Memory. Moreover, The Rock Hyraxes Updated Sparrow Algorithm is used to fine-tune the weights of DBN to improve the prediction accuracy of the suggested work. The suggested hybrid optimization method is the hybridization of the standard Sparrow Search Algorithm and Rock Hyraxes Swarm Optimization, respectively. Eventually, the output from the optimized hybrid method will reveal the compression energy of concrete. Ultimately, the efficiency of the suggested method is verified by the comparative estimation. The MAPE of the suggested method is 235.32, which is 30.6%, 21.64%, 20.4%, and 11.4% superior than the CLPSO, ABC, SSA + Hybrid Classifier and RHSO + Hybrid Classifier, respectively.

Mechanical Properties and Crack Resistance of Basalt Fiber Self-Compacting High Strength Concrete: An Experimental Study.

Pure self-compacting concrete has many disadvantages, such as early shrinkage and cracking. The addition of fibers can effectively improve the properties of resistance to tension and cracking of self-compacting concrete, thereby the effect of improving its strength and toughness can be achieved. Basalt fiber is a "new green industrial material" that has unique advantages, such as high crack resistance and being lightweight compared with other fiber materials. In order to study the mechanical properties and crack resistance of basalt fiber self-compacting high-strength concrete intensively, the self-compacting high-strength concrete of C50 was designed and obtained using the absolute volume method with multiple proportions. Orthogonal experimental methods were used to study the influence of the water binder ratio, fiber volume fraction, fiber length, and fly ash content on the mechanical properties of the basalt fiber self-compacting high-strength concrete. Meanwhile, the efficiency coefficient method was used to determine the best experiment plan (water binder ratio 0.3, fiber volume ratio 0.2%, fiber length 12 mm, fly ash content 30%), and the effect of fiber volume fraction and fiber length on the crack resistance of the self-compacting high-performance concrete was investigated using improved plate confinement experiments. The results show that (1) the water binder ratio had the greatest impact on the compressive strength of basalt fiber self-compacting high-strength concrete, and as the fiber volume fraction increased, the splitting tensile strength and flexural strength both increased; (2) there was an optimal value for the effect of the fiber length on the mechanical properties; (3) with the increase in fiber volume fraction, the total crack area of the fiber self-compacting high-strength concrete significantly decreased. When the fiber length increased, the maximum crack width first decreased and then slowly increased. The best crack resistance effect was achieved when the fiber volume fraction was 0.3% and the fiber length was 12 mm. Therefore, basalt fiber self-compacting high-strength concrete can be widely used in engineering fields, such as national defense construction, transportation, and building structure reinforcement and repair, due to its excellent mechanical and crack resistance properties.