Types Of Self-compacting Concrete Research Articles

Bond behavior of recycled tyre steel fiber reinforced concrete and basalt fiber-reinforced polymer bars under static and fatigue loading conditions

Nowadays, there is a growing demand for the development of structures and construction materials from recycled or reused and renewable resources, in line with circular economy principles and the goal of sustainable development. The present study explores promising solutions for increasing the sustainability of concrete structures, through the application of basalt fibers reinforced polymer (BFRP) rebars, whose raw materials show an unlimited availability on earth, as well as recycled steel fibers from waste tyres (RTSF), for RTSF reinforced concrete structures with BFRP reinforcements. Three different types of self-compacting concretes with 1.1% fiber volume fractions of industrial and/or recycled steel fibers were developed, where 50% and 100% of the industrial steel fibers (ISF) weight was replaced by RTSF. Five different groups of pull-out specimens, with total number of 26 specimens, were fabricated to evaluate bond performance of BFRP rebar embedded in RTSF reinforced concrete. The understanding of the bond behaviour is critical to the effective design of reinforced concrete structures under both static and dynamic loadings. The influence of the type of reinforcement, dosage of the adopted RTSF, type of loading, and concrete flow direction on bond stress versus slip behavior, maximum bond stress, and failure mode are analysed and discussed. One of the main contributions of this research regards the understanding of the effect of RTSF orientation on bond performance obtained when BFRP rebars are pulled out from RTSF reinforced concrete. Compared to ISF, using RTSF for reinforcing concrete can increase the bond strength between BFRP rebars and fiber reinforced concrete up to 6.3% under static and 9.7% under fatigue loading regime. As the future research in this area, it is recommended to evaluate the long-term bond durability of BFRP reinforced FRC embedded in seawater, the environmental and economic feasibility of using BFRP and TRSF for reinforcing concrete structures, and fiber orientation and dispersion using image analysis and 3D visualization.

Mechanical Properties and Microstructure Characteristics of Self-compacting Concrete with Different Admixtures Exposed to Elevated Temperatures

Self-compacting concrete (SCC) is a high-performance concrete widely used as a building material. The present investigation examines the effects of age and cooling type (air-cooled and water-cooled) of SCC after being exposed to elevated temperatures and compares them to those of normal conventional concrete (NCC). Two types of concrete; i.e., NCC and SCC, were developed and studied for early-age and residual strengths. SCC was developed with three different types of admixtures; namely, fly ash (FA), silica fume (SF) and metakaolin (MK) as binder materials, by replacing the cement. The mechanical characteristics of FA- and SF-blended SCC before heating show similar results, whereas MK-based SCC possesses greater strength than other mixes. In the case of specimens exposed to high temperature of 1000℃, MK-blended SCC produced the lowest residual strength compared to FA- and SF-based mixes. Further microstructural investigation was conducted to examine the internal structure of the specimens exposed to various heating temperatures. From the results, it is concluded that the higher the strength gain upon aging, the greater the strength loss upon temperature rise. KEYWORDS: Self-compacting concrete, Fly ash, Silica fume, Metakaolin, Residual strength, Microstructure.

Investigation on Strength Characteristics of Self Compacting Concrete incorporated with AR Glass Fibers

This project presents the experimental study on self-compacting concrete (SCC) with replacement of cement by various percentage of Silica Fume and Fly Ash. The main objective is to determine the Flexural strength, Compressive strength and Split tensile strength of Self compacting concrete by partial replacement of cement by Silica Fume and Fly Ash. The use of fly ash in concrete today is an important subject and is of growing importance day by day. Using fly ash in concrete many provide both economic advantages and enhanced properties in the production of concrete. The addition of super plasticizer increases the workability of concrete. The work involves making seven types of SCCs mixes. For each mix preparation, twenty-one cube specimens, twenty-one-cylinder specimens and twenty-one beam specimens are cast and cured. The specimens are cured in water for 7 days, 14 days and 21 days. The results show that SCC with 5% SF and 10% gives higher values of Compressive strength, Split Tensile strength and Flexural Strength compared to other percentages of Silica Fume and Fly Ash. According to the SCC result, various percentages of AR Glass Fiber (0.1% to 0.4%) added with the optimum SCC (5% of SF+ 10% of FA) and super plasticizer is mixed with optimum SCC. After each mix proportion, specimens are cast and cured for 28 days in water and hardened properties are determined. The results show that the higher the percentage of glass fiber, the higher the values of concrete Compressive strength, Split Tensile Strength and Flexural Strength.

A robust mix design method for self-compacting concrete

• A theoretical framework for analyzing SCC’s fresh behavior was established. • Multilevel excess layer model and rheology-based workability criteria were merged. • Generalized self-compacting zones reflect the robustness of SCC mix design. • A robust mix design method balancing the SCC’s content and rheology was proposed. Raw material properties greatly influence the workability of self-compacting concrete (SCC). This paper explored a robust approach to realize the mix design of SCC. A theoretical framework, which combines the excess layer composition model and rheology-based workability criteria, was proposed to analyze the fresh behaviors of the concrete. In the framework, the film-thickness-based composition model established the correlation between concrete’s content with the film’s thickness and the aggregate’s characterization. The suspending cell model could quantify the film’s separating, bearing, and lubricating effects, therefore characterizing the mixture’s flowability and stability. Besides, the derived rheology threshold defined the fresh mixture’s flow spread conditions. The framework was experimentally verified, and the experiment-based threshold calibration referring to the slump flow test significantly improved the framework’s accuracy. Two generalized self-compacting zones (SCZs) for analyzing the robustness of SCC mix design, under the coordinate of film’s thickness and rheology, were theoretically calculated. Through the analysis of the evaluation law of generalized SCZs, the area of the film-thickness-based SCZ and paste-rheology-based SCZ were able to reflect the control reliability of component content and paste rheology in SCC designing. On this basis, a robust mix design method of SCC was proposed by balancing the two ranges. The discussion on the extension of mix design framework to other types of SCC, industrial application, and reinforced structures demonstrated the framework’s broad applicability.

Axial Compressive Properties of Self-Compacting Concrete Filled Steel Tube Short Columns with Ground Desulfurization Slag.

Desulfurization slag (DS) is the solid waste discharged from the bottom of the circulating fluidized bed (CFB) boiler. It has good pozzolanic activity, self-hardening property and large expansibility. In this paper, ground desulfurization slag (GDS) is used as mineral admixture to replace cement to prepare self-compacting concrete (SCC). In order to find out the influence laws of different factors on the axial compressive properties of the self-compacting concrete filled steel tube (CFST), seven types of SCC are prepared and nine groups of CFST short column are fabricated. Filling ability test, compressive strength test and axial compressive test are performed. The filling ability and the compressive strength of the SCCs are investigated, and the axial compressive properties of the CFSTs are researched. The results show that the amount of polycarboxylate superplasticizer (PS) increases with the amount of GDS, and the addition of GDS decreases the 3d, 7d and 28d compressive strength of the SCCs. The optimum amount of GDS for SCCs and CFSTs is 30%. When the amount of GDS is 30%, the ultimate bearing capacity of CFST short column (GP3) is the highest, which is 33.6% higher than that of GP1 without GDS. The influence law of the GDS’s amount on the CFSTs’ ultimate bearing capacity is quite different from that of the GDS’s amount on the SCCs’ compressive strength. The ultimate bearing capacity of CFSTs can be significantly improved by adding GDS. Sodium sulfate can improve both the compressive strength of the SCC and the bearing capacity of the CFST.

Assessment of self-compacting concrete without super plasticizer in bridge construction

Bridge design plays a vital role in the field of civil engineering. The materials to be considered, method of construction is an important factor along with the codal provisions. Self-compacting concrete (SCC) has been a popular choice for civil engineering projects due to its ability to create cohesive concrete. This article discussed the possibility of producing an SCC without employing a superplasticizer and just utilising locally available mineral admixtures, with a well graded coarse aggregate size of 25 mm, which is a completely a new method of preparation of SCC. The enhanced features were evaluated and verified in accordance to EFNARC standards. The mechanical properties of SCC without super plasticizer are compared with M25 Conventional Concrete. During the preliminary study, the mechanical characteristics of the SCC produced using the mentioned technique. Followed by the evaluation of the flexural behaviour of the SCC for beam specimens. Based on the findings, finally it can be concluded that this kind of SCC is a potential and successful alternative to the conventional type of SCC produced using Glenium B233 products, as well as being cost effective.

Transport mechanisms as indicators of the durability of precast recycled concrete

The objective of this paper was to analyze the influence of crushed precast concrete waste on the transport mechanisms as indicators of the durability of precast recycled self-compacting concrete (SCC) as an alternative to the coarse fraction of natural aggregate. The replacement percentages were 20%, 50% and 100%, by weight, of the silica gravel 2/12.5 mm. Two types of SCC were manufactured: the first with a minimum compressive strength of 30 MPa (HR-30) and the second with a minimum strength of 45 MPa (HR-45). The recycled SCC’s mechanical characteristics such as compressive strength, splitting tensile strength, flexural strength and modulus of elasticity were analyzed. Regarding the physical properties related to transport mechanisms, the influence of the recycled aggregate on the porosity, absorption, penetration of water under pressure, density of hardened concrete and ultrasonic pulse velocity was analyzed. All these properties were compared with those of a control concrete. The results of the mechanical tests provide values close to those obtained for the control SCC, while, in terms of durability the results fulfil the limit values that are considered for a good quality concrete. Therefore, it can be concluded that the use of crushed precast concrete waste with different degrees of substitution is a viable alternative in the manufacture of more sustainable SCC.

Influence of Recycled Precast Concrete Aggregate on Durability of Concrete’s Physical Processes

The research presented in this article analysed the influence of incorporating precast concrete waste as an alternative to coarse aggregate in self-compacting concrete to generate new precast elements. The experimental study involved the characterization of recycled aggregate and the design of the mix of the new self-compacting concrete (SCC). The experimental study evaluates the physical processes that affect the durability of concrete with percentages of incorporation such as 20%, 50% and 100% of recycled aggregate. Two types of SCC were manufactured with minimum compressive strength of 30 MPa and 45 MPa. The properties analysed were density of hardened SCC, shrinkage cracking, freeze-thaw resistance, resistance to ageing by thermal shock and abrasion resistance. The results obtained were compared with those of the control concrete, observing great capacity of the SCC under physical aggressions that affect durability. The results of this research show that it is possible to use the recycled aggregate coming from precast pieces in order to the manufacture of self-compacting recycled concrete in the same precast industry. However, high loss of proprieties occurs for a 100% substitution, while for 20% and 50%, the variations with respect to control concrete are smaller. In addition, taking advantage of this waste to incorporate it back into the production chain contributes to more sustainable construction.

A Comparative Study between the Effect of Steel Fiber on Ultrasonic Pulse Velocity (UPV) in Light and Normal Weight Self-Compacting Concretes

This research presents a comparative study to highlight the differences between the effect of using various contents of steel fibers on the ultrasonic pulse velocity (UPV) in two types of self-compacting concretes (SCC) which are identical in their constituent materials, the only difference between them is the coarse aggregate type (normal in one and light in the other) with various specimen lengths (200mm cylinders and 100mm cubes). In this work, six types of mixes were casted, the first three (Mix1, Mix2 and Mix3) are of normal-weight SCC having steel fiber content (Vf) : 0.0%, 0.4% and 0.8% respectively, and the other three (Mix4, Mix5 and Mix6) are of light-weight SCC with the same aforementioned steel fiber contents respectively. It turns out that, the ultrasonic pulse velocity is smaller in light-weight SCC than in normal-weight SCC, and the percentage of this reduction is higher in cylindrical samples than in cubic samples, and this percentage of reduction is reduced with the increasing in steel fiber contents. It also turns out that, the ultrasonic pulse velocity is increased with the increase in steel fiber contents, and this percentage of increase is higher in light-weight SCC than in normal-weight SCC, and it is also larger in cylindrical samples than in cubic samples. Moreover, when the specimen length has been focused on, it was found that, the ultrasonic pulse velocity is larger in (100mm) cubic specimens than in (100×200mm) cylindrical ones, and the percentage of this rise is also larger in light-weight SCC than in normal-weight SCC, and it is reduced with increasing steel fibers contents.

Elman ANNs along with two different sets of inputs for predicting the properties of SCCs

In this investigation, Elman neural networks were utilized for predicting the mechanical properties of Self- Compacting Concretes (SCCs). Elman models were designed by using experimental data of many different concrete mixdesigns of various types of SCC that were collected from the literature. In order to investigate the effectiveness of the selected input variables on the network performance in predicting intended properties, utilized data in artificial neural networks were considered in two sets of 8 and 140 input variables. The obtained outcomes showed that not only can the developed Elman ANNs predict the mechanical properties of SCCs with high accuracy, but also for all of the desired outputs, networks with 140 inputs, compared to ones with 8, have a remarkable percent improvement in the obtained prediction results. The prediction accuracy can significantly be improved by using a more complete and accurate set of key factors affecting the desired outputs, as input variables, in the networks, which is leading to more similarity of the predicted results gained from networks to experimental results.

The effect of fibres in the rheology of self-compacting concrete

The successful use of self-compacting concrete (SCC) in the construction industry is based on the simplification of pouring procedures, as it fills the formwork merely by the action of its own weight. However, the presence of fibres might undermine the fresh-state properties and, hence, minimise the advantages obtained from use of SCC. From the point of view of fibre reinforced concrete (FRC), the flow of SCC enhances the positioning of the fibres and therefore the residual tensile strength of the composite material. Consequently, study of the rheology of SCC-FRC permits the characterisation and classification of the mix and provides a remarkable tool for design. That is to say, it is essential in analysing fresh state not only by conventional slump flow tests but also by associating such results with those obtained by a rheometer. The significance of this research lies in the comparison of the fresh-state results obtained through slump flow and V-funnel tests with those from a BT-Rheometer, using two types of SCC and both steel and polyolefin fibres. The results show the remarkable influence of the type of fibres and limitations of measurement in terms of physical parameters. This provides relevant information for future applications of the fresh state of FRC-SCC whether using steel or polyolefin fibres.

Experimental determination of the influence of additives on shrinkage in self-compacting concrete

The paper deals with the influence of additives on the progress of shrinkage and mass losses in self-compacting concrete. Limestone and fly ash at varying amounts were used as an additive in the production of four types of self-compacting concrete. Volume changes were observed from an early stage of setting (the measurement was commenced within 1 hour of mixing) using shrinkage drains with a moveable wall, followed by a long-term manual measurement using an external strain gauge. For the first 48 hours the volume-change measurement was continuous, and for the next few months it was performed manually. Mass losses were determined simultaneously with shrinkage – during the first 48 hours by weighing on a special weighing table capable of continuous recording, and manually afterwards.

Behavior of The RC Slab-Beam System Using Self Compacting Concrete

The present study includes an experimental investigation of the behavior of square reinforced concrete slabs. These slabs are with and without edge beams under uniformly distributed load with corner supports using two types of self compacting concrete (SCC), the first type of SCC incorporated limestone filler and the other was without filler, the results obtained are compared with those obtained from conventional concrete (CC).The experimental program consists of testing nine square slab samples. Three of these slab samples are flat in shape with panel dimensions of 1050×1050×50 mm depth. The others three slab samples are of the same outer dimensions with surrounding edge beams of depth to slab thickness equal 100/50 and 100 mm width. The last three slab samples are similar to the former slab-beam systems but with increasing the depth of edge beams by 50%.In general, for a specified flat plate panel, the ultimate load carrying capacity can be increased, if the panel is restricted by four surrounding beams. The slab-beam samples with surrounding beams of depth to slab thickness equal to 3 showed greater ultimate load capacity by about 79.37%, 52% and 97.82% when compared with the corresponding flat slabs samples produced using CC, SCC with and without filler, respectively.

Low cement content SCC (Eco-SCC) – the alternative for ready-mix traditional concrete

Self-Compacting Concrete (SCC) is often regarded for in-situ applications as a more expensive and less environmentally friendly version of traditional concrete for use in places where the latter is highly inconvenient for various reasons. To counteract this belief, a new type of SCC has been proposed, called Eco-SCC or green-SCC. In comparison to typical SCC this building material has lower powder content resulting in low cement content and a slightly lower paste volume. The disadvantage of this approach is high water content and low viscosity resulting in high vulnerability of fresh concrete to sedimentation. Additionally, comparing to EN-206 limits, mixes with too low cement content are often obtained. This is why a research program has been undertaken to check the possibility of obtaining fresh Eco-SCCs of higher viscosity, thereby fulfilling all EN-206 requirements. It was possible to obtain concretes of C25/30-C35/45, SF2, VF2, PL2, containing 265-300 kg/m3of cement and 165-190 kg/m3of water owing to the use of limestone powder and typical rounded aggregate of local origin with very low sand to a total aggregate ratio ofs/a= 0.4. Based on Global Warming Potential (GWP) analysis, a modification of Eco-SCC definition is proposed: Eco-SCC is an SCC having cementitious materials volumetric content no greater than 100 dm3/m3(or mass content no greater than 315 kg/m3).

Performance analysis of self compacting concrete without super plasticizer

The use of self compacting concrete (SCC) in civil engineering works has become an attractive option which produces confident cohesive concrete. This paper reviewed the feasibility of preparing a SCC without using super-plasticizer but with only mineral admixtures that are available locally, with the coarse aggregate size of with 20 mm well graded aggregates which is entirely a different way of preparation of SCC. The enhancement aspects were tested and ascertained with the EFNARC guidelines. The hardened properties of SCC were tested and compared with control concrete of M25 grade. In the preliminary investigation, mechanical properties of the SCC which have been prepared by the above said method were tested by its unique testing methodologies. Based on the test results, in the second phase, the flexural behavior of the SCC specimens, using beam specimens were tested for its load carrying capacity by loading frame. In both the phases of investigation, the results revealed that this type of SCC will be promising and effective combination to that of the traditional type of SCC prepared by Glenium product and also cost effective.

Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

Fresh and hardened properties of binary blend high strength self compacting concrete

Self compacting concrete (SCC) made a remarkable impact on the concrete construction industry because of its innovative nature. Assessment of optimal ratio between chemical and mineral admixtures plays a vital role in developing SCC. In the present work three different mineral admixtures were used as partial substitute in different proportions to cement to produce SCC with a characteristic compressive strength of 60MPa. All the three types of SCC were investigated for its fresh and hardened properties. From the results, 50% GGBFS, 10% SF and 20% MK were found to the optimum values as partial substitute to cement.

Demoulding vertical elements: Recommendations for apply maturity functions

Many standards recommend different minimum demoulding times depending on site conditions. Different parameters are taken into account in determining the minimum demoulding time, but the only one that is always taken into account is concrete temperature. Therefore, a methodology for determining the minimum demoulding times for vertical elements of self-compacting concrete (SCC) based on maturity functions is studied.Maturity functions establish a relationship between maturity and in-situ resistance. While maturity may be measured by measuring the temperature over time, there are different option for determining resistance in-situ, and thus the objective of this work is focused on methods for measuring resistance at early ages.An experimental study was carried out to establish which method for determining resistance in-situ is best suited to the determination of the resistance-maturation curve. To that end, the suitability and consistency of each method were studied.In addition, an experimental validation of the methodology was carried out, in which the demoulding methodology was applied to 11 columns tested at a construction site. The validation was carried out with two different types of SCC and different types of formwork.

Effect of water–powder ratio on shear thickening response of SCC

The effect of the water–powder ratio on rheological properties of three types of self-compacting concretes (SCCs)—powder type SCC, viscosity modifying admixture (VMA) type SCC and powder–VMA combination type SCC were tested by RHM-3000 ICAR rheometer. The application of the Herschel–Bulkley (H–B) model and the modified Bingham model was discussed, and the effect of the water–powder ratio on shear thickening response of three types of SCCs were compared. The results showed that yield stresses of the three types of SCCs increased with the increase of water–powder ratio for the concrete with the similar slump flow and air content. However, the plastic viscosities differed in the opposite sense. The shear thickening response of SCC was found decreased with the increase of water–powder ratio, and there was a critical water–powder ratio from shear thickening to shear thinning. The shear thickening response could be well described by both H–B model and the modified Bingham model with good correlations, but the parameter of c/μ in the modified Bingham model was found to be more sensitive to the change of shear thickening. The shear thickening response of VMA type SCC was found to be the most sensitive to the change of water–powder ratio, and the least was combination type SCC.

Mechanical behaviour of self-compacting concrete made with recovery filler from hot-mix asphalt plants

The aim of this paper is to assess the feasibility of the use of a fine grain waste generated in hot-mix asphalt plants (HMA), namely recovery filler (RF), as filler materials in self-compacting concrete (SCC) production. A comparative study of two types of SCC was performed. The first concrete type was made incorporating recovery filler (SCC-RF) of a dolomitic nature and the second was made with commercial siliceous filler (SCC-SF), the latter used as reference. Good results of self-compatibility were obtained using RF. The thermogravimetric study showed that in SCC-SF the higher loss weight occurs in the dehydration zone (0–400°C) and in SCC-RF it occurs in the decarbonation area (550–735°C). The aging mechanism of both concrete types (SCC-SF and SCC-RF) was different. In the SCC-SF mixes, portlandite undergoes carbonation processes and pozzolanic reactions and in the SCC-RF mixes it only undergoes carbonation processes. The experimental results (splitting tensile strength, flexural strength and static modulus of elasticity) show the validity of using EHE-08, initially proposed for NVC (Normally Vibrated Concrete), in SCC. The ultrasonic pulse velocity values for SCC-SF was greater than for SCC-RF, which can be attributed to compacity and compressive strength. The shrinkage behaviour was better in SCC-RF than SCC-SF, mainly due to the greater particle size of recovery filler (RF), although the SCC-RF mixes showed lower density and mechanical strength than SCC-SF. In short, the SCC manufactured with recovery filler from plants manufacturing hot-mix asphalt (HMA) – SCC-RF – is expected to have better features than SCC-SF in relation to shrinkage and early appearance of cracks.