High Strength Self-compacting Concrete Research Articles

Mechanical and durability properties of sisal-Nylon 6 hybrid fibre reinforced high strength SCC

The higher paste volume in Self Compacting Concrete (SCC) makes it susceptible to have higher creep coefficient and cracking. Microcracks which are developed during the process of hardening of concrete makes the composite weak. This inherent internal flaw in concrete can be healed by blending it with fibre. A single fibre may be competent only for a narrow range of strain and crack growth rate, hence, may be ineffective for the comprehensive improvement of strength or ductility of concrete. This emanates in Hybrid Fibre Reinforced Concrete which acquires the advantages from the synergistic action of blended fibres. In this study, high strength SCC is developed with sisal-Nylon 6 mono and hybrid fibre combination proportioned at 0/100, 25/75, 50/50, 75/25 and 100/0 of total fibre volume. It is observed that hybridisation improved the flexural and tensile properties vis-à-vis mono fibre mixes. Also the stress-strain and ductility behaviour are augmented by hybridisation. The developed fibre reinforced concrete underwent acceptable water absorption and prevents chances of fibre deterioration which affect concrete durability. Even though nylon enhances mechanical properties it induces durability issues when exposure is considered. A statistical analysis using ANOVA is carried out to prove the effectiveness of hybridisation and fibre volume on mechanical properties of hybrid fiber reinforced self-compacting concrete.

Mechanical Properties of Recycled Aggregate Self-Compacting High Strength Concrete Utilizing Waste Fly Ash, Cellular Concrete and Perlite Powders

The sustainability of engineering products has become a basic requirement instead of a mere choice because the harmony between economic activity and the earth’s ecosystem must be seriously considered. The influence of using three unprocessed waste powder materials as cement replacing materials (CRMs) and/or coarse recycled concrete aggregate (RCA) as a partial replacement of coarse natural aggregate (NA) on fresh and mechanical properties of self-compacting high-strength concrete (SCHSC) is investigated in this study. The activation index of the CRMs on the cement paste is tested as an initial step. The CRMs, namely, waste fly ash (WFA), waste perlite powder (WPP) and waste cellular concrete (WCC), are tested through 21 mixtures allocated by seven different series with three mixes of each. The mechanical properties of the 21 concrete mixes are determined after one, three and nine months of curing. Results of compressive strength, splitting tensile strength, flexural strength and modulus of elasticity are presented. This work shows that the mechanical and environmental performance of SCHSC can be improved by the replacement of NA by RCA of up to 50% and the replacement of cement by WPP or WFA of up to 15%. Using WCC is not recommended to be reached 15% and using WFA is preferable to be with incorporating RCA rather than NA alone. Findings indicate that incorporating waste materials can be valuable in SCHSC, thereby potentially leading to an increasingly green environment and paving the way for advancements in sustainable construction.

Comparison of classical, double skin and double section CFST stub columns: Experiments and design formulations

With the continuing developments in composite design technology, such as classical Concrete Filled Steel Tubes (CFST), concrete filled double skin tubes and concrete filled double section tubes, understanding the performances of such columns in a comparative way is timely. Although significant amount of literature has been gathered around the themes of concrete filled classical and double skin columns, the number of studies on double section columns is very limited. Nevertheless, in existing research, double section column concept has been proven to be very efficient in providing very high strength, ductility and stiffness. The challenge here is to find a route from concept to design which requires significant amount of comparative experiments on classical, double skin and double section columns. This paper, for the first time, examines the performances of concrete filled classical, double skin and double section stub columns which have practical range of material and geometrical properties. Experimental procedures were undertaken for composite columns with normal and high strength self-compacted concrete. To be able to address the effect of tube configurations, two types of outer and two types of inner steel tubes with different mechanical and geometrical properties were utilized. The experimental program revealed the robust characteristics of double section columns. Furthermore, the modified versions of EC4 and AISC 360–16 formulations were assessed against the test results for design purposes. It is shown here that the modified versions of the prediction methods have the potential to be utilized in field applications for double skin and double section columns.

An Experimental Investigation on High Strength Self-Compacting Concrete Using Jute Fibre

An Experimental Investigation on High Strength Self-Compacting Concrete Using Jute Fibre

Properties of self-compacting high-strength concrete containing multiple use of recycled aggregate

Advances in recycling can exceed traditional practice in that a non-renewable resource can at least become a partially renewable resource. This research attempts to support the cradle-to-cradle concept by testing the effect of reused recycled concrete aggregates (RRCA) on the fresh, physical, mechanical, and microstructure properties of self-compacting high-strength concrete (SCHSC). Two generations of recycled aggregate concrete (RAC) are produced; the first and second are created by recycled concrete aggregate (RCA) and by RRCA, respectively. For each generation, two replacement amounts are used (25% and 50% by mass). Results show that using RRCA does not affect the fresh properties of SCHSC, and up to 50% RRCA replacement amount by mass can be adopted for enhancing the mechanical and microstructure properties of reused recycled aggregate concrete (RRAC). Computed tomography indicates that the porosity of RRCA is less than that of RCA.

Influence of pre-treated alum sludge on properties of high-strength self-compacting concrete

Abstract: The disposal of alum sludge (AS) produced from drinking water treatment plants is gradually becoming a threat to the environment. The conventional disposal by landfill is not feasible because AS is considered as hazardous waste. By contrast, treated alum sludge (TAS) contains useful chemical compounds (silicon dioxide and aluminium trioxide which are the main constituents of cement). This study explored the influence of TAS on the production of high-strength self-compacting concrete (HSSCC) made up of 5%, 10%, 15%, 20% and 25% cement replacement. The experimental work was divided into 15 mixes as well as three control mixes with three different water/powder (w/p) ratios (0.36, 0.38 and 0.4). The fresh properties of self-compacting concrete (SCC) were determined via the slump flow, V-funnel, V-funnel at T5 min and L-box tests to meet the flowability requirements. The strength and durability properties of SCC were also tested at different specimen ages. In addition, the effects of elevated temperature on TAS-incorporated concrete were observed at different temperatures for 3 h. Experimental results revealed the encouraging effects of TAS on the fresh, hardened and durability properties of HSSCC with maximum 15% of the cement component partially replaced with TAS. Meanwhile, losses of mass and strength were observed to be higher in the TAS-incorporated SCC than in the control concrete.

Study on effect of variations of meta-kaolin addition on Self-Compacting parameter of High Strength Concrete

High strength self-compacting concrete (HSSCC) is one of the concrete innovations that have a high quality standard. This type of concrete has a high compressive strength and can compact without tools. Meta-kaolin (MK) is used in this research as an addition (admixture) to increase the quality of HSSCC and to meet criteria of SCC. Meta-kaolin (MK) is made from kaolin which a white powder is measuring 0.5 to 5 micron that then heated at 500– 900oC. Parameters that are studied in this research are setting time, workability, and the compressive strength of HSSCC. Final results of the research shows that the addition of MK decrease workability of HSSCC. Only MK addition at 5%, 7.5%, and 10% fulfils filling ability and passing ability parameter of SCC, otherwise the compressive strength increases linearly.

Analytical review of the mix design of fiber reinforced high strength self-compacting concrete

Despite application of fiber reinforced concrete, high strength concrete and self-compacting concrete in the construction industry in the last decades, the investigations about combination of these types of concrete in Fiber Reinforced High-Strength Self-Compacting Concrete (FRHSSCC) is very rare in the literature. This study reviews a wide range of experimental data of the mix design in terms of the components and their proportions and the compressive strength of FRHSSCC in the last 12 years. The applied coarse and fine aggregates, chemical and mineral admixtures, fibers, cement, water, powder components and the ratios of water to cement and water to binder are broadly analyzed and evaluated. In addition, the compressive strength of the FRHSSCC mixtures are evaluated. The relationship between the compressive strength with water to cement and water to binder ratios in the mixture, water content, fine and coarse aggregates and the powder content is also discussed and compared in the case studies. Considerable variety of the mix designs with different components and proportions to achieve FRHSSCC without the mixing problems is evident in the collected case studies.

Ultimate stress increase in unbonded tendons in post-tensioned indeterminate I-beams cast with high strength normal and self compacting concrete

The use of un-bonded tendons is prevalent in post-tensioned concrete structures. Equations for prediction of stress in un-bonded tendons of post-tensioned normal (vibrating) concrete flexural members have been given in various codes. They are based on experience and don’t account all of important parameters such as concrete strength (normal and high strength) and its type (vibrating and non-vibrating concrete). Since self-compacting concrete (SCC) is nearly a new innovation therefore, understanding the implementation of this type of non-vibrating concrete on the ultimate unbonded tendon stress is critical. For this aim, in this paper there are presented experimental results of six continuous un-bonded post-tensioned I-beams in two groups were casted and monitored by different electrical strain gauges. In the first tested group, the beams (UPN1-12, UPN1-18, UPN1-22) were consisting of high strength normal concrete (HSNC) where as in the second group (UPS1-12, UPS1-18, UPS1-22) high strength self-compacting concrete (HSSCC) were tested. The variables included the type of concrete and percentage of bounded non-prestressed steel. Experimental monitored results of ultimate stress increase in unbonded tendons are compared with predicted equations of different researchers and standards. It was found that, the proposed equation is in better agreement with the test results. The results of standard error of estimate Sy/x, indicates that for two types of HSCs, the ACI 318-2011 provides better estimates than AASHTO-2010 model whereas this model provides better estimates than BS 8110-97.

Size and Shape effects of testing specimens on the compressive Strength of SCC

To control the quality of concrete during concreting works, there are various moulds that are used for casting concrete samples according to different standards at different countries. And these differences in the shapes and sizes of concrete samples can cause variations in the results of measured compressive strength. Self-compacting concrete (SCC) have a structural strength and high flowability. This material used in modern concrete technology and extensively in the construction applications of high-rise buildings and long-span concrete structures.This research concentrated on the effect of specimen sizes and shapes on compressive strength of High strength SCC, Specimens were normally cured in the Lab. and tested at age of 28 days. Results were plotted, and indicated that for all testing specimens, there was a significant Influence of size and shape of the specimens on the measured compressive strength. Common sizes that have used for testing compressive strength of concrete were investigated; (100 X100 X100), (150X150X150) mm for cubes and (100 X 200), ( 150 X300) for cylinders. To determine the best conversion factors, linear relationship added as a trend line between compressive strength measured based on testing cylinders to that measured based on testing cubes, on the other hand relationships was conducted to relate compressive strength tested on cubes and cylinders of different sizes.

Cyclic response analysis of high-strength self-compacting concrete beam-column joints

In this paper, finite element analysis software “DIANA” is implemented to simulate quasi-static cyclic loading test results of three full-scale beam-column joints cast with high-strength self-compacting concrete (HSSCC). The specimens were designed according to the New Zealand concrete standard (NZS3101 2006). Material models for concrete and steel were calibrated based on the physical characteristics of the materials derived either from laboratory tests or using expressions available in literature. Two-dimensional curved-shell elements were used in modelling the specimens. As the specimens were designed following the code requirements for seismic actions, bond between the reinforcement and concrete was assumed as perfect. In order to obtain a more representative prediction, both the longitudinal and transverse reinforcement were modelled in their actual locations. Pushover analyses were first conducted to check the mesh sensitivity; after which the modelled specimens were subjected to reversed cyclic loading histories applied in the experimental tests. Seismically important response parameters such as damping, stiffness, concrete and steel contributions in the joint shear resistance, joint shear deformation, strain development in the joint stirrups, elongation of the plastic hinge zone, development of compressive stress, and cracking pattern were extracted from the analytical predictions and compared to the experimental results. It was found that the adopted modelling and analysis approach was capable of predicting cyclic performance of HSSCC beam-column subassemblies with reasonable accuracy.

The influence of using accelerator addition on High strength self-compacting concrete (HSSCC) in case of enhancement early compressive strength and filling ability parameters

Efficiency in a construction works is a very important thing. Concrete with ease of workmanship and rapid achievement of service strength will to determine the level of efficiency. In this research, we studied the optimization of accelerator usage in achieving performance on compressive strength of concrete in function of time. The addition of variation of 0.3% - 2.3% to the weight of cement gives a positive impact of the rapid achievement of hardened concrete, however the speed of increasing of concrete strength achievement in term of time influence present increasing value of filling ability parameter of self-compacting concrete. The right composition of accelerator aligned with range of the values standard of filling ability parameters of HSSCC will be an advantage guidance for producers in the ready-mix concrete industry.

Finite Element and Experimental Investigation on the Flexural Response of Pre-tensioned T-Girders

A number of analytical and numerical approaches exist for modeling concrete structural members. Finite-element analysis (FEA) is a numerical method that is widely applied to concrete structures based on the use of the nonlinear behavior of materials. The challenge of modeling prestressed concrete structures lies in the treatment of the interface between concrete and prestressing tendons. The FEA-modeling technique discussed in this study is based on general-purpose finite-element packages. This study describes FEA of full-scale high-strength self-compacting concrete, HSSCC pre-tensioned T-girders and its comparison with experimental results. Three 9 m length fully pre-tensioned bridge girders, PHSSCC were designed and cast using HSSCC. The girders were instrumented to monitor deflection, pre-tensioned losses, tendon, steel bar, and concrete strains. The girders were then load tested (until failure), predominantly under flexure, and their service and ultimate results including cracking, flexural stiffness, flexural strength, and different ductility indexes were investigated and compared with FEA results. The software package ABAQUS was used to simulate girders and their bonding conditions to verify the accuracy of FEA. A very good agreement was achieved for numerical and experimental crack patterns. The comparison of finite-element modeling (FEM) and experimental results of load-upward and downward deflections indicated satisfactory agreement throughout the load history of the beams until failure. Comparing FEM and experimental results, reasonable agreement was observed for the two methods of ductility indexes. Finite-element modeling tends to overestimate stress in prestressed tendons at the ultimate state of specimens.

Effect of mix design on the size-independent fracture energy of normal- and high-strength self-compacting concrete

Self-compacting concrete has a characteristic microstructure inherent to its specific composition. The higher content of fine particles in self-compacting concrete relative to the equivalent vibrated concrete produces a different fracture behavior that affects the main fracture parameters. In this work, a comprehensive experimental investigation of the fracture behavior of self-compacting concrete has been carried out. Twelve different self-compacting concrete mixes with compressive strength ranging from 39 to 124 MPa (wider range than in other studies) have been subjected to three-point bending tests in order to determine the specific fracture energy. The influence of the mix design and its composition (coarse aggregate fraction, the water to binder ratio and the paste to solids ratio) on its fracture behavior has been analyzed. Moreover, further evidence of the objectivity of the size-independent fracture energy results, obtained by the two most commonly used methods, has been provided on the self-compacting concrete mixes.

Effects of curing types on the strength of high Strength self-compacting concrete

Curing strongly influences the strength and durability of hardened concrete through its remarkable effect on the hydration of cement. The present study conducted experiments to show the effects of different curing processes on the compressive strength of high-strength self-compacting concrete (HSSCC). Three mixes of HSSCC were prepared with w/cm ratio of 0.265, 0.345, and 0.375. Silica fume, which is 9 % by weight of the cementitious material, was used. Standard cubic specimens were cast to test the compressive strength at 3, 7, and 28 days. Specimens were cured using different curing systems, namely, immersion in water, covering the surface with wet burlap, coating by a bituminous membrane, and open-air curing. Furthermore, different moistening conditions were studied by totally curing specimens in dry air and curing in water for different periods (1, 3, 7, and 28 days) and using the remaining time to store them in dry air before testing the compressive strength at the age of 28 days. Test results indicated that covering concrete with a wet burlap is the most economic and effective method to cure HSSCC and that curing in water for 3 to 7 days is necessary for HSSCC to obtain reasonable and good results.

The effect of curing conditions on the durability of high performance concrete

This study researches compressive strength and durability of the high strength self-compacting concrete (SCC) impacted at early stage by the curing conditions. The mixture compositions of metakaolin containing waste and cenospheres as partial cement replacement (15 wt%) were compared to reference SCC with 100% cement. The specimens prepared in advance were demoulded 24h after casting of the SCC and the specific curing conditions were applied for up to 28 days: standard water curing at 20°C (i); indoor curing at 20°C, RH 60% (ii) and low temperature air curing (2°C) at RH 60% (iii). Results indicate that at early stage (14 days) indoor curing conditions increase compressive strength of the SCC whilst no strength loss has been detected even at a low temperature curing. The further strength gain has been substantially reduced for samples cured indoor and at a low temperature with significant variation observed for long term compressive strength (180 days). The metakaolin containing waste has proved to be an effective partial cement replacement and it has improved strength gain even at a low temperature curing. Meanwhile cenospheres have reduced the SCC strength and with no positive effect on strength observed within the standard term. Freeze-thaw durability and resistance to the chloride penetration have been improved for the SCC cured at low temperature. The SCC with metakaolin containing waste has proved to be the most durable thus demonstrating importance of effective micro filler use.

Influence of pumice and zeolite on compressive strength, transport properties and resistance to chloride penetration of high strength self-compacting concretes

This paper investigates the effect of two different natural pozzolan (pumice and zeolite) on compressive strength (fc), transport properties and resistance to chloride penetration both in immersion and tidal conditions when used in high strength self-compacting concrete (HSSCC). First, the chemical and mineralogical composition as well as the microstructure and the pozzolanic activity of the natural pozzolan are studied. Then, two percentages, 10% and 15%, of pumice and zeolite instead of Portland cement in HSSCC are investigated. Five concrete mixtures with a control mixture without any pozzolan are prepared and tested in both fresh and hardened states. The results show that the studied zeolite is a clinoptilolite that presents higher pozzolan activity compared to pumice. However, the compressive strength of mixtures containing zeolite remains low compared to control mixture. On the contrary, mixtures with pumice present compressive strength values close or higher than the ones of the control mix at both early and long term ages with a remarkable increase at long term. For durability purposes, the transport properties of the different mixtures are studied through capillary absorption, water absorption, water penetration, electrical resistivity, chloride migration and diffusion tests. The results show that, both pumice and zeolite pozzolan are found to have a significant effect on the increase of the resistance to chloride penetration in both immersion and tidal conditions. However, zeolite mixtures exhibit better resistance. This research shows that, the substitution of Portland cement by 15% of pumice or 10% of zeolite in HSSCC is affordable in all aspects.

Permeation properties of high strength self-compacting and vibrated concretes

Metakaolin is a supplementary cementing material (SCM), which has a significant potential to produce High Strength Concrete (HSC) and Self-Compacting Concrete (SCC). Because of the lower processing temperature compared to cement clinker, use of metakaolin can contribute to sustainability through energy savings, as well as reductions in greenhouse gas emissions. The present study envisages the permeation properties of high strength self-compacting concrete developed using metakaolin and vibrated normal concretes having strength categories of 60, 80, 100, 120MPa. All the SCCs developed using metakaolin satisfies the criteria of EFNARC guidelines. The permeation properties of the concretes were assessed though water permeability, water absorption, sorptivity and rapid chloride permeability tests. The results indicate that water permeability, water absorption and sorptivity values of both the concretes are comparable. SCCs containing metakaolin exhibited a significant reduction in chloride diffusion for replacements above 15%. Thus, the overall results show that metakaolin possesses significant potential as an efficient pozzolanic mineral admixture for the production of high strength SCC with promisingly superior permeation properties.

Experimental Study of Composite High Strength Self-Compacting Concrete

This test uses polycarboxylate superplasticizer by adding 15% quantitative fly ash, 10%, 15%, 20% of slag, and 5%,7.5%, 10% of silica fume of the total amount of the cementitious material to be an equivalent replacement for cement. Ordinary materials were used to make the C70 high strength self-compacting concrete. The concrete slump, expansion degree, and the axial compressive strength of concrete were studied. Through testing, the mix proportion of each group of concrete slump was determined to be above 250mm. And the expansion degree to be above 550mm. The axial compressive strength satisfied the design strength value. At the same time, the optimal mix ratio was proposed. And the economic performance of each group was analyzed. There are references for a similar experimental design and engineering application.

Режим прогрева высокопрочного самоуплотняющегося напрягающего бетона

Режим прогрева высокопрочного самоуплотняющегося напрягающего бетона