Plain Self-compacting Concrete Research Articles

Shear strength of functionally graded self-compacting concrete deep beams reinforced with steel and GFRP bars

Glass fiber-reinforced polymer (GFRP) bars are emerging as a potential replacement for steel rebars due to their vulnerability to corrosion. However, the shear behavior of GFRP bars is not well established, especially in functionally graded self-compacting concrete (SCC) deep beams reinforced with hybrid rebars (GFRP and steel). This article experimentally explores the behavior of functionally graded high-strength SCC deep beams having a hybrid of steel and GFRP bars as tension reinforcement. A total of fourteen deep beams were prepared with varying reinforcement ratios and steel fiber volume fractions. There were three groups of deep beams: (i) plain SCC (i.e., no fibers) beams, (ii) fiber-reinforced SCC (FRSCC) beams having 0.6 % and 1.2 % steel fibers, and (iii) functionally graded deep beams. The functional grading was achieved by casting beams in two layers, with the first layer of lower two-thirds depth having steel fibers and the second layer without fibers. The beams were shear deficient and tested in flexure. The shear resistance of functionally graded deep beams was compared with beams having fibers in full depth and without fibers. The test results reveal the significance of the hybrid system of rebars, which is found to effectively improve the structural capacity of concrete beams and increase the load required to initiate cracking. In addition, the mixing of fibers in concrete enhanced the deep beam shear capacity by 15–23 % for 0.6 % fibers and 37–39 % for 1.2 % fibers. The increase in the shear resistance of concrete deep beams was not influenced by the use of hybrid rebars compared to using GFRP bars only. A model is developed for assessing the shear resistance of functionally graded fiber-reinforced concrete deep beams by incorporating the dowel action of hybrid longitudinal reinforcing bars. The study indicates that the dowel action provided by GFRP bars is comparable to the steel bars of the same area.

Performance of hybrid glass/steel fibre self-compacting concrete beams under static flexural loading

In this paper, it is proposed to study the static flexural performance of hybrid (glass and steel) fiber reinforced M30 grade self-compacting concrete (SCC) beams made with glass fiber reinforcement polymer (GFRP) re-bars. Nan Su mix design approach is adopted to develop the M30 grade plain SCC (PSCC) mixes. Glass fibre SCC (GFRSCC), steel fibre SCC (GFRSCC) and hybrid fibre SCC (HFRSCC) mixes are prepared using the optimum dosages of glass (0.05%) and steel fibres (1%) by volume fraction. HFRSCC reinforced beams of size 1200 *200*150 mm will be casted with steel and GFRB rebars and tested to study the flexural properties such as ultimate flexural strength, load at first crack, deflection at the center, crack width and crack patterns. For the above fibred beams, load-deflection relations will be established. The HFRSCC beam made with GFRP rebars have the load carrying capacity 37.03% more than HFRSCC beam made with steel rebars. The deflection for the HFRSCC beam made with GFRP rebars is 61.52% more than beam made with steel rebar HFRSCC beam made with GFRP rebars increases the load at first crack, ultimate flexural strength, and deflection at the centre at failure and the crack width for same HFRSCC beam made with steel rebars

Development of Self-Compacting Concrete Incorporating Rice Husk Ash with Waste Galvanized Copper Wire Fiber

This research work is devoted to the experimental investigation of both rheological and mechanical properties of self-compacting concrete (SCC) produced with waste galvanized copper wire fiber and rice husk ash (RHA). In the study, three different volume fractions of 0.5 p to 0.75 percent, 1 percent of scrap copper wire fiber as reinforcing material, and 2 percent RHA as cement replacement were used. To evaluate the fresh characteristics of SCC, the slump flow, J-ring, and V-funnel experiments were conducted for this investigation. Compressive strength, splitting tensile strength, and flexural strength of the concrete were conducted to assess the hardened properties. The test was carried out to compare each characteristic of plain SCC with this modified SCC mixture, containing RHA as pozzolanic materials and copper fiber as reinforcing material. Incorporating copper fiber in the SCC leads to a drop in fresh properties compared to plain SCC but remains within an acceptable range. On the other hand, the inclusion of 2% RHA makes the SCC more viscous. Although adding 2% RHA and 1% copper wire in SCC provide the highest strength, this mix has an unacceptable passing ability. The SCC mix prepared with 2% RHA and 0.75% copper fiber is suggested to be optimum in terms of the overall performance. According to this study, adding metallic fiber reinforcement like copper wire and mineral admixture like RHA can improve the mechanical properties of SCC up to a certain level.

Experimental and Numerical Investigation of Fracture Behaviors of Steel Fiber–Reinforced Rubber Self-Compacting Concrete

This paper presents the experimental and numerical studies of flexural-fracture behaviors of steel fiber–reinforced rubber self-compacting concrete (SRSCC) materials. The scrap-tires rubber aggregate was used to partially (10%, 15%, and 25%) replace the fine aggregate based on its volume for SRSCC samples, and the microsteel fiber was introduced with an addition ratio of 0.2% based on the entire mixture volume. The plain self-compacting concrete (SCC) and the rubberized SCC specimens were produced for comparison. The three-point bending test on the single-edge notched beam showed the increased flexural strength and total fracture energy of SRSCC samples by adding steel fiber and rubber. The critical fracture parameters including initial fracture energy (Gf) and fracture toughness (KІc) were determined based on the Load-CMOD curves and two parameters fracture model. With these properties, the bilinear tension-softening model (aggregate interlock effect) and trilinear tension-softening model (aggregate interlock and fiber-bridging effects) were calibrated for normal SCC and SRSCC, respectively. The tension-softening functions were utilized in the FEM model to predict the flexural-fracture behaviors of corresponding specimens, and the numerical simulation results showed reasonable agreement with experiments. Overall, the experimental testing data and numerical simulation model can reveal the detailed fracture behavior of SRSCC for future improved material design.

Performance of Fiber Self Compacting Concrete at High Temperatures

The goal of this study is to assess the fresh and hardened properties of self-compacting concrete (SCC) prepared using locally available materials. This research includes also the impact of polypropylene (PP), steel and hybrid fibers on the same properties. In addition, the mechanical properties of SCC specimens (with and without fibers) at high temperatures, including as compressive, tensile, and flexural strengths, will be determined. Four different SCC mixtures (with and without fibers) are prepared, tested, and assessed in order to attain these goals. The specimens were heated to various temperatures (200, 400, 600, and 800) at a rate of 5 degrees Celsius per minute for each test. The temperature was remained constant at the target temperature for one hour before cooling to ensure a consistent temperature throughout the specimen. According to the test results, all of the mixes have good consistency and workability in terms of filling and passing ability. In addition, the inclusion of fibers lowered the workability of SCC slightly. Also, the compressive, tensile, and flexural strengths improved with increasing temperature up to 200 °C and dropped at temperatures over 200 °C, according to these findings. Within the SCC, the PP fibers lowered and removed the risk of spalling. Concrete mixtures containing steel fibers and hybrid fibers have the finest mechanical characteristics and spalling resistance as temperature rises. Weight losses were lower in SCC mixtures with PP and steel fibers than in those without PP and steel fibers. As the temperature rose, all SCC mixes lost mass and UPV decreased until the samples spalled (as in plain SCC and SCC with steel fibers) or were questionable (as in SCC with PP and SCC with hybrid fibers). Doi: 10.28991/cej-2021-03091779 Full Text: PDF

Strength And Durability Properties Of Steel Fiber Reinforced Self Compacting Concrete

In this present study the durability characteristics of Steel fiber reinforced Self compacting concrete (SFRSCC) is determined for M30 and M40 grade concrete mixes. Along with durability strength and sorptivity is carried out and comparison is made with Plane self-compacting concrete (SCC) by chemical resistances, Initial Surface Absorption Test (ISAT).
 In the present study, the rational mix design procedure for self-compacting concrete is used. SCC mixes contains large quantity of powder (material whose parcel size is 0.125 mm) to maintain the plastic yield of the properties of fresh concrete as per the general guidelines for design of SCC mixes given in the EFNARC (2005). The present project consists of two phases. In the first phase, SCC mixes for different grades are developed without steel fibers and with steel fibers. The mechanical properties like compressive strength of the different grades were studied. In the second phase, based on the experimental results, durability properties were studied with the using of specimens of size 100 mm × 100 mm × 100 mm. Durability studies like Acid attack factors, Acid-Durability factors, Sulphate attack factors, Sorptivity are studied for the Plain SCC and steel Fiber Reinforced SCC and a comparison is made.

Structural performance of corroded reinforced concrete beams made with fiber-reinforced self-compacting concrete

The structural performance of corroded beams made with fiber-reinforced self-compacting concrete (SCC) was evaluated in this study. SCC samples reinforced with glass chopped fibers (GF) and polypropylene fibers (PF) without steel reinforcement were first made and assessed in terms of fresh properties, compressive strength, and flexural strength. Cylindrical SCC samples were then subjected to accelerated corrosion in order to determine the influence of SCC mixtures on the steel reinforcement corrosion in terms of the mass loss. Deep beams with a dimension of 700 mm × 100 mm × 300 mm were then made with selected mixtures and subjected to accelerated corrosion before evaluating the structural performance. Findings from this study showed that fiber-reinforced SCC can be utilized in the production of reinforced concrete without any detrimental effects on fresh and mechanical properties. The incorporation of GF and PF at a dosage of 0.06% and 0.1%, respectively enhanced the 90 days compressive strength and flexural strength by 15.4% and 40.8% compared to reinforced concrete made with plain SCC. Results from this study also showed that the use of fiber-reinforced SCC enhanced the structural performance of corroded beams in terms of flexural load capacity, stiffness, ductility and ultimate energy.

Crack Detection and Localisation in Steel-Fibre-Reinforced Self-Compacting Concrete Using Triaxial Accelerometers.

Cracking in concrete structures can significantly affect their structural integrity and eventually lead to catastrophic failure if undetected. Recent advances in sensor technology for structural health monitoring techniques have led to the development of new and improved sensors for real-time detection and monitoring of cracks in various applications, from laboratory tests to large structures. In this study, triaxial accelerometers have been employed to detect and locate micro- and macrocrack formation in plain self-compacting concrete (SCC) and steel-fibre-reinforced SCC (SFRSCC) beams under three-point bending. Experiments were carried out with triaxial accelerometers mounted on the surface of the beams. The experimental results revealed that triaxial accelerometers could be used to identify the locations of cracks and provide a greater quantity of useful data for more accurate measurement and interpretation. The study sheds light on the structural monitoring capability of triaxial acceleration measurements for SFRSCC structural elements that can act as an early warning system for structural failure.

Effect of packing factor and fine aggregate/total aggregate ratio on the development of self-compacting concrete

This paper presents the effect of packing factor and fine aggregate/total aggregate ratio on the performance of the self-compacting concrete (SCC). A higher PF value would imply a greater amount of the coarse and fine aggregates used, thus, decreasing the content of binders in SCC. In this paper M30 grade plain SCC mixes are developed with the different combinations of packing factors (PF) (varying from1.12 to 1.18) and fine to total aggregate ratios (s/a) (0.50 to 0.57) and found that the PF & s/a combinations of 1.12 & 0.53 and 1.14 & 0.57 are found to be optimum as these combinations gave maximum compressive strengths which can be attributed to high achievement of particle packing densities in SCC mixes. As PF increases powder content decreases and aggregate content increases requiring more paste to make the SCC mix workable. Less value PF will have high particle packing density yielding more strength due to improved microstructure of SCC mixes. At PF & s/a combinations of 1.12 & 0.53 and 1.14 & 0.57, the workability of SCC mixes is superior because of high paste volume and less aggregate content.

Fresh and mechanical performance and freeze-thaw durability of steel fiber-reinforced rubber self-compacting concrete (SRSCC)

The self-compacting concrete (SCC) with the replacement of recycled rubber aggregates is limited for the field application due to high-performance requirements. The steel fiber was introduced to the rubberized SCC (RSCC) to enhance its performance and promote its application. The fresh and mechanical properties and durability performance of steel fiber-reinforced rubber self-compacting concrete (SRSCC) were evaluated. The SRSCC samples were prepared with replaced rubber aggregate based on fine aggregate volume percentages of 10%, 15%, and 25% and a consistent steel fiber ratio of 0.2%. The plain SCC and rubberized SCC samples were also produced for comparison. The fresh performance was evaluated with slump flow, J-ring flow, V-funnel, and U-box tests. The results showed that both filling and passing ability could be affected by the added steel fiber and rubber aggregate. However, the SRSCC could still meet most of the recommended criteria for passing and filling abilities when the rubber content is lower than 25%. Regarding the hardened properties, the compressive strength was reduced in rubber SCC samples with increased rubber contents by comparing with the control SCC samples. Nevertheless, SRSCC samples with 10% rubbers have higher splitting tensile strength than RSCC and plain SCC. Also, the SRSCC specimens showed excellent freeze-thaw resistance after 600 F-T cycles. The relative dynamic modulus of elasticity slightly increased without any dimensional expansion in SRSCC samples. In summary, the proposed SRSCC can meet required flowability, filling and passing abilities along with good mechanical and freeze-thaw performance. This study will provide lab test data for the applications of recycling waste tire aggregates in steel fiber-reinforced SCC.

Pullout behaviour of ribbed bars in self-compacting concrete with steel fibers

This research mainly focuses on the pullout behaviour of different ribbed bars size embedded in plain Self-Compacting Concrete (SCC) and also in SCC with Steel Fibers (SCCSF). The diameter of the ribbed bars was 12, 16 and 20 mm. The steel fibers used in this study were the hooked end type with 35 mm length and an aspect ratio of 63.6. This study attempts to investigate factors influencing the pullout behaviour by using the embedment length recommended by RILEM RC6 Part 2 which is 5 times the bar diameter using the direct pullout test method. A total of 9 specimens with a dimension of 200 mm cube were prepared and tested. It was found that the proposed embedment length was large for 12 and 20 mm diameter bars but fitting for bond stress investigation with the 16 mm diameter bar. The addition of steel fibers in SCC improves the compressive and tensile strengths of SCCSF and provides concrete confinement that enhances the bond between ribbed bars and the surrounding concrete. Besides, the presence of steel fibers also changes the failure mode of SCCSF specimens especially with 20 mm diameter rebars in which the failure mode changes from premature splitting to pullout.

Numerical and experimental analysis of behaviour of steel fibre reinforced selfcompacting concrete slabs under loading

The paper deals with testing of self-compacting concrete slabs with scattered steel reinforcement, which are designed for the production of garden furniture or benches. A self-compacting concrete was designed for the experiment and its composition was further modified by the addition of steel fibres. Plain self-compacting concrete was used to produce test specimens with nominal dimensions of 40×40×160 mm, which were used to determine the basic properties of concrete, and test slabs for experimental analysis of their behaviour under load. The self-compacting concrete with steel fibres was only used to produce test slabs. The slabs were loaded in three different ways, of which one was to simulate real loading of the horizontal part of a concrete bench. The results of the loading tests are compared to the results of a nonlinear numerical analysis conducted using the finite element method.

Underwater abrasion of steel fiber-reinforced self-compacting concrete

Hundreds of tons of concrete may be ruined due to the abrasion erosion phenomenon that takes place in several hydraulic structures. Such unfavorable action can impose high maintenance costs and reduce the life span of these structures. The high-velocity water flow which carries large amounts of sediments is basically the main cause of this phenomenon. To better understand concrete abrasion in hydraulic structures, an experimental investigation was conducted to study the underwater frictional abrasion of self-compacting concrete (SCC) using the ASTM C1138 test method. Six SCC mixtures were prepared with different design grades of 30, 40 and 50 MPa and different micro-steel fiber contents of 0, 0.5, 0.75 and 1.0%. Four fresh SCC tests were adopted, while abrasion and control tests were conducted at ages of 7, 28 and 90 days. The ASTM C1138 tests showed that increasing the mixture strength by 20 MPa improved the abrasion resistance more effectively than the inclusion of 1.0% of steel fiber. Compared to the 30 MPa plain SCC, the 90-day abrasion resistance improved by 78% for SCC with 50 MPa strength, while the inclusion of 1.0% of micro-steel fiber enhanced the resistance by only 26%.

High-performance fibre-reinforced heavyweight self-compacting concrete: Analysis of fresh and mechanical properties

Fibre-reinforcement of most of the concrete technologies, such as heavyweight concrete (HWC) and self-compacting concrete (SCC), would promote their practical applications through upgrading their mechanical properties, and subsequently, structural performance. This study evaluates the fresh and mechanical properties of fibre-reinforced heavyweight self-compacting concrete (FRHWSCC). Magnetite was used as heavyweight aggregate (HWA). Hooked-end steel and polypropylene (PP) fibres with length of 60 and 65 mm and diameter of 0.75 and 0.85 mm, respectively, were applied as reinforcements. Two different HWA content (75% and 100%), and four different volume fractions including 0.25%, 0.50%, 0.75%, 1.00% for steel, and 0.10%, 0.15%, 0.20%, 0.25% for PP fibres were utilized. To evaluate the fresh properties of FRHWSCC, slump flow test including slump flow diameter and T500mm, and J-Ring test have been performed. Hardened-state density, compressive, tensile, and flexural strength were measured to assess the mechanical properties of FRHWSCC. The obtained results for the fresh properties revealed that despite the negative impact of HWA and fibres on the workability of SCC, the FRHWSCC with both steel and PP fibres were still capable to retain their self-compacting characteristics according to the EFNARC standards. The hardened densities of specimens were above the density threshold for HWC, except for the FRHWSCC containing steel fibre, which showed slight decrease by increasing the steel fibre content to 0.5%, 0.75%, and 1.00% at 75% magnetite content, revealing the void formation within the cement paste. Compressive, tensile, and flexural strength results showed enhancement in the mechanical properties of FRHWSCC by increasing the fibre content, however, for both fibre types, increasing the HWA content impacted the mechanical properties in a negative manner, especially by aging the concrete. Finally, the load-deflection curves analysis confirmed the more ductile failure mode for the FRHWSCC comparing to plain SCC.

The impact resistance and mechanical properties of fiber reinforced self-compacting concrete (SCC) containing nano-SiO2 and silica fume

In this study, an extensive study including an experimental and analytical approach describes the effects of presence 1% nano-SiO2 and 7% silica fume on the key mechanical properties (compressive, tensile and flexural strength) and impact resistance of such compositions with inclusion of different fibre volume fractions of Polypropylene (PP) (.25, .5, .75 and 1%) and water-to-cement ratios (.27, .34, .41). The experimental tests have been implemented on two hundred and seventy specimens. Experimental results indicated that using both silica fume and nano-SiO2 instead of cement into the plain self-compacting concrete (SCC) leads to improved impact resistance and mechanical properties. This improvement was higher in terms of impact resistance compared to mechanical properties. Moreover, it was observed that using nano-SiO2 particles consequences to reduce the wall effect between PP fibre and its surrounding matrix. Reduction of this effect enhanced the impact resistance and mechanical properties of fibre-reinforced SCC. Moreover, a statistical/ analytical study was carried out on the executed large experimental database and it was observed that the impact resistance and mechanical properties of specimens containing silica fume and nano-SiO2 follow a normal distribution. Furthermore, the highest rate of gaining the number of post initial crack blows to failure for the fibre-reinforced specimens registered for specimens with water-to-cement ratio of .41.

Relationship between Deflection and Crack Mouth Opening Displacement of Self-Compacting Concrete Beams with and without Fibers

There are only a few research results for predicting the relationship between deflection and the crack mouth opening displacement (CMOD) of self-compacting concrete (SCC) beams with and without fibers. A series of bending beam tests on SCC, with different fiber types have been carried out. For this purpose, four SCC mixes—plain SCC, steel, polypropylene, and hybrid fiber reinforced SCC—are considered in the test program. Based on the experimental results, a model for predicting the relation between the deflection and CMOD of SCC has been established per each mix. These models rely on the load–deflection relation and the load–CMOD relation of bending beam. A well agreement has been found between the suggested model and the test results. The results of this study indicate that the load–deflection diagram is very similar to that of the load–CMOD diagram, and there is a linear relation between the mid-span deflection and CMOD of SCC.

Short term bond shear stress and cracking control of reinforced self-compacting concrete one way slabs under flexural loading

Fibre-reinforced self-compacting concrete (FRSCC) is a high-performance building material that combines positive aspects of fresh properties of self-compacting concrete (SCC) with improved characteristics of hardened concrete as a result of fibre addition. To produce SCC, either the constituent materials or the corresponding mix proportions may notably differ from the conventional concrete (CC). These modifications besides enhance the concrete fresh properties affect the hardened properties of the concrete. Therefore, it is vital to investigate whether all the assumed hypotheses about CC are also valid for SCC structures. In the present paper, the experimental results of short-term flexural load tests on eight reinforced SCC and FRSCC specimens slabs are presented. For this purpose, four SCC mixes - two plain SCC, two steel, two polypropylene, and two hybrid FRSCC slab specimens - are considered in the test program. The tests are conducted to study the development of SCC and FRSCC flexural cracking under increasing short-term loads from first cracking through to flexural failure. The achieved experimental results give the SCC and FRSCC slabs bond shear stresses for short-term crack width calculation. Therefore, the adopted bond shear stress for each mix slab is presented in this study. Crack width, crack patterns, deflections at mid-span, steel strains and concrete surface strains at the steel levels were recorded at each load increment in the post-cracking range.

Experimental Methods on Glass Fiber Reinforced Self Compaction Concrete

Self Compacting Concrete (SCC) is able to flow under its own weight and completely fill the formwork, even in the presence of congested reinforcement, without any compaction, while maintaining homogeneity of the concrete. Compaction is difficult to be done in conditions where there are dense reinforcement and large casting area. Usage of SCC will overcome the difficult casting conditions and reduce manpower required. Addition of fibers will enhance the tensile and ductile behavior of concrete with brittle nature. SCC was added with relatively short, discrete, and discontinuous glass fibers to produce Glass Fiber Reinforced Self Compacting Concrete (GFRSCC). The purpose of this study is to investigate the workability and mechanical properties of plain SCC and GFRSCC. The laboratory testing included slump flow test, L-Box test, sieve segregation resistance test, density test, ultrasonic pulse velocity (UPV) test, compressive strength test, splitting tensile strength test, and flexural strength test. The dosage of super plasticizer required increased as fiber content increased. There has been a lack of studies for productivity improvement in the construction industry. A review of literature was done where an inventory of productivity related factors were found and interpolated. A survey of construction practitioners was conducted to rank and determine the degree of influence of various factors on construction productivity. We have selected the major factors such as Material, Labor and accessed it both quantitatively and qualitatively for a real time construction project. The results enhanced profit and productivity. I. Introduction SCC can be considered as a concrete with high flow ability that can be placed and compacted under its own weight without any external vibration, assuring complete filling of formworks and also the complete covering of the reinforcing bars even when the space between the reinforcements is very narrow. SCC is characterized by high flow ability in its fresh state and increased strength in its hardened state because of a compact matrix structure. SCC has many advantages that include faster construction, better surface finishes, easier placing, reduction in noise levels and improved durability. The term Fiber Reinforced Concrete (FRC) can be defined as a concrete structure having randomly oriented and dispersed fibers. Fibers can be defined as small wire-like reinforcements which are made of either steel or polymers having high ductility. The fibers are produced in a wide range of sizes and shapes, stiff or flexible etc. Addition of fibers into concrete improves the overall ductility of the concrete imparting toughness, greater tensile strength, and resistance to fatigue, impact, blast loading and abrasion. Fibers are added not only to improve the ductility of concrete but also, more importantly to control the cracking, by the bridging of the fibers across the cracks, which delay the propagation and widening of localized cracks. The use of glass fibers in SCC might bring together the advantages of both fibers and SCC. Glass Fiber Reinforced Self-Compacting Concrete (GFRSCC) combines the advantages of SCC in its fresh state and that of fibers in its hardened state. Because of the superior performance of SCC in its fresh state, addition of fibers will lead to a more uniform dispersion of fibers which is very critical for the performance of any fiber reinforced composite. Also the compactness of SCC matrix due to higher amount of finer particles may improve the interface zone properties and consequently the fiber-matrix bond leading to enhanced post-cracking toughness and energy absorption capacity S. No Properties Values

Creep and Shrinkage of Self-Compacting Concrete with and without Fibers

Fiber-reinforced self-compacting concrete (FRSCC) is a high-performance building material that combines positive aspects of fresh properties of self-compacting concrete (SCC) with improved characteristics of hardened concrete as a result of fiber addition. Considering these properties, the application ranges of both FRSCC and SCC can be covered. To produce SCC, either the constituent materials or the corresponding mix proportions may notably differ from the conventional concrete (CC). These modifications besides enhance the concrete fresh properties affect the hardened properties of the concrete including creep and shrinkage. Therefore, it is vital to investigate whether all the assumed hypotheses about conventional concrete are also valid for SCC structures. In the present paper, a numerical and experimental study about creep and shrinkage behavior of FRSCC and SCC is performed. Two new creep and shrinkage prediction models based on the comprehensive analysis on the available models of both CC and SCC are proposed for FRSCC and SCC structures. In order to evaluate the predictability of the proposed models, an experimental program was carried out. For this purpose, four SCC mixes plain SCC, steel, polypropylene, and hybrid FRSCC are considered in the test program. Several specimens were loaded and deformation in non-loaded specimens was also measured to assess shrinkage. All specimens were kept under constant stress during at least 364 days in a climatic chamber with temperature and relative humidity of 22oC and 50%, respectively. Results showed that the new models were able to predict deformations with good accuracy, although providing deformations slight overestimated.

Effects of specimen size and shape on compressive and tensile strengths of self-compacting concrete with or without fibres

Self-compacting concrete (SCC) can be placed and compacted under its own weight. Modifications in the mix design of SCC may significantly influence the material's mechanical properties. Therefore, it is vital to investigate whether all the assumed hypotheses about conventional concrete also hold true for SCC structures. This paper discusses an experimental programme that was carried out to study the effects of specimen size and shape on the compressive and tensile strength of SCC and fibre reinforced SCC. For this purpose, cube specimens with 100 and 150 mm dimensions and cylinder specimens with 100 × 200 and 150 × 300 mm dimensions were casted. The experimental programme examined four SCC mixtures: plain SCC, and steel-, polypropylene- and hybrid-fibre reinforced SCC. Compressive and tensile strengths were tested after 3, 7, 14, 28 and 56 days. The paper also investigates correlations between compressive and tensile strengths and the size and shape of the specimen.