Rheological Properties Of Self-compacting Concrete Research Articles

A Study on the Rheology of Scc with the Addition of Fly Ash in Opc, Ppc and, Psc Cements with Different Mixing Times

In this paper, a study was performed on the rheological properties of self-compacting concrete by the addition of Supplementary Cementitious Material (SCM) as Fly Ash with various percentages of 15%, 20%, 25%, and 30% in the different types of cement OPC, PPC, and PSC. The mix designs of self-compacting concrete were done by two methods of constants: Water-Binder Ratio Constant and Weight and Volume of Aggregates Constant for varying percentages of addition of Fly Ash with a fixed cement content of 380 kg per cubic meter. Flow ability (Flow Table and V Funnel) and Passing Ability (L-Box and U-Box) tests were carried out on fresh concrete in accordance to EFNARC with three different mixing times 5(initial), 30, and 90 minutes were done to find the self-compactibility of designed concrete mixes. Varying dosages of Super Plasticizer (Auromix 450) were added to obtain the required flow ability and passing ability of SCC without bleeding of water and segregation of aggregates. Self-compactibility of the designed SCCs was obtained for 20%, 25%, and 30% addition of SCM in Water-Binder Ratio Constant Method and 15%, 20%, and 30% addition of SCM in Weight and Volume Constant Method.

Rheological property and stability of nano-silica modified self-compacting concrete with manufactured sand

Self-compacting concrete (SCC) of high fluidity may lead to the high tendency of segregation, especially when manufactured sand (MS) is used. In this work, the rheological properties of SCC are optimized by adding nano-silica (NS) and limestone powder (LP) at different water-to-binder ratios (W/B). The segregation tendency of SCC is evaluated by calculating the stability index (i.e., the degree of segregation of aggregate) through image analysis method. The result shows that MS greatly decreases the stability of SCC, and the static stability index increases from 10.3% to 29.13% when the amount of MS exceeds 20%, increasing risk of segregation. NS can improve the stability of SCC during vibration significantly, however, when the dosage exceeds 0.3%, the fluidity (slump flow) is significantly reduced by 30%. LP improves the stability of SCC by increasing the plastic viscosity. Furthermore, the relationship between the dynamic yield stress/plastic viscosity and the instability index are linearly fitted, the former of which shows a higher correlation coefficient. Finally, the workability and stability of SCC are comprehensively evaluated by the rheological interval box, that is, the SCC with MS owns the best workability when yield stress is (0 ∼ 15.72 Pa) and plastic viscosity is (76.8 ∼ 250.4 Pa·s).

Statistical mix design method for self-compacting concrete with limestone fillers

This study presents a statistical mix design method for self-compacting concrete (SCC) with limestone fillers (LF) content that considers mortar rheological properties and material packing characteristics. The effect of LF on the rheological properties of SCC was investigated through seven SCC mixes with different LF replacement levels. A basic water demand experiment was designed to obtain the packing density of mortar, and the equivalent packing density was defined and calibrated to represent the effect of LF. The relative spread and relative flow formula were modified based on the equivalent packing density, and the bilinear interpolation method was used to analyses the mortar results.

Explainable Ensemble Learning Models for the Rheological Properties of Self-Compacting Concrete

Self-compacting concrete (SCC) has been developed as a type of concrete capable of filling narrow gaps in highly reinforced areas of a mold without internal or external vibration. Bleeding and segregation in SCC can be prevented by the addition of superplasticizers. Due to these favorable properties, SCC has been adopted worldwide. The workability of SCC is closely related to its yield stress and plastic viscosity levels. Therefore, the accurate prediction of yield stress and plastic viscosity of SCC has certain advantages. Predictions of the shear stress and plastic viscosity of SCC is presented in the current study using four different ensemble machine learning techniques: Light Gradient Boosting Machine (LightGBM), Extreme Gradient Boosting (XGBoost), random forest, and Categorical Gradient Boosting (CatBoost). A new database containing the results of slump flow, V-funnel, and L-Box tests with the corresponding shear stress and plastic viscosity values was curated from the literature to develop these ensemble learning models. The performances of these algorithms were compared using state-of-the-art statistical measures of accuracy. Afterward, the output of these ensemble learning algorithms was interpreted with the help of SHapley Additive exPlanations (SHAP) analysis and individual conditional expectation (ICE) plots. Each input variable’s effect on the predictions of the model and their interdependencies have been illustrated. Highly accurate predictions could be achieved with a coefficient of determination greater than 0.96 for both shear stress and plastic viscosity.

Performance of self-compacting concrete incorporating waste glass as coarse aggregate

The purpose of this paper is to develop gather data on the rheological and mechanical properties of self-compacting concrete (SCC) containing varying percentages of waste glass aggregate (WGA). In this current experiment, the coarse aggregate was substituted by adding WGA, with replacement percentages of 0%, 10%, 20%, and 30% by weight being investigated. The rheological properties of SCC were performed to explore the consequence of WGA using various methods, including the J-ring, slump flow, L-box, and V-funnel. In contrast, the compressive, flexural, modulus of elasticity, and stress-strain responses of hardened concrete were assessed in this study. The results of the fresh concrete tests revealed that the substitution of an optimal level of waste glass in SCC provides adequate implementation in flowability, passing ability, and viscosity behaviors. Besides, hardened characteristics were shown to have a steady decrease in strength with increasing WGA content in the concrete mixtures.

Experimental and statistical evaluation of rheological properties of self-compacting concrete containing fly ash and ground granulated blast furnace slag

This study examines an attempt to produce self-compacting concrete (SCC) containing fly ash (FA), ground granulated blast furnace slag (S) and both (FA + S). The effects of these materials on the rheological properties of the SCC mixes were studied experimentally. The study began with three groups of SCCs, each with 25% water binder (w/b) and 550 kg/m3 total binder content. Instead of superplasticizers (SP), the chemical admixtures were lignosulphonates (LS), which replaced Portland cement (PC) at levels by weight of 10%, 20%, 30% 40%, 50%, and 60%. The fresh properties of the mixtures were examined experimentally for slump flow diameter, T50 time, V-funnel time, and L-box height ratio. In the mixtures with FA alone, a continuous decrease was observed in compressive strength. Increases in strength ended at 40% in the case of FA alone, and 30% for both the S and FA + S mixes. Statistical analysis was carried out to assess the effect of experimentally substituted materials FA and S, with results showing that S had a greater influence than FA on T50 time, V-funnel, L-box height ratio, and compressive strength, while FA had more effect than S on the slump flow diameter test.

High Temperature Performance of Self-Compacting Concrete Containing Boron Active Belite Cement

Abstract The boron active belite cement is a cement type different from the Portland Cement due to the presence of B2O3 at 3–4%. The prominent properties are low hydration temperature, low early strength, and high final strength for the boron active belite cement concrete. The aim of this study is to observe self-compacting concrete properties, which includes boron active belite cement and silica fume, at the high temperatures. Withal, the cement types were decided as CEM I, CEM II, and boron active belite cement. Some mechanical and durability properties of manufactured samples were also investigated, experimentally. The samples were designed for 0.35 water/binder ratio and 2% hyper plasticizer, while the silica fume is replaced 7.5% for cement. Some rheological properties of self-compacting concrete, such as the experiments of flow diameter, flow time (t50), V-flow time, L-box and J-ring were observed at fresh stage. As high temperature related parameters, the samples were planned to be tested for 100, 200, 300, 400, 600 and 750°C, to acquire the compressive strength, tensile splitting strength, ultrasonic pulse velocity, and the unit weight. All the samples met the mentioned relevant criteria of self-compacting concrete. Withal, the presence of the boron active belite cement was enhanced by the flowability of the fresh concrete. The long time resulting compressive and splitting tensile strengths of the samples, which were produced with boron active belite cement implied greater values, then the CEM I and CEM II ones. The increasing high-temperature, decreased the strengths for all samples, and weight loss for the boron active belite cement used samples.

Effects of Fly Ash, Slag, and Nano-Silica Combination on Corrosion Induced Crack in Reinforced Self Compacting Concrete

This paper presents an experimental study to evaluate the effect of mineral admixtures includes fly ash, ground granulated blast furnace slag (ggbfs), and nano Silica(NS) to understand rheological, mechanical and durability properties of self-compacting concrete (SCC). For the test, a fraction of OPC is replaced by the mineral admixtures in a fixed quantity such as 20%fly ash and 30%ggbfs in all mixes and different percentages of nano-silica such as 1.5%, 3%, 4.5%, 6%, 7.5%, 9%. The rheological properties of SCC were known by conducting a slump flow test, V-funnel test, and the mechanical properties understand by conducting compressive strength test, flexural strength test, and split tensile strength test. The results indicated that the presence of cement with fly ash, ggbfs improved the fresh properties of concrete at an initial dosage of nano-silica(NS) and by the increment in a dosage of these NS reduces the fresh properties of SCC. Hardened properties were shown good improvement in strength than that of the control concrete mix, the increment in strength shown up to the addition of certain(optimum) dosage of NS thereafter decreases the strength. The addition of NS shows higher strength at a dosage of 6%. Further durability test such as Accelerated corrosion test was conducted to determine the crack development age. The mix FGNS.6% for which maximum strength value obtained was taken for conducting the test. The control mix specimen cracked at 12th day and the specimen mix FGNS.6% cracked at 18th day from starting of the experiment.

Modelling fresh and hardened properties of self-compacting concrete containing supplementary cementitious materials using reactive moduli

In traditional mix design approaches for self-compacting concrete (SCC), the impact of the reactivity of the supplementary cementitious materials is based on the definition of the SCM type. This is problematic because the chemical composition, and therefore reactivity, of a given type of SCM is highly variable. As a result, mix designs developed with a specific SCM may not be transferable to other locations where the SCM chemical composition is not the same. To address this shortcomings, in this study, a unified approach to assess and model the fresh and hardened properties of self-compacting concrete containing supplementary cementitious materials is developed based on the application of the reactive moduli, which is formulated using the fraction of key oxides (SiO2, Al2O3, Fe2O3, CaO, MgO) in a unary or blended binder and the remaining key mix ingredients. An extensive test database containing the results of 1577 tests from 102 studies on fresh and hardened properties of SCCs, including slump flow, J-ring flow, initial and final setting time, T500 time, V-funnel time, segregation resistance index and H2/H1 ratio measured from L-box test together with the 28-day compressive strength is compiled to develop this approach. The predicted fresh and hardened properties of SCC correlate well with the experimental results. Having related the slump flow and the reactive moduli, the relationship between the slump flow and the other fresh and rheological properties of SCCs are also established. Examples of applications are presented to show how to proportion a SCC mix using the approach, and it is validated against test results not included in the calibration set. The approach presented in this study should serve as a means for the reliable and efficient proportioning of SCC a directly apply in engineering practices and can be applied directly in practice.

A smoothed particle hydrodynamics study on effect of coarse aggregate on self-compacting concrete flows

Coarse aggregates increase inhomogeneity and alter rheological properties of self-compacting concrete. In this work, the effect of coarse aggregates on self-compacting concrete is studied by considering its pipe flow. Self-compacting concrete is modelled as suspension of coarse aggregates in cement mortar and a two-phase Smoothed Particle Hydrodynamics (SPH) model is employed. Cement mortar, a yield-stress fluid, is modelled by fluid SPH particles, while each coarse aggregate is represented by a group of solid SPH particles, which moves as a rigid body. Simulation results show that, at the same volume fractions, the flow rate is higher for larger coarse aggregates, that is up to 24% in the investigated cases. Both effective yield stress and effective plastic viscosity of the concretes increase with the coarse aggregate content. Effective yield stress is smaller for bigger coarse aggregates. The reduction in effective yield stress is a consequence of bigger averaged gap between larger coarse aggregates through which the cement mortar flows.

Investigations of Mixing Technique on the Rheological Properties of Self-Compacting Concrete

Rheological properties are of significant importance in successful placement and performance of self-compacting concrete (SCC). In this work, the rheological properties of SCC, combined with a powder-viscosity modifying admixture, were investigated based on a series of experimental studies. The modified Bingham model was applied to determine the rheological parameters and shear thickening behavior of SCC. The effects of mixing procedures, including charging sequence, mixing time and mixing speed, were analyzed. The results show that the shear thickening of SCC is reduced by first mixing the aggregate and water and then adding other raw materials. The direct contact between aggregate and water leads to a large amount of free water to be adsorbed by the aggregate system, resulting in an increase of the yield stress. In order to ensure an excellent fluidity and a low shear thickening behavior of SCC, the mixing time should be controlled at 4–5 min and the mixing speed at 30–45 r/min.

An enhanced mix design method of self-compacting concrete with fly ash content based on paste rheological threshold theory and material packing characteristics

This study investigated an enhanced mix design method of self-compacting concrete (SCC) with fly ash (FA) content based on paste rheological threshold theory and material packing characteristics. Seven SCC mixes with FA replacement levels of 0%, 10%, 20%, 30%, and 40% by volume were conducted to investigate the effect of FA on the rheological properties of SCC. A basic water demand experiment of mortar was designed to obtain the packing density of mortar. Furthermore, the equivalent packing density was defined and calibrate to quantify and represent the effect of FA. The yield stress and plastic viscosity threshold formula were modified based on the equivalent packing density. And the bilinear interpolation method was used to analyze the paste and SCC results. Besides, twenty seven SCC series with different water to cement ratio, FA replacement levels were conducted to verify the applicability of the enhanced method. The results show that, the relative accuracies of the improved method are higher than 83%, whereas those of the initial method are no greater than 60%.

Effects of curing regimes on the physico-mechanical properties of self-compacting concrete made with ternary sands

This paper investigates the effects of curing regimes on the physico-mechanical properties of self-compacting concrete (SCC) made with ternary sands in order to valorize local materials, reuse of industrial wastes and to benefit from their properties for the composition of SCC. Three types of sands were used in ternary combinations: river sand (RS), crushed sand (CS) and dune sand (DS). First, we started by the measurement of the porosity of seven ternary combinations of sand (RS-CS-DS), included the 100%RS as reference combination. Subsequently, the rheological characteristics of SCCs in fresh state are characterized and analyzed. Finally, studying the effects of curing regimes (three regimes were used: wrapped in a plastic sheet, water curing and air curing) on the compressive strength of SCC made with different systems of ternary sands. The obtained results proved that beyond 40% of RS substitution by (CS + DS); the porosity of the sand mixture is increased. The porosity of the combination C2 (60% RS + 20% CS + 20% DS) is lower than those of the other combinations. In addition, the rheological properties of SCC are decreased, which requires the additional quantities of water or superplasticizer to meet the self-compacting properties. Whatever the curing regimes, we can say that the partial replacement of RS by (20% CS + 20% DS) offers the best compressive strength at all ages and gives good rheological characteristics to the SCC. The use of ternary sand (C2) also contributes to the improvement of SCC compactness. The results show that the water curing as well as wrapped curing provide better results than air curing.

The rheological properties of self-compacting concrete containing superplasticizer and air-entraining agent

This work investigates the effect of a polycarboxylate superplasticizer (SP) and a rosin resin type air-entraining agent (AE) on the rheological properties of powder-viscosity modifying admixture (VMA) combination type self-compacting concrete (SCC). The modified Bingham model was applied to describe the shear thickening behavior of this specific SCC. The results showed that both the yield stress and plastic viscosity of SCC deceased significantly while the shear thickening behavior of mixtures was intensified with an increase of SP dosage. The addition of AE led to an increase of yield stress and a decrease of plastic viscosity, whereas a high air content weakened the shear thickening behavior of SCC. The shear thickening behavior was found to be completely disappeared and shear thinning behavior occurred when the air content reached 8.7%, which indicated that increasing the air content was an easy and effective way to reduce the shear thickening behavior of SCC.

The Effect of Temperature on the Properties of Fresh Self-Compacting Concrete

Abstract The rheological properties of self-compacting concrete are closely influenced by temperature and the time. Previous studies which aim was to research the effect of temperature on self-compacting concrete workability, showed that the behaviour of fresh SCC at varying temperatures differs from that of normal vibrated concrete. The paper presents the study of rheological properties of fresh self-compacting concrete mixtures made with portland, blast furnace and component cement. Two types of superplasticizers were used. It was proven that temperature has a clear effect on workability; it can be reduced by selecting the appropriate superplasticizer and cement.

Experimental investigation on self-compacting concrete reinforced with steel fibers

Self-Compacting Concrete (SCC) has been originally developed in Japan to offset a growing shortage of skilled labors, is a highly workable concrete, which is not needed to any vibration or impact during casting. The utilizing of fibers in SCC improves the mechanical properties and durability of hardened concrete such as impact strength, flexural strength, and vulnerability to cracking. The purpose of this investigation is to determine the effect of steel fibers on mechanical performance of traditionally reinforced Self-Competing Concrete beams. In this study, two mixes Mix 1% and Mix 2% containing 1% and 2% volume friction of superplasticizer are considered. For each type of mixture, four different volume percentages of 60/30 (length/diameter) fibers of 0.0%, 1.0%, 1.5% and 2% were used. The mechanical properties were determined through compressive and flexural tests. According to the experimental test results, an increase in the steel fibers volume fraction in Mix 1% and Mix 2% improves compressive strength slightly but decreases the workability and other rheological properties of SCC. On the other hand, results revealed that flexural strength, energy absorption capacity and toughness are increased by increasing the steel fiber volume fraction. The results clearly show that the use of fibers improves the post-cracking behavior. The average spacing of between cracks decrease by increasing the fiber volume fraction. Furthermore, fibers increase the tensile strength by bridging actions through the cracks. Therefore, steel fibers increase the ductility and energy absorption capacity of RC elements subjected to flexure.

Verification of Rheological Properties of Self-Compacting Concrete with Reinforcement

The paper presents results of mechanical and physical tests of self-compacting concrete with fibre reinforcement. Self-compacting concretes belong to special types of concretes with filling ability without invoking external dynamic forces. Especially high storage rate and concrete access even in densely stored reinforcement, high homogenisation, low water-cement ratio and exclusion of external vibrations are benefits of SCC concretes. The highest risks that must be considered when designing this type of the concretes are their resistance to segregation, sedimentation, blocking and bleeding. Several SCC formulas with two types of fibres (steel, polypropylene) were designed and compared and the effects of fibres reinforcement on concrete selected properties were monitored in fresh and hardened condition, too.

Pumice powder as filler of self-compacting concrete

An experimental study on the rheological and mechanical properties of self-compacting concrete with pumice powder used as filler additive is presented. Self-compacting concrete (SCC) shows its peculiar characteristics in the fresh state and many researches have been developed with reference to its rheological characteristics paying attention to the techniques of self-compacting properties assessment. One of the most important aspect in concrete mix-design is the type and the amount of fillers with respect to water and cement: this amount has great influence not only on self-compacting properties (fluidity, segregation, etc.), but also on the mechanical properties of the mixture. Volcanic materials like white pumice have pozzolanic properties, so that it is possible to use powdered pumice in SCC manufacturing with a double effect: on one hand as filler and on another hand as a pozzolanic element in the mixture. The experimental campaign investigates SCC properties when white pumice powder is used as filler with or instead of silica fumes or flying ashes. From the rheological model of the paste, varying the components of the mixture, the determination of pumice powder amount and the consequences on the rheological properties of SCC are investigated. SCC with pumice powder is compared to other mixtures with silica fume and marble powder as filler, through tests on fresh and hardened concrete. Compressive and tensile strength tests were carried out together with the evaluation of fracture energy with the aim of characterizing the constitutive law of SCC with pumice powder. Results from shrinkage tests in the first days of curing are reported and comparisons with ordinary concrete manufactured with the same basic components are shown in order to evaluate the suitability and effectiveness of pumice powder added as filler to self-compacting concrete mix-design. Pozzolanicity of pumice strictly influences the mechanical properties with a significant increase of compressive strength after 28days of curing.

Evaluation of Fresh and Hardened Properties of Self-Compacting Concrete

This paper compared the rheological properties and compressive strengths of self-compacting concrete (SCC) and conventional cement concrete. The flowability and segregation resistance of freshly mixed concrete specimens were examined by the V-funnel apparatus, while the characteristics of passing ability were investigated with the L-box apparatus. Cylindrical concrete specimens of 100 mm diameter × 200 mm length were investigated for compressive strength. The rheological properties of SCC are incomparable with those of the conventional concrete due to their diverse testing methods and characteristics of individual flow. The compressive strength results of hardened concrete showed that SCC gained strength slowly compared to the conventional cement concrete due to the presence of admixtures and its 28 days strength was lower than conventional cement concrete, but SCC eventually had potentials of higher strength beyond 90 days. Finally, the effect of water-cement ratio on the plastic properties of self-compacting concrete was quite negligible compared to conventional concrete.

A Study on the Influence of Coarse Aggregate on Rheological Properties of Self-Compacting Concrete

This paper presences the influence of coarse aggregate-space coefficient on the rheological properties of self-compacting concrete (SCC). The results indicate that coarse aggregate-space coefficient has significant influence on slump flow and V-funnel flow time of SCC, when the maximum aggregate particle size is 16mm and the volume ratio of sand and motor is 0.43, meanwhile water binder ratio is 0.38. The higher the coarse aggregate-space coefficient, the lager the slump flow, the shorter the V-funnel flow time. The range of coarse aggregate-space coefficient of SCC is suitable for 1.31~1.58 under the condition of the paper. The suitable range can guarantee excellent rheological properties and stability of SCC mixture. There is little effect of coarse aggregate-space coefficient on compressive strength in this paper tests.