Self-compacting Concrete Specimens Research Articles

Performance of self-compacting concrete with treated rice husk ash at different curing temperatures

Self-compacting concrete (SCC) is currently gaining traction as a replacement to conventional vibrated concrete. Its distinct microstructure leads to varied mechanical behaviour under different curing temperatures. In the past various supplementary cementitious materials (SCMs) were used in SCC to investigate their respective effects on the performance. However, there has been no systematic studies conducted to determine the effect of different curing temperature on the sensitivity reaction of rice husk ash (RHA) in SCC. This research focuses on high-strength SCC with SCMs such as RHA, silica fume (SF), fly ash (FA), and ground granulated blast-furnace slag (GGBS), exploring their applicability for concrete structures under varying curing temperatures. Heat of hydration, compressive strength and open porosity of SCC specimens were assessed at various temperature. Results indicate high curing temperatures expedite the hydration and pozzolanic reaction, refining the microstructure and increasing the early-age concrete strength, but compromising the long-term performance, potentially mitigated by the use of SCMs. Conversely, lower curing temperature, impedes hydration leading to gradual strength gain, particularly with SCMs, yet yielding significant strength increases at later concrete age. SCMs presence and curing temperature significantly influence maturity function-based strength predictions, impacting strength trends in the samples studied.

Transport Properties of Internally Cured Self Compacting Concrete with Fly Ash

Proper curing of concrete has a major beneficial effect on the transport properties of concrete which in turn influences its durability. This paper attempts to study the effect of fly ash on the transport properties of internally cured Self-Compacting Concrete specimens under ambient conditions. Two internal curing materials, Lightweight Expanded Clay Aggregates [LECA] and Superabsorbent Polymer [SAP] were chosen for the study. Properties such as sorptivity, resistance to chloride ion penetration and chloride ion migration specimens with varying percentages of fly ash replacement from 30% to 50% are presented under different curing conditions namely conventional curing, sealed curing with internal curing materials and ambient curing with internal curing materials. The results showed that the impermeability of concrete improved with an increasing percentage of fly ash replacements owing to the presence of internal curing water to improve hydration along with fly ash that moderates the heat of hydration and drying. The internal curing efficiency also improved with the increase in the percentage of fly ash replacement. Under ambient conditions, the mixes with fly ash above 45% replacement have shown very good mechanical and durability properties indicating a refined pore structure leading to enhanced transport properties.

Enhancing the Properties of Steel Fiber Self-Compacting NaOH-Based Geopolymer Concrete with the Addition of Metakaolin

There is a demand for innovative construction materials that offer enhanced mechanical characteristics while also being cost-effective and environmentally friendly. This paper examines the fresh properties and mechanical properties of geopolymerized self-compacting concrete (SCC) reinforced with steel fibers, containing 0–100% metakaolin (MK) by mass, as an eco-friendly substitute for Portland cement. SCC combinations included one or more waste cementitious materials (WCMs), such as metakaolin (MK), NaOH as an alkaline activity, and double-hook end steel fibers. For every NaOH geopolymer SCC blend, the mechanical characteristics (compressive strength, splitting tensile strength, flexural strength), as well as the new properties (lump flow, V-Funnel, L-box test), were read up. The findings indicate that combining metakaolin and steel fibers reduces the flowability of NaOH-based geopolymer SCC. On the other hand, incorporating MK and steel fibers enhances the compressive and flexural strength of NaOH-based geopolymer SCC with 25% metakaolin and 0.3% steel fiber. In contrast to the fiber-reinforced NaOH-based geopolymer SCC samples, which could transfer a sizable load even when the crack mouth opening deflection rose at flexural strength, the fiber-free SCC samples showed a brittle and abrupt fracture. The findings showed that the addition of NaOH as an alkaline activator, MK, and steel fiber had a negative impact on the fresh state properties; however, their combined use greatly enhanced the bond strength and flexural performance of the NaOH geopolymer SCC specimens. Doi: 10.28991/CEJ-2024-010-07-011 Full Text: PDF

Compression behaviour of self-compacting concrete under dynamic loading at different ages

Self-compacting concrete (SCC) is widely used in reinforced concrete buildings, owing to its ability to consolidate by weight and its lack of requirement for external vibration. Reinforced concrete buildings can be subjected to high strain rate loading during the early days of construction or in their service life. Thus, it is critical to understand the behaviour of concrete under high strain rate loadings at different ages. Minimal studies have previously focused on the early-age behaviour of concrete under high strain rates. This study tries to fill this gap. It focuses on the behaviour of M40 grade SCC under three levels of strain rate loading at ages of 1, 3, 7, 14 and 28 d. The split-Hopkinson pressure bar (SHPB) was used to test 45 SCC specimens of diameter 100 m and thickness 50 mm at high strain rates, ranging from 30 s−1 to 110 s−1, and the determined compressive strength, peak strain and elastic modulus results are compared with quasistatic test results of SCC specimens. The dynamic increase factor (DIF) determined in the SHPB experiment is compared with the CEB-fib code model. The results indicate that the DIF reduces as the concrete's strength and age increase.

Mechanical Properties of Lightweight EPS Self-compacting Concrete Reinforced with Steel Fibers

This study aims to evaluate experimentally the mechanical characteristics of Self-Compacting Concrete (SCC) comprising expanded polystyrene beads (EPS) to produce flowable lightweight concrete reinforced with steel fibers. In this paper, the effect of steel fibers and EPS content on the fresh and hardened mechanical properties of SCC specimens, using two percentages for Polystyrene aggregate replacement (25% and 50%) and three values for volume fraction of steel fiber content (0%, 0.75%, and 1.5%), were examined. Fresh mixture properties were determined using slump flow, L-box, and V-funnel tests. Mechanical properties for hardened samples were obtained using standard specimens for compressive strength, density, split, and flexural strength. The study showed that EPS content has no adverse effect on the rheological features of the SCC. However, workability falls below specification limits when adding steel fibers to SCC. Results revealed that using 25% of EPS content resulted in lightweight structural concrete, while lightweight moderate-strength concrete was produced using 50% of EPS content. Furthermore, the study has shown that the split and flexural tensile strength were reduced substantially by 53% and 60% due to EPS addition. However, adding steel fibers remarkably improved the indirect tensile strength and Modulus of rupture by 46% and 80%, respectively. The mode of failure of the concrete specimens containing EPS beads and steel fibers did not show brittle failure behavior generally encountered in normal-weight concrete, indicating a more ductile behavior.

Microstructural and Residual Properties of Self-Compacting Concrete Containing Waste Copper Slag as Fine Aggregate Exposed to Ambient and Elevated Temperatures

In recent times, with rapid development in the construction sector, the use of enormous amounts of materials is required for the production of concrete. Fire penetrates concrete, leading to chemical contamination, small cracks, and lightening. These effects can significantly change the properties of concrete’s structure, reduce its strength and durability, and also change the behavior of the structure and lead to effects on the environment. An attempt was made to study the effects of elevated temperature on the mechanical characteristics of self-compacting concrete (SCC) with by-products including fly ash as a partial replacement for cement and waste copper slag as a partial replacement for fine aggregate at 0%, 10%, 20%, 30%, 40%, 50%, 60%, and 70%. The SCC specimens were subjected to elevated temperatures ranging from 200, 400, 600, and 800 °C, respectively, for a steady-state of two hours in a digital muffle furnace. The residual compressive strength, mass loss, ultrasonic pulse velocity, and residual density along with a visual inspection of cracks and color changes were observed. In this study, with over 400 °C temperatures, surface fractures appeared. The residual compressive strength (R-CMS) of all the individual temperatures of the SCC-WCS% mixes exhibited a gain in strength range from 31 to 34 MPa at 400 °C, 26 to 35 MPa at 600 °C, and 22.5 MPa to 33.5 MPa at 800 °C, respectively. Microstructural analysis of SCC-WCS% mixtures subjected to elevated ambient temperatures is carried out with a scanning electron microscope (SEM) and X-ray diffraction (XRD).

Effect of water re-curing on the physico-mechanical and microstructural properties of self-compacting concrete reinforced with steel fibers after exposure to high temperatures

The present work aims to investigate the influence of water re-curing- on the physico-mechanical properties and the microstructural of heat-damaged steel fiber-reinforced self-compacting concrete. The experimental approach involves subjecting self-compacting concrete specimens, with and without steel fiber reinforcement, to various high temperatures (400, 600, and 800 °C), with a heating rate of 5 °C/minute. After cooling to ambient temperature, these samples were subjected to water re-curing for 30 days. Non-destructive measurement techniques, such as those of the ultrasonic pulse velocity and dynamic modulus of elasticity, and destructive measurement techniques, such as those of the flexural strength and compressive strength, were performed to assess the level of thermal damage caused to specimens as well as the degree of recovery. Moreover, scanning electron microscope (SEM) analyses were also performed to examine the morphological changes that occurred in concrete and at the fiber/concrete interface. The results obtained showed that the water re-curing process has remarkable effects on the recovery of the microstructure of thermally damaged specimens and its physical and mechanical properties as well. The recovery rate was more important for temperatures above 400 °C. Furthermore, it was found that self-compacting concretes reinforced with steel fibers recurred after exposure to 400 °C and 600 °C exhibited better behavior than self-compacting concrete without fibers, particularly in terms of mechanical resistance.

Machine Learning Models for the Prediction of the Compressive Strength of Self-Compacting Concrete Incorporating Incinerated Bio-Medical Waste Ash

Self-compacting concrete (SCC) is a special form of high-performance concrete that is highly efficient in its filling, flowing, and passing abilities. In this study, an attempt has been made to model the compressive strength (CS) of SCC mixes using machine-learning approaches. The SCC mixes were designed considering lightweight expandable clay aggregate (LECA) as a partial replacement for coarse aggregate; ground granulated blast-furnace slag (GGBS) as a partial replacement for binding material (cement); and incinerated bio-medical waste ash (IBMWA) as a partial replacement for fine aggregate. LECA, GGBS, and IBMWA were replaced with coarse aggregate, cement, and fine aggregate, respectively at different substitution levels of 10%, 20%, and 30%. M30-grade SCC mixes were designed for two different water/binder ratios—0.40 and 0.45—and the CS of the SCC mixes was experimentally determined along with the fresh state properties assessed by slump-flow, L-box, J-ring, and V-funnel tests. The CS of the SCC mixes obtained from the experimental analysis was considered for machine learning (ML)-based modeling using paradigms such as artificial neural networks (ANN), gradient tree boosting (GTB), and CatBoost Regressor (CBR). The ML models were developed considering the compressive strength of SCC as the target parameter. The quantities of materials (in terms of %), water-to-binder ratio, and density of the SCC specimens were used as input variables to simulate the ML models. The results from the experimental analysis show that the optimum replacement percentages for cement, coarse, and fine aggregates were 30%, 10%, and 20%, respectively. The ML models were successful in modeling the compressive strength of SCC mixes with higher accuracy and the least errors. The CBR model performed relatively better than the other two ML models, with relatively higher efficiency (KGE = 0.9671) and the least error (mean absolute error = 0.52 MPa) during the testing phase.

Influence of calcium carbonate on green self-compacting concrete incorporating porcelain tile waste as coarse aggregate replacement

The disposal of ceramic tile waste poses a significant environmental challenge in the construction industry. This study aims to explore the influence of calcium carbonate (CC) on the properties of self-compacting concrete (SCC) incorporating porcelain tile waste as a coarse aggregate replacement. The objective is to enhance the performance of SCC while addressing the limitations of recycled ceramic aggregates and achieving the desired strength class. SCC specimens were cast by partially and completely substituting natural crushed rock with varying percentages of porcelain tile aggregates (PTA-0, 25 %, 50 %, 75 %, and 100 %) and cement with calcium carbonate (CC-10 %, 20 %, and 30 %). Workability assessments, mechanical properties, and durability were evaluated and compared against those of reference concrete. The experimental findings revealed that the incorporation of CC and PTA positively influenced the workability, mechanical properties and durability of SCC. Notably, the SCC mixture incorporating 10 %CC and 25 %PTA demonstrated exceptional performance, achieving the highest compressive strength of 64.9 MPa at 28 days. Moreover, even with complete substitution, the compressive strength reduction remained below 5 %. These results highlight the potential of PTA and CC-based SCC mixtures as an efficient and sustainable approach for utilizing porcelain tile waste in high performance concrete production. The findings contribute to addressing environmental concerns, promoting waste management practices, and reducing the reliance on natural resources in the construction industry.

Self-compacting concrete produced with recycled concrete aggregate coated by a polymer-based agent: A case study

Understanding the effects of recycled concrete aggregate (RCA) and polymer impregnation on the properties of self-compacting concrete (SCC) is crucial for the construction industry's efforts to reduce environmental impact and utilise recycled materials. This study aims to examine the impact of RCA inclusion and polymer impregnation on the properties of SCC, in response to the urgent demand for sustainable construction practices. Two different methods of polymer impregnation were evaluated to assess their impact on the workability and hardened characteristics of SCC. The SCC mixtures were prepared using river sand (natural fine aggregate (NFA)), natural crushed limestone (natural coarse aggregate (NCA)) and a polymer impregnation level of 0.05 wt% of the water content, with a water-to-cement ratio of 0.34. RCA was used as a complete replacement for NFA and NCA, adhering to the American Society for Testing and Materials (ASTM) C33 standards for recycled fine concrete aggregate (RFCA) and recycled coarse concrete aggregate (RCCA)The workability of the SCC mixtures was evaluated based on the criteria set by the European Federation of National Associations Representing for Concrete (EFNARC). Among the hardened properties, the compressive strength of the hardened properties was tested at four different time intervals (1, 3, 7 and 28 days), and the integrity of the SCC specimens was assessed using ultrasonic pulse velocity. The polymer impregnation process resulted in a slower compressive strength development rate compared to that observed in the control concrete. However, combining polymer impregnation type 1 with either RFCA and NCA or RCCA and NFA significantly increased the 28-day compressive strength by 5.02% and 1.80%, respectively. These findings provide valuable insights into the behaviour of SCC incorporating RCA and polymer impregnation. Optimising the selection and combination of materials can enhance the performance and sustainability of SCC in construction applications.

A PCA-Based Approach for Very Early-Age Hydration Monitoring of Self-Compacting Concrete Using Embedded PZT Sensors.

This work proposed a novel approach based on principal component analyses (PCAs) to monitor the very early-age hydration of self-compacting concrete (SCC) with varying replacement ratios of fly ash (FA) to cement at 0%, 15%, 30%, 45%, and 60%, respectively. Based on the conductance signatures obtained from electromechanical impedance (EMI) tests, the effect of the FA content on the very early-age hydration of SCCs was indicated by the predominant resonance shifts, the statistical metrics, and the contribution ratios of principal components, quantitatively. Among the three, the PCA-based approach not only provided robust indices to predict the setting times with physical implications but also captured the liquid-solid transition elongation (1.5 h) during the hydration of SCC specimens with increasing FA replacement ratios from 0% to 45%. The results demonstrated that the PCA-based approach was more accurate and robust for quantitative hydration monitoring than the conventional penetration resistance test and the other two counterpart indices based on EMI tests.

Durability evaluation of binary and ternary concrete mixtures by corrosion resistance approach

The use of pozzolans as cement substitutes has become widespread in concrete technology in recent years. This is due to the improvement of concrete properties as well as from the perspective of sustainable development and reduction of cement consumption. In this study, the effect of 45% ground granulated blast furnace slag, 7% silica fume, 35% fly ash, and 15% zeolite as binary and ternary mixtures on durability and corrosion resistance of Self-compacting concrete specimens were investigated. The studied parameters included compressive strength, electrical resistivity, water absorption, rapid chloride ion penetration Test and corrosion test also scanning electron microscopy images were used to analyze the microstructure of the concrete samples. Results showed that replacement cement with slag, silica fume, fly ash, and zeolite is generally increased the durability parameters and corrosion resistance of concrete. In all experiments, silica fume has shown better behavior in terms of durability, so that its electrical resistance after 90 days is more than 3.3 times that of the control specimen and other parameters such as water absorption and chloride ion penetration showed approximately 37% And 74% less than conventional concrete respectively. Also, corrosion results indicated that samples containing silica fume had the highest corrosion resistance and reduced the corrosion rate by more than 6 times after 15 test cycles.

Evaluation of the Rheological and Durability Performance of Sustainable Self-Compacting Concrete

Self-Compacting Concrete (SCC) is a special concrete that can flow easily across congested reinforcements. Also, it is easy to work with and does not segregate. The present investigation aims at the design and development of sustainable SCC with the employment of industrial by-products such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBFS), and Expanded Perlite Aggregate (EPA). Four SCC mixes were developed to attain a target strength of 30 MPa. Workability tests (slump flow, J-ring, and V-funnel tests) were performed following the EFNARC guidelines to ensure fresh SCC properties. Detailed experiments were conducted to evaluate the durability characteristics of the developed SCC, such as water absorption, sorptivity, acid attacks (sulphuric, nitric, sulphate, and chloride), the Rapid Chloride Penetration Test (RCPT), and finally, the elevated temperature test. Weight loss, strength loss, and physical observations of the acid and temperature effects of SCC mixes were evaluated. Also, the study focuses on the cost and sustainable index of SCC mixes and compares them with OPC mixes. From the experimental data analysis, it was observed that the developed SCC showed excellent physical and mechanical properties with a considerable reduction in cement content. SCC specimens with FA and EPA exhibit excellent acid and temperature resistance. Following the sustainable analysis, it was noted that SCC mixes reduce about 15–17.2% of carbon emissions compared to the OPC mix.

The effect of elevated temperature on self-compacting concrete: Physical and mechanical properties

Concrete’s thermal properties are more complex than for most materials because not only is the concrete a composite material whose constituents have different properties, but its properties also depend on moisture and porosity. Exposure of concrete to elevated temperature affects its mechanical and physical properties. In the current study, M40 and M80 grades of plain self-compacting concrete (SCC) mixes are developed using Nan Su mix design principles to investigate the effect of elevated temperatures on 1) weight and compressive strength 2) compressive strength of SCC when tested cool and hot 3) effect of 2, 4 and 6 hrs. exposure duration of elevated temperatures on compressive strength 4) modulus of elasticity 5) size of testing specimen and 5) effect of thermal cycles on SCC mixes. Results derived the following conclusions 1) the M80 specimens lose more strength than M40 SCC specimens when subjected to elevated temperatures ;2) specimens heated and then permitted to cool before testing lose more strength than those tested while hot; 3) the longer the duration of heating before testing, the larger the loss in strength; 4) The decrease in modulus of elasticity caused by elevated-temperature exposure is more pronounced than the decrease in compressive strength. 5) Small test specimens generally incur greater strength losses than larger ones and 6) Specimens subjected to several cycles of heating and cooling lose more strength than those not subjected to thermal cycling.

Effect of Recycled Aggregate Concrete and Steel Fibers on the Strength of Self-Compacting Concrete

The accumulation of waste materials in landfills without treatment threatens public health and the environment. The quantity of solid waste continually increases, causing environmental pollution. One of these wastes that should receive scientific treatment is concrete waste. The use of concrete waste as fine or coarse aggregate in self-compacting concrete (SCC) is one of the useful solutions to this problem. This study aims to reuse concrete waste as coarse aggregate in the production of SCC and find out the influence of different steel fiber contents on the strength of SCC. The steel fibers (SF) were used to reinforce SCC in three different volumes (0, 0.5, and 1 % of concrete volume), and the recycled coarse aggregate (RCA) was used to replace natural coarse aggregate (NCA) in five replacement levels of 0, 25, 50, 75, and 100%. The compressive and tensile strengths of the SCC specimens in the hardened state were determined. The results of the experimental study refer to the steel fiber having a positive effect on the enhancement of mechanical properties, particularly the tensile strength of SCC. The addition of 50% recycled aggregates in the concrete mix contributed to increasing the compressive strength by about 20%. Therefore, it can be said that the dual use of recycled aggregates with steel fibers produced concrete with high specifications compared to ordinary concrete. Another positive effect lies in the disposal of concrete waste, which contributes to an economic return in addition to reducing the effect on the environment.

Performance of SCC Concrete with Additional Materials of Rice Husk Ash

Concrete with high ductility, workable, high strength, easy to flow without compaction, and durable is a concrete need in the future. Concrete with this quality, one of which is to make self-compacting concrete (SCC). This paper reports performance of self compacting concrete (SCC) containing rice hush ash. Rice husk ash is waste from burning rice husks. The purpose of this study was to determine the performance of SCC concrete with the addition of rice husk ash. SCC specimens were made using rice husk ash (RHA) and SCC without rice husk ash (NRHA). The specimens were made with water cement ratio 0.30. Superplastisizer used is a type Naptha 511P. The result indicated that the workability of SCC containing rice hush ash (RHA) more workable compare SCC without rice hush ash (NRHA). The initial setting time of SCC with rice hush ash more slowly compare SCC without rice hush ash. The compressive strength, flexural strength, and tensile strength of SCC RHA mor higher compare SCC without RHA (NRHA). The tensile strength value of RHA and without RHA concrete meets the tensile strength requirements of RSNI T-12-2004.

Compressive Properties of Self-Compacting Concrete after Cooling from High Temperatures

Self-compacting concrete (SCC) has been widely used in building structures. However, previous research focused only on the mechanical properties and working properties of SCC at room temperature. Thus, there is limited research on the change of compressive strength of SCC after a fire. This paper aims to investigate the compressive properties of SCC after being cooled from high temperatures. The SCC specimens were firstly heated to a target temperature of 100–700 °C and were then cooled to ambient temperatures by water or in air. The heating and cooling damage to the SCC specimens was assessed by the mass loss and the ultrasonic pulse velocity (UPV) separately. Afterward, the axial compression tests were carried out to investigate the compressive properties of the fire-affected SCC specimens under uniaxial compression. The residual mass, UPV, stress–strain curves, post-fire failure characteristics, and compressive strengths of the SCC specimens were discussed in detail. The mass loss of the SCC specimens showed an obvious increase with the rising temperatures, while the UPV exhibited a converse pattern. The mass loss of the SCC specimens after being naturally cooled increased more significantly, while the two cooling methods used in this experiment had little effect on the UPV. When the SCC specimens were cooled from 100 °C, the compressive strength of the SCC specimens cooled in air or water dropped by 32.54% and 35.15%, respectively. However, while the heating temperature rose to 700 °C, the compressive strengths of the SCC specimens cooled in air or water dropped sharply by 72.98% and 86.51%, respectively. Finally, an improved mathematical model for SCC after cooling from high temperatures was proposed based on Jones and Nelson’s equation. This improved material model matched the experimental results well, which demonstrates that the proposed constitutive model can provide better predictions for the SCC structures after a fire.

Effect of protective coating on axial resistance and residual capacity of self-compacting concrete columns exposed to standard fire

Self-Compacting Concrete (SCC) is a green construction material widely used in the construction industry. While normal weight concrete has notable performance under fire conditions, the open literature continues to lack works examining the structural fire performance of SCC elements. Intending to bridge this knowledge gap, the present study aims to understand the efficiency of different protective coatings on fire response and the residual capacity of SCC short columns. In this experimental investigation, SCC columns were primarily cast from Supplementary Cementitious Materials (SCM) such as Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS) with partial replacement of fine aggregate by utilising the optimum content of Expanded Perlite Aggregate (EPA). Then, a thermal protective coating comprising of Cement Perlite Plaster (CPP) was developed using Ordinary Portland Cement (OPC) and the EPA. The fire performance of SCC elements was examined when protected with the newly developed coating as well as Gypsum Plaster (GP), Basalt Wrapping (BW), and Carbon Wrapping (CW) when exposed to ISO 834 standard fire curve for 60, 90, 120, and 180 min. The experimental results revealed that SCC specimens developed using GGBFS had better resistance to all exposure durations than the FA-SCC specimens. Also, it was noted that the CPP-protected SCC specimens exhibited higher residual strength capacity, followed by GP-protected SCC specimens, compared to the BW and CW-SCC specimens under axial load.

Combined Effect of Ternary Blended Cementitious Materials in Self-compacting Concrete

Self Compacting Concrete (SCC) is a type of special concrete which possess self packing and flowability to fill the formwork space completely by its own weight without any external vibration or compaction. Research studies on finding efficient, economical and eco-friendly materials to replace the conventional concrete materials are increasing day-by-day. An important constituent material of concrete is cement which contributes to the environmental hazardous problem of CO2 emission. In this view, the present study investigated the fresh and hardened properties of SCC in which cement is partially replaced by multi-cementitious materials namely fly ash, alccofine and Recycled Concrete Powder (RCP). Fly ash and alccofine are evident materials to replace cement in concrete. In addition to the substitution of cement by 20% replacement by fly ash and 10% replacement by alccofine, recycled concrete powder collected from construction wastes are also incorporated (5%, 10%, 15%, 20%) and investigated. Water/binder ratio is kept constant as 0.45. Polycarboxylate based super plasticizer (Conplast SP430) was used. The experimental program comprises testing the fresh stability by determination of flowability, passing ability and viscosity, mechanical strength testing including compressive strength, split-tensile strength and flexural strength and durability properties such as water absorption, sorptivity and acid-attack of SCC specimens. The test results showed that 10% recycled concrete powder exhibited better performance in fresh stability and satisfied performance mechanical strength. Increase in RCP content beyond a limited proportion possesses detrimental effects on the durability characteristics.

Experimental investigation on the impact resistance of rubber self-compacting concrete

Stiffness degradation and micro-cracks are commonly observed in the self-compacting concrete subjected to long-term vibration and impact loading. Adding rubber particles to the concrete is a universal approach to improve impact resistance. Exploiting the dynamic mechanical properties of the rubber self-compacting concrete under impact loading is of great significance. Herein, a comprehensive investigation of rubber self-compacting concrete under impact loading was carried out using a split Hopkinson pressure bar. The influence of rubber replacement rate, rubber particle size, and strain rate on impact resistance was considered. 108 rubber self-compacting concrete specimens along with 36 ordinary self-compacting concrete ones were designed. As a result, the dynamic stress–strain relationship of rubber self-compacting concrete was proposed. The results show that rubber self-compacting concrete's dynamic peak strain and peak stress were higher than ordinary self-compacting concrete with similar static compressive strength. The dynamic compressive strength and DIF-σ and DIF-ε of rubber self-compacting concrete can be increased with strain rate. The sensitivity of growth rates of DIF-σ and DIF-ε to strain rate decreases with the strain rate. DIF-σ and DIF-ε showed a positive linear correlation with rubber content. The increase of rubber content reduces the dynamic compressive strength of rubber self-compacting concrete. Compared with other sizes, the dynamic compressive strength and DIF-σ and DIF-ε of 12 mesh (1 ∼ 2 mm) rubber particles are generally higher.