Assessment of fresh properties of self-compacting concrete incorporating GGBS and recycled concrete aggregate

This study investigates the fresh properties of self-compacting concrete (SCC) developed using recycled concrete aggregates (RCA) as coarse aggregate replacement and ground granulated blast-furnace slag (GGBS) as cement replacement. This study employs an integrated statistical framework to simultaneously analyze, interpret, and optimize multiple SCC fresh performance parameters. SCC mixes were prepared with 15% to 45% GGBS and 20% to 100% RCA, and their fresh properties were evaluated through slump flow, T500, J-ring, V-funnel, L-box, and U-box tests. Microstructural and chemical characterization of the raw materials was conducted using scanning electron microscopy (SEM) and X-ray fluorescence (XRF) to assess morphology and compositional compatibility before evaluating the fresh properties of SCC. Results showed that workability decreased with increasing RCA but improved with GGBS by up to 30% due to enhanced paste volume and reduced internal friction. Regression analyses revealed strong correlations between key fresh property parameters, such as slump flow and T500 (R2 = 0.971), J-ring and V-funnel (R2 = 0.880), and L-box and U-box (R2 = 0.947). A two-way ANOVA confirmed that GGBS and RCA have a statistically significant effect on fresh properties (p < 0.001). Furthermore, response surface methodology (RSM) to identify optimal mix proportions and principal component analysis (PCA) to explore the underlying structure of the test methods were also performed. The results indicate that a mix with 30% GGBS and 60% RCA provides optimal fresh properties, confirmed by PCA and regression analyses. These findings provide a practical framework for designing sustainable SCC mixtures using construction and industrial waste materials, enabling engineers to balance workability, passing ability, and sustainability requirements in real-world construction applications.

This paper reports the effects of coarse and fine recycled concrete aggregates (RCA) on fresh and hardened properties of self-compacting concrete (SCC) containing ground granulated blast-furnace slag (GGBFS) as cement replacement. For this purpose, three SCC mixes groups, were produced at a constant water to binder ratio of 0.38. Both fine and coarse recycled aggregates were used as natural aggregates (NA) replacement at different substitution levels of 0%, 25%, 50%, 75% and 100% by volume for each mix group. Each group, included 0, 15% or 30% GGBFS as Portland cement replacement by weight. The SCC properties investigated were self-compactability parameters (i.e., slump flow, T500 time, V-funnel flow time, L-box passing ability and sieve stability), compressive strength, capillary water absorption and water penetration depth. The results show that the combined use of RCA with GGBFS had a significant effect on fresh and hardened SCC mixes. The addition of both fine and coarse recycled aggregates as a substitution up to 50% of natural aggregates enhance the workability of SCC mixes, whereas the addition from 50 to 100% decreases the workability, whatever the slag content used as cement replacement. An enhancement of workability of SCC mixes with recycled aggregates was noticed as increasing GGBFS from 0 to 30%. RCA content of 25% to 50% as NA replacement and cement replacement of 15% GGBFS seems to be the optimum level to produce satisfactory SCC without any bleeding or segregation. Furthermore, the addition of slag to recycled concrete aggregates of SCC mixes reduces strength losses at the long term (56 and 90 days). However, a decrease in the capillary water absorption and water permeability depth was noticed, when using RCA mixes with slag.

Behaviour of sustainable slag enriched concrete: Effect of fully replacement of natural coarse aggregate with construction waste

Latest concrete materials dataset and ensemble prediction model for concrete compressive strength containing RCA and GGBFS materials

Bond, durability and microstructural characteristics of ground granulated blast furnace slag based recycled aggregate concrete

Geopolymer concrete is environmentally friendly concrete as it relies on minor treated natural materials or industrial by-products like fly ash, GGBS, silica fumes etc,. which have high alumina (Al2O3) and silica (SiO2) content, significantly reducing carbon footprints. To overcome the challenge of compaction due to the highly viscous nature of geopolymer concrete, self-compacting geopolymer concrete (SCGC) has been developed to flow and compact under its weight, eliminating the need for additional compaction. Self-compacting geopolymer concrete is an innovative concrete that combines the benefits of geopolymer concrete and self-compacting concrete. In this study, mineral admixtures of fly ash, ultra fine ground granulated blast-furnace slag (GGBS), and micro silica were used in different mix proportions. For all mixes, the water-to-powder (binder content) mass ratio (w/p) was maintained as 0.35, the total powder content was 400 kg m−3, and glass fibre 1.5% of the binder content were used. The water to powder (binder content) mass ratio (w/p) selected after numerous trial mixes was 0.35. The test specimens were cured at 70 °C. In this study, to measure fresh properties, tests on concrete slump flow test, L-box test, V-Funnel test, and T50 V- Funnel test, J-ring were conducted. This paper illustrates the way an ANN (Artificial Neural Network) model may be employed to find the mix proportion of concrete mixes. The fresh and mechanical Properties of SCGC were conducted for different molarities of eight molarities, ten molarities, and twelve molarities. Microstructural studies such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out, and the results are presented.

This study considered the effects of recycled concrete aggregate (RCA) as a replacement of both coarse and fine aggregate in concrete. The coarse portion was replaced by 100% RCA and the fine portion was replaced with RCA at various amounts up to 50%. In addition, fly ash and ground granulated blast furnace slag were utilized as partial replacements of cement. All mixtures were prepared using the twostage mixing approach and the coarse and fine RCA were in a partially saturated condition. The use of RCA fine aggregate (RFA) reduced the concrete strength. However, it was found that the concrete can have a statistically similar compressive strength to concrete with 100% coarse RCA and no RFA. The shrinkage for almost all recycled concrete mixes was statistically similar at early ages, but at later ages, concrete containing RFA can potentially shrink more, especially if slag and fly ash are used to replace cement. The findings suggest that, with proper design, both RCA and RFA can be used in concrete pavement applications.

PurposeThe purpose of this study is to investigate the behaviour of M40 grade of self-compacting concrete (SCC) with high volume of ground granulated blast furnace slag (GGBS) (50%) and recycled concrete aggregate (RCA) content up to 100% to assess the mechanical properties of SCC. As per guidelines of IS: 383 – 2016, the RCA can be replaced up to 20% of natural coarse aggregate up to M25 grade of concrete. This study assesses the mechanical properties of SCC beyond 20% of RCA content. Based on the experimental investigations, the compressive strength of mixes decreases as the content of RCA increases. It is found that concrete mixes with 20% RCA and shows the maximum compressive strength at 56 days.Design/methodology/approachThe fresh properties as per EFNARC and IS: 10262–2019 guidelines, ultrasonic pulse velocity testing, mechanical properties and microstructure analysis have been conducted to evaluate the performance of SCC with RCA for practical applications.FindingsFrom the experimental investigations, it is found that up to 50% of recycled coarse aggregate can be used for structural applications.Originality/valueThe environmental pollution and dumping of waste on green land can be reduced by effective utilization of recycled coarse aggregate and GGBS in the production of SCC.

Development of sustainable concrete using recycled coarse aggregate and ground granulated blast furnace slag

Properties of sustainable concrete containing fly ash, slag and recycled concrete aggregate

The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1% by volume steel fibers. The use of recycled concrete aggregate in the conventional and 50% slag mixes was also studied. Properties investigated included compressive and tensile strengths, elastic modulus, coefficient of permeability, thermal conductivity and durability in seawater and sulfate solutions. It was determined that the mixes containing 50% slag gave the best overall performance. Slag was particularly beneficial for concrete that used recycled aggregate and could reduce strength losses. Initial durability results indicated that corrosion of fibers in the different concrete mixes when exposed to seawater was minimal. Future research needs to include more detailed studies of mix design and properties of concrete for wind turbine foundations. Emphasis on slag-modified mixes with natural and recycled concrete aggregate is recommended. The proportion of slag that can be incorporated in the concrete needs to be optimized, as does the grading of recycled aggregate. The potential for using silica fume in conjunction with slag is worth exploring as this may further enhance strength and durability. Longer-term durability studies are necessary and other pertinent properties of concrete that require investigation include damping characteristics, pullout strength, fatigue strength and risk of thermal cracking. The properties of sustainable concrete mixes need to be integrated with studies on the structural behavior of wind turbine foundations in order to determine the optimal mix design and to examine means of reducing conservatism and cost of foundations.

The rising environmental burden of Portland cement production has intensified the demand for eco-friendly binders that support sustainable construction. This study investigates the development and performance of eco-friendly self-compacting geopolymer concrete (SCGC) produced from industrial by-products, including fly ash (FA), ground granulated blast furnace slag (GGBFS), silica fume (SF), metakaolin (MK), and glass waste powder (GWP). Twenty-one binder formulations were evaluated for fresh-state workability, mechanical performance, durability, and microstructural characteristics under different curing regimes. Fresh properties were assessed using slump flow, V-funnel, L-box, and J-ring tests, while hardened-state evaluations included compressive and flexural strength, Young’s modulus, and water absorption. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were performed on selected mixes to examine microstructural features and crystalline phase development. Results highlight a strong dependency of SCGC performance on binder composition and curing conditions. Mixes rich in GGBFS and SF demonstrated superior mechanical and durability performance, achieving compressive strengths of up to 102.4 MPa under water curing and 107.6 MPa under heat curing, along with negligible water absorption, reflecting a dense and well-developed gel matrix. SEM micrographs confirmed homogeneous, compact microstructures in high-performing mixes, while XRD analysis revealed broad amorphous humps indicative of well-formed N-A-S-H and C-A-S-H gel phases with minimal crystalline residues. In contrast, FA-dominant mixes displayed delayed strength development, and MK-GWP-rich systems exhibited higher porosity and reduced strength. This study underscores the significance of precursor synergy, optimized curing strategies, and microstructural refinement in tailoring SCGC for high-performance, durable, and low-carbon applications in sustainable construction with values ranged from 38.64 GPa (Mix 21) to 25.04 GPa (Mix 19) at 28 days. Stiffer mixes corresponded to denser matrices containing GGBFS and silica fume, whereas lower values were linked to weaker bonding and higher porosity.

Temporal flowability evolution of slag-based self-compacting concrete with recycled concrete aggregate

Multi-criteria feasibility of real use of self-compacting concrete with sustainable aggregate, binder and powder

Durability of self-compacting concrete made with Recycled Concrete Aggregates and mineral admixtures