Workability Of Fresh Concrete Research Articles

Image‐based quality control of fresh concrete based on semantic segmentation algorithms

AbstractIn practice, various empirical methods such as the flow table test or the slump test are in use worldwide for assessing the workability of fresh concrete on the construction site. The majority of these tests has in common, that fresh concrete is subjected to some kind of defined flow process on a standardized table‐like platform and that the geometrical properties of the material after the flow has ceased is determined by simple means such as measuring the flow cake diameter or its sag. The paper at hand proposes a novel image‐based approach for an automatic derivation of concrete properties as part of the flow table test. The image‐based method enables a digital evaluation of concrete properties. By combining digital image analysis and deep learning methods, not only the consistency but also an abundance of additional concrete properties can be derived from image data. In this way, the quality control of the fresh concrete can be expanded to include a large number of additional parameters, currently not available to the producer nor to the construction site. This data can be integrated into a digital control loop, with which communication between the concrete producer and the construction site can be automated using highly precise real‐time data.

Analysis of the Impact of Superplasticizer on the Compressive Strength of Periwinkle Shell Concrete

This research project investigates the compressive strength characteristics of superplasticized concrete incorporating periwinkle shell (PS) as partial replacements for granite coarse aggregate. The study aims to assess the influence of superplasticizer content and curing age on the compressive strength development of the novel concrete mixtures. Comparative analysis with plain concrete (control specimen) reveals that superplasticized concrete with periwinkle shell partial replacement exhibits a slower strength development. Results indicate that the compressive strength of superplasticized PS concrete attains its maximum strength (22.07 kN/mm²) at 21 days with a 15% partial replacement and 0.5% superplasticizer content. The findings suggest that optimal strength development for PS partial replacement performs best at higher percentages (15%). Concerning the workability of fresh concrete, PS partial replacement exhibits a consistent increase in slump values with higher percentages of replacement and superplasticizer content, peaking at 55mm at 15% partial replacement and 1.5% superplasticizer content. This study contributes valuable insights into the optimization of compressive strength and workability of superplasticized concrete with PS partial replacements, offering a sustainable and resource-efficient alternative to conventional concrete mixtures

Crack-healing and rheological properties of high content fly ash/slag/silica fume green and sustainable cement-based materials incorporating crystalline admixture and calcium alginate biomass hydrogel

Cracking is an important factor affecting the durability of concrete. Rheological properties are important performance indicators of the workability of fresh concrete. Ion chelator (CA) is one kind of crystalline admixture, which can enhance crack-healing of concrete by promoting the formation of calcium carbonate in wet environment. Calcium alginate hydrogel (CaAlg) can maintain the humidity of cementitious matrix and promote the crystallization of inorganic minerals. Therefore, in this study, CaAlg bead was prepared to further improve the crack-healing of cementitious materials containing CA. Self-healing performance was evaluated by visual crack closure and water permeability test. Rheological property was measured by rotor rheometer. Healing mechanism of cementitious materials with CA and CaAlg was analyzed. Results showed that with the increase of CaAlg dosage, yield stress and plastic viscosity of paste decreased gradually. Meanwhile, fly ash and slag reduced viscosity of pastes, while silica fume increased the viscosity of pastes. CA could evidently improve the permeability and mechanical properties of mortar, especially for slag mortar. Self-healing performance test and characterization showed that CaAlg could further enhance crack-healing process of mortar with CA, especially for pure cement and slag mortar. Microscopic testing indicates that CaAlg could induce the formation of vaterite and calcite on its surface to further improve crack-healing efficiency.

Sustainable solutions for Workable and Strong concrete: Cordia Gel and Waste Engine Oil Admixtures

To produce high strength or rich cement concrete having low water to cement ratio with adequate workability is the biggest challenge for the construction industry. To achieve the necessary workability, the world is now using costly chemical admixtures. Research should be carried out to explore materials having potential to be utilized as costeffective chemical admixtures in concrete. The primary goal of this research is to investigate the combined effect of Cordia Gel (CG) and Waste Engine Oil (WEO) as chemical admixtures on fresh and hardened properties of concrete. Fresh properties of concrete were examined in terms of workability and hardened properties were investigated by compressive strength test and Ultrasonic Pulse Velocity (UPV) test on cubical specimen of dimensions 100mm x 100mm x 100mm after 7, 28 and 90 days of curing in water. Four different percentages of WEO (0.5%, 1%, 1.5% and 2%) were used and percentage of CG kept constant as 0.5% with respect to weight of cement and results were compared with the control mix. Results revealed that workability of fresh concrete increased with increasing amount of CG and WEO. However, a decreasing trend was observed for compressive strength and UPV of hardened concrete when higher values of admixtures were added. The usage of CG and WEO as chemical admixtures in concrete can be a sustainable and cost-effective way to achieve the desired results

Effect of solvothermal-treated polyethylene on the mechanical properties of sandcrete blocks and concrete

In building construction, seepage and dampness in walls present serious problems since they can cause structural failures and damage in both residential and commercial contexts. Finding more affordable options is necessary as mitigating these problems frequently requires expensive fixes. This study aims to evaluate the effects of solvothermal-treated polyethylene added at concentrations ranging from 0 to 1.0% on the mechanical properties of concrete and sandcrete blocks. In addition to assessing the workability, split tensile strength, and compressive strength of concrete samples at different levels of the polyethylene (PE) inclusion, the study looked into the water absorption capacity, density, and compressive strength of sandcrete blocks. The blocks’ compressive strength and water absorption capacity reduced as the amount of polyethylene additives rose, although there was a slight increase in the density. These changes remain well within the Nigerian Industrial Standards’ specified limits. Hardened concrete shows a drop in density, compressive strength, and split tensile strength with increasing polyethylene content, while fresh concrete's workability decreases as the percentage increases. 0.4% incorporation of the treated polyethylene achieved the target strength of 20 N/mm2 while Sandcrete blocks with up to 1% of the solvothermal treated polyethylene had compressive strengths more than the 2.5 N/mm2 minimum required for non-load-bearing walls. About 61% reduction in water absorption was achieved in 48 h by the blocks, presenting a promising and cost-effective solution for seepage-related issues in building construction.

Effect of nano-silica on the flexural behavior and mechanical properties of self-compacted high-performance concrete (SCHPC) produced by cement CEM II/A-P (experimental and numerical study)

The extensive use of cement exacerbates the greenhouse effect by increasing carbon dioxide (CO2) emissions. So, many standards recommend using Portland-composite cement in construction as one of the methods for reducing CO2 emissions, especially cement CEM II/A-P. This paper presents an extensive experimental and numerical study to investigate the effect of micro and nano-silica on the flexural behavior and mechanical properties of Self-Compacted High-Performance Concrete (SCHPC) produced by cement CEM II/A-P. The extensive experimental work consisted of eight mixtures: three with micro-silica (MS), four with nano-silica (NS), and a reference mixture without silica. For both MS and NS, different percentages of adding or replacement content were tested to study their effect on the following: (a) the workability of fresh concrete, (b) concrete compressive strength, (c) splitting tensile strength, (d) flexural behavior including flexural tensile strength, and (e) the optimum percentage of each of the MS and NS to get the maximum structural and economic benefits of using for SCHPC with CEM II/A-P. Also, through a statistical program, these experimental results were used to obtain accurate formulae that could predict both the splitting tensile strength (fsp) and modulus of rupture (fctr) for SCHPC with adding nano-silica. In addition, the numerical study verified the experimental results based on the finite element program ANSYS. The flexure behavior of SCHPC beams is verified using the Microplane model (recently added to ANSYS). The experimental results showed that adding NS is more effective than replacing or adding MS for SCHPC mixture with CEM II/A-P to increase the concrete compressive strength, splitting tensile strength, and flexural tensile strength, especially for the mixture with adding NS content of 4 %. The numerical results showed the ability of the coupled damage-plasticity microplane model to simulate the flexural behavior of the tested SCHPC beams with MS or NS well. This research confirms nano-silica's structural and economical efficiency in the behavior of SCHPC beams. It was found that the optimum percentage of adding NS is 4 % for SCHPC mixtures with CEM II/A-P.

An Engineered Production Formula for Enhanced Artificial Stone Utilizing Stone Cutting Slurry and a Superplasticizer

The purpose of this paper is to demonstrate the technical feasibility of utilizing some of the local industrial waste (stone cutting wastewater and marble) in manufacturing artificial stone and enhancing its quality, with the addition of a superplasticizer (liquefier). The paper reviews the previous work and presents new experimental work. Artificial stone samples were casted according to two starting formulas obtained from local production facilities. Later on, an engineered production formula was developed and tested, based on product quality. The investigated experimental parameters included: compressive strength, water absorption, and workability of fresh concrete. The experimental results indicated that high compressive strength and a low water absorption for artificial stone is technically feasible. In term of the compressive strength of artificial stone the marble dust contributed better than limestone wastewater.

The effect of chemical oxygen demand of domestic wastewater on workability, mechanical, and durability of self- compacting concrete

Due to worldwide water scarcity, especially in arid regions, and the substantial use of drinking water in concrete production, the consideration of gray water usage is growing. However, wastewater contamination adversely affects concrete's mechanical strength and durability, with Chemical Oxygen Demand(COD) as one of the indicator. In the present work, the effect of COD of different types of domestic wastewater on workability, mechanical, and durability properties of self-compacting concrete (SCC) with 400 kg/m3 and 440 kg/m3 of cement, and water-to-cement ratios of (w/c) 0.36 and 0.5 for 12 different SCC mixture designs were investigated. The results of the experiments indicated that increasing the COD of domestic wastewater negatively impacts the workability of fresh concrete. Additionally, as the COD of the wastewater increases, the compressive strength of SCC decreases at 7 and 28 days when using raw sewage, sewage sludge, and artificial wastewaters. However, by 90 days, the compressive strength showed no significant difference compared to SCC made with tap water. With increasing COD of wastewater, the 28-day tensile strengths of SCC decreased by 6–10 %. The COD of wastewater did not significantly affect the flexural strength. However, the fracture toughness, at a water-cement ratio (w/c) of 0.5, decreased with increasing COD, reaching a reduction of 36 % at a COD of 940 mg/L. As the COD concentration rises, water absorption increases. In SCC samples containing sludge water and raw sewage, capillary water absorption was at its maximum due to the presence of impurities, as well as organic and mineral materials.

A Comprehensive Review on the Use of Wastewater in the Manufacturing of Concrete: Fostering Sustainability through Recycling

The primary aim of this review article is to find the influence of wastewater and its characteristics on recycling as an alternative to potable water for concrete preparation. On the other hand, scarcity, and the demand for freshwater for drinking are also increasing day by day around the globe. About a billion tons of freshwater is consumed daily for concrete preparation for various operations such as mixing and curing, to name a few. The rapid development of certain industries such as textile, casting, stone cutting, and concrete production has caused the water supply to be severely affected. Recycling wastewater in concrete offers various potential benefits like resource conservation, environmental protection, cost savings, and enhanced sustainability. This article reviews the effect of various types of wastewater on various physical and chemical properties of wastewater, rheological characteristics, strength, durability, and microstructure properties of concrete. It also explores the potential effects of decomposing agents on enhancing concrete properties. Currently, limited research is available on the use of various types of wastewater in concrete. Hence, there is a need to develop various methods and procedures to ensure that the utilization of wastewater and treated wastewater is carried out in the production of concrete in a sustainable manner. Although wastewater can reduce the workability of fresh concrete, it can also increase its strength and long-term performance of concrete. The use of various types of wastewater, such as reclaimed water and tertiary-treated wastewater, was found to be superior compared to those using industrial- or secondary-treated wastewater. Researchers around the globe agree that wastewater can cause various detrimental effects on the mechanical and physical properties of concrete, but the reductions were not significant. To overcome limited scientific contributions, this article reviews all the available methods of using various types of wastewater to make concrete economically and environmentally friendly. This research also addresses possible challenges with respect to the demand for freshwater and the water crisis.

Automatic concrete slump prediction of concrete batching plant by deep learning

The workability of fresh concrete is highly important in terms of construction quality and safety. Slump tests are required every 120 m³, yet automated monitoring for each concrete batch remains unavailable in the actual concrete batching plant. To mitigate this issue, we propose an automatic slump prediction method based on the VGG16 neural network by analyzing the video from the final discharge hopper of the batching plant. Additionally, Explainable AI (XAI) is adopted to evaluate and validate our automatic concrete quality inspection approach. Iteratively examining XAI outputs and applying necessary adjustments in data preprocessing helps to achieve better overall performance. The proposed video classification method performed by averaging over the image-level predictions can classify the concrete into four slump classes with an average precision of 85% and an average F1 score of 87%. This demonstrates the possibility of continuous quality evaluation for all concrete produced in the concrete batching plant.

UTILIZATION OF WASTE BAKELITE AS A FIBER REINFORCE TO IMPROVE MECHANICAL PROPERTIES OF CONCRETE

Waste Bakelite is mainly from automotive production, it can create waste management problems due to its toxic substances. The consensus of previous research works in waste Bakelite as aggregate in concrete mixture and mortar still has problems such as low strength and high toxics of concrete products. Selected shapes of waste Bakelite are similar to a fiber which could be used to reinforce concrete. In this research, waste Bakelite was selected into a suitable shape and was mixed with a proportion of 0%, 3%, 5%, and 7% by volume of concrete. The slump of fresh concrete, compressive strength, and flexural strength were tested. The results discovered that the addition of 3% to 7% waste Bakelite bar as a fiber had no negative significant impact on the workability of fresh concrete. In addition, the adding bar shape of waste Bakelite 5% by volume into concrete showed a positive effect on the mechanical tensile strength and flexural strength of concrete while the product shows almost non-toxics discharge from colorimetric observation.

Experimental Study on Workability of Natural Aggregate Concrete Incorporated with Crumb Rubber

This study investigated the effect of crumb rubber on the workability of fresh concrete. Crumb rubber was used to replace fine aggregate at 0%, 5%, 10%, 15% and 25%. Physical properties (particle size gradation, specific gravity, bulk density and aggregate impact value) of the aggregates: sharp sand, Bida natural stone and crumb rubber were determined. Furthermore, the sharp sand and Bida natural stone used for this research were characterized as normal weight aggregates while the crumb rubber was characterized as a light weight aggregate. Workability of the concrete in its fresh state was extensively studied. Generally, the workability of fresh concrete reduced as the crumb rubber increased from 0% to 25%. The reduction in slump values was adduced to the absorbent nature of the crumb rubber. Hence, the research recommended a water-to-cement ratio of 0.55 – 0.60 for use in the production of concrete containing crumb rubber. It was concluded that crumb rubber can be used to produce low workability concrete for use in mass concrete foundations, lightly reinforced concrete elements and roads.

Experimental Study on Preparation and Characteristics of Concrete Modified by Construction Waste

With the advancement of urbanization construction, the proportion of construction waste to the total urban waste continues to increase, especially waste concrete. The treatment and reuse of waste concrete is a major trend that poses enormous pressure on environmental protection. This article focuses on the problems in the preparation of recycled aggregates from waste concrete, which has important practical value. This article presents a new type of recycled concrete prepared through surface modification of recycled coarse aggregate and design experiments to change the replacement rate of coarse aggregate. The physical properties of recycled coarse aggregate, workability of fresh concrete, and mechanical properties of recycled concrete are analyzed. The research results indicate the following: (1) Through surface modification, recycled concrete can improve the workability of fresh concrete at a fixed water cement ratio, which can meet the requirements of mixing, transportation, and pouring of fresh concrete. (2) By modifying the surface of recycled aggregates, the strong water absorption performance of recycled aggregates caused by old mortar and surface defects has been reduced. And the modification effect of recycled aggregate improves the hydration process of recycled concrete, making the surface structure dense and further enhancing the strength of recycled concrete. (3) The compressive strength of recycled concrete specifications from construction waste shows a decreasing trend with the increase in coat aggregate replacement rate. The final ratio is as follows: modular dose of 12%, modification time of 90 min, and 20% recycled aggregate content.

Synergistic effect of recycling waste coconut shell ash, metakaolin, and calcined clay as supplementary cementitious material on hardened properties and embodied carbon of high strength concrete

Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK), and calcined clay (CC) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). Abundantly available as industrial or agricultural waste, these materials, when combined with Portland cement (PC), offer synergistic benefits. This not only improves concrete performance but also addresses waste disposal issues, presenting a sustainable and environmentally friendly solution for long-term use in HSC production. However, this study performed on fresh and mechanical characteristics of HSC blended with CSA, MK, and CCA alone and together as SCM after 28 days of curing. A total of 504 samples of standard concrete were cast and the cubical samples were tested to achieve the targeted compressive strength about 80 MPa after 28 days. The experimental results indicated that the rise in tensile, flexural and compressive strengths of 9.62%, 8.27%, and 10.71% at 9% of CSA, MK, and CC as SCM after 28 days of curing. As SCM content increases, the density, porosity and water absorption of concrete decrease. Moreover, the workability of fresh concrete is getting reduced when the concentration of SCMs increases in HSC. In addition, the concrete's sustainability assessment revealed that employing 18% MK, CC, and CSA as SCM reduced carbon emissions by approximately 11.78%. It is suggested that using 9% CC, MK and CSA together in HSC yields the best results for practical applications in civil engineering.

Effect of Waste Brick Clay Powder on Self Compacted Concrete

This research investigates the effect of waste clay bricks powder in producing self-compacting concrete by partial replacement of cement. Bricks were crushed to particle sizes smaller than 75 microns. Percentages of cement of 5, 10 and 12.5 % by weight were replaced by the power at w/c ratios of 0.4, 0.425 and 0.45. Fresh concrete workability then measured and hard concrete properties were determined at 28 days. The results show that waste bricks powder can be utilized partially instead of cement to produce concrete with self leveling fresh properties and good hard properties. Consequently, this proves that waste bricks can be recycled to minimize both the effect of waste material on the environment and the heat needed for cement production.

Effect of Organic Corrosion Inhibitor on Mechanical and Transport Properties of concrete

In this paper, the effect of organic corrosion inhibitors on Mechanical and Transport Properties of concrete was studied. Two types of organic inhibitors, one is added to the concrete mix (sika Ferrogard®-901), and another one applied on the concrete surface (sika Ferrogard®-903. The properties of the fresh concrete (workability and air content) and of the hardened concrete (compressive strength, Porosity, and water absorption) were evaluated. The transport properties (permeability, capillary absorption, and diffusion) were also evaluated. From the results, it was found that the effect of the organic inhibitor (Ferrogard®-901) was clear on the properties of fresh concrete. so that Workability increased with the addition of organic corrosion inhibitors. The effect of (OCI) on the compressive strength at all ages was not significant. The effect of organic inhibitors on the porosity of concrete was also not significant, although the porosity of the samples with Ferrogard®-901 was lower. As for the permeability test, both samples containing (sika Ferrogard®-901) and (sika Ferrogard®-903) outperformed the control sample. In addition to the clear effect of (sika Ferrogard®-901) in reducing the permeability. Both organic inhibitors affected the diffusion and capillary absorption of concrete.he

Modelling Water Absorption Index and Compressive Strength of Paving Stone Composites with Polyethylene Terephthalate (PET) as Total Binder Replacement

Packing density method of mix design of concrete is new method to design different types of concrete. The mix design obtained from the packing density method has suitable workability, maximum packing density and minimum voids ratio. The geometrical characteristics like shape, size and proportion of fine aggregate and coarse aggregate affect packing density. The objective of this research is to study the mix design of concrete using packing density method and develop the correlation between bulk density, packing density and voids ratio. In this work large number of trail to decide the proportion of aggregate for that optimum bulk density and packing density calculated for different varying proportion of 20 mm: 12.5 mm coarse aggregate (i.e. 90:10, 80:20,70:30, 65:35, 60:40 and 50:50) and for varying proportion coarse aggregate: fine aggregate (i.e. 90:10, 80:20, 70:30, 60:40, 55:45 and 50:50). To finalize the mix design using packing density method also varies the percentage of excess cement paste (i.e. 5%, 7%, 9%, 10%, 11% and 12%). Tests were performed for the properties of fresh concrete like workability test (Slump cone) and hardened concrete like compressive strength, split- tensile strength, pull-out test, rebound hammer and flexural Test etc. tests were determined at 7, 14 and 28 days. The obtained results for above mentioned test using packing density method at 9% of excess cement paste are satisfying the standard results.

The effect of JKR surface energy on the flowing property of fresh concrete in DEM simulation

The effect of Johnson–Kendall–Roberts (JKR) surface energy on the flowing property of fresh concrete was numerically studied. The fresh concrete was simplified into coarse aggregate and mortar, both described as the particles. The Hertz-Mindlin with JKR contact model was employed to describe the constitutive relationship of fresh concrete. The contact parameters were calibrated through experiment and numerical simulation of multiple flow tests. The impact of these contact parameters on the residual height (Hr) of fresh concrete after slumping was examined using a slump test. The significance degree of mortar–mortar contact parameters on the Hr was studied using an orthogonal test. The effect of the surface energy ( γ ) on the flow index (Bm) and flow time (Tv) of fresh concrete was studied intensively based on the L-box flow and V-funnel tests. The mortar–mortar contact parameters, γ and rolling friction coefficient (μ r), most significantly impacted the Hr. The mortar–mortar surface energy ( γ m-m) significantly impacted Bm and Tv compared to the aggregate–mortar and aggregate–aggregate surface energies (( γ a-m) and ( γ a-a), respectively). The effect of γ a-a, γ a-m, and γ m-m on Bm was interconnected. Under appropriate parametric values, the Bm was the most stable, and the workability of fresh concrete was the best. In addition, as γ increased, Hr and Bm decreased and Tv increased. The flowability of the fresh concrete worsened.

Development of Ultra-High Performance Geopolymer Concrete Containing Recycled Fine Aggregate Replacement

The construction industry continually strives to enhance sustainability and reduce environmental impact. Developing innovative concrete materials that utilize recycled aggregates and alternative cementitious binders has gained significant attention in this context. This abstract presents a study on developing ultra-high-performance geopolymer concrete (UHPGC) by replacing fine aggregates with recycled materials. This research aims to develop UHPGC by incorporating recycled fine aggregate waste (RFAW) as a partial replacement for fine aggregate. Four different concrete mixes were prepared and tested to evaluate RFAW's influence on the performance of UHPGC, considering replacements of up to 30% of fine aggregate. The study examined the fresh properties and mechanical characteristics of the resulting material. The experimental outcomes demonstrated that adding RFAW enhanced the workability of fresh concrete, making it more easily manageable. However, the mechanical properties of the hardened concrete were slightly affected to some extent. Specifically, the compressive strength decreased from 119 MPa to 103 MPa when 30% RAW was added. Conversely, with lower replacement percentages of 10% and 20%, the concrete exhibited no reduction in strength compared to the 30% replacement levels. This reduction in strength could be attributed to a weaker bond between the geopolymer gel and the recycled fine aggregate particles. Additionally, it was observed that as the proportion of RFAW increased, the water absorption of the UHPGC also increased. This indicates that the concrete had a higher tendency to absorb moisture. Nevertheless, the findings suggest that RFAW waste could be a viable resource for producing environmentally friendly UHPGC with improved physical, mechanical, and durability properties with appropriate optimization. The outcomes of this study can promote sustainable construction practices by reducing the reliance on virgin materials and promoting the circular economy within the civil engineering industry.

Image‐based analysis of fresh concrete flow ‐ determining the correlation between flow behavior and rheological properties

AbstractBesides compressive strength, the workability of fresh concrete is one of the most important characteristics of concrete. Only by adapting the rheology of the fresh concrete to the geometry of the element to be casted, the formation of air voids and damages can be avoided. This holds even more so true for 3D printable concrete. Currently, empirical test methods such as the slump test are used to determine rheological parameters. Rheometer tests, on the other hand, allow a much deeper insight into the rheological properties of concrete but are more challenging. Further, all currently available test methods can only be applied on a batch basis.In the paper at hand, a new approach for an automatic digital concrete quality control is presented using modern computer‐vision based analysis methods. Using a newly developed experimental setup, the flow of mortar down an inclined open channel is studied using a monocular camera setup. Differences in the mortar's rheology result in different flow behaviors which can be optically detected. Utilizing dense optical flow, rheological parameters are determined from the acquired monocular image sequences. The results shown in this paper prove that the computed flow behavior of the investigated mortars precisely correlates with their rheological properties, demonstrating the high potential of the method for an automated in‐line testing of fresh concrete e.g. during the discharge of a mixing truck.