V-funnel Flow Research Articles

Suitability of using mussel shells as partial replacement of aggregates in self-compacting concrete

Abstract The handling of mussel shell wastes in coastal regions presents an issue that may be addressed by using mussel shells as a construction material. Shells from waste mussels replace aggregate in concrete, whole or in part. The shells of the mussels are well suited to be incorporated as aggregate into a concrete mix since they are primarily composed of limestone, a substance similar to the other ingredients in concrete. The current study focuses on the suitability of using mussel shells to replace aggregates in self-compacting concrete (SCC). The aggregates were substituted with mussel shells in 5, 10, 15, and 20 percentages. The mixes were initially tested for workability, including slump cone test, L-box test, flow test, and V-funnel test, followed by determining the mechanical behavior, such as flexural strength (FS), compressive strength (CS), and split tensile strength (STS). Also, the microstructural analysis of the mixes was done using scanning electron microscopy (SEM) and energy dispersive x-ray (EDX). The results showed that the concrete’s fresh, hardened, and microstructural properties could be improved by substituting aggregates with mussel shells up to 15%. Some prime results of the SCC mix exhibited a slump flow value range of 600–700 mm, a V-funnel flow time of 10–13 sec, an L-box test ratio greater than 0.8, CS of 41.97–52.93 MPa, STS of 3.69–4.18 MPa, and FS of 3.75–4.28 MPa. The study concludes that better-performed SCC can be produced at an optimum dosage of 15% mussel shells to partially replace aggregates.

Enhancing the performances of self-consolidating composite mortars with Alfa fibers and slag: A combined Taguchi-ANN optimization

Alfa fiber-reinforced self-compacting mortars (SCMs) offer enhanced workability. Thus, the potential of combining natural Alfa fibers and ground granulated blast furnace slag (GBFS) to optimize the rheological and mechanical properties was ascertained. The effect of fibers and GBFS on the properties of SCMs after treatment with linseed oil and NaOH was also evaluated. Partial substitution of cement by slag (10 % and 30 %.) was achieved. Mini cone spreading, V-funnel flow tests as well as compressive and bending tests at 7 days and 28 days were performed on the prepared mixtures. For optimization and predictive purposes, both Taguchi optimization and Artificial Neural Network modeling were employed. Our results indicated that, according to Taguchi experimental design, the use of 1 % fiber in the initial mixture achieved a good distribution within the paste and improved flexural strength. In addition, the treatment of fibers with NaOH actually improved the structure and bonding surface. Fiber content and GBFS replacements achieved the desired rheological and mechanical characteristics. Prediction of both compressive and flexural strengths was successfully achieved by an accurate application of machine a learning algorithm based on six inputs, one hidden layer and four outputs. The combined ANN-Taguchi approach provided accurate predictions of SCM performances and identified a robust mix-design that was less prone to fluctuations in the initial material properties. Alfa fibers and GBFS promoted both fresh and hardened properties. This study demonstrated the effectiveness ML and statistical optimization in developing high-performance, sustainable-SCMs with superior workability and strengths, making them ideal for various construction applications.

Effect of para-wood ash and calcium carbonate on the properties of eco-friendly self-compacting mortar reinforced with electronic waste fibers

This paper deals with reducing CO2 emissions from cement production and finding alternative uses for electronic waste (E-waste) fibers in some innovative applications in self-compacting mortar (SCM). In the present research, an attempt has been made to establish the optimum incorporation of E-waste fiber into SCM by varying the fiber content from 5 % to 25 %, combined with para-wood ash and calcium carbonate as supplementary cementitious materials. In this laboratory study, the mix design had a constant water-to-powder ratio of 0.35 and a cement content of 550 kg/m³. Additionally, 20 % of the cement volume was replaced by 10 % para-wood ash and 10 % calcium carbonate. The results indicated a continuous increase of the mini-slump values from 255 mm for the control mix to 270 mm for the mix with the highest fiber content. Mini V-funnel flow times increased from 3.63 to 8.83 s as the fiber content increased. Lower fiber contents of 5 % improved compressive strength because they had a reinforcing role in the matrix of SCM besides the microcrack-bridging role. Higher contents of 10–25 % decreased the strength due to the clustering of fibers and resulting voids. SEM analysis at 28 days showed increased voids with higher percentages of E-waste fibers and para-wood ash alone. The results underline that optimizing fiber content is critical in balancing workability and mechanical properties, and 5 % e-waste fiber content can be considered optimal for enhancing the performance of SCM. This work also creates part of sustainable construction practice with the green solution required to reduce CO2 emissions and work accumulation against E-waste.

Mechanical performance of eco-friendly self-compacting concrete (SCC) mixtures and two-way slabs partially containing cement kiln dust as cement replacement and internally reinforced with waste plastic mesh

A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was investigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.

Influence of Basalt Fiber on the Rheological and Mechanical Properties and Durability Behavior of Self-Compacting Concrete (SCC)

This experimental study presents the influence of basalt fiber on the rheological and mechanical properties and the durability behavior of self-compacting concrete (SCC). In this study, a total of five self-compacting concrete mixtures were prepared: one as a control mix and the other mixes with 0.05%, 0.1%, 0.15%, and 0.2% basalt fibers. Slump flow and V-funnel flow tests were employed to assess the influence of basalt fibers on the rheological properties of fresh self-compacting concrete (SCC). Additionally, mechanical properties, including compressive strength, splitting tensile strength, and flexural strength, were analyzed. Furthermore, the mechanical properties were assessed following exposure to elevated temperatures (400 °C and 600 °C) as well as 100 and 200 freeze-thaw (F/T) cycles. Additionally, water absorption and ultrasonic pulse velocity tests were conducted on the SCC mixes after 28 days of curing. The results revealed that the addition of fiber has a significant effect on the rheological properties of fresh SCC mixtures. As the volume of fibers increases, the reduction in rheological properties increases. Basalt fiber had no effect on the compressive strength, while the splitting and flexural strength were significantly enhanced by 33% using basalt fiber. As temperatures and freezing-thawing cycles escalated, the mechanical properties of SCC exhibited a decline. Experimental findings indicated that elevating the temperature to 600 °C resulted in a decrease of over 20% in both the tensile and compressive strengths of SCC. Moreover, the results demonstrated that the incorporation of basalt fibers substantially enhanced the mechanical properties of SCC when subjected to high temperatures and freezing-thawing cycles. In addition, water absorption increased slightly by the incorporation of basalt fiber.

The influence of nanosunflower ash and nanowalnut shell ash on sustainable lightweight self-compacting concrete characteristics

The absence of biodegradability exhibited by plastics is a matter of significant concern among environmentalists and scientists on a global scale. Therefore, it is essential to figure out potential pathways for the use of recycled plastics. The prospective applications of its utilisation in concrete are noteworthy. The use of recycled plastic into concrete, either as a partial or complete substitution for natural aggregates, addresses the issue of its proper disposal besides contributing to the preservation of natural aggregate resources. Furthermore, the use of agricultural wastes has been regarded as a very promising waste-based substance in the industry of concrete manufacturing, with the aim of fostering the creation of an environmentally sustainable construction material. This paper illustrates the impact of nano sunflower ash (NSFA) and nano walnut shells ash (NWSA) on durability (compressive strength and density after exposure to 800 °C and sulphate attack), mechanical properties (flexural, splitting tensile and compressive strength) and fresh characteristics (slump flow diameter, T50, V-funnel flow time, L-box height ratio, segregation resistance and density) of lightweight self-compacting concrete (LWSCC). The waste walnut shells and local Iraqi sunflower were calcinated at 700 ± 50 °C for 2 h and milled for 3 h using ball milling for producing NSFA and NWSA. The ball milling succeeded in reducing the particle size lower than 75 nm for NSFA and NWSA. The preparation of seven LWSCC concrete mixes was carried out to obtain a control mix, three mixtures were created using 10%, 20% and 30% NWSA, and the other three mixtures included 10%, 20% and 30% NSFA. The normal weight coarse aggregates were substituted by the plastic waste lightweight coarse aggregate with a ratio of 75%. The fresh LWSCC passing capacity, segregation resistance, and filling capability were evaluated. The hardened characteristics of LWSCC were evaluated by determining the flexural and splitting tensile strength at 7, 14 and 28 days and the compressive strength was measured at 7, 14, 28 and 60 days. Dry density and compressive strength were measured after exposing mixes to a temperature of 800 °C for 3 h and immersed in 10% magnesium sulphate attack. The results demonstrated that the LWSCC mechanical characteristics were reduced when the percentages of NWSA and NSFA increased, except for 10% NWSA substitution ratio which had an increase in splitting tensile strength test and similar flexural strength test to the control mixture. A minor change in mechanical characteristics was observed within the results of LWSCC dry density and compressive strength incorporating various NSFA and NWSA` contents after exposing to temperature 800 °C and immersed in 10% magnesium sulphate attack. Furthermore, according to the findings, it is possible to use a combination of materials consisting of 10–20% NSFA and 10–20% NWSA to produce LWSCC.

Exploring the interrelationships between composition, rheology, and compressive strength of self-compacting concrete: An exploration of explainable boosting algorithms

This study introduces a novel methodology for enhancing the compressive strength of self-compacting concrete (SCC) via the use of the Explainable Boosting Machine (EBM), a sophisticated and interpretable machine learning algorithm. It presents a data-driven model that aims to accurately predict the strength of SCC by considering the intricate interactions among its various elements. Additionally, the model provides insights into the variables that influence SCC's compressive strength. By using EBM in conjunction with XGBoost and CatBoost algorithms, this study conducts a comparative examination of predictive abilities using datasets related to composition and rheology. The findings reveal that CatBoost has greater predictive performance using rheology dataset, as shown by an R2 value of 0.977. Conversely, XGBoost exhibits a higher predictive capability using the composition dataset, as indicated by an R2 value of 0.947. The EBM can provide comprehensive explanations at both global and local levels. It effectively identifies the key factors that have a significant influence on compressive strength. These factors include the coarse aggregate content, cement content, water content, viscosity, and V-funnel flow time. The study findings provide more evidence to support the notion that including rheological data into the model leads to a notable improvement in its accuracy. This outcome further confirms the existence of a direct correlation between rheological properties and compressive strength. The explanatory insights provided by EBM give practical instructions for customising SCC mixes to attain desired strengths. This facilitates quality control and enables personalised concrete design in the field of construction. This study highlights the potential of interpretable machine learning algorithms in improving the predictive modelling of SCC features. This advancement may lead to the development of more durable, efficient, and customised building materials.

The effect of using seashells as cementitious bio-material and granite industrial waste as fine aggregate on mechanical and durability properties of green flowable sand concrete

The present work is a study of the feasibility of using seashell powder (SSP) combined with industrial granite waste (GW) to develop a new green flowable sand concrete (FSC). The GW was used to replace the natural sand at levels of 0, 10, 20, 30, 40, and 50% by volume, and the SSP has been used to substitute the cement at levels of 5, 10, and 15% by weight. Slump flow and V-funnel flow time tests have been used to investigate the fresh properties of FSC mixtures. Compressive strength, modulus of elasticity, ultrasonic pulse velocity (UPV), water absorption, porosity, and acid attack tests were used to assess the mechanical and durability properties of hardened FSC mixtures. XRD, TGA, and SEM analyses were performed to evolve the microstructure of hardened FSC. The results showed a decrease in the fresh properties of FSC mixtures with the substitution of sand by GW. Nonetheless, the inclusion of SSP as filler mitigated this adverse effect, and all FSC mixes were subsequently discovered to be within the standard limits. The combined use of 50 vol% GW and 10 wt% SSP developed FSC with the greatest compressive strength (67 MPa), modulus of elasticity (40 GPa), and UPV (4175 m/s), as well as the lowest porosity (2.9%) and absorption (2.4%) at 90 days, compared to the control FSC. Moreover, using up to 10 wt% SSP with a fineness of 8000 cm2/g may enhance the durability of GW-based FSC against acid attack. Microstructural analyses indicated denser microstructure, stronger ITZ, and weaker porosity. The developed eco-friendly FSC effectively showed a decrease in production costs and carbon emissions, reducing the level of waste and protecting natural resources, which provides an emerging approach for its application in advanced green concretes for future work.

The Influence of Mineral Additives and Sands on the Performance of Self-Compacting Sand Concretes

Abstract The chosen plan for our case study is a network mixture design consisting of 21 mixtures. The application of this method has proven to be immensely useful in studying the influence of composition parameters (composite design) and the utilization of various types of mineral additives (mixture design). The application of the Design of Experiments (DOE) method, based on a statistical approach, allowed for a better understanding of the effect of formulation parameters, including the proportion of alluvial sand (75%), dune sand (25%), the total amount of sand kept at constant percentages, the dosages of brick powder, limestone filler and ceramic powder (all varying from 0 %, 20 %, 40 %, 60 %, 80 %, and 100 %), while keeping the dosage of superplasticizer and the water/binder ratio constant. This approach helped to understand the interactions between these parameters and their impact on the process. Mathematical models relating the variations of these parameters to the workability and compressive strength of such concrete mixtures have been established. The results obtained show that the workability of SCSC (expressed by slump flow and V-funnel flow) improves with the increase in the dosage of limestone filler (FC), brick powder (PB), and ceramic powder (PC), with element having a different impact, be it alone or in a combination. Moreover, they all improved the behavior of SCSC in both the fresh and hardened states. The experiment shows that increasing the proportions of FC and PC in the mixture, whether linear, binary, or ternary, leads to a significant improvement in compressive strength. Furthermore, better strength is observed in the ternary mixture at 28 days, with a strength of 43 MPa, with the following proportions (FC 70%, PB 20%, PC 10%). Finally, the result at 180 days of 48 MPa confirms the following proportions (PC 60 %, FC 30 %, PB 10 %) The compliance of some SCSC compositions was tested according to the recommendations of the French Association of Civil Engineering.

Design of self-compacting ultra-high performance concrete (SCUHPC) towards to the cementitious materials packing optimization

UHPC is a cement-based material characterized by outstanding strength and durability, but its high viscosity poses challenges for field application. Herein, we built a Horsfield theory modified cementitious packing structure by utilizing fly ash microsphere (FAM), aiming to release water, thus, reduce viscosity. The wet packing density indicated that FAM could optimize the packing structure, and transform locked water into free water. Meanwhile, 1H NMR revealed the variation of adsorbed water to free water due to the surface characteristics of FAM. Consequently, more free water could be obtained, which thereby reduced the viscosity up to 75 %. The slump flow, t500, v-funnel flow time and J-ring tests were further conducted to assess the workability, where the results indicated the modified UHPC met the standards for self-compacting concrete. Besides, the synergistic water-reducing strategy attributed to cementitious materials packing optimization can maintain a low w/b (<0.2), which contributes to an ultrahigh strength of 120.5 MPa, realizing the feasibility of developing self-compacting UHPC This study provides a new approach to enhance the workability of UHPC without sacrificing mechanical property and durability, expanding the field application of UHPC.

Rheological properties and mechanical strength of self-compacting mortars produced with marble powder and calcined clay

The use of calcined clays [CC], combined in ternary blended with the limestone filler and cement has received considerable attention in recent years. This paper discusses the results on the rheological and compressive strength of three types of calcined clays in combination with marble powder and cement, used as ternary binder in self-compacting mortars. A simplex-lattice mixture design approach was used, with five levels, to establish the different binder combinations. The responses of the system were evaluated in terms of rheological properties and compressive strength. The tests conducted on SCM ternary mixes are slump flow diameter, v-funnel flow time, yield value, viscosity and compressive strength at 28, 90 and 365 days. It was concluded that the replacement of cement with calcined clays and marble powder in ternary mixes reduced the flowability by decreasing slump flow and increasing v-funnel time. However, the combined effect of marble powder and calcined clays is more appropriate to produce flowable SCM mixes while maintaining an adequate viscosity. In terms of compressive strength. A progressively increasing trend was observed for 28 days compressive strength with the increase in marble powder and calcined clays in binary proportions.

Production of SCC Using Bagasse Ash as Fine Aggregate

Abstract: In this study an experimental investigation on production of self-compacting concrete with bagasse ash as partial replacement of fine aggregate is done. River sand has been partially replaced with bagasse ash from 0% to 80% by volume. Cement and fly ash is used as a powder material. Two concrete mixtures with cement content of 375 Kg/m3 and 500 Kg/m3 was proportioned. The workability properties such as slump flow, inverted flow, V-funnel flow time and J-ring flow were measured. The hardened properties such as density, compressive strength, split tensile strength, modulus of elasticity and flexural strength of concrete in each mixture were measured at various ages. Water absorption and weight loss ratio on drying of concrete was measured at 28 days. Micro structural properties such as SEM and XRD analysis were examined for SCC specimens.From the test results, it was found that (a) Workability properties depends upon the bagasse ash content (b) Partial replacement of BA up to 20% by volume of bagasse ash enhanced both the workability and hardened properties of self-compacting concrete (c) SEM micrograph images shows that irregular porous particles increases as BA increases and XRD pattern reveals that presence of silica peak increases as the BA content increases from 10% to 80%.

The Effect of Polypropylene Fibers on the Behavior of Fiber Self-Compacting Concrete

Fiber self-compacting concrete (FSCC), is a concrete that has been combined with fiber in its mix design. Extensive benefits of self-compacting concrete (SCC) in full fill the mold and achieving full compaction without vibration, with good behavior after concrete cracking, raise the idea of self-compacting concrete production. The fundamental challenge in this area is the unsatisfactory performance of concrete with fibers; In other words, using fibers in concrete will reduce concrete fluidity. Therefore, determining the appropriate percentage of fibers in SCC can be a precursor to extending the use of FSCC. In this study, polypropylene fibers with 0.5, 1, 0.1, and 2% of concrete mix design have been added to the self-compacting concrete mix design. Its impact on the performance of concrete has been evaluated using time and diameter of slump-flow, L-Box, J-ring, and V-funnel flow time tests. Based on the criteria defined by EFNARC standard, it was indicated that the FSCC containing 0.5% polypropylene fibers has an acceptable performance. Additionally, the effect of polypropylene fiber on the mechanical properties of hardened concrete has been studied using compressive strength and tensile tests and shown that changes in FSCC compressive strength and tensile with 0.5% polypropylene fiber are negligible.

Prediction of self-consolidating concrete properties using XGBoost machine learning algorithm: Part 1–Workability

The interest in implementing self-consolidating concrete (SCC) in major construction projects has increased significantly in recent years. This paper reports the results of an extensive survey of experimental data of more than 1700 SCC mixtures from over 100 studies published in the last decade. The survey included the SCC mixture proportioning, key fresh properties including flowability, passing ability, and segregation resistance, as well as some of the derived properties (e.g., paste volume). The statistical analysis of the reported parameters showed wide variations in values. The outcome of the survey indicates that SCC mixture design and workability properties do not systematically lie within the recommendations reported in various guidelines. A wide range of workability tests is used; however, only 22 % of the studies reported values for segregation resistance. The slump flow test was the most tested fresh property and the most reported values are in range of 591–760 mm (X¯ = 679 mm). The V-funnel time was the second most reported test, and the most of reported values are in range of 4.0–20 s (X¯ = 11 s). The study devised and evaluated the efficacy of using machine learning (ML) models, namely Extreme Gradient Boosting (XGBoost), to predict the two most reported workability characteristics of SCC, namely slump flow and V-funnel flow time. The model was formulated to predict slump flow and V-funnel time using a refined sub-database of 852 tests (the extreme data i.e., 5 % from each side, for the both properties and the empty data was deleted). The findings revealed that the XGBoost model can provide an accurate prediction for the slump flow and V-funnel values, thus indicating its potential as a powerful tool for SCC optimization. The findings provide valuable insights into the application of ML in SCC research and contribute to the development of more efficient and sustainable construction practices.

Obsidiyen Tozu Katkılı Kendiliğinden Yerleşen Betonun Taze Beton ve Mekanik Özelliklerinin İncelenmesi

Self-compacting concrete (SCC) is a special type of concrete with high workability. This type of concrete is preferred and used as innovative concrete because it does not require vibration, has high fluidity, can be applied quickly and requires minimum workmanship. The high workability of self-compacting concrete depends on the type and amount of various chemical and mineral admixtures in its content. In this study, self-compacting concrete groups were produced by using obsidian powder, which is a rock of volcanic origin, at 15, 20 and 25% ratios instead of cement. In these groups; flow-table, V-Funnel flow, L-box, U-box fresh concrete tests and compressive strength tests were carried out after 7 and 28-days of standard water curing. When the test results are examined; it was determined that obsidian powder improved the self-compacting fresh concrete properties. In addition, it has been determined that the concrete mixtures produced using obsidian can have high compressive strength.

Lightweight SCC Development in a Low-Carbon Cementitious System for Structural Applications.

The utilization of manufactured lightweight aggregates adds another dimension to the cost of the preparation of self-compacting concrete (SCC). The common practice of adding absorption water to the lightweight aggregates before concreting leads to inaccurate calculations of the water-to-cement ratio. Moreover, the absorption of water weakens this interfacial bond between aggregates and the cementitious matrix. A particular type of black volcanic rock with a vesicular texture known as scoria rocks (SR) is utilized. With an adapted sequence of additions, the occurrence of water absorption can be minimized to overcome the issue of calculating the true water content. In this study, the approach of preparing the cementitious paste first with adjusted rheology followed by the addition of fine and coarse SR aggregates enabled us to circumvent the need for adding absorption water to the aggregates. This step has improved the overall strength due to the enhanced bond between the aggregate and the cementitious matrix, rendering a lightweight SCC mix with a target compressive strength of 40 MPa at 28 days, which makes it appropriate for structural applications. Different mixes were prepared and optimized for the best cementitious system that achieved the goal of this study. The optimized quaternary cementitious system included silica fume, class F fly ash, and limestone dust as essential ingredients for low-carbon footprint concrete. The rheological properties and parameters of the optimized mix were tested, evaluated, and compared to a control mix prepared using normal-weight aggregates. The results showed that the optimized quaternary mix satisfied both fresh and hardened properties. Slump flow, T50, J-ring flow, and average V-funnel flow time were in the ranges of 790-800 mm, 3.78-5.67 s, 750-780 mm, and 9.17 s, respectively. Moreover, the equilibrium density was in the range of 1770-1800 kg/m3. After 28 days an average compressive strength of 42.7 MPa, a corresponding flexural load of over 2000 N, and a modulus of rupture of 6.2 MPa were obtained. The conclusion is then drawn that altering the sequence of mixing ingredients becomes a mandatory process with scoria aggregates to obtain high-quality lightweight concrete for structural applications. This process leads to a significant improvement in the precise control of the fresh and hardened properties, which was unachievable with the normal practice used with lightweight concrete.

Influence of glass wool fiber reinforcement and heat resistant coating on behavior of self-compacting mortar at elevated temperatures

In present study, the influence of glass wool fiber (GWF) reinforcements and the application of heat resistant paint has been studied on the performance of self-compacting mortar (SCM) at ambient condition and at elevated temperatures of 200 °C, 400 °C, 600 °C, and 800 °C. Sixteen mix designs were prepared for SCM (with 25% fly ash) using GWF reinforcement of 0%, 0.5%, 1%, 1.5%, and varying the effective water to cement (w/c) ratio as; 0.43, 0.49, 0.55, and 0.70. The intrusion of GWF resulted into decrease in slump flow and v-funnel flow speed, increase in yield stress and plastic viscosity, whereas, the influence of effective w/c ratio on rheology of fresh SCM mix was opposite to glass wool fiber (GWF). For all variation of effective w/c ratio and GWF reinforcements, the values of slump flow and v-funnel flow were within the EFNARC limits. Increasing GWF reinforcement and the effective w/c ratio, compressive strength of SCM were decreased, but GWF yielded positive impact on flexural strength. SCM with 1% GWF reinforcements showed best result at effective w/c of 0.43, imparting highest flexural strength of 8.7 MPa. The application of heat resistant coating has shown a significant protection to SCM samples up to the maximum heating temperature of 800 °C by limiting the loss of mechanical strength within small percentage, whereas, the loss of mechanical strength was severe (about 45% to 65%) for uncoated samples. Thermogravimetric (TG) analysis of SCM powder revealed the thermal stability of SCM mix up to 1000 °C and the mass loss occurred correspond to the heating at temperature of 400 °C and 800 °C was 0.3%, and 7.5%, respectively.

Fresh Properties of Self-Consolidating Expired Cement-Fly Ash Cold Bonded Lightweight Aggregate Concrete With Different Mineral Admixtures

The experimental program evaluated the fresh properties of self-consolidating lightweight concretes (SCLC) produced from expired cement EC cold-bonded lightweight coarse aggregates (ALA) with silica fume (SF) and fly ash (FA). Twelve mixtures of SCLC were prepared, the binder in the control mix was just Portland cement (PC), whereas other mixes included binary and ternary of (PC), 20% of (FA), and/or (10%) of (SF) with (0%, 50%, and 100%) as partial replacement of (ALA) with coarse natural aggregates. Fresh features of (SCLC) were evaluated by measuring their slump flow diameter, T500 slump flow time, V-funnel flow time L-box height ratio, and column segregation, (SCLC) with and without mineral admixtures have their fresh characteristics compared. It was found that increasing the quantity of ALA replacement resulted in a reduction in the amount of superplasticizer required to obtain a constant slump flow diameter of SCLC. Combining (SF) and/or (FA) lowered both the V-funnel flow time and the slump flow time, whereas the L-box height ratio increased from (0.82) to (0.86) with the addition of fly ash for reference mix. With the combined action of mineral admixtures, the percentage of column segregation decreases by (16.7%) compared with the reference mix. The maximum slump flow was (792) mm with a mix of (M6).

The Effect of Brick and Glass Powder on the Mechanical Properties and Porosity of Self-Compacting Mortar

Abstract The use of glass and brick powder waste as supplementary cementious material provides an effective approach to produce concrete in order to effectively save resources and solve environmental pollution problems. This study shows the evolution of the preparation of an eco-friendly self-compacting mortar (SCM) with various fineness levels and replacement ratios of crushed glass and crushed calcined brick waste. Cement was replaced by weight, by 8, 12, 16, 20, 24% of glass powder (GP) and 4, 8, 12, 16 and 20% of crushed brick powder (BP), with three specific surface Blaine (SSB) fineness measurements (F1=3300cm2/g,F2=4400 cm2/g and F3=6000 cm2/g) for both wastes. Mini-slump and V-funnel flow time tests of fresh SCM were evaluated. Compressive and flexural strength developments of cured SCMs were determined on 7, 14, 28, 5 6, and 90 days. In addition, porosity of SCM was also evaluated. The results revealed that the (SCM-GP) mix increases workability and reduces superplasticizer dosage, while the (SCMBP) mix reduces workability with a slight increase in superplasticizer. When the GP fineness is higher than the cement fineness, the compression strength with GP contents up to 16% is superior to without the GP, whereas for the BP the strength improvement is up to 8%, while the compression strength decreases when the GP and BP fineness is close or lower than the cement fineness. The porosity diminishes with the increase of the fineness; the 12% of the GPF3 indicated the lowest porousness at 400 days, whereas for SCM-BP the 8BPF3 is the least porous mixture.

Crushed-stone sand for use in the development of self-compacting concrete (SCC)

SCCs, usually known as self-compacting concrete, are a kind of very fluid concrete having the capacity to flow without suffering any vibration. In order to reduce the possibility of bleeding and segregation, their makeup requires the inclusion of a significant number of fines. The usage of crushed sand, which is plentiful in limestone fines, may be shown to be a successful solution in terms of economics and ecology. This research examines the rheological, mechanical, and durability properties of self-consolidating concrete after adding quarry limestone fines to manufactured crushed sand (SCC). Five distinct SCC mixes were made with a consistent water-to-cement ratio of 0.40 and a cement content of 490 kg/m3 in order to accomplish this objective. The combinations substituted crushed limestone fines for crushed sand in varying proportions. The slump flow test, the V-funnel flow time test, the L-box height ratio test, the segregation resistance test, and the rheological test were all performed on the fresh SCC mixes using a rheometer. The compressive, tensile, and flexural strengths of SCC mixtures were assessed at the conclusion of the 28-day curing period. It was shown that raising the replacement amount of limestone fines in SCC mixes resulted in a decrease in both the slump flow and the yield stress when employing the two separate test modes in the fresh condition Samples of 7th and 28th day cubes were collected from the optimized mix proportion and subjected to Scanning Electron Microscope (SEM), X- Ray Diffraction (XRD). The images were interpreted and the result from micro-structural analysis were compared with their compressive strength. All of the SCC combinations examined had acceptable filling and passing capabilities, and no segregation was discovered in any of them. Using limestone fines instead of crushed sand also reduces the amount of water that is absorbed by capillaries, stops chloride ions from moving, and improves performance.