Sand Concrete Research Articles

Influence of Partial and Total Replacement of Used Foundry Sand in Self-Compacting Concrete

In this work, the feasibility of partially and totally replacing natural sand with used foundry sand in self-compacting concrete was studied. Natural sand was replaced in 50% and 100% vol. by used foundry sand. The fresh state properties parameters analyzed in this study were slump flow, t500, V-funnel, Japanese ring and L-box following EFNARC guidelines. Results indicated an improvement in the fresh state properties when used foundry sand was utilized for partial and total replacement. The mechanical properties compressive strength and splitting tensile strength were obtained and analyzed at 7 and 28 days. Regarding the compressive strength, used foundry sand enhanced compressive strength by up to 67% compared to control concrete. For splitting tensile strength, the self-compacting concrete with 50% vol. of used foundry sand displayed a slight decrease (2.8%) compared with the control concrete. SEM images showed that the concretes with used foundry sand had a less porous and more compacted matrix than the control concrete. It was concluded that the incorporation of used foundry sand in large volumes can be utilized as a sustainable alternative natural fine aggregate.

Fracture behavior of dredged sand concrete under freeze–thaw cycles

In order to investigate the frost resistance and fracture behaviors of dredged sand concrete, three kinds of concrete with different dredged sand contents (0%, 25%, and 50%) by weight were designed and subjected to different freeze–thaw cycles (0, 25, 50, 75 and 100). Three-point bending fracture tests were performed on the frozen concrete specimens combined with acoustic emission (AE) technique. The results show that the mass loss of dredged sand concrete increases, the relative dynamic elastic modulus and compressive strength decreases with the increase of the freeze–thaw cycles. With the increase of dredged sand content, the pore structure is improved, so the fracture behavior and frost resistance of concrete are improved. With the increase of the dredged sand content of concrete, the fractal dimension of the fracture surface decreases. With the increase of the freeze–thaw cycles, the fractal dimension of the fracture surface increases, and the fracture surface is rougher. The higher the freeze–thaw cycles, the lower the peak load, fracture toughness and fracture energy of dredged sand concrete. The higher the content of dredged sand, the greater the fracture energy of dredged sand concrete. The accumulate AE counts, AE energy and AE b-value can reflect three-stage failure process of dredged sand concrete. The damage model of dredged sand concrete established based on the AE events obeys Weibull distribution, which can reflect the effect of freeze–thaw cycles on damage.

Elaboration of a Self-Compacting mortar based on concrete demolition waste incorporating blast furnace slag

The high consumption of natural sand in the manufacture of mortar and concrete has inevitably led to serious ecological impacts. On the other hand, the steel industry is always accompanied by the production of unused by-products such as granulated blast furnace slag. This research aims to use a fine fraction of construction and demolition (C&D) waste as a substitute for natural sand and, ground granulated blast furnace slag (GGBFS) as a substitute for cement for the manufacture of self-compacting mortars. 15 mortars are formulated where 0, 25, 50, 75 and 100% natural sand (NS) are replaced by recycled concrete sand (RCS) and 0, 20 and 40% ordinary cement are replaced by GGBFS. The obtained results show that it is possible to manufacture self-compacting mortars with RCS, with an optimum of 50%. The use of this type of sand affects negatively the porosity and capillarity water absorption of mortars; this can be compensated by the use of GGBFS as a cement substitute. A 20% slag substitution rate can also improve the long-term compressive strength.

Study on the Preparation and Properties of Bridge Concrete Using Low Carbon Aggregates

It is an outstanding solution for protecting the environment using manufactured sand instead of natural river sand in concrete. In this paper, tunnel granite muck was processed into low carbon, coarse and fine aggregates, and low carbon aggregates were used to prepare bridge concrete. Meanwhile, the mechanical properties, anti-permeability, and frost resistance of concrete were investigated. The results demonstrated that the concrete prepared using low carbon aggregate had higher mechanical properties than concrete prepared using river sand. The chloride ion penetration resistance of concrete using low carbon aggregate is better than that of concrete using river sand, and frost resistance has been improved.

Use of E-Waste in Metakaolin Blended Cement Concrete for Sustainable Construction

This paper investigates the use of non-metallic portion (NMP) reclaimed from e-waste (i.e., waste printed circuit board—PCB) as replacement of natural sand in the blended cement concrete by using Metakaolin (MK) as supplementary cementitious material for its effect on the mechanical, durability, microstructural, and mineralogical properties of concrete. It was found that the blended mixes containing NMP and MK outperformed the control mix. With the addition of 10% NMP and 10% MK, the maximum compressive strength was obtained, with the splitting tensile and flexural strength following the same trend. The performance of the mixes was lowered above 10% replacement levels, although it was still better than the control mixture. When compared to other mixes, 10% NMP and 10% MK concrete had the lowest sorptivity and water absorption values, as well as the highest resistance to chloride-ion penetration. FESEM was used to confirm the results, and then XRD was used to determine the elemental classification. This study lays the groundwork for a long-term strategy for utilising NMP and MK as extremely effective concrete additives.

Cyclic Shear Behavior of Frozen Cement-Treated Sand-Concrete Interface.

The cyclic shear behavior of frozen cement-treated soil-concrete interfaces is critical for analyzing soil-structure interfaces and foundation design in cold regions and artificially frozen ground. The cyclic shear behavior of the interface between frozen cement-treated sand and structure is investigated in this paper at various normal stresses and temperatures. Experimental results include the variation of the peak shear stress, peak normal displacement, shear stiffness with the number of cycles, and the relationship between peak shear stress and smoothness under certain conditions. Peak shear stresses of warm frozen cement-treated sand and cold frozen cement-treated sand varied with cycle number. Additionally, the former is significantly larger than the latter in the stable phase. The peak normal displacement showed the same results, indicating that the ice crystals formed on the surface and the strength of the frozen cement-treated sand have significant differences at various temperatures. The study's findings aid in understanding the complexities of the cyclic shear behavior of frozen cement-treated sand and structure interfaces and provide references on frozen cement-treated sand zones in practical engineering.

Flexural Performance of Steel Bar Reinforced Sea Sand Concrete Beams Exposed to Tidal Environment

The advancement of marine engineering has brought close attention to the durability of concrete structures. In order to investigate the time-varying performance of reinforced concrete beams in a marine environment and to better apply sea sand directly in marine engineering, this paper describes tests and analysis on the flexural performance of reinforced sea sand concrete beams after being exposed to a tidal environment. Eight beams were tested using four-point static loading equipment. The variation parameters included the type of mixing water, longitudinal reinforcement rate, sea sand replacement rate and duration of service. The force damage process and damage pattern were observed. The load–maximum width crack curve and load–deflection curve were obtained. The effects of each variation parameter on the mechanical properties such as ultimate bearing capacity, initial rigidity, energy dissipation coefficient and ductility coefficient were analyzed. The test results show that compared with the specimens exposed to the tidal environment for 90 days, the peak load of the specimens decreased by 5.6%, the initial rigidity decreased by 60.9% and the ductility coefficient decreased by 41% after 270 days of exposure, while the peak deflection and energy dissipation indexes first increased and then decreased. The seawater mixing can enhance the peak load and cracking load of the specimens, but the initial rigidity, peak deflection, energy dissipation coefficient and ductility coefficient of the specimens are reduced to some extent. The initial rigidity of the specimens tended to increase with the increase in the sea sand replacement, but the peak load decreased. Under the same reinforcement rate, reducing the diameter of the reinforcement is beneficial to improve the initial rigidity of the specimen, while using the reinforcement with higher elongation can effectively enhance the peak deflection of the specimen. Based on the Chinese code, the calculation method of flexural bearing capacity with modified concrete strength is proposed, and the calculation results are in good agreement with the test results.

Critical state shear strength at concrete–sand–bentonite slurry interfaces: mix proportions and rate effects

This paper describes direct shear testing of a range of sand–bentonite slurry mixes, identified as a gap in the literature. In the absence of a concrete interface, there was an apparent transition zone from sand-governed strength (bentonite content ≤30%) to clay-governed strength (bentonite content ≥80%), which was linked to the sample void ratio. When a concrete interface was introduced, the critical stress ratio (critical state shear stress normalised by the effective normal stress) was found to change linearly with bentonite slurry content, reflecting an interface sliding failure mechanism. The testing also considered the effect of shearing rates ranging from 0·0025 to 10 mm/min on interface shear strength. The mixtures containing greater bentonite slurry content displayed a greater decrease in the critical stress ratio with increasing shear rate. Very few studies have explored the influence of the relative sand–clay mix composition on interface shear resistance; these results provide a better understanding of their mechanical behaviour and forms a basis for future research in this area.

Study of the Structure and Properties of Electrical Sand Concrete under Prolonged Exposure to Sulfate Environment

Destructive processes accompanying sulfate corrosion of concrete significantly affect the durability of products and structures based on Portland cement. In the presented study, the long-term effect of sulfate corrosion on the electrical properties of electrically conductive sand concrete was studied. In the course of the study, the following were tested: an electrically conductive composition and a control composition based on plain Portland cement. The analysis of changes in the mineral composition of the samples over the course of time in an aggressive solution was carried out. The results show that during the exposure period of the samples from 28 to 224 days, the absorption of sulfate ions slows down and averages 26% for the control composition and 29% for the electrically conductive composition, of the total volume of absorbed sulfates. At the same time, the course of sulfate corrosion was accompanied by a 6% increase in the density of samples of both compositions, as well as a cyclic change in mechanical strength within 15%. In its turn, the key indicator of the electrical characteristics of the compositions-electrical resistivity-tended to increase throughout the experiment. These results can be recommended for assessing the durability and the nature of the operating conditions of electrical concretes used in aggressive environments.

An Experimental Study on Filler And Binder Material To Make Polyblock

Abstract: The Polyblock system known generally as either ICFs (Insulated Concrete Forms) or LCFs (Light Weight Concrete Forms) ICF/LCF systems have been used for over 30 years. In countries where thermal, insulation and energy efficiency are key requirements. This study reviewed the variations in 88% filler and 12% binder material mixture components that effectedthe properties. The effect of resin content filler (Slag/ Industrial Waste) and binders (Unsaturated Polyester) purpose, conventional filler such as concrete sand can also bond. All of these materials are to be tested according to the standard test procedure. The effect of about mentioned filler is studied in this paper.

Assessment of corium concrete interaction and impact of water ingression mechanism using top flooding strategy for a small PWR with MELCOR 2.2

Molten Corium Concrete Interaction (MCCI) process is a critical phenomenon in the management of the late phase of a severe accident. Determination of water ingression (WI) and melt eruption (ME) impact on the ablation process is necessary for the assessment of cavity erosion. A model is developed to study the MCCI for Siliceous (SIL) and Limestone Common Sand (LCS) concretes in dry and water-filled cavities using MELCOR 2.2 code for a small PWR. It is found in this study that the ablated volume is greater in the SIL as compared to the LCS concrete. WI and ME were able to successfully halt the ablation process for LCS concrete under water flooding. Even with WI, SIL concrete ablation cannot be completely stopped in the axial and radial directions. In terms of concrete ablation, the cavity constructed with LCS is found to be safer than the cavity constructed with SIL concrete.

Study on the mechanical properties of desert sand concrete

In this paper, the manufactured sand was replaced by desert sand with contents to prepare desert sand concrete with different grades. Then the compressive strength, axial compressive strength, static compressive elastic modulus and axial tensile strength of desert sand concrete were tested to analyze the influence of desert sand replacement rate on the mechanical properties of concrete at different ages and different grades. It was shown that the negative influence of desert sand on the compressive strength of concrete would be increased with the increase of concrete grade, and the influence increased with the increase of age. The addition of sand would be resulted in the decrease of axial compressive strength and static elastic modulus of concrete, and with the increase of concrete grade, the strength would be decreased obviously. The addition of desert sand had no significant effect on the axial tensile strength of concrete in general.

Dynamic bending study of glass fiber reinforced seawater and sea-sand concrete incorporated with expansive agents

To meet the growing requirements of global air transport, pavement materials with excellent dynamic bending performances are in demand. Meanwhile, replacing fresh water and river sand with seawater and sea sand in concrete helps preserve the environment and reduces concrete costs. In this study, the dynamic bending performance of seawater sea sand concrete (SSSC) mixtures incorporated with glass fiber (GF) and expansive agent (EA) were explored using a 100-mm diameter split Hopkinson pressure bar (SHPB) device. Modified sleeves were installed to perform three-point dynamic bending tests. Microstructures of the specimens were observed using scanning electron microscopy. Test results show that GF and EA worked synergistically to improve the dynamic bending performances of SSSC. Specimens incorporated with both GF and EA show stronger strain rate effects than SSSC specimens with GF or EA. The combined use of GF and EA apparently strengthened fiber-mortar interfaces and significantly enhanced specimen ultimate displacements at high strain rates.

Sustainable usage and the positive environmental impact of wastewater dry sludge-based concrete

The paper examined the application of dry sludge in lightweight concrete and the associated environmental risk. Population growth has led to an increase in residential and commercial wastewater sludge production. The sludge is deposited to a designated landfill, rendering the area useless and posing a significant environmental concern. The need for lightweight materials in the construction sector has resulted in the replacement of dry sludge for the basic components of concrete. The dry sludge came from the WWTPs in Polokwane, Limpopo Province, was used as a partial replacement for sand (0, 2.5, 5, 7.5, 10, and 12.5%) in concrete. The samples prepared were cured in wastewater and potable water. The results showed that the partial substitution of sand with 7.5% dry sludge in the concrete mixture reached the desired strength of 25 MPa and can be employed in lightweight structural applications. Concrete cube unit weight reduced by 0.8, 2.3, 2.6, 3.9, and 4.6% compared to the control sample when 2.5, 5.0, 7.5, 10, and 12.5% of the sand was substituted with sludge. Concrete samples were submerged in iodine water for 28, 90, and 140 days to test the leaching of soluble metals. The levels of heavy metals in leachate were far lower than what the US Environmental Protection Agency (EPA) considers to be safe, under their Toxicity Characteristics Leaching Procedure (TCLP) standards. EDX examination of sludge-based concrete showed a considerable reduction in metal weight percentage, the concentration of calcium increased by 69% due to the cement content; and the blending aggregates lowered silicon, aluminium, iron, and potassium by 33.3, 66.9, 34.2, and 77.8%. Therefore, wastewater may be utilized as a concrete curing medium, and sludge-based concrete can be used for simple structural repairs at WWTPs.

Study on Mechanical and Microstructural Properties of Concrete with Fly Ash Cenosphere as Fine Aggregate—A Sustainable Approach

The utilization of waste materials in concrete lowers its cost, and this method of dealing with the problem of trash disposal is viewed as the most environmentally friendly. Fly Ash Cenospheres (FAC) are one of the principal wastes produced by coal power stations. The huge volume of FAC produced worldwide has created a sustainability challenge, owing to the potential implications of inappropriate disposal. Using cenospheres in concrete materials would make effective and efficient use of these waste products while also supplementing what the present raw material, such as river sand, can supply for concrete material production. Though the application of FAC in concrete is currently carried out by the construction industry, there is still a lack of understanding about its performance in concrete with Manufactured Sand (M Sand) as fine aggregate. Therefore, in this paper, a comprehensive study explores the concept of adding FAC to M Sand concrete. The properties of fresh and hardened concrete, such as density, workability, compression, split tensile, flexure, and impact resistance after the addition of FAC in volume replacement (0–100% with a difference of 5% at thirteen different ratios) is represented, followed by microstructural analysis. From the results, it can be concluded that strength reduction takes place as FAC content increases from 0–100%, however, the strength is within the target limit of 31.2 N/mm2 of conventional concrete (CC) of grade M25 when the percentage replacement is below 35% of volume. Therefore, reducing the volume of fine aggregate does not negatively affect the strength properties, but also impacts the environmental concern positively with optimum recommendation of 35% of fine aggregate as FAC.

Experimental Research on the Effects of Waste Foundry Sand on the Strength and Micro-Structural Properties of Concrete

Now a days, a great distance has to be travelled to find good quality natural river sand. These supplies are also running out very quickly. So, a replacement for river sand is being sought after. Natural river sand is non-renewable and takes millions of years to be produced. By using manufactured sand, natural sand is completely replaced. Lack of research has led to the substitution of leftover waste foundry sand for manufactured sand in concrete. By adding used foundry sand to concrete, it is possible to enhance mechanical properties like compressive strength, fracture toughness, and flexibility. Using tests on cubes, cylinders, and unreinforced beams, the mechanical properties of concrete made with waste foundry sand and manufactured sand as fine aggregate were assessed. Tensile, splitting, and flexural strengths of the concrete were all determined after 7, 14, 28, 56, and 90 days of curing. SEM, EDS, and Thermo Gravimetric Analysis (TGA/DCs) were also used to perform micro structural analyses on the control mixture and mixtures containing 10, 20, 30, 40, and 50% waste foundry sand. The strength differences that occur when fine aggregates are replaced with waste foundry sand in different proportions are better understood, thanks to the micro structural experiments. In order to justify its use as a replacement for fine aggregate in terms of strength and microstructure studies, just the right amount of WFS was added to the concrete. Doi: 10.28991/CEJ-2022-08-10-010 Full Text: PDF

Effects of Polypropylene Fibers on the Frost Resistance of Natural Sand Concrete and Machine-Made Sand Concrete.

In order to study the effect of polypropylene fibers on the frost resistance of natural sand and machine-made sand concrete, polypropylene fibers (PPF) of different volumes and lengths were mixed into natural sand and machine-made sand concrete, respectively. The freeze–thaw cycle test was carried out on polypropylene-fiber-impregnated natural sand concrete (PFNSC) and polypropylene-fiber-impregnated manufactured sand concrete (PFMSC), respectively, and the apparent structural changes before and after freezing and thawing were observed. Its strength damage was analyzed. A freeze–thaw damage model and a response surface model (RSM) were established used to analyze the antifreeze performance of PFMSC, and the effects of the fiber content, fiber length, and freeze–thaw times on the antifreeze performance of PFMSC were studied. The results show that with the increase in the number of freeze–thaw cycles, the apparent structures of the PFMSC gradually deteriorated, the strength decreased, and the degree of freeze–thaw damage increased. According to the strength damage model, the optimum volume of PPF for the PFNSC specimens is 1.2%, and the optimum volume of PPF for the PFMSC specimens is 1.0%. According to the prediction of RSM, PFNSC can maintain good antifreeze performance within 105 freeze–thaw cycles, and when the PPF length is 11.8 mm, the antifreeze performance of PFNSC reaches the maximum, its maximum compressive strength value is 33.8 MPa, and the split tensile strength value is 3.1 MPa; PFMSC can maintain a good antifreeze performance within 96 freeze–thaw cycles. When the length of PPF is 9.1 mm, the antifreeze performance of PFMSC reaches the maximum, its maximum compressive strength value is 45.8 MPa, and its split tensile strength value is 3.2 MPa. The predicted values are in good agreement with the measured values, and the model has high reliability.

Development of a low-alkalinity seawater sea sand concrete for enhanced compatibility with BFRP bar in the marine environment

To enhance the durability performance of Basalt Fiber Reinforced Polymer (BFRP) bar reinforced Seawater Sea Sand Concrete (SWSSC) structure components in the marine environment, this paper investigated the feasibility of reducing SWSSC alkalinity to improve its compatibility with BFRP bars. The low-alkalinity ternary mixtures were designed with ordinary Portland cement (OPC), silica fume (SF) and fly ash (FA) through the simplex centroid design method. The evolutions of micro-morphology and hydration phase were characterized by isothermal calorimeter, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and thermogravimetric analysis. The added SF and FA inhibit the formation of AFm phases and Friedel's salt, and consume the Portlandite content in seawater cement paste. Exposure in the marine environment can lead to magnesium and sulfur abundant zonation in the low-alkalinity SWSSC. The durability performances of BFRP bars reinforced SWSSC columns are evaluated through accelerated aging tests in a simulated marine environment at 55 °C. The tensile strength degradation of BFRP bars embedded in low-alkalinity SWSSC is significantly mitigated due to the less alkaline and less moist internal environment. After 180-day accelerated aging, the tensile strength retentions of BFRP bars wrapped by low-alkalinity and normal SWSSC are higher than 70% and less than 24%, respectively. After accelerated aging in seawater, the load-bearing capacity of BFRP bars reinforced low-alkalinity SWSSC column slightly improves and the ductility remains unaffected. Meanwhile, the ductility of BFRP bars reinforced normal SWSSC column is reduced by about 30% after conditioning. The research outcomes can serve as a solid base for the durability design of BFRP-SWSSC structures in the marine environment.

Valorization and recycling of packaging belts and post-consumer PET bottles in the manufacture of sand concrete

The valorization of local by-products in the manufacture of a new range of sand concrete and the improvement of their properties, will lead to seek an arrangement between performance and cost in order to achieve a resistant material. Waste recycling affects two very important affect namely the environmental impact and the economic impact. The main objective of our work is to contribute to optimize the formulation of sand concrete as part of the recovery of waste, which is harmful to the environment given its bulky and unattractive nature, it is waste plastic. Most PET bottles become waste after use, causing environmental problems. To solve this problem, a method for recycling PET bottles as fibers to strengthen concrete is proposed. Two types of plastic waste are added to sand concrete; the first concerns the recycling of post-consumer bottles in PET, in the form of polyester fiber supplied by the company RET-PLAST and the second type concerns the packaging belts made of polyethylene terephthalate (PET). The properties in the fresh state (workability and density) and in the hardened state (compressive strength, tensile strength and water absorption) of the various produced concretes are analyzed and compared against their respective controls. From the experimental results, it can be concluded that the reinforcement of the cement matrix with PET fibers with a rate of 1% improves the mechanical properties of sand concrete as well as a remarkable decrease in its water absorption capacity.

Performance evaluation of sodium silicate waste as a replacement for conventional sand in geopolymer concrete

Excessive exploitation and increased demand for conventional sand made an unbalanced ecosystem; a suitable and sustainable alternative has to be adopted to preserve the ecosystem. The present investigation examines the performance of Sodium Silicate Waste (SSW), an industrial by-product of 100% sand replacement in geopolymer concrete (GPC). The investigation's significance lies in employing industrial waste SSW as an alternative for regular mining sand. The densities of all GPC mixes fall between 2136.7 kg/m3 and 1750.28 kg/m3. Following EN 206-1, the SSW blended GPC can be termed as lightweight concrete, which falls under energy-efficient and sustainable construction practices. The test results show that the percentage increase in industrial waste SSW from 25% to 100% improves the Compressive Strength (CS) to peak at 45.01 MPa. Comparative analysis between River Sand (RS) and SSW mixes shows that SSW blended GPC mixes produced higher strength with the increasing SSW content than GPC mixes with RS. From the Eco-efficient performances, it is concluded that replacing RS with SSW with 25%–100% may lead to sustainable GPC production in terms of cost, carbon, and energy efficiencies.