Sand Concrete Research Articles

Effects of seawater and sea sand on early creep of concrete under different stress levels

Early-age creep of seawater sea sand concrete has a profound effect on construction engineering. This study investigates the ramifications of seawater and sea sand on the early-age creep behavior of concrete subjected to different compressive stresses. To discern the impact of seawater and sea sand on deformation, creep tests were conducted. In parallel, mechanical tests, shrinkage deformation tests, and capillary water absorption tests were conducted to elucidate the influence of seawater and sea sand on macroscopic performance. Moreover, mercury intrusion porosimetry and scanning electron microscopy were deployed to scrutinize the concrete's pore structure and microstructure. The findings reveal that seawater and sea sand precipitate augmented shrinkage and creep deformations in concrete, with seawater exerting a more pronounced effect. Furthermore, seawater and sea sand diminish the porosity of concrete, optimizing its pore structure by curtailing the count of large pores and augmenting the number of gel pores and capillary pores, thereby bolstering its durability. Seawater also reduces the critical stress threshold for the manifestation of nonlinear creep in early-age concrete, while sea sand exerts a minimal influence. These insights hold substantial implications for comprehending the influence of seawater and sea sand on the early-age creep of concrete and offer valuable guidance for their practical deployment in engineering projects.

Sulfate Corrosion Resistance of Reclaimed Coal Gangue Sand Concrete Reinforced with Silica Fume

Sulfate Corrosion Resistance of Reclaimed Coal Gangue Sand Concrete Reinforced with Silica Fume

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.

Upcycling of End-of-Life-Vehicle (ELV) plastics as a replacement for natural fine aggregate in concrete

End-of-life vehicle (ELV) plastics pose technical challenges in conventional recycling due to their diverse polymer compositions. Consequently, landfilling remains the prevailing disposal method. This study explores an innovative approach by upcycling ELV plastics as a substitute for natural sand in concrete. The study investigates the physical, mechanical and economic performance of ELV plastic-containing concrete. Plastic aggregates were prepared from real-world ELV plastics, featuring particle sizes below 4.75 mm, with over 90 % falling within the range of 1.18–4.75 mm. The research involves replacing natural sand with ELV plastics at varying volumes (0 %, 15 %, 25 %, 35 %, and 40 %) and examines the effect of sand replacement on various concrete properties. The results suggest that as the replacement ratio increases, the workability, density, and strength of concrete decrease. However, the 28-day compressive strength of concrete at the maximum replacement rate of 40 % was found to be 39 MPa, which suffices for certain non-structural strength applications, such as traffic routes, shared-use paths, local streets and curbs. In addition, compared to previous studies using mixed commodity plastics, ELV plastics lead to significantly lower strength reductions at high replacement ratios. Scanning Electron Microscopy (SEM) analysis reveals a distinctive rough and fibrous aggregate morphology, which enhances physical binding and provides bridging effects within the concrete matrix, potentially mitigating strength loss. Moreover, the economic analysis highlights a significant potential to commercialize ELV plastics for concrete applications. This study demonstrates that ELV plastics can be effectively used at high replacement rates (up to 40 % by volume) in non-structural applications.

Bond-slip behaviour between recycled sand concrete and steel bars

The bond-slip behaviour between concrete and steel bars is an important factor that affects the structural bearing capacity, deformation performance, and durability. In order to explore the applicability of recycled sand concrete in reinforced and prestressed concrete structures, this study conducted center pull-out tests on C40 and C60 recycled sand concrete with 50% and 100% replacement ratios of recycled sand, reinforced with plain bars and ribbed bars. The influence of strength grade and recycled sand replacement ratio on the bond performance of recycled sand concrete with steel bars were analysed. A bond-slip constitutive model for recycled sand concrete was established, and finite element analysis were conducted to validate it. The results showed that the bond failure mode of recycled sand concrete with plain bars and ribbed bars were both characterized by steel bar pull-out failure. With the increase of the strength of recycled sand concrete, the bond strength was also increased. However, as the replacement ratio of recycled sand concrete increases, the bond strength first increased and then decreased. The main reason is that when the replacement ratio was 50%, the hydration reaction was sufficient to improve the interfacial bond strength. A formula for calculating the critical anchorage length of steel bars suitable for recycled sand concrete is proposed. A two-stage constitutive model for the bond-slip behaviour of recycled sand concrete was established, and its accuracy was verified through finite element finite element analysis. This study provides a reference for the application of recycled sand concrete in structures.

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.

Research on the Fracture Behavior of Ultra-fine Dredged Sand Concrete Based on the Microstructure Characteristics

Abstract The dredged sand generated by the dredging projects has been abandoned and reclaimed from designated areas. It meets the requirements of environmental construction and resource utilization, if the dredging sand can be used as building material in construction. In order to investigate the fracture behavior of dredged sand concrete, five kinds of concrete with different dredged sand replacements (0 %, 12.5 %, 25 %, 37.5 %, 50 %) were designed in this article. Three-point bending fracture tests were carried out on the concrete. The test results show that with the increase of dredged sand replacement, the initiation load, peak load, fracture toughness, and fracture energy first decrease and then increase. Computerized tomography scan and mercury intrusion porosimetry tests show that with the increase of dredged sand replacements, the porosity, pore volume, and pore surface area increase first and then decrease. Dredged sand can improve the pore structure, increase the compactness of concrete, and improve the fracture behavior of concrete. Scanning electron microscopy and X-ray diffraction tests show that dredged sand mainly plays the role of physical filling, and proper dredged sand can improve the compactness of concrete.

Optimizing Physical and Mechanical Properties of Recycled Filler and Fiber Sand Concrete: A Full Factorial Design Approach

Optimizing Physical and Mechanical Properties of Recycled Filler and Fiber Sand Concrete: A Full Factorial Design Approach

Study on sulfate diffusion test and mathematical model of manufactured sand concrete under typical freeze-thaw environment in Northwest China

In the construction industry, it is imperative to replace natural sand with manufactured sand. The environment in northwest China is very complex and harsh. The application of manufactured sand concrete in such a harsh environment needs scientific and comprehensive research to meet the requirements. However, there is a gap in the study of sulfate freeze-thaw resistance of manufactured sand concrete in the complex environment of Northwest China. Therefore, this study investigated the northwest environment, designed an indoor sulfate freeze-thaw cycle experiment system close to the real environment, and designed a conductive titration method to test the sulfate ion content in hardened concrete. The influence of the freeze-thaw cycle on the diffusion depth of sulfate ions in manufactured sand concrete was studied. Finally, the following conclusions are obtained: In the process of conductometric titration, hydrochloric acid is used as the dissolution solution, Ag2O and CO2 are used as neutralizers, and Ba(NO3)2 is used as the titration solution, which can perfectly eliminate the significant influence ions in the test solution, and can accurately test the content of sulfate ions in hardened concrete. The sulfate ion content of concrete at different depths was tested, and it was found that the two sides of sulfate erosion caused by freeze-thaw cycles were mainly reflected in about 100 freeze-thaw cycles. The limit number of freeze-thaw cycles N0 and the limit diffusion depth X0 are proposed, and the diffusion equation of manufactured sand concrete under the action of sulfate freeze-thaw cycles is derived. The proposed diffusion parameter v is unique to the concrete, which can well judge the sulfate freeze-thaw resistance of the concrete. When v is closer to 0, it shows that the resistance of concrete to sulfate freeze-thaw erosion is better. For the northwest environment of China, the manufactured sand concrete should ensure v < 6; the environment in Northwest China has a very complex multi-factor erosion environment. It is worth noting that this study is only applicable to laboratory conditions. To improve the accuracy and reference value of experimental research, future research needs to add more comprehensive environmental impact factors and collect actual data in the northwest environment of China for verification.

Effects of Waste Plastic and Glass Aggregates on the Strength Properties of Ambient-Cured One-Part Metakaolin-Based Geopolymer Concrete

The production of Portland cement (PC) is associated with carbon emissions. One-part geopolymer “just add water” is a user- and environmentally-friendly binder that can potentially substitute PC. However, there is limited research on the setting time, fresh, and strength properties of one-part metakaolin (MK)-based geopolymer concrete (OMGPC) incorporating recycled aggregates. Hence, the study explored the fresh, mechanical (compressive, flexural, splitting tensile, and E-modulus) and microstructural properties of ambient cured (7-, 28-, and 90-day) OMGPC containing recycled waste plastics (RESIN8) and recycled fine waste glass aggregate (FWG) at 5% and 10% by volume of the sand. The study result shows that 2% trisodium phosphate by wt. of the binder retard the initial and final setting times of OMGPC. At the same time, the incorporation of RESIN8 and FWG aggregates improved the workability of geopolymer concrete. The lightweight properties of RESIN8 aggregate reduce the hardened density of OMGPC, while the FWG specimens show a similar density to the control. The compressive strength of RESIN8 and FWG OMGPC range from 19.8 to 24.6 MPa and 26.9 to 30 MPa, respectively, compared to the control (26 to 28.9 MPa) at all curing ages. The flexural and splitting tensile strength of the OMGPC range from 2.2 to 4.5 MPa and 1.7 to 2.8 MPa, respectively. OMGPC is a viable alternative to Portland cement, and FWG can substitute sand in structural concrete by up to 10% and RESIN8 aggregate at 5% by volume of the natural sand.

Review of the Short-Term Properties of Confined Seawater Sea Sand Concrete Columns under Compression

The environmental concerns raised by the over-exploitation of fresh water and river sand have driven researchers to explore seawater sea sand concrete (SWSSC) as a substitute for conventional concrete in structural columns. With numerous investigations on this in the past, there is a need to systematically classify and comprehensively understand the response of confined SWSSC columns to promote their usage as structural columns. Consequently, the objective of this review is to summarise and analyse the experimental work conducted so far on confined SWSSC under different compressive loadings. Confined SWSSC columns are classified into five confinement schemes based on the cross-section of the specimens: single-skin, single-skin multilayered, single-skin with additional reinforcement, double-skin, and double-tube-confined SWSSC columns. Based on the findings of the reviewed studies, it can be concluded that the compressive strength and the ductility of the SWSSC can be enhanced through confinement, with effectiveness majorly depending on the material and geometrical properties of the confinement providing material. The existing research work on SWSSC confinement lays out a strong base for future investigations in this area, which will eventually facilitate the acceptance of SWSSC as structural columns, especially for coastal and marine infrastructure.

Effects of desalinated sea sand on the alkali–silica reaction of seawater and sea sand concrete

The application of seawater and sea sand concrete (SWSSC) can reduce the construction period and cost of island infrastructure, but it may also bring the risk of alkali–silica reaction (ASR) owing to the presence of alkali ions in seawater and sea sand. To compare the characteristics of ASR between SWSSC and seawater and desalinated sea sand (DSS) concrete, the properties and the ASR products of mortar bars with different DSS content were studied. When the DSS proportion increased from 0% to 100%, the sodium (Na+), potassium (K+) and calcium (Ca2+) ion concentration of the specimens decreased by 22.6, 2.0 and 45.1 mg L−1, respectively, the pH decreased by 0.05 and the expansion of mortar bars was reduced by 0.16%. Desalination of sea sand could not eliminate the risk of ASR of SWSSC completely. The 14 days expansion of mortar bars with 100% DSS was 0.13%, and the precursors of ASR-P1 were observed by SEM. The experimental results of micriscopic tests all showed that with the increase of DSS proportion, the content of Na-shlykovite and ASR-P1 were reduced. A small amount of magnesium (Mg) in ASR products was detected. This study can provide a basis for the application of SWSSC in island infrastructure.

Pengaruh Pemanfaatan Kulit Kerang Sebagai Pengganti Sebagian Agregat Halus dengan Menggunakan Pasir Pantai Terhadap Kuat Tekan Beton dan Mutu K-200

The influences of shells utilization as smooth aggregate replacement by using sands beach on the concrete compressive strength and the quality of k-200, the use of smooth aggregate substitutes, such as manually broken clam shells and beach sand obtained from Paciran, Lamongan Regency. The mixture used in making concrete is concrete with quality K-200 (fc'16.60 Mpa). Concrete sand will be replaced by 50% with beach sand, and mixed variations will be carried out with the addition of shells by 10%, 15%, and 20%. The test results show that the average compressive strength of normal concrete is 16.60 Mpa. For a mixture with shell waste by 10% and sea sand by 50%, the average compressive strength value is 15.09 Mpa. In a mixture with shell waste by 15% and sea sand by 50%, the average compressive strength value is 14.62 Mpa. While in a mixture with shellfish waste of 20% and sea sand of 50%, the average compressive strength value is 14.13 Mpa. The concrete variant with the highest average compressive strength value is the normal variant with a value of 16.60 Mpa, while the concrete variant with the lowest average compressive strength value is the variant with shell waste of 20% and sea sand of 50%, with a value of 14.13 Mpa.

Influence of pore structure characteristics on the strength of aeolian sand concrete

Influence of pore structure characteristics on the strength of aeolian sand concrete

Study on the Bonding Performance of BFRP Bars with Seawater Sand Concrete.

A total of 66 sets of pullout specimens were prepared to investigate the bonding properties of basalt fiber-reinforced polymer reinforcement (hereinafter referred to as BFRP) with seawater sand concrete (hereinafter referred to as SSC). The volume dosages of mono-doped glass fibers and mono-doped polypropylene fibers were 0.1%, 0.2%, and 0.3%; the total volume dosage was set to be constant at 0.3%; and the doping ratios of the hybrid fibers were 1:2, 1:1, and 2:1. The effect on the bonding performance of BFRP reinforcement with SSC was studied on the condition of the diameter D of the BFRP reinforcement being 12 mm; the bond length of SSC being 3D, 5D, and 7D; and the surface characteristics of the reinforcement being sandblasted and threaded. The research showed that due to internal cracks in the matrix, salt crystals in the pores, chloride salts with high brittleness and expansion, as well as sulfate corrosion products such as "Frederick salts" in SSC, the concrete became brittle, resulting in more brittle splitting failures during the pullout test. Doped fibers can increase the ductility effect of concrete, but the bonding effect between the threaded fiber reinforcement and the SSC was not as good as that of the sandblasting group. When the bond length was 5D, the bonding effect between the BFRP reinforcement and SSC was the best, and the bonding performance of the experimental group with doped fibers was better than that of the threaded group. Finally, by combining the ascending segment of the Malvar model with the descending segment of the improved BPE model, a constitutive relationship model suitable for the bond-slip curve between BFRP reinforcement and SSC was fitted, which laid a theoretical foundation for future research on SSC.

Recycled Sand and Aggregates for Structural Concrete: Toward the Industrial Production of High-Quality Recycled Materials with Low Water Absorption

Concrete recycling to produce aggregates is crucial in reducing the demand for virgin materials in the construction industry, particularly for the most widely used building material—concrete. A potential solution to enhance the quality of recycled aggregates involves the removal of the adhered cement paste from their surfaces. In this study, samples of industrial demolished concrete were selectively separated into recycled sands and aggregates while removing the hydrated cement paste. The recycled materials were characterized to assess their suitability for structural concrete production. The behavior and underlying mechanisms of recycled sands and aggregates proved to be identical, irrespective of their size. Water absorption emerged as a key parameter for evaluating the purity and quality of these materials. The statistical analysis revealed that when the water absorption of recycled aggregates and sand falls below 5%, the compressive strength may, at most, decrease by 15% (97.5% confidence) at any replacement level. Consequently, they can entirely replace virgin materials without a significant negative impact on fresh or hardened concrete properties at a constant cement content. Concrete samples with recycled materials had comparable workability, strength, and durability characteristics to references with virgin materials. The production of high-quality recycled aggregates and sand can facilitate complete concrete recycling and hence significantly contribute to virgin materials preservation, thus making concrete more sustainable.

Experimental Study on the Substitution of Waste Rubber Tyre Ash with Natural Sand in the Cement Concrete

The importance of using recycled materials like rubber in construction materials is rising rapidly today. By incorporating used rubber into cement and mortar, we can save landfill space and reduce our dependence on natural resources. Rubber scrap can be mixed in as either fine or coarse aggregate. Add it to Portland cement for a stronger, more durable product (PC). This paper reviews the studies conducted so far on the feasibility of using waste rubber in place of conventional PC-based mortar and concrete’s natural fine aggregate. The strength and water-absorption capacity of materials made from ash from scrap rubber tyres were measured. Test results indicate that waste rubber ash was substitute with natural sand up 10% then strengths of the sample were enhanced after increasing the content of waste rubber tyre ash then strength was decreased. Water absorption capacity of samples was improved as increased the content of waste rubber tyre ash into concrete mix.

Improve the Consumption of Cement and Sand in Massive Concrete

Improve the Consumption of Cement and Sand in Massive Concrete

Performance Evaluation of Bottom Ash as Aggregate Replacement in Conventional Roller Compacted Concrete (RCC): An Experimental Study

The escalating demand for construction materials, coupled with the depletion of natural resources such as sand, necessitates environmentally conscious alternatives in concrete production. This study investigates the viability of utilizing bottom ash as an eco-friendly substitute for natural sand in roller compacted concrete (RCC). The focus is on evaluating workability and mechanical properties, examining bottom ash replacements at 0%, 20%, 25%, and 30% for fine aggregate. The research employs a comprehensive methodology, assessing workability and mechanical strength, encompassing compressive, split tensile, and flexural strengths across various concrete formulations. Comparative analyses with conventional concrete provide conclusive insights. Significantly, the study consistently highlights the superiority of RCC specimens featuring a 25% bottom ash replacement, exhibiting the highest strength values. This establishes the 25% replacement ratio as optimal for achieving robust roller-compacted concrete. Despite a slight reduction in workability with increasing bottom ash replacement, it remains within acceptable limits for practical applications. Comparative analyses between bottom ash RCC and conventional RCC underscore the superior mechanical attributes of the former, suggesting its potential as a sustainable alternative in concrete construction. By substituting natural sand with bottom ash, this research addresses environmental concerns related to the depletion of sand reserves. It actively contributes to sustainable practices within the concrete industry, demonstrating the viability of bottom ash as a substitute for natural sand in roller compacted concrete production. In conclusion, the study advocates for environmentally friendly practices and offers a practical solution to mitigate the ecological impact of sand resource depletion in the realm of concrete construction. The findings emphasize that the optimum percentage of bottom ash for compressive strength, split tensile strength, and flexural strength tests is within the range of 0% to 12%.

Improve the consumption of cement and sand in massive concrete

Improve the consumption of cement and sand in massive concrete