Properties Of Concrete Research Articles

Influence of elevated temperature exposure on the residual compressive strength and radiation shielding efficiency of ordinary concrete incorporating granodiorite and ceramic powders

This research investigates the potential of utilizing types of construction waste as partial cement replacements within concrete formulations. Notably, granodiorite and ceramic powders were introduced at varying substitution ratios. The impact of these waste materials on the compressive strength and radiation shielding effectiveness of traditional concrete was evaluated under both ambient and elevated temperature conditions. Additionally, several microstructural tests like X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and Energy dispersive X-ray (EDX) were conducted to assess the influence of using the optimal replacement ratios of the investigated waste powders on the studied properties of concrete. Results revealed a substantial improvement in the investigated properties of the concrete. Remarkably, a 7% substitution with waste granodiorite powder (WGDP) yielded the optimal mix for compressive strength, exhibiting increases of 24.7%, 26.1%, 22%, and 28% at room temperature, 400 °C, 600 °C, and 800 °C, respectively. Likewise, a 7% replacement with waste ceramic powder (WCP) exhibited quantifiable improvements in compressive strength, with approximately 23.1%, 23.5%, 25.6%, and 32.6% at room temperature, 400 °C, 600 °C, and 800 °C, respectively. For microstructure analysis, XRD analysis confirmed enhanced pozzolanic activity with reduced portlandite and increased calcium silicate hydrate (CSH) formation for the optimal WGDP and WCP mixes compared to the control mix. TGA analysis revealed higher CSH decomposition in modified mixes, indicating greater pozzolanic reaction. Furthermore, density and EDX analyses showed denser microstructures in waste powders-incorporated mixes due to finer particle packing and secondary hydration effect. The radiation shielding investigation show that the optimum WCP mix (C7) enhances the attenuation capability of concrete. The optimum WGP mix (GD7) also contributes positively to attenuation, though to a lesser extent than C7. Ordinary concrete (CO) exhibits the lowest LAC, indicating its baseline performance in linear attenuation. Thus, the studied CM-concrete samples provide the best protection against fast neutrons which pave the way for the utilization of industrial waste, especially ceramic and granodiorite waste, in enhancing the properties of concrete towards radiation shielding against gamma rays and neutrons.

The Impact of Differently Prepared Mixed Plastic Waste Granules on the Structure and Properties of Concrete

The relatively low production cost and short lifespan of plastic products contribute significantly to the annual accumulation of plastic waste, raising serious environmental concerns. Conventional disposal methods like landfill and incineration not only waste valuable resources but also result in substantial secondary pollution. In response to the imperatives of sustainable development and environmental protection, in this work, different preparation methods (mechanical processing; heating and covering with milled sand and glass; covering plastic granules with polymers and then mineral materials such as microsilica and waste metakaolin; using other chemical additives) for plastic granules from waste and their influence on the properties of cementitious materials were studied. Lightweight concrete properties such as density, ultrasound pulse velocity, flexural and compressive strength, water absorption, and the interaction zone between the cement matrix and plastic granules were analyzed. It was determined that one-third by volume of natural aggregate can be replaced with specially prepared plastic granules from waste, obtaining a bending strength of the lightweight concrete of about 5 MPa, a compressive strength at 28 days of approximately 30 to 35 MPa, a density of about 1850 kg/m3, and an ultrasound pulse velocity of 3900 m/s.

Prediction of mechanical properties of eco-friendly concrete using machine learning algorithms and partial dependence plot analysis

Rice husk ash concrete (RHAC) shows promise as a beneficial supplementary material in concrete. However, determining mechanical properties such as compressive strength (CS) and splitting tensile strength (STS) of RHAC through conventional lab-scale methods is laborious and time-consuming. In this research, seven important variables were selected as inputs to predict CS and STS using machine learning (ML) models, including Gaussian Process Regression (GPR), Random Forest Regression (RFR), and Decision Tree Regression (DTR) with grid search optimization. The result presented revealed that selected machine learning models provide well accuracy for CS and STS estimates. Among these, the DTR model demonstrated superior performance, with CS prediction R2, RMSE, MAE, and MAPE values of 0.964, 3.314, 2.225, and 5.068, at the testing stage respectively. For STS at the testing stage, DTR achieved R2 of 0.969, RMSE of 0.177, MAE of 0.1322, and MAPE of 3.413. GPR and RFR models also performed well, with R2 values of 0.9434 and 0.9530 for CS prediction. The partial dependence plot (PDP) analysis revealed the optimal mix design parameters for achieving the desired strength. These results offer valuable insights for sustainable construction, allowing engineers to efficiently predict and optimize material performance, reducing the reliance on time-consuming lab methods.

Seawater-mixed concretes containing supplementary cementitious materials: compressive strength, e-modulus, electrical resistivity, and life cycle assessment

Water and concrete are the materials humans consume the most on earth. By 2040, several countries are expected to face extreme water stress and the need for significant growth in their infrastructure simultaneously. Water is a fundamental ingredient for concrete production, and the need for infrastructure growth can further increase the water demand for concrete production and thus affect these regions facing water scarcity. Including supplementary cementitious materials (SCMs), non-metallic fibres, and coated/polymer reinforcements can increase the feasibility of producing concrete with seawater (SW). There is a lack of information on the long-term strength and durability properties of SW-mixed concretes (SWC) produced with SCMs. This paper optimises binder compositions with CEM I, fly ash, ground granulated blast furnace slag (slag), and metakaolin suitable for adapting SWC based on performance indicators. Binary and ternary blended concretes of similar binder content (360 kg/m3) and w/b (0.45) were designed and cast with the SCMs mentioned above. Compressive strength, surface resistivity, and accelerated carbonation tests were conducted on the concrete produced with freshwater (FW) and seawater (SW). SWC produced with 30% slag and 15% metakaolin had higher electrical resistivity and an improvement in compressive strength (up to 30%) than other combinations used for producing SWC. Life cycle assessment identified that the concretes produced with fly ash, and ternary combination of fly ash and metakaolin had the least water depletion potential (WDP) compared to other SW-mixed concretes. Also, the replacement of FW by SW reduces the WDP up to 50%.

Research on Recycling and Utilization of Shredded Waste Mask Fibers to Prepare Sustainable Engineered Cementitious Composites

The widespread disposal of single-use masks has led to significant environmental concerns. This study investigated the effects of incorporating shredded waste mask fibers (SWMFs) on the compressive and flexural properties of concrete. The experimental design included four fiber volume fractions, i.e., 0%, 1%, 2%, and 3%, with three different sizes of mask fibers. The influences of these fibers on the load-bearing capacity, deformation behavior, and energy absorption of concrete under compression and flexure was examined. Scanning electron microscopy (SEM) was used to analyze the microstructure. The results show that the addition of 1% SWMFs enhances the mechanical performance, with the compressive and flexural strengths of 20.69 MPa and 6.95 MPa, respectively, for B-sized fibers. Furthermore, the incorporation of discarded mask fibers improved the toughness of the material. In the design with general strength requirements, a B-dimensional SWMFs of 1% volume can be incorporated, which can improve the bending toughness by 75% for the control group.

Effective Mechanical Properties of a Composite Material Reinforced by Oil Shale Ash Particles

This study determined the elastic properties of composites and concretes reinforced with oil shale ash (OSA) particles, a byproduct of oil shale combustion in an electric power plant in Estonia (Auvere). Since 2018, OSA has no longer been classified as hazardous waste in the EU, enabling its reuse in sustainable materials. The present research examined the effect of OSA on the elastic properties of epoxy–OSA and concrete–OSA composites. The experimental results show that the elastic modulus of epoxy resin increases with an increase in the ash concentration, while it decreases in concrete with a higher OSA content. Theoretical models, including the rule of mixtures, finite element method (FEM), Mori–Tanaka method, and Halpin–Tsai method, were used to predict these properties numerically. The rule of mixtures and FEM generally overestimated the modulus for epoxy–OSA, whereas the Mori–Tanaka and Halpin–Tsai methods provided closer predictions. For concrete–OSA, the compressive strength tests followed the LVS EN 12390-3:2019 standards, with elastic modulus conversions being made via IS 456:2000 Clause 6.2.3.1, which showed a variable decrease across different strength classes. The findings highlight the potential of OSA as a reinforcing filler in construction materials, promoting environmental sustainability by repurposing industrial waste while offering mechanical benefits.

Effect of Using Plant Fiber on The Properties of Concrete

With light weight, wide sources, low cost and renewable, plant fiber concrete has become the preferred green building materials. This paper reviews the research status of bamboo fiber, flax, hemp, jute, ramie and other high-strength plant fibers, and discusses their basic properties and defects, such as strength, interface bonding, thermal insulation, as well as fiber corrosion, adhesion, water absorption and workability. In view of these, the strategies of pretreatment, use of mineral admixtures, optimization of bonding materials and improvement of mixing process are put forward. The results show that reasonable improvement measures can significantly improve the performance of plant fiber concrete. This paper provides theoretical and technical support for the application of plant fiber concrete, and looks forward to its wide application prospect in the field of civil engineering.

Using Optimization Techniques on Mechanical Characteristics and Sustainability Assessment of Rubberized Concrete Blended with PVA Fiber Through Response Surface Methodology

The construction sector is promoting eco-friendly materials to combat global warming. Researchers use crumb rubber (CR) in concrete due to its ductility and hardness, but studies show it can decrease strength. Therefore, the addition of PVA fiber improves the mechanical properties of CR concrete. The research aims to assess the mechanical and physical characteristics of concrete by utilizing RSM modeling and optimization, comparing the effects of CR replacement for sand and PVA fiber by volume fraction. It has been observed that the optimum compressive, tensile and flexural strengths were observed by 49 MPa, 4.31 MPa, and 5.88 MPa at 10% of sand replaced with CR and 1.5% of PVA fiber together at 28 days, respectively. In addition, water absorption improves with increased CR and PVA fiber in concrete, while dry density decreases with increased CR and PVA fiber quantity in concrete at 28 days, respectively. Moreover, RSM was utilized to develop response prediction models with R2 coefficients ranged from 97 to 99%. Furthermore, the enhancement of embodied carbon is seen when the volume percent of PVA fiber and CR increases in concrete. Additionally, using 10% CR instead of sand and adding 1.5% PVA fiber has been proven to deliver favourable outcomes for the construction sector therefore it is recommended for construction purpose.

A machine learning approach to predicting pervious concrete properties: a review

A machine learning approach to predicting pervious concrete properties: a review

Will More Cement in Your Mixture Hurt You?

An old rule of thumb states that if you need more strength in a concrete mixture, just throw more cement at it. Sometimes that helped, sometimes not. Today many engineers realize that there are many other variables in a mixture that effect strength as much as, or more than, cement content. They also realize that increased cement content in a concrete mixture can lead to a number of effects that may reduce the life of the pavement. Many properties of concrete are adversely affected by over-cementing the mixture. These are discussed to help the reader understand why optimizing the cement content will help produce an efficient mixture that will meet the project requirements. By first determining the voids in the aggregate portion of the concrete mixture and then increasing that volume by an amount necessary for workability, a volume of paste can be determined that will approximate the optimum cementitious content to both maximize strength and also provide a workable mixture. Also discussed are the effects of increasing the cement content in a concrete mixture, including durability, strength, heat generation, shrinkage, set time, workability, CO2 footprint, as well as cost.

Age-Dependent Flexural Properties of Fiber Reinforced Concrete Used in Thin Overlays

This paper presents measured age-dependent flexural properties of fiber-reinforced concrete (FRC) as are used in the design of thin overlay pavements. A laboratory investigation was performed to quantify the pavement design properties, particularly residual strength ratio of FRC as a function of age. Four different types of structural macro-fibers, made of steel or polypropylene, and of different lengths or aspect ratios were investigated. Also different fiber volume contents from 0%, 0.5%, and 1.0% were studied for all fiber types and ages. The results confirmed that there is a significant agedependency to the residual strength ratio. The short steel FRC at high fiber volume content was the only mixture which showed constant residual strength ratio as a function of time. All other FRC mixtures exhibited a reduced residual strength ratio when tested at later ages.

Evaluation of Cement Content and W/C Influence on Mechanical Behavior of Concrete Pavements

Concrete pavements with zero slump under pressure and high rate vibration has highly attracted the interests of engineers. In this study, fifteen different experimental mix designs with different cement content have been studied to improve the concrete pavement properties. Influence of effective factors on these kinds of concretes has also been considered. Then the relations between cement content and abrasion resistance, flexural and compressive strength, and water absorption have presented. The cement content was found as the most important factor in increasing and decreasing the abrasion and water absorption. Increasing the cement content up to 300 (Kg/m3) not only increased the abrasion resistance but also increases the amounts of cement content do not have always a good effect on a concrete quality and strength.

Experimental Investigation of Young Concrete Properties Needed for Proper Analysis of Concrete Pavements Behavior During the Hardening Process

In this paper there are presented results of experimental investigation of young concrete properties. During design process of concrete structures there is used number of mechanical properties of concrete that are not normally part of the concrete specifications. Desirable values are often related to primary parameter of concrete – mean concrete compressive strength. Some of them are poorly or even not at all described at the very beginning of concrete maturing. This paper describes results obtained from common mechanical test of compressive and tensile strength, shrinkage strain and two author’s test dealing with creep under constant compressive and tensile stresses of young concrete and also temperature development in quasi-adiabatic conditions.

Fresh and Hardened Properties of Concrete with Fractionated Reclaimed Asphalt Pavement

A study was completed to investigate the changes in fresh and hardened properties when using coarse, fractionated reclaimed asphalt pavement (FRAP) as a partial replacement of virgin coarse aggregate in a ternary blended concrete. The FRAP replacement levels were 0, 20, 35, and 50%. The ternary blended concrete consisted of 65% Type I Portland cement, 25% Grade 100 ground granulated blast furnace slag, and 10% Class C fly ash. Two coarse FRAP sources were investigated: one washed (16 mm maximum size) and one dirty (12.5 mm maximum size). The dirty FRAP source was additionally processed in the laboratory by washing and sieving over a 4.75 mm sieve to reduce the amount of fines and agglomerated sand/asphalt particles. The fresh concrete properties showed that adding FRAP had little to no effect on the air content, increased the slump, and reduced the unit weight. The fresh and hardened concrete characteristics (compressive, split tensile, and flexural strength) demonstrated that replacement levels up to 35% FRAP could be utilized without compromising existing concrete material specifications for paving. Surprisingly, washing the coarse dirty FRAP did not provide any strength benefit over the dirty, unprocessed FRAP for the sources evaluated.

Transverse Joint Distress and Mid-slab Cracking Distress in PCC Pavements: A Petrographer’s Perspective

A forensic investigation was conducted on twenty jointed plain concrete and reinforced concrete pavements in the Ohio Department of Transportation system that have shown above average performance to date (Lankard, 2010). Included are three Interstate pavements, six US routes, and eleven State routes. The oldest pavement in the study was constructed in 1946 and the youngest in 1997. Petrographic examinations and concrete property measurements were made on cores that were taken (in 2009) through transverse control joints and through mid-slab cracks where they were present. The 10 cm (4 in) diameter, full-depth cores were taken at sites where no deterioration was manifest on the wearing surface at the time of coring. However, eighty percent of the joint cores showed some level of sub-surface cracking distress; as did seventy percent of the cores taken through a mid-slab crack. The origin, evolution, and consequences of this distress are discussed.

Causes and Effects of Longitudinal Shrinkage and Temperature Stresses on JPCP for Dutch Conditions

In 2010 Houben has published a paper on the modelling of the process of cracking at transverse joints in jointed plain concrete pavements (JPCP). Houben uses equations from the standard Eurocode 2 for the time-dependent concrete properties and considers the thermal deformation and the shrinkage (drying and autogenous) for different design and construction conditions. For properties that are not available in standards, Houben made assumptions based on engineering judgment. In this present paper the point of departure is the Houben model, and now the assumptions made in his work are studied more in depth. The paper also includes an improvement of the development of the concrete elastic modulus and strength. Accordingly, the objective of this paper is to improve the theoretical background of the assumptions and the determination of the effects of longitudinal shrinkage and temperature stresses on JPCP for Dutch conditions. Concerning one of the most important influencing factors, the relaxation, a new equation is proposed. From both the theoretical and the practical point of view these improvements describe in a better way the causes and effects of longitudinal shrinkage and temperature stresses on JPCP for Dutch conditions.

The Influence of Rice Husk Ash Incorporation on the Properties of Cement-Based Materials.

Rice husk ash is a kind of biomass material. Its main component is silicon dioxide, with a content of up to 80%. It has high pozzolanic activity and can react with hydroxide in cement. When treating rice husks, rice husk ash with high volcanic ash activity and a good microaggregate filling effect can be obtained by selecting a suitable incineration environment. These advantages make rice husk ash an ideal concrete admixture, replacing the traditional admixture such as fly ash and slag in concrete. This paper summarizes the preparation methods and physical and chemical properties of rice husk ash, as well as the physical and chemical properties of rice husk ash concrete, such as mechanical properties, temperature resistance, freezing resistance, permeability resistance and chemical erosion resistance. The results show that using 20% rice husk ash as a substitute material for cement improves the resistance strength, compressive strength, flexural strength, and permeability of concrete. In short, the incorporation of rice husk ash can effectively improve the performance of cement-based materials, which will be conducive to the green development of the building material industry and the implementation of the two-carbon strategy.

Experimental Investigation of Durability Properties of Polymer Coated Pumice Aggregate Lightweight Concretes.

Pumice aggregates with low density and high porosity are widely used in lightweight concrete. The high water retention ability of pumice aggregates adversely affects the properties of fresh concrete. Additionally, pumice aggregates' inadequate mechanical strength and durability hinder concrete performance. In recent years, research on coated aggregates has gained traction to improve the physical properties, mechanical strength, and durability characteristics of concrete. In this study, coarse pumice aggregates were coated with polyester and partially substituted with uncoated aggregates at ratios of 0%, 25%, 50%, 75%, and 100% in lightweight concrete formulations. Specific weight and water absorption tests were performed on the aggregates, while slump and unit weight tests were performed on fresh concrete mixtures. SEM-EDX analyses, unit weight, water absorbing capacity, sorptivity, compressive strength, freeze-thaw resistance, and sulfate resistance tests were performed on concrete specimens. The results indicated that the polyester coating significantly increased the specific weight of the aggregates and decreased the water absorption rates by up to 85%. Despite the coated aggregates resulting in decreased compressive strength of concrete specimens, they demonstrated reduced water absorbing capacity and sorptivity characteristics relative to reference concrete. Moreover, concrete made with coated aggregates exhibited better results in freeze-thaw and sulphate resistance tests.

Advancements in the Use of Bayer Red Mud as a Sustainable Cementitious Material in Concrete: Challenges and Opportunities

Bayer red mud is an industrial waste residue formed in the alumina process produced by the Bayer process in the alumina plant. At present, the main disposal method of red mud is to send it to red mud dam for storage. Due to its high alkali content, it causes serious pollution to the surrounding environment and becomes an ecological problem to be solved urgently. In this paper, the application progress of Bayer red mud in concrete is summarized. This paper focuses on the possibility of red mud as a cementitious material and deeply discusses the influence of red mud on the working performance and mechanical properties of concrete. Finally, the shortcomings in the current research of red mud concrete are pointed out, to provide a reference for the research direction of Bayer red mud in concrete.

Optimizing thermoelectric energy harvesting from concrete surfaces: a comparative study of graphite powder and steel fiber reinforcement

ABSTRACT Adopting alternative energy sources becomes imperative, despite the existing technical and practical obstacles in its implementation. This study aimed to explore the energy harvesting potential of the thermoelectric effect on concrete surfaces. By examining the impact of incorporating graphite powder into concrete (at 0.5–2.5% of cement weight) and steel fiber (at 1–2% of concrete volume), we investigated and compared the thermal, electrical, and mechanical properties of concrete. The findings revealed that adding graphite powder at a 2.5% weight-to-cement ratio led to a maximum upper surface temperature of 50.4°C and subsequently generated a maximum voltage of 0.27 volts. However, the side surface temperature, located in the same position, yielded lower results than the upper surface. It is crucial to incorporate a device for converting thermoelectric energy into voltage, necessitating a shallow placement of the thermoelectric device near the high-temperature, well-tempered concrete pavement surface to ensure efficient energy harvesting.