M30 Grade Research Articles

Investigation Report on Characteristics Strength Partial Replacement of Fine Aggregate with Copper Slag and Granite Powder

Concrete is one of the most widely used construction materials, consisting of cement, fine aggregates, coarse aggregates, and water. Traditionally, Ordinary Portland Cement (OPC), river sand, and Hard Broken Granite (HBG) stone are used in concrete production. However, the over-extraction of these natural resources has led to environmental concerns and increased costs. This has created a need for sustainable alternatives that maintain concrete’s quality and performance. This study investigates the partial replacement of fine aggregates with copper slag and granite powder in M25 grade concrete. Copper slag, a by-product of copper smelting, and granite powder, obtained during granite stone cutting, possess physical and chemical properties that make them suitable for concrete. Additionally, Pozzolana Portland Cement (PPC) is examined as a sustainable alternative to OPC. PPC, with its pozzolanic characteristics, enhances workability, chemical resistance, and long- term strength while reducing the carbon footprint. The research evaluates the mechanical and chemical properties of concrete incorporating PPC, copper slag, and granite powder. The study also highlights the environmental and economic benefits, demonstrating how these materials can contribute to sustainable construction practices. By promoting the use of industrial by-products and alternative binders, this research aims to develop high-performance, eco-friendly concrete suitable for modern construction needs. Keywords: Concrete, sustainable construction, fine aggregate replacement, copper slag, granite powder, Pozzolana Portland Cement (PPC), M25 grade concrete, industrial by-products, environmental sustainability.

The Performance of Waste Marble Instead of Coarse Aggregate

Now a days we are faced with an important consumption and a growing need for aggregates because of the growth in industrial production, this situation has led to a fast decrease of available resources. On the other hand, a high volume of marble production has generated a considerable amount of waste materials; almost 70%of this mineral gets wasted in the mining processing and polishing stages which have a serious impact on the environment. The processing waste is dumped and threatening the aquifer. Therefore, it has become necessary to reuse these wastes particularly in the manufacture of concrete products for construction purposes. This experimental study presents the variation in the strength of concrete when replacing aggregates by waste marble from 0% to 100% in steps of 25%, 50%, 75% & 100%. M25 grade of concrete were taken for study of slump value is reducing for more % of replacing the stone dust. The compressive strength of concrete cubes at the age of 7, 14 and 28 days were obtained at room temperature. From test result it was found that the maximum compressive strength is obtained only at 50% replacement of coarse aggregate by waste marble at room temperature. This result gives a clear picture that waste marble can be utilized in concrete mixtures as a good substitute for coarse aggregate giving higher strength.

Pervious Concrete Incorporating Manufacturing Sand as a Partial Replacement for Coarse Aggregate

Pervious concrete has recently acquired popularity as a low-impact development strategy in pavements due to its structural, economic, and road-user benefits. The use of a single cement replacement material improved the performance of pervious concrete compared to replacing cement with fly ash or using cement alone. The most effective way for increasing the mechanical, hydraulic, and durability performance of pervious concrete was to replace both cement and aggregates with fly ash and produced sand. Replacement of 25% FA with cement was considered viable for cement replacement, while replacement of coarse aggregate with M-sand by 5%, 10%, or 15% was considered practical for aggregate replacement. The PC specimen had a cube size of 150mm x 150mm x 150mm and was cured in water for 7, 14, 28 days. The compressive strength test is performed in a laboratory after curing. The compressive strength of the pervious concrete is then compared to that of the M15 grade of concrete. The PC specimens had cylinder dimensions of 150mm dia by 300mm height and were cured in water for 28 days. Permeability testing is performed in a laboratory after curing. Key Words: Pervious Concrete (PC), Fly ash (FA), Manufacturing sand (M- Sand), Compressive strength, Permeability.

Effect of Incorporating Natural Zeolitic Tuffs in Concrete Mixed and Cured Using Seawater

Concrete production has increasingly used seawater to overcome the challenge of freshwater scarcity. Although the use of seawater in concrete still has a controversial reputation, it is a promising application, particularly when combined with mineral admixtures such as natural zeolitic tuffs (ZT). This paper aims to investigate the effect of using locally quarried ZT on the strength of unreinforced concrete mixed and/or cured using seawater. The mix proportions of the concrete were selected to obtain the optimum combination for the M20 grade of concrete with a water-to-cement ratio of 0.69. Moreover, 150mm-cubes and cylinders of 100 mm diameter by 200mm height were cast from the concrete mixtures, which contain 0%, 5%, 7.5%, 10%, and 25% of ZT as a partial replacement of silica sand. Splitting tensile tests and compressive strength tests were conducted on these specimens at 7, 28, and 90 days. The results show the harmful effect of seawater on the strength of plain concrete (without ZT) at 7, 28, and 90 days of curing, especially when seawater is used in both mixing and curing of the concrete. However, adding ZT in seawater-based concrete improved its strength apparently, especially at early curing ages. For example, using 10% of ZT as a partial replacement of silica sand increased the compressive strength of seawater based-concrete by 105.4%, 28.3%, and 34.6% after 7, 28, and 90 days of curing, compared with concrete without ZT and produced using seawater. These results contribute to the enhancement of the sustainability of both freshwater and concrete material through the use of ZT in producing concrete, particularly in areas where freshwater is scarce or expensive.

Experimental analysis and gene expression programming optimization of sustainable concrete containing mineral fillers.

Rapid urbanization has led to a high demand for concrete, causing a significant depletion of vital natural resources, notably river sand, which is crucial in the manufacturing process of concrete. As a result, there is a growing need for environmentally sustainable alternatives to fine aggregate in concrete. Quarry dust (QD) has evolved as a viable and ecologically friendly substitute in response to this demand. In the past, limited experimental investigations and only conventional modeling techniques were used to promote sustainable mineral fillers in concrete. This study proposed a robust soft computing technique using gene-expression programming (GEP) to enhance the usability of sustainable alternatives in concrete. Initially, an experimental study was carried out to examine the feasibility and mechanical characteristics of concrete made from materials including quarry dust and superplasticizer as a partial replacement for fine aggregate. Ten mixed proportions with various proportions (0%, 20%, 40%, and 60%) of quarry dust were used to make M15 and M20 grades of concrete. A series of experimental tests, such as workability, compressive strength (CS), and tensile strength (TS), were conducted to examine the fresh and hardened properties of modified concrete. The established database from the experimental investigations was then used to develop machine learning (ML) models using GEP. The outcomes of the GEP models were validated by comparing them with multi-linear regression (MLR) models and using various statistical metrics such as root mean squared error (RMSE), performance index (PI), correlation coefficient (R), and external validation methods. Finally, sensitivity analysis was performed to investigate the influence of ingredients such as mineral fillers, superplasticizers, and others on the mechanical properties of concrete. To enhance the practical usage of the study, a graphical user interface (GUI) was also created. The study revealed that 40% of the replacement of fine aggregates with mineral filler and superplasticizer shows the optimum properties. GEP models outperformed MLR, achieving R² values of 0.96 in CS and 0.92 in TS, compared to MLR's lower values of 0.85 in CS and 0.81 in TS. The proposed GEP equations and user-friendly GUI can be used to develop the pre-mix design of concrete using quarry dust and superplasticizers.

Strength characteristics of steel fiber reinforced concrete with sugarcane bagasse ash and wood ash

Abstract Fibre-reinforced concrete is an ancient technique that involves adding natural or synthetic materials to control deformations and cracking during service. Additionally, the use of agricultural waste materials like sugarcane bagasse ash (SBA), rice husk ash, wood ash (WA), and sawdust, as well as industrial by-products such as ground granulated blast furnace slag, fly ash, and copper slag, has been widely researched as substitutes for traditional binder materials. In line with these studies, an investigation was conducted to explore the surface profile and strength characteristics of steel-fibre reinforced concrete. Percentage Replacement of Steel Fiber (PRSF) by the concrete volume, along with the binder material, was partially replaced with WA and SBA. The concrete samples were cast for M20 grade, and the binder was replaced by 5% of SBA and partial replacement of WA by 5%, 10%, and 15% for cement. From the outcomes, the most desirable percentage recommended was 2% steel-fibre by volume of concrete, 5% replacement of SBA, and 10% replacement of WA by cement, which shows a reasonable amount of increase in the strength of concrete with a maximum of 28 curing days. Also, surface morphological studies of composites were studied using a Scanning Electron Microscope (SEM), by which the bonding property and performance of concrete show a considerable increase in the strength of the composites.

Multi-objective optimization and prediction of strength along with durability in acid-resistant self-compacting alkali-activated concrete

Sustainability in concrete production reduces the environmental impact and conserves resources, yielding durable concrete. This study focuses on developing and analyzing an acid-resistant Self-Compacting alkali-activated concrete (SCAC). Optimization of mix proportions of SCAC containing GGBFS as a binder was performed through experimental methods and multi-objective optimization. The fresh and mechanical characteristics of SCAC were evaluated, examining the impact of sodium hydroxide (NaOH) molarity and sodium silicate to sodium hydroxide (SS/SH) ratio on strength loss under acid exposure. Optimal mix proportions were identified experimentally for both M25 and M45 SCAC grades. A comprehensive database of 120 observations from experimental findings was used to develop a machine learning (ML) model to predict compressive strength and loss of strength due to acid attack. The gradient boost regression with R2 of 0.96 and the long short-term memory (LSTM) model with R2 of 0.93 were established to be best performing in predicting strength and strength loss respectively. These models were then used as objective functions in a multi-objective optimization to maximize strength and minimize acid-induced strength loss. A cost-based comparison of experimentally and analytically optimized mix proportions was provided. The established optimal NaOH molarity and SS/SH ratio for both M25 and M45 grade SCGC were 12 M and 2.3 along with 12 M and 2.5 respectively. This research offers valuable insights for further experimental work on sustainable and resilient SCAC.

CO2-sequestering ability of M20 grade concrete with bio-char and iron ore tailing powder

<p style="line-height:200%;margin-bottom:.0001pt;text-align:justify;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:200%;">The research aims to investigate the CO<sub>2</sub>-sequestering ability of M20 grade concrete with biochar and Iron ore Tailing Powder (ITP). The biochar was prepared by slow pyrolysis of corn stover. The obtained biochar were categorized in two series as untreated biochar and biochar subjected to pre-treatment by heating until it catches fire. The fine aggregate in the concrete was replaced with biochar at 0%, 5%, 10% and 15%. The iron ore tailing powder obtained by crushing and sieving of iron ore waste products. The cement was replaced with ITP at 0%, 25% and 50% by its weight. Water to binder ratio was maintained at 0.45, the workability of the concrete was maintained with the help of super plasticizer. The compressive strength test, CO<sub>2</sub> uptake, porosity and mercury intrusion porosimetry test were conducted to understand the effect of biochar and ITP in concrete. The test result indicate that the mix containing pre-treated biochar with 25% ITP substitution has the maximum CO<sub>2</sub> sequestration capacity without compromising its strength characteristics.</span></p>

Sustainable Utilization of Calcined Granite Powder as Partial Replacement for Cement in Concrete Mixtures: A Mechanical and Environmental Assessment

<p class="heading1" style="line-height:150%;margin-bottom:0cm;margin-right:0cm;margin-top:0cm;tab-stops:36.0pt;text-align:justify;text-justify:inter-ideograph;"><span style="font-size:11.0pt;font-weight:normal;line-height:150%;">The escalating environmental concerns associated with cement production have prompted to explore alternative materials for partial replacement, aiming to reduce the carbon footprint of the construction industry. This research investigates the incorporation of calcined granite powder, a byproduct of granite processing, as a sustainable supplementary cementitious material. The granite powder, which is conventionally disposed of in landfills, was collected directly from the industry and subjected to calcination to enhance its pozzolanic properties.The experimental investigation involved replacing cement with calcined granite powder in varying proportions (0-50%) in concrete mixes of M30 grade. Mechanical properties such as compressive strength, flexural strength, and durability were assessed to evaluate the performance of the formulated mixes. Remarkably, the mix containing 70% cement and 30% calcined granite powder exhibited a substantial increase in </span><span style="color:#00B0F0;font-size:11.0pt;font-weight:normal;line-height:150%;">compressive strength by 7 %,  flexural strength by 11 % and 13 % increase in tensile strength </span><span style="font-size:11.0pt;font-weight:normal;line-height:150%;">compared to the conventional M30 mix. Furthermore, a life cycle assessment (LCA) was conducted using SimaPro software to analyze the environmental impact of the formulated concrete mixes. The results indicated that the concrete mix with 40% calcined granite powder and 60% cement not only demonstrated superior mechanical properties but also proved to be environmentally sustainable, exhibiting reduced global warming potential. This finding underscores the potential of calcined granite powder as a viable and eco-friendly alternative, contributing to the sustainable evolution of concrete production.</span></p>

Performance Evaluation of Drying Shrinkage and Durability in Pavement Quality Concrete with Recycled Aggregate, GGBS and I-Crete

<p style="line-height:200%;text-align:justify;"><span>The study examines replacement of natural aggregates (NA) with Recycled Aggregate (RA) in Pavement Quality Concrete (PQC) M40 grade (M1) with 25%, 50%, 75% and 100% RA replacing NA in M2, M3. , M4 and M5 mixes. The compressive strength decreases with higher RA, but all mixes reach the target strength at 28 and 90 days. M5 was tested by adding Ground Granulated Blast furnace Slag (GGBS) in increments of 5% to 15% in M6, M7 and M8 to reduce the cement content. The main performance parameters include compressive strength, drying shrinkage, water penetration, Rapid Chloride Permeability Test (RCPT) at 28 and 90 days and sorptivity at 28 days. M5 reduced compressive strength but increased drying shrinkage, sorptivity, penetration depth and RCPT charge passage. Increasing the GGBS by 10% in M7 improved the strength, while increasing the GGBS by 15% in M8 decreased the strength compared to M1 and M5.</span> <span>To address strength degradation, the study incorporated 2% I-Crete along with GGBS in 5% increments from 15% to 35% in M9 to M13 mixes. M11 mix (2% I-Crete, 25% GGBS) showed better strength, reduced shrinkage and lower RCPT charge, ensuring better durability for SEM and XRD pavement applications.</span></p>

An Experimental Study on Concrete Strength Optimization with Surkhi as an Eco-Friendly Sand Substitute

Concrete is a widely used construction material, with sand as key component. However, excessive extraction of sand has led to a significant environmental consequences, including erosion, ecological imbalance, habitat destruction, and water quality issues. This study aims to develop an economical and sustainable alternative to traditional sand-based concrete while maintaining its structural integrity. It explores the potential of using Surkhi (a waste product from burnt clay bricks) as a partial replacement of sand in concrete. For this study, 120 concrete cube samples were prepared in the laboratory.Concrete cubes of M20 and M25 grades were prepared using design and nominal mixes, with different proportions of Surkhi (0%, 10%, 20%, 30%, and 40%) and tested to evaluate the workability, cost-effectiveness, and compressive strength. Compressive strength tests were conducted on concrete cubes at 7 and 28 days to investigate their mechanical properties. The results shows that a 10% replacement of sand with Surkhi optimizes the strength and workability of concrete without compromising its performance, thus supporting sustainable construction practices. However, the negative impact in concrete strength due to addition of higher proportions of Surkhi should be carefully considered. Furthermore, a cost analysis indicates that replacing sand with Surkhi can help to reduce the production costs, while promoting its use as an eco-friendly alternative. The findings provides valuable insights into the potential of Surkhi to reduce environmental damage and costs without compromising performance at moderate replacement levels. However, further research is recommended to assess the long-term durability and structural integrity of Surkhi-based concrete in various applications.

Experimental Study On Self-Compacting Concrete Mix Design By Using Yucca Zeolite

This report aims to present the experimental investigation on mix proportioning of normal concrete and self-compacting concrete with yucca zeolite. The study area comprises of ordinary portland cement of grade 53,mix proportioning of normal concrete for grade of concrete M40, M30 and M20 whereas mix proportioning for self-compacting concrete for grade of concrete M40, M30 ,M20.The parameters considered are cement content, Water cement ratio i.e. for normal concrete 0.4, 0.42, 0.45 and for self-compacting concrete 0.62, 0.44, 0.43 respectively. To reduce the risk of shrinkage, frost attack and corrosion of concrete, yucca zeolite as a mineral admixture and to increase the bond strength techno plast S 300 as a super plasticizer is added. The responses of material testing, normal concrete tests that includes slump flow test and compressive strength test recorded. Also, tests on self-compacting concrete recorded from slump flow test, J ring test, V funnel test, L box test, U box test, Rheological parameters, Compressive strength at 7 and 28 days. The various properties of SCC are ascertained with the IS code 1199:2018 [part 6] IS code 456:2000, IS code 10262:2019.

Impact of plastic waste fiber and treated construction demolition waste on the durability and sustainability of concrete

This study explores the mechanical and durability properties of Plastic-Fibre Reinforced Concrete, incorporating hand-shredded plastic fibers sourced from polyethylene bags and PET bottles. Evaluations, including compressive and split tensile strength tests, were conducted on M40 grade mixes containing plastic fibers and 100% treated Construction and Demolition Waste (CDW), comparing them with conventional concrete. The results demonstrate a significant enhancement in strength properties with the addition of 0.25%, 0.5%, 0.75%, and 1% plastic-fibres, alongside the complete replacement of coarse aggregate with CDW, particularly noticeable at both 7 and 28-day curing ages. Although higher fiber dosages led to a slight reduction in compressive by 7% at the optimum percentage of 0.25% of PE and 0.5% of PET, the flexural strengths and split tensile strength exhibited a proportional increase of 11.7% and 18%. Surface analysis via Scanning Electron Microscopy (SEM) and elemental composition determination using Energy Dispersive Spectroscopy (EDS) revealed minimal fiber damage post-exposure, confirming its efficiency and contribution to higher strength and reduced weight loss in optimum mix. This novel approach combines manually recycled plastic waste as fibers with treated CDW, enhancing concrete properties while promoting sustainability. Sustainability analysis indicates that utilizing 100% CDW and plastic fiber contributes to reduced energy consumption, lower carbon emissions, and economic benefits. These findings underscore the potential of integrating non-degradable plastics into concrete mixtures, combined with treated CDW, offering both environmental sustainability and enhanced performance advantages in construction materials.

Mechanical Properties of Concrete Blended with Rice Husk Ash, Oyster Shell Powder, and Ferrous Powder

Due to emerging global environmental awareness, the increasing demand on synthesizing green materials for structural purposes became prevalent. This study utilized agricultural, aquacultural, and industrial waste as partial replacement for fine aggregates in concrete. One standard and six concrete samples with various proportions (20% and 40%) of rice husk ash (RHA), oyster shell powder (OSP), and ferrous powder (FeP) were constructed and tested for their mechanical properties (i.e., compressive and split tensile strength). The samples containing 20% and 40% FeP attained the highest compressive (22.71 MPa) and split tensile strength (1.379 MPa), respectively, which are closest to the control, M25 grade concrete (C-M25), (23.87 MPa), and (1.44 MPa), respectively. Concrete fracture analysis indicated that the cylinders were well constructed as implied by the fracture types. The C-FeP is the best concrete mixture attaining superior compressive and split tensile strength values.

Investigating alkali-activated concrete with recycled aggregate substitution in experimental research

Abstract In the present experimental investigation, a constant (optimum) percentage of GGBFS and fly ash in Alkali activated concrete (AAC) of M40 grade equivalent concrete. The natural aggregates are incorporated at percentages of 0.5 and 1.0 in the AAC composition. The studies indicate that Fly ash AAC demonstrates lower strength due to the necessity of heat curing for proper development, while the inclusion of Recycled Concrete Aggregate (RCA) leads to decreased compressive, split tensile, and flexural strengths, indicating a detrimental effect on mechanical properties. Despite slightly improved performance with 100% RCA content, it remains inferior to natural aggregates, attributed to adhered cement mortar potentially enhancing strength properties, which shows the need for further research to optimize mix designs and fully exploit the benefits of these alternative materials in AAC production.

Properties and eco-cost effectiveness of concrete containing waste blast furnace slag and demolition waste

Abstract This work aims to develop eco-friendly, cost-effective concrete using ground granulated blast furnace slag (GGBFS) and recycled coarse aggregate (RCA). Seven concrete mixes are prepared with different combinations of RCA and GGBFS. Properties like 28-day compressive strength, rapid chloride permeability and abrasion resistance have been studied. Physical and microstructural investigations have been carried out to justify the variation in the properties. Moreover, environmental impact and cost-effective analyses are performed. It is found that the strength of concrete mix with 50% RCA and 45% GGBFS closely satisfies the desired strength for M25 grade concrete. Also, the mix has shown good resistance against abrasion and chloride permeability. Physical examination reveals that ITZ has played a significant role in the strength variation. Similarly, microstructural investigation reveals that the formation of voids due to RCA and the filling of the voids by GGBFS are the two phenomena responsible for variation in durability. Further, the negative environmental impacts and cost of concrete can be reduced up to 62.93% and 11.9%, respectively, compared to the control concrete using RCA and GGBFS. Since this mix provides desired strength and durability, environmental benefit and cost benefit over normal concrete, this concrete becomes eco-cost efficient.

Assessing the Usage of Barytes Powder and Cuddapah Stone Dust as Supplementary Cementitious Materials in Concrete of Grade M30 and M35

This research studied the effects of using Barytes powder and Cuddapah stone waste as substitutes for cement in M30 and M35 grade concrete using OPC. Cement production is known to harm the environment and consume a lot of energy, making the search for alternative materials to replace cement in concrete important.In this study, different amounts of Barytes powder and Cuddapah stone waste were added to concrete mixes as partial replacements for cement. The resulting concrete was tested for compressive strength and compared to normal concrete. The experiment involved making concrete samples with varying percentages of cement replacement, ranging from 0% to 50%, using Barytes powder, Cuddapah stone waste and Combination. The samples underwent standard curing and testing according to Indian standards.The research analysed the results to find the optimum percentage of cement replacement that provided satisfactory mechanical properties. This study determined the feasibility and effectiveness of using Barytes powder and Cuddapah stone waste as partial replacements for cement in concrete production.

Investigating the influence of various metakaolin combinations with different proportions of pond ash and Alccofine 1203 on ternary blended geopolymer concrete at ambient curing.

This paper explores the use of a ternary blended geopolymer concrete (TBGPC) incorporating metakaolin (MK), pond ash (PA), and Alccofine 1203 (AF). Three combinations of MK (25%, 50%, and 75%) with varying proportions of PA and AF were prepared, validating against M30 grade cement concrete (CC). TBGPC was prepared with an 8 molarity sodium hydroxide, sodium silicate to sodium hydroxide ratio of 2.0, liquid to binder ratio of 0.5, and an ambient curing mode. For CC, a water to cement ratio of 0.42 and water curing mode were adopted. The mechanical properties and durability behavior of TBGPC and CC specimens were evaluated through compressive strength, rapid chloride penetration test, permeability test, sorptivity test, and water absorption test. The M50P35A15 mix demonstrated remarkable compressive strength improvements, showing a 203% increase over the CC mix at 1day and 250% by 3days. This trend continued with a 155% increase at 7days, 68% at 28days, and 52% at 90days, consistently outperforming the CC mix. Additionally, microstructure characteristics of the M50P35A15 mix were analyzed through SEM studies, providing validation for the observed strength development. Notably, M50P35A15 mix demonstrated substantially higher early and later strength gain. This enhancement in strength was attributed to the gradual densification of the microstructure over time and the formation of additional NASH and CASH gel in M50P35A15 mix. At 28days, the M50P35A15 mix exhibited excellent durability characteristics, with a Coulomb value of 1008, permeability of 10mm, sorptivity of 0.45mm/√min × 10-4, and water absorption of 1.07%. This study demonstrates the potential of MK, PA, and AF as viable materials for sustainable geopolymer concrete, offering a low-carbon alternative to traditional cement concrete with superior strength and durability aspects.

Investigation on Key Influencing Factors Affecting Temperature Distribution in Concrete

Concrete is an unavoidable composite material used in buildings and structures. The behavior of concrete under the effect of fire is always critical, causing more structural damage. This research proposes experimental investigation on various factors that affect temperature distribution in concrete when exposed to fire. Water cement ratio, grade of concrete, curing period, type of admixtures, and fibers are the factors taken into consideration. The test was carried out in the temperature range of 100 °C to 600 °C. The temperature was measured at various depths of the specimen and then compared. Results from experiments show that grade of concrete, water-cement ratio, curing period and admixture type significantly influences the temperature distribution in concrete whereas contribution of fiber type is negligible. Comparison of temperature distribution at 25 mm from the bottom of specimen at 600 °C for M20 grade with 0.5 and 0.4 water cement ratio was done. It is found that temperature distribution in concrete goes higher as water cement ratio goes higher. There is an increase of 22.6% of temperature distribution for 0.5 water cement ratio than 0.4. Concrete samples which were cured for 14 days, and 28 days were tested, temperature distribution in concrete cured for 14 days is higher than that cured for 28 days. It is because of the curing time of calcium silicate hydrate (CSH) gel, and it was not fully matured and there was no moisture to finish the hydration process of cement.

Development of a novel DNA-shaped steel fiber and its performance on fresh and hardened concrete

Adding small discrete random fibers in concrete has enhanced concrete behavior in various ways. Diverse types of fibers are available in terms of materials, shapes, and applications. Different shapes of steel fibers are available like hooked ends, crimped, stranded, helix, spherical, etc. Having the grade of concrete and the fiber dosage added as constant, the structural behavior and performance will vary for different types of fibers. It shows that the shape of fiber has a great role in enhancing the properties of concrete. The challenges in existing two-dimensional steel fibers in concrete like the mechanism and contribution of fiber in arresting cracks developed in all directions and balling effect can be overcome by a new type of three-dimensional steel fiber. A novel three-dimensional DNA-shaped steel fiber is designed and fabricated. This paper presents the fresh concrete and hardened concrete properties of DNA-shaped fiber-reinforced concrete (DNAFRC) and compares it with hooked-end fiber-reinforced concrete (HEFRC) by incorporating a volume fraction varying from 0.5 % to 2 % of grade M30 concrete and aspect ratio of 60 for both fibers. The fresh properties of concrete were evaluated by measuring the slump for workability and wash-out test for the fiber distribution. The hardened concrete properties were assessed by compressive, split tensile, flexural, impact, shear, and pull-out strength which demonstrated considerable increase by 5 % at 1.5 % volume fraction, 32 %, 136 %, 21 %, and 35 % at 2 % volume fraction respectively for DNAFRC than the HEFRC. Scanning Electronic Microscope (SEM) images were studied on failed samples to evaluate the bonding of DNA fiber with concrete.