Constant Water-cement Ratio Research Articles

Characteristics of Fibre-Reinforced Cement-Sand Blocks with Quarry Dust as Replacement for Sand

The present investigation delved into the mechanical performance of fibre-reinforced cement-sand blocks with quarry dust as a replacement for sand. The introduction of fibres and quarry dust in the matrix is an attempt to achieve higher performance with available cement content and reduce the utilization of natural sand to improve the sustainability of the product. The experimental programme attempted to study the influence of quarry dust on the density, compressive strength, water absorption, sorptivity, and efflorescence characteristics of the blocks. The parameters considered include quarry dust (QD) content (replacement of sand from 0% to 100% in increments of 20%), a constant fibre content of 0.5%, and a constant water-cement ratio of 0.5. An attempt was also made to compare the strength performance of the blocks with various code requirements as well as results from similar previous investigations. The replacement of sand with QD resulted in a reduction in the density of the blocks from 2365 kg/m3 to 2008 kg/m3. The results of the investigation revealed that 60% quarry dust replacement of natural sand developed the maximum strength of the blocks. After 28 days of curing, blocks with up to 60% QD replacement were able to produce strength more than 16 MPa. The water absorption increased only marginally from 5.52% to 5.83% for 60% QD replacement. Moreover, the blocks were able to meet the requirements of all the different types of blocks as stipulated by Bureau of Indian Standards including stabilized soil blocks, concrete solid blocks, concrete hollow blocks, lime-based blocks, and lime-flyash blocks of class up to 17.5.

Performance of Ceramic Tiles Waste as a Partial Replacement of Brick Aggregate on Mechanical and Durability Properties of Concrete

The availability of natural aggregates such as stone chips is a particularly challenging issue nowadays. Ceramic materials are increasingly being used in new projects such as tiles, sanitary fittings, electrical insulators, and so on, due to ceramic’s fragile properties, which often break during production, shipping, and installation. So, ceramic waste is one of these materials that are probably cost-efficient to use as a substitution (0%, 25%, 50%, and 75%) for brick chips. This research examined the mechanical strength properties of ceramic tile waste (CTW) concrete, including its compressive strength and splitting tensile strength, and utilized a water absorption test to assess its durability and performance. This research used a mix ratio of 1:1.5:3 with a constant water-cement ratio (w/c) of 0.45, and a water-reducing superplasticizer named Conplast SP337 was used. For the mechanical and durability tests, a total of seventy-two (72) concrete cylinders of 100 mm × 200 mm were cast, cured, and tested at 7, and 28 days. Mechanical strength results revealed a significant increase of around 16.71% for 50% CTW concrete mixtures at the place of brick aggregates, and the water absorption performance improved with the incorporation of CTW in concrete mixes.

Experimental Studies on Paver Block Concrete using Granite and Kota Stone Waste with Environmental effects on Strength

The need to address the worldwide demand for the preservation of limited resources has prompted the exploration of alternate materials. The application of waste materials in the concrete sector is experiencing a growing trend due to its potential to mitigate costs and minimize environmental repercussions. This study aims to assess the appropriateness of utilizing waste materials from granite and Kota stone for the production of interlocking concrete paver blocks (ICPB). The current study examines the potential use of waste materials from granite and Kota stone as substitutes for natural aggregates in the production of concrete interlocking paving blocks. The focus is on applications that cater to pedestrians and non-traffic scenarios. Concrete blocks of M30-grade were cast for this study. The replacement percentages were ranged from 0% to 100% for Kota stone as coarse aggregates and from 0% to 40% for granite waste as fine aggregates and total of 543 samples were cast using the replacement level. The mix proportion ratio used was 1:1.57:2.76 (cement: sand: aggregates) while continuing a constant water-cement ratio of 0.45. Weathered Kota stone waste (0, 25, 50, 75, 100%) was also used as anauxiliary for coarse aggregates in M30-grade concrete. The tests conducted covered the physical characterization of the constituent materials, determination of compressive strength, split tensile strength, flexural strength, abrasion resistance, and water absorption tendency for both hardened concrete blocks and I-shaped interlocking pavers. The result indicates that while using stone waste (granite and Kota stone), the required compressive strength was achieved up to a replacement level of 100% Kota stone and 5% granite waste. Flexural strength and splitting tensile strength were also satisfactory at all replacement ratios, along with normal water absorption and minimum abrasion. Paver blocks were also cast from waste stones at various replacement levels. In this study, concrete blocks were also cast using weathered Kota stone waste, which also provided sufficient strength at some level of replacement. The findings suggest that waste stone may be a viable option for manufacturing interlocking pavers, contributing to the development of an environmentally conscious and sustainable pavement infrastructure.

Comparative analysis of time dependent temperature profiles of hydrating mass concretes of different mix ratios

In mass concrete, heat due to cement hydration in most cases is not easily released and is otherwise confined within its core. Consequently, mass concrete may exhibit quite remarkable increase in temperatures internally depending on majorly the vicinity temperature and the proportion of cement in mixture ratio. When the surface tensile stresses resulting from temperature difference between its core and surface exceeds the strength of the concrete, cracks could develop at the surface. Two mass concrete blocks of dimensions 1.10 m × 1.10 m × 1.10 m each and mixes of 1: 2: 4 and 1: 3: 6 with constant water cement ratio (w/c) of 0.60 were used in the study. Type-K thermocouples were used to monitor the temperature variance in mass concretes. BK Precision 710 temperature meter dual input was used to determine the temperature readings at time intervals. Thermometer was used to measure the environment temperatures within the vicinity of the mass concretes. Generally, the trends of the temperature profiles exhibit an initial uniform temperature which rises to peak values at 24 hours of concrete placement and then declined to constant temperature at mostly 120 hours and beyond. The sole source of heat in hydrating concrete is the cement paste, and higher cement content leads to higher quantity of heat release. Therefore, the mass concrete block of mix ratio 1:2:4 exhibited higher quantity of heat release than that of 1:3:6 especially at the core.

INFLUENCE OF MIX PROPORTION ON WORKABILITY OF LATERIZED CONCRETE

The increase in infrastructural development in the tropic has led to high demand for concrete production. Consequently, its constituents became very scarce and costly, especially the naturally occurring constituents. Laterite as an abundant naturally occurring material in the tropics is only put in use as filling material or in road construction. This study presents the determination of influence of nominal mix proportion (1:2:4, 1:1.5:3 and 1:1:2) at a constant water cement ratio of 0.5 with laterite fully replacing sand (fine aggregate). 72 numbers of cubes of size 100 mm were prepared for the different concretes, while 12 numbers were cast for each mix proportion and cured in the curing tank at 3, 7, 14, 28 days. Though the laterite was found to be a normal weight aggregate, it was also identified as A – 7 – 6, medium plastic clayey and porous material, with a specific gravity of 2.59. For the fresh concrete, the slump value and degree of workability were obtained using the Vee-bee consistometer and slump tests in both laterite and conventional concrete in all the three mix proportions (1:2:4 : 0.5, 1 : 1.5 : 3 : 0.5, 1 : 1 : 2 : 0.5). The Vee bee second for the mix proportions (1:2:4 , 1:1.5:3 and 1:1:2 ) are 13:18 , 09:44 and 6.0 for the conventional concrete while 14:47 , 12: 41 and 9:30 for Laterized concrete.

Experimental Investigation on the Utilization of Marble and Scoria Powder as Partial Replacement of Cement in Concrete Production

This paper explores how marble and scoria powder can be used as partial substitutes for ordinary Portland cement in creating C-25 concrete. Both materials contain over 50% of the major oxides found in cement, with marble high in CaO and scoria high in SiO2. Experimental investigations were conducted to study the chemical, physical, mechanical, and fresh properties of concrete containing marble and scoria powder. For the investigation, 13 different mixes, including the control mix, were used with a constant water–cement ratio of 0.5 and a slump range of 25–50 mm for concrete with a compressive strength (CS) of 25 MPa. Marble-to-scoria ratio of 2 : 1, 1 : 1, and 1 : 2 was used, and then the combined fraction of both marble waste and scoria in concrete was increased from 0% to 20% in 5% range. Including the control test specimens, a total of 117 (150 × 150 × 150 mm) concrete cubes for CS test, 39 (100 × 100 × 500 mm) concrete beam specimens for flexural strength test, 39 (100 × 200 mm) cylinder specimens for splitting tensile strength (STS) test and, 39 (100 × 100 × 100 mm) cube specimens for water absorption test were cast and tested at 3, 7, 28, and 56 days. The test results indicate that marble and volcanic scoria powders with marble-to-scoria ratio of 1 : 1 could replace cement up to 15% without compromising the CS and up to 10% without compromising the flexural and STS; also, the water absorption decreases up to 10% replacement; however, the workability of the fresh mix decreases as the combined replacement level of marble and scoria increases. Generally, a 10% replacement with marble-to-scoria ratio of 1 : 1 produces concrete with higher compressive, flexural, tensile strength, and water absorption manifestations when compared to conventional concrete.

Investigation on the surface hardness and durability-related properties of concrete containing coconut shell as partial substitute to coarse aggregates

Purpose Using coconut shell aggregates (CSA) in concrete benefits agricultural waste management and reduces the demand for mineral resources. Several studies have found that concrete containing CSA can achieve strengths that are comparable to regular concrete. The purpose of the present work is to evaluate the concrete’s durability-related properties to supplement these earlier findings. Design/methodology/approach Cylindrical specimens were prepared with a constant water–cement ratio of 0.50 and CSA content ranging from 0% to 50% (at 10% increment) by volume of the total coarse aggregates. The specimens were cured for 28 days and then tested for density, surface hardness, electrical resistivity and water sorptivity. The surface hardness was measured to describe the concrete resistance to surface wearing, while the resistivity and sorptivity were evaluated to describe the material’s resistance to fluid penetration. Findings The results showed that the surface hardness of concrete remained on average at 325 Leeb and did not change significantly with CSA addition. The distribution of surface hardness was also similar across all CSA groups, with the interquartile range averaging 59 Leeb. These results suggest that the cement paste and gravel stiffness had a more pronounced influence on the surface hardness than CSA. On the other hand, concrete became lighter by about 9%, had lower resistivity by 80% and had significantly higher initial sorptivity by up to 110%, when 50% of its natural gravel was replaced with CSA. Future work may be done to improve the durability of CSA when used as coarse aggregate. Originality/value The present study is the first to show the lack of correlation between CSA content and surface hardness. It would mean that the surface hardness test may not completely capture the porous nature of CSA-added concrete. The paper concludes that without additional treatment prior to mixing, CSA may be limited only to applications where concrete is not in constant contact with water or deleterious substances.

Orthogonal experimental design for compressive strength of recycled coarse aggregate concrete with silica fume-slag-fly ash hybrid micro-powders

Recycled Coarse Aggregate Concrete (RAC) is a type of concrete that uses recycled coarse aggregate (RCA) instead of natural coarse aggregate (NCA), which helps to reduce the negative environmental impact of construction waste. In order to improve the low compressive strength of RAC and solve the problem of shortage of natural aggregates, this paper develops a high-performance concrete called recycled coarse aggregate concrete with silica fume-slag-fly ash hybrid micro-powders (HMRAC) by replacing part of the cement with a mixture of micronized silica fume (SF), slag (SG) and fly ash (FA) and using RCA of 50% mass instead of NCA. The optimum combination parameters and prediction model for the compressive strength of HMRAC were also proposed by orthogonal experimental design. A constant water-cement ratio of 0.45 and a 50% mass replacement of natural coarse aggregate (NCA) by recycled coarse aggregate (RCA) were adopted in the experiment, and the mass replacement ratios of silica fume (SF), slag (SG), and fly ash (FA) for ordinary Portland cement (OPC) were used as the test variables. In total, 16 combinations were tested, including a control group where 50% of the NCA mass was replaced by RCA. First, we investigated the degree and significance of the effect of the mass substitution ratio of SF, SG, and FA on the compressive strength of HMRAC using analysis of variance (ANOVA) and extreme difference analysis. Then, we determined the optimal combination ratio of SF, SG, and FA. Secondly, multiple regression analysis was used to propose a multiple regression model for predicting the compressive strength of HMRAC. Finally, we computed and analyzed the carbon emissions of HMRAC. The results indicated that the mass substitution rates of FA and SG had a greater effect on the compressive strength, and the mass substitution rate of SF had a lesser effect on the compressive strength. The interaction of SF, SG, and FA can significantly enhance the compressive strength of RAC. The optimal compressive strength performance of HMRAC was observed when the proportions were as follows: SF constituted 10%, SG made up 15%, and FA accounted for 5%. The regression model has reasonable accuracy and a small standard deviation of residuals. It can effectively predict the compressive strength value of HMRAC, aligning well with the experimental results. It exhibits a superior carbon reduction rate of 21.90%, compared to conventional concrete.

Recycling of Periwinkle Shell Waste as Partial Substitute for Sand and Stone Dust in Lightweight Hollow Sandcrete Blocks towards Environmental Sustainability.

Global consumption of nonrenewable natural aggregate for construction activities is now becoming a significant concern. Reusing agricultural or marine-based wastes could offer a promising alternative to achieve natural aggregate conservation and a pollution-free environment. This study investigated the suitability of using crushed periwinkle shell (CPWS) as a reliable constituent material for sand and stone dust in producing hollow sandcrete blocks. The CPWS was used to partially substitute river sand and stone dust at 5, 10, 15 and 20% in sandcrete block mixes using a constant water-cement ratio (w/c) of 0.35. The weight, density and compressive strength of the hardened hollow sandcrete samples were determined after 28 days of curing along with the water absorption rate. Results showed an increase in the water absorbing rate of the sandcrete blocks as CPWS content increased. Mixes containing 5% and 10% CPWS substitute for sand with 100% stone dust surpassed the minimum targeted strength of 2.5 N/mm2. The compressive strength results suggested that CPWS is most suitable to be deployed as a partial substitute for sand as a constant stone dust material, thus imply that the construction industry can achieve sustainable construction with agro or marine-based wastes in hollow sandcrete production.

Effects of Styrene Butadiene rubber on the properties of Normal Concrete

This work titled “examining the effects of Styrene butadiene rubber latex on properties of normal concrete” is aimed at exploring the potential in the use of SBR latex in concrete to investigate how different properties of concrete can be improved. Styrene Butadiene Rubber Latex with brand name “Top Shield” was added by virtue of volume of cement in the concrete mix in percentages of 0, 5, 10, 15 and 20%. A total of 135 samples consisting of 45 pieces of 150mm*150mm*150mm cubes, 45 samples 100*100*500mm beams and 45 pieces of 200mm*10mm diameter cyl-inders were cast. A concrete mix design using ACI was used targeting a strength of 25N/mm2 and a mix ratio of 1:2.4:2.6 was used at a constant water cement ratio of 0.44 adopted. Samples were cured for 3, 7, 28 days. Samples were tested to investigate different properties of concrete test through slump, compressive strength, flexural strength, split tensile strength, water absorption, ultrasonic pulse velocity and scanning electron microscopy tests were conducted on the samples. Regression analysis of result was conducted using excel multiple regression tool and mathematical formulae were developed to help field workers and researchers forecast the degree of certain properties of interest and to determine how each variable affect the end result. Results showed positive improvement in all properties tested for. Preliminary quality control tests were carried out on the respective ingredients of concrete to determine their suitability with reference to ASTM Standard. The study recommended that further research should consider the use of a higher percentage of SBR latex to find the optimum compressive and tensile properties of the concrete.

Assessing Fresh Concrete Performance and Water Absorption Characteristics of Concrete with Partially Replaced Broken Tiles

A number of research seeking alternative materials to augment normal coarse aggregate to reduce overreliance on granite while saving the environment is on the rise. This study assessed the workability, water absorption and density of concrete with waste ceramic tiles as partial replacement for crushed granite coarse aggregate. Crushed waste ceramic tiles from ceramic manufacturing industries and construction sites were blended with crushed granite for concrete production. A mix ratio 1: 1.11: 2.72 (cement: sand: coarse) for nominal C30 concrete was produced with (0, 10, 20, 30, 40, 50 and 100) percent volume ceramic waste replacement for crushed granite at constant water-cement ratio of 0.5 to produce concrete cubes and cured for 7 and 28 days. Tests conducted revealed concrete workability and density decreased with increasing ceramic waste while water absorption increased with increasing ceramic waste but not above acceptable limits. However, use of waste ceramic tiles as partial replacement for crushed granite in concrete is encouraged, but not exceeding 20% maximum for structural concrete. This mode of recycling ceramic waste could positively promote green construction for sustained environment; hence, it should be encouraged with conditional limitation and further research of its use.

Assessing Structural Performance of Ceramic Waste as Partial Replacement of Coarse Aggregate on Properties of Concrete

The need to reduce the increasing demand for crushed granite as coarse aggregate as well as the need to safeguard the environment from degradation has given rise to various researches on alternative materials that can serve the same purpose while minimizing environment hazard. This study assessed the suitability of waste ceramic tiles as coarse aggregate in concrete and to ascertain its strength against normal crushed granite. Crushed waste ceramic tiles from ceramic manufacturing industries and construction sites were mixed with crushed granite stones as partial replacement for concrete. A mix ratio of 1: 1.11: 2.72 (cement: sand: stones) for nominal C30 concrete was produced with (0, 10, 20, 30, 40, 50 and 100) percent volume ceramic waste aggregate replacement for crushed granite at a constant water-cement ratio of 0.5. Concrete cubes of size 150mm x 150mm x 150mm were produced and tested for 7 days and 28 days compressive strength, density and water absorption. The results revealed the viability of waste ceramic tiles as partial replacement for crushed granite in concrete production, but the partial replacement should not exceed 20% as recommended maximum for structural concrete. This mode of recycling ceramic waste could positively sustain the environment.

Investigation into the Effect of Rice Husk Ash in Partial Replacement of Cement in Concrete

The purpose of this study was to investigate the properties of Rice Husk Ash (RHA) as a partial cement replacement material in concrete production based on analysis of its contribution to strength in comparison with Ordinary Portland Cement (OPC). The analysis was focused on: the chemical properties of RHA, workability, density, compressive strength, and tensile strength of concrete. The RHA was obtained from Mwea, Kirinyaga County, Kenya and burned in a kiln to produce white ash which was tested. Chemical analysis to determine the pozzolanic properties of RHA was done using the Gravimetric method, Flame Photometry and Atomic Absorption Spectroscopy while particle size distribution of RHA was carried out using sieve analysis and hydrometer analysis. Concrete mixes with different ratios of OPC to RHA binder were cast into cuboid and cylindrical samples. The binder was made by replacing OPC with RHA at intervals of 10% by mass to a maximum of 50% replacement. A binder, sand, and ballast ratio of 1:1.5:3 were maintained with a constant water-cement ratio of 0.6. The cast samples were subjected to water curing on the third day at room temperature. Workability tests were performed on fresh concrete while compressive strength tests and tensile strength tests were performed on hardened concrete in all the mixes. The results were compared with OPC concrete. Results indicated that Kenyan RHA has high silica, alumina, and iron oxide content of about 92%. The workability slightly improves with 10% partial replacement of OPC with RHA but decreases with further addition of RHA. It was also deduced that the optimal binder mix was 10% partial replacement of OPC with RHA however the compressive strength was lower than the OPC concrete by 2.3%. The tensile strength of concrete increased with the addition of RHA up to an optimum of 10%.

Durability study on engineered cementitious composites with hybrid fibers under sulfate and chloride environments

Engineered cementitious composite (ECC) is an exclusive type of cement mixture composite which imparts high ductility and high tensile strength. Over the decades, enormous strides have been made in creating ECC with extreme tensile ductility, on the order of several hundred times than that of normal concrete or fiber reinforced concrete. The experimental behaviour of ECC which is combined with polyvinyl alcohol (PVA) and steel fibers has been investigated in this research. The main aim of the research is to study the durability of ECC through compressive strength for long-term exposure condition under chloride, sulfate and combined sulfate–chloride environmental conditions experimentally. In the present work, six different ECC mixtures with constant water-cement ratio were prepared with the total volume fiber fraction (Vf) of 2%. ECC mechanical properties such as compressive strength, flexure strength and uni-axial tensile strength have been experimentally determined. The test results emphasize that the flexural strength and uni-tensile strength of the ECC specimens with the combination of 1.5% PVA and 0.5% steel fibers were improved as supposed to conventional ECCs. The durability property has been carried out only for the optimized dosage of fibers after exposed to aggressive solutions. The performance of optimized dosage of ECC mixture with hybrid fibers was barely affected by the aggressive solutions of chloride and sulfate–chloride when compared the same with water.

Aptness of nano alumina (Al2O3) with high range water reducer-incorporated concrete

PurposeThe purpose of this paper is to study the effect of nano alumina (Al2O3) on the properties of fresh concrete, hardened concrete and microstructure of concrete incorporated with high range water reducer (HRWR). This initiative was taken to improve characteristic properties of concrete using nano alumina because nano alumina can be easily be manufactured from a scrap of industrial aluminum products, so its incorporation in concrete will not only reduce industrial aluminum waste but will also change the morphology of concrete at the microstructural level.Design/methodology/approachTo accomplish the objectives of the research, four different concrete mixes with the constant water–cement ratio (W/C) and superplasticizer (SP) content 0.4 and 0.6% by weight of cement, respectively, were prepared, whereas nano alumina content was altered by 0.3% and 0.4% by weight of cement. Fresh property of concrete was analyzed by using slump cone test, whereas hardened properties of concrete were analyzed through compression test and flexural strength test. The interaction of nano alumina with concrete composite was evaluated using an X-ray diffraction test.FindingsIt was observed that 0.6% superplasticizer by weight of cement increased workability by 22% but with the addition of 0.3%, nano alumina by weight of cement workability decreased by 31%. Compressive strength increased by 4.88% with the addition of 0.6% superplasticizer but with the addition of 0.3% nano alumina by weight of cement compressive strength increased by 18.60%. Also, flexural strength increased by 1.21% with the addition of 0.6% superplasticizer by weight of cement but with the addition of 0.3% nano alumina by weight of cement flexural strength increased by 8.76%. With the addition of superplasticizer, alite and belite phases remained un-hydrated but with the addition of nano alumina alite phase was hydrated while belite phase was un-hydrated. The size of belite crystals in mixes having nano alumina was less than that of mix having 0.6% superplasticizer. Also with the addition of nano alumina, a calcium aluminum silicate phase was formed which was responsible for the increment of strength in mixes having nano alumina.Originality/valueIncorporation nano alumina (Al2O3) in concrete will not only reduce industrial aluminum waste but will also reduce CO2 emission. Nano alumina (Al2O3) also changes morphology of concrete at micro structural level.

Experimental and examination of Recron 3S fibre on reinforced concrete

Concrete is a key element which solidifies and hardens after mixing the water with cement, fine aggregate and coarse aggregate due to the process of chemical reaction called hydration. The new habit forming of Recron 3S (polypropylene) fibre is a state of art reinforcing material in many appliances; especially it was found to be adequate in concrete. Our exploratory and examination consists of M40 grade design concrete mix. We provide a constant water cement ratio as 0.4 while adding the fibre in certain proportions. We carried out the test of slump cone, compaction factor, compressive strength, split tensile strength and flexural strength test. We take the strength test at the period of 7, 14 and 28 days. Inclusion of Recron 3S FIBRE in concrete were analysed and compared with conventional concrete.

“Mechanical and durability performance of self-compacting concrete with waste ceramic tile as a replacement for natural river sand”

Ceramic waste is generated in huge quantity during production, transportation and fixing stages.This waste ceramic is discarded in open spaces which generates a lot of environmental issues. The main purpose of this research is utilization of waste ceramic tile as a substitution for natural river sand in self-compacting concrete. Natural river sand (NRS) was substituted by waste ceramic tile (WCT) in different percentages 0–100% by weight. The self-compacting concrete (SCC) mixes were prepared with a constant water-cement ratio 0.33. Slump flow, T-500, V-funnel, L-box, J-ring and U-box were examined for fresh state of the SCC. Mechanical strength, sorptivity and dry shrinkage were conducted to test the hardened state of SCC. The fresh state properties reduced as the quantity of waste ceramic tile is increased, however all properties satisfied the acceptable limits of EFNARC standards. The outcomes of mechanical strength showed a meaningful increment in SCC mixtures up to an incorporation of 60% of WCT. The sorptivity and dry shrinkage performance improved with the incorporation of WCT in SCC mixes. The sorptivity and dry shrinkage results confirm the best performance for the SCC made with 60% of WCT.

The effect of waste electronic plastics and waste marble dust as a partial aggregate replacement on concrete

Concrete is the most abundant material used in construction on present scenario where aggregates comprise of about three-fourth volume of concrete. On 2019, 28 Mt of E-waste generation was recorded in Nepal and its management has created a burden to the landfill sites. Also, marble dust is a waste obtained during processing and installation of marble which can be used as filler or fine aggregate in concrete for strength enhancement. Utilization of crushed E–waste plastics and waste marble dust in concrete will introduce a green and environment friendly method of construction without any compromise in the utility parameter and would represent positive effect to minimize the environmental degradation and replace naturally available aggregates which are continuously been used. The strength effects of waste electronic plastics and waste marble dust as aggregate replacement in concrete was studied in this research. For this study, 12 sets of concrete mixes were prepared with constant water cement ratio of 0.55. Marble dust was used as a sand replacement at 2.5%,5%,7.5% and 10% by volume of sand. Further 2 sets of 4% and 6% replacement of sand by marble dust was prepared to find out the optimum value as 5% replacement showed greater compressive strength. E-wastes plastics were then used as replacement to coarse aggregate at 1%, 2%, 3%, 4% and 5% along with 5% replacement of sand by waste marble dust. The workability test, compressive strength and flexural test of the mixes were determined. Based on the study, result showed that the compressive strength at 5% replacement of sand by marble dust was maximum while E-waste plastics replaced up to 4% had compressive strength greater than that of nominal mix concrete of grade M20. Flexural strength also increased of concrete containing E-plastic than that of normal concrete.

Effect of GGBS and fly ash on mechanical strengthof self-compacting concrete containing glass fibers

In the era of building engineering the intensification of Self Compacting Concrete (SCC) is world-shattering magnetism. It has lot of rewards over ordinary concrete i.e., enrichment in production, cutback in manpower, brilliant retort to load and vibration along with improved durability. In the present study, the mechanical strength of CM-2 (SCC containing 10% of rice husk ash (RHA) as cement replacement and 600 grams of glass fibers per cubic meter) was investigated at various dosages of cement replacement by fly ash (FA) and GGBS. A total of 17 SCC mixtures including two control SCC mixtures (CM-1 and CM-2) were developed for investigating fresh and hardened properties in which, ten ternary cementitious blends of SCC by blending OPC+RHA+FA, OPC+RHA+GGBS and five quaternary cementitious blends (OPC+RHA+FA+GGBS) at different replacement dosages of FA and GGBS were developed with reference to CM-2. For constant water-cement ratio (0.42) and dosage of SP (2.5%), the addition of glass fibers (600 grams/m3) in CM-1 i.e., CM-2 shows lower workability but higher mechanical strength. While fly ash based ternary blends (OPC+RHA+FA) show better workability but lower mechanical strength as FA content increases in comparison to GGBS based ternary blends (OPC+RHA+GGBS) on increasing GGBS content. The pattern for mixtures appeared to exhibit higher workablity as that of the concentration of FA+GGBS rises in quaternary blends (OPC+RHA+FA+GGBS). A decrease in compressive strength at 7-days was noticed with an increase in the percentage of FA and GGBS as cement replacement in ternary and quaternary blended mixtures with respect to CM-2. The highest 28-days compressive strength (41.92 MPa) was observed for mix QM-3 and the lowest (33.18 MPa) for mix QM-5.

Sustainable Production of Concrete using Coir Fibres

This paper reports the investigation conducted in India using coir fibres as an additive substance used in the preparation of sustainable concrete mixtures. It is meant to be used as energy-saving building components. The coir fibres were added in different percentages 2%, 4%, and 6%, and to compare the results of these the reference concrete was also prepared without coir fibres. The study focuses on investigating the different parameters such as workability, density, water absorption, compressive strength, flexural strength, and split tensile strength. The concrete blends were made while maintaining a constant water cement ratio of 0.52. The results of this study revealed that the addition of coir fibres in concrete mixes enhances the mechanical properties of concrete. An optimal percentage was proposed as 4 percent for the addition of coir fibres in concrete. It is possible to produce sustainable concrete with the use of coir fibres.