Decrease In Compressive Strength Research Articles

Pengaruh Penambahan Limbah Bulu Ayam Terhadap Kuat Tekan Beton K-250

Along with the times, various innovations have been made to improve the performance of concrete, Innovations carried out include aiming to produce and value structural materials that have good properties with economical and economical methods and costs, Efforts to improve the quality of concrete are also carried out by mixing other ingredients in the mixture. In this study, the author used chicken feather fiber as an added ingredient to the mixture concrete. This study aims to find out how the process of making concrete with added chicken feather waste with an additional composition of 0.1%, 0.5%, and 1.5%, and whether the added material of chicken feather waste with a composition of 0.1%, 0.5%, and 1.5%, can increase the compressive strength of concrete or vice versa. In this research method using the experimental method, the test objects made for each addition to the percentage of chicken feather waste are as many as 3 samples, with a cylindrical mold size of 15 cm in diameter with a height of 30 cm, by passing the treatment process for 28 days. The conclusion of this study is that concrete is added with chicken feather waste with variations of 0.1%, 0.5%, and 1.5% addition, the planned compressive strength is 20.8 Mpa. A decrease in compressive strength was produced in each use of added chicken feather waste with a composition of 0.1%, 0.5%, and 1.5%, the more added chicken feather waste, the compressive strength value of concrete decreased, the initial normal composition produced a compressive strength of 21.56 Mpa, while the composition of 0.1% decreased with a compressive strength result of 10.64 Mpa, then with a composition variation of 0.5% decreased again with a compressive strength value of 3.21 Mpa. And for a composition variation of 1.5% it decreases with a compressive strength value of 0.16 Mpa. With this research, it is known that chicken feather waste material cannot be an alternative to add concrete mixture in the future.

Effect of Aluminium Fiber on the Strength property of Concrete

This experimental work is aimed at determining the influence of aluminium waste fiber on plain cement concrete. To achieve this aim, compressive strength test has been conducted. The compressive strength test has been conducted in Compression machine. The plain cement concrete with the ratio 1:1.5:3 at 0.55 water cement ratio has been utilized in this study. Aluminium waste has been used as additional material in concrete. The weight of aluminium has been taken from 0.5%, 1.5% and 1.5% by weight of cement of varying aspect ratios that are 2.5 (length=0.5 inch, width=5mm), 5 (length=1inch, width=5mm) and 7.5 (1.5 inch, 0.5mm). A total number of ten batches, each batch contained six cubes and were casted for evaluation of compressive strength test. The curing ages selected for this particular study have been 7 and 28 days. It has been observed in this study that aluminium waste has resulted into a decrease in compressive strength of concrete as compared to normal concrete. This study has made application of solid waste as addition material in concrete. Therefore, this study will be helpful to reduce environmental pollution.

A Comparative Study Investigating the Feasibility and Potential of Utilising Polymer, Demolition & Glass Waste as a Partial Replacement for Fine and Coarse Aggregate in Concrete

The construction industry is a key CO2 contributor. Contemporary research focuses on formulating cement replacement composites; however, less attention is deliberated to formulating fine/coarse aggregate replacement composites. The waste from different fields contributes enormously to adverse environmental effects, thus necessitating reuse/recycling. The demolition/reconstruction of old buildings/infrastructure is adding further to the waste contribution by the construction industry. The total quantum of fine/coarse aggregate in the construction industry is estimated to be around 20 billion tons, contributing around a billion tons of CO2 . Therefore, even partial replacement of virgin sand/coarse aggregates with various waste materials like glass, rubber, plastic, tyres, recycled concrete and others will economise the cost of manufacturing the concrete with reduced CO2 footprints as eco-friendly materials. This study conducted a comparative analysis for investigation of the characteristic compressive and split tensile strength of concrete composites with partial replacement of virgin sand/coarse aggregate by 10-30% of Crushed Glass (CG), Crumb Rubber (CR), Recycled PET Bottles (RPB), Recycled Concrete Aggregate (RCA) and 5-10% of Shredded Tyres (ST). Generally, all the composites demonstrated par/ better strength with the control mix, achieving the target strength of C55/67 concrete. The composites with CG, RPB and RCA exhibited an improvement in compressive strength, attaining more than 70 MPa (high-performance concrete strength) and up to 10% improvement in split tensile, attaining 4.3 MPa. CR and 5-10% ST exhibited a slight decrease in compressive strengths. All the composites formulated in this study explicate their diverse uses for multipurpose infrastructural applications in the construction industry as improved, economical, eco-friendly waste absorbent composites.

In‐situ compressive and tensile performances of high strength engineered cementitious composite at elevated temperatures

AbstractThe study provides novel insights on the compressive and tensile strength of high strength engineered cementitious composite (HSECC) at elevated temperatures under in‐situ testing condition. An optimized mix design was employed and cylinder and dogbone specimens were tested to study the compressive and tensile strength of HSECC at elevated temperature. The tested results under in‐situ test condition were compared with the residual state by exposing the specimens to temperature up to 600°C. It was found that specimens under in‐situ condition showed a drastic decrease in compressive strength (26.8%–34.5%) at 200°C and the performance was much inferior to that observed for residual state which showed only 12.2% decrease. This trend was consistent for both tensile and compression test results. After this, the in‐situ specimens underwent slight increase in the compressive strength with only around 25% decrease at 400°C and 14%–16% decrease at 600°C. However, the residual state specimens underwent continuous decrease in strength. Therefore, this study confirmed that for high strength cementitious composites exposed to elevated temperatures, the residual test results should not be considered as the lower limit and in‐situ testing results are essential for accurately predicting the behavior of cementitious composites. Thus, this research underscores the importance of conducting both in‐situ and residual state tests in the design of HSECC structural members.

Comprehensive investigation of performance of construction and demolition waste based wood fiber reinforced geopolymer composites

This study focuses on developing eco-friendly building materials by valorising construction and demolition waste (CDW) in geopolymer matrices. Various CDW-based materials, including brick, tile, concrete, and glass waste, were utilized. Additionally, CDW-based waste wood fiber (WWF) was chemically treated and integrated as a reinforcing fiber. The developed CDW-based WWF-reinforced geopolymer composites were extensively evaluated through workability, strength, durability, and microstructural analysis. Findings showed that incorporating 2.00 vol % and 4.00 vol % WWF in geopolymer composites resulted in a slight decrease in compressive strength, while at 6.00 vol % and 8.00 vol % WWF, significant decreases were observed. Flexural strength showed improvement up to 4.00 vol % WWF, with significant enhancement of 17.67 % compared to plain geopolymer. This enhancement was attributed to the increased adhesion capability and improved interlocking and compatibility between the geopolymer matrix and chemically treated WWF. However, the advantages of WWF addition were limited at higher usage ratios due to its higher water absorption capacity and potential agglomeration behaviour. In this context, water absorption increased with WWF, ranging from 30.87 % to 59.01 %, while improvements in freeze-thaw resistance were observed up to 6.00 vol % WWF usage. The microstructural analysis further corroborated these findings by confirming the presence of interlocking and agglomeration phenomena within the composites.

Synthesis of foamed glass–ceramics from high‐titanium blast furnace slag using Na3PO4·12H2O as a foam stabilizer

AbstractWe report the effects of sodium phosphate dodecahydrate (Na3PO4·12H2O) as a foam stabilizer on the crystalline phases, microstructure, and properties of foamed glass–ceramics derived from solid industrial wastes. Our findings reveal that Na3PO4·12H2O acts as a pore structure stabilizer, enhancing pore uniformity by releasing P2O5 during decomposition. Additionally, it lowers the softening temperature and viscosity by supplying Na2O. X‐ray diffraction analysis demonstrates that Na3PO4·12H2O does not alter the primary crystal types but does influence the crystallinity and morphology. With an increase in Na3PO4·12H2O content, the porosity and water absorption improve, but the bulk density, thermal conductivity, and compressive strength decrease. The optimal properties are achieved with 4 wt% Na3PO4·12H2O, resulting in significantly higher compressive strength compared to foamed glass–ceramics prepared from other solid wastes. This study provides valuable guidelines for effectively reusing solid industrial wastes to fabricate foamed glass–ceramics.

Strength Reduction Due to Acid Attack in Cement Mortar Containing Waste Eggshell and Glass: A Machine Learning-Based Modeling Study

The present study utilized machine learning (ML) techniques to investigate the effects of eggshell powder (ESP) and recycled glass powder (RGP) on cement composites subjected to an acidic setting. A dataset acquired from the published literature was employed to develop machine learning-based predictive models for the cement mortar’s compressive strength (CS) decrease. Artificial neural network (ANN), K-nearest neighbor (KNN), and linear regression (LR) were chosen for modeling. Also, RreliefF analysis was performed to study the relevance of variables. A total of 234 data points were utilized to train/test ML algorithms. Cement, sand, water, silica fume, superplasticizer, glass powder, eggshell powder, and 90 days of CS were considered as input variables. The outcomes of the research showed that the employed models could be applied to evaluate the reduction percentage of CS in cement composites, including ESP and RGP, after being exposed to acid. Based on the R2 values (0.87 for the ANN, 0.81 for the KNN, and 0.78 for LR), as well as the assessment of variation between test values and anticipated outcomes and errors (1.32% for ANN, 1.57% for KNN, and 1.69% for LR), it was determined that the accuracy of the ANN model was superior to the KNN and LR. The sieve diagram exhibited a correlation amongst the model predicted and target results. The outcomes of the RreliefF analysis suggested that ESP and RGP significantly influenced the CS loss of samples with RreliefF scores of 0.26 and 0.21, respectively. Based on the outcomes of the research, the ANN approach was determined suitable for predicting the CS loss of mortar subjected to acidic environments, thereby eliminating lab testing trails.

Mechanical properties and microstructure of roller compacted concrete incorporating brick powder, glass powder, and steel slag

Abstract The objective of this study is to explore the feasibility of developing environmentally friendly green roller-compacted concrete (RCC) by utilizing locally available materials. The research investigates the behavior of RCC properties when different amounts of solid waste materials (brick powder, glass powder, and steel slag) are added as substitutes for cement content. To accomplish this, four laboratory tests were conducted: compressive strength, flexural strength, X-ray diffraction analysis, and scanning electron microscope imaging. These tests aimed to identify the changes in concrete properties resulting from the inclusion of waste construction materials as cement replacements. The study employed an approach that involved adding waste materials to the concrete mixture, with replacement percentages ranging from 10.0 to 40.0% in increments of 10.0%. Consequently, 12 concrete mixtures were prepared to examine the effects of adding waste materials (10.0–40.0%) as substitutes for cement content. In addition, one reference mixture was designed without any inclusion of waste materials for comparison purposes. In general, the results indicate that as the percentage of waste construction materials increases in the mixtures, there is a corresponding decrease in compressive strength. However, it is noteworthy that the strength activity index (SAI) exceeded 75% according to ASTM C618 standards. This indicates that the waste construction materials possess pozzolanic properties, making them suitable for use as cement replacements in RCC mixtures.

Development of carrageenan-immobilized lytic coliphage vB_Eco2571-YU1 hydrogel for topical delivery of bacteriophages in wound dressing applications

Bacteriophages are employed as cost-effective and efficient antibacterial agents to counter the emergence of antibiotic-resistant bacteria and other host bacteria in phage therapy. The increasing incidence of skin wounds is a significant concern in clinical practice, especially considering the limitations of antibiotic therapy. Furthermore, the lack of an effective delivery system that preserves the stability of bacteriophages hampers their clinical implementation. In recent years, there has been a growing amount of research on bacteriophage applications in veterinary and biomedical sciences. In our study, lytic coliphage vB_Eco2571-YU1 was isolated against pathogenic Escherichia coli host bacteria, and hydrogel wound dressing materials were fabricated with marine polysaccharide carrageenan (carr-vB_Eco2571-YU1) for their antibacterial activity. Transmission electron microscopy (TEM) morphology identified it as a Myoviridae coliphage with an icosahedral head length and width of approximately 60 and 56.8 nm, respectively, and a tail length of 119.7 nm. The one-step growth curve of coliphage revealed a latent period of 10 min, a rise period of 15 min, and a burst size of 120 virions per cell. The bacteriolytic activity of unimmobilized coliphages was observed within 2 h; however, strain-specific phage resistance was acquired after 9 h. In contrast, carr-vB_Eco2571-YU1 showed a sharp decline in the growth of bacteria in the log phase after 2 h and did not allow for the acquisition of phage resistance by the E. coli strain. The stability of coliphage under different pH, temperature, osmolarity, detergents, and organic solvents was evaluated. We also studied the long-term storage of carr-vB_Eco2571-YU1 hydrogels at 4 °C and found that the titer value decreased during a time-dependent period of 28 days. These hydrogels were also found to be hemocompatible using a hemolysis assay. The addition of plasticizer (0.6 % (w/v)) to the carrageenan (2 % (w/v)) to prepare carr-vB_Eco2571-YU1 hydrogels showed a decrease in compressive strength with enhanced elasticity. This phage therapy using polymeric immobilization of bacteriophages is a promising next-generation wound dressing biomaterial alternative to conventional wound and skin care management.

Experimental Investigation of the Size Effect on Roller-Compacted Hydraulic Asphalt Concrete under Different Strain Rates of Loading.

Asphalt concrete is widely used in hydraulic structure facilities as an impermeable structure in alpine cold regions, and its dynamic mechanical properties are influenced by the strain rate and specimen size. However, the specimen size has an important effect on mechanical properties; few systematic studies have investigated on the size effect of hydraulic asphalt concrete (HAC) under dynamic or static loading rates. In the present study, four sizes of cylindrical roller-compacted hydraulic asphalt concrete (RCHAC) specimens with heights of 50 mm, 100 mm, 150 mm, and 200 mm were prepared and tested under different loading rates ranging from 10-5 s-1 to 10-2 s-1 to investigate the size effects of mechanical properties and failure modes at the temperature of 5 °C. The effect of strain rate on the size effects of the compressive strength and the elastic modulus of RCHAC have also been explored. These tests indicate that when the specimen size increases, the compressive strength and failure degree decrease, while the elastic modulus increases. When the height increases from 50 mm to 200 mm, the compressive strength at different strain rates decreased by more than 50%. Furthermore, the elastic modulus increased by about 211.8% from 0.51 GPa to 1.59 GPa at a strain rate of 10-5 s-1, and increased by 150% from 5.08 GPa to 12.71 GPa at a strain rate of 10-2 s-1. As the strain rate increases, the variation trends with the size of the compressive strength, elastic modulus, and failure degree are distinctly intensified. A modified dynamic size effect law, which incorporates both the specimen size and strain rate, is proposed and verified to illustrate the dynamic size effect for the RCHAC under different loading rates.

Влияние термической обработки на свойства композиционных материалов АМг2–10%TiC и АМг6–10%TiC, полученных методом самораспространяющегося высокотемпературного синтеза

Dispersion-strengthened composite materials belong to the group of promising structural materials characterised by a diverse combination of properties. The paper considers examples of the creation and heat treatment of composite materials based on aluminium alloys strengthened by the titanium carbide dispersed phase characterised by high hardness, elastic modulus, and good melt wettability. At present, self-propagating high-temperature synthesis (SHS) is the most accessible, inexpensive and effective way to obtain them. The authors substantiate the expediency and show their successful experience of the formation in the composition of the AMg2 and AMg6 industrial alloys of a titanium carbide dispersed phase with a particle size of 130 nm in an amount of up to 10 wt. % using the SHS method, which makes it possible to increase the hardness of the alloys. Additional heating of the AMg2–10%TiC and AMg6–10%TiC samples after synthesis also contributes to the further increase in hardness. The complex of studies of physical, mechanical and operational characteristics presented in the paper was carried out to compare the properties of the work-hardened matrix alloys and the samples of composite materials before and after heating. The test results showed that heat treatment reduces the porosity of the composites and significantly increases their hardness and microhardness. A slight decrease in compressive strength at a significant increase in wear resistance is observed. It was found that composite materials are characterised by high corrosion resistance to carbon dioxide and hydrogen sulfide corrosion corresponding to the level of matrix alloys. The results obtained allow recommending the developed materials for the production of parts of the connecting rod and piston group, bearings and other wear-resistant parts of friction units.

Water Absorption Rate in Porous Concrete Paving Block as a Permeable Pavement Structure

Controlling surface water runoff is one way to maintain environmental sustainability. Rainwater on the road surface is one of the problems that must be controlled. Most road surfaces are covered with waterproof material so that rainwater cannot infiltrate into the ground, which then accumulates and causes flooding. This research aims to study porous concrete paving blocks to prevent flooding. This paving block material is made from a coarse aggregate of 4 – 9.5 mm as the main component for making porous concrete paving blocks with height variations of 6 cm, 8 cm, and 10 cm. Concrete Paving Block is used to compare the performance of Porous Concrete Paving Block. Compression, porosity, and infiltration rate tests have been carried out to see its characteristics. Based on tests that have been carried out, porous concrete paving blocks have a porosity ranging from 19 - 23% and an infiltration rate ranging from 0.17 - 0.42 cm/second; however, porous concrete paving blocks experience a decrease in compressive strength of 58 - 60% when compared to concrete paving blocks conventional.

Investigation of cementitious composites reinforced with metallic nanomaterials, boric acid, and lime for infrastructure enhancement

<abstract> <p>Nanomaterials integration within construction materials could promote the generation of more sophisticated structural materials, as it imbues reinforcement at the nanoscale. This research adopted experimental approaches to assess the influence of metallic nanomaterials on the performance of cementitious composites with various ratios of boric acid (1%, 3%, and 5% by sand's weight) and lime (0.5%, 1.5%, and 2.5% by sand's weight), respectively, for use in construction infrastructure facilities. This research provides valuable insight into the potential of using boric acid and lime as well as metallic nanomaterials to strengthen cement-based composites. Initial curing stages revealed a notable decrease in compressive strength attributed to the inhibitory effects of boric acid and lime on cement hydration. However, the introduction of TiO<sub>2</sub> nanoparticles demonstrated significant enhancements in compressive strength and durability. Statistical analysis emphasized the significance of nanomaterials in augmenting compressive strength, with implications for long-term performance. This study has shown that the addition of nano-titanium dioxide TiO<sub>2</sub> can significantly enhance the compressive strength of Portland cement mortars, particularly when used in conjunction with appropriate ratios of boric acid and lime. The results of the 7 days test indicated that the inclusion of boric acid and lime in the cement mortars significantly decreased the compressive strength. However, the addition of nano-TiO<sub>2</sub> to cement mortars containing 1% boric acid and 0.5% lime resulted in a 31-fold increase in compressive strength compared to cementitious composites without nano-TiO<sub>2</sub>. In contrast, the compressive strength significantly increased by 1.2 times, 85.3 times, and 65.1 times, respectively, after 56 days for the addition of boric acid (1%, 3%, and 5%) with lime (0.5%, 1.5%, and 2.5%), respectively, in the presence of nano-TiO<sub>2</sub>, compared to the 7 days strength. The results also illustrated that, in general, the incorporation of various types of nano-TiO<sub>2</sub> into cementitious composites containing boric acid and lime increases their compressive strength as the ratios of boric acid and lime increase, as long as sufficient curing time is allowed.</p> </abstract>

Evaluation and optimization of mechanical properties of laterized concrete containing fly ash and steel fiber using Taguchi robust design method

The present study employs the S/N ratio and multiple regression analysis to evaluate the mechanical properties of laterized concrete with fly ash and steel fiber. The study considers compressive, split tensile, and flexural strengths as responses at 7 and 28 days. The Taguchi L16 (4 *4) orthogonal array experimental design is applied to optimize the performance of mechanical properties of concrete by using the design of experiments. The replacement of 25% of the granite aggregate with laterite aggregate resulted in a 12.44% increase in the strength of M30-grade concrete after 28 days. The composite's compressive strength decreases when the replacement level exceeds 25%. The split tensile and flexural strengths of the composite showed an increase of 14.54% and 16.93%, respectively, compared to the control mix. Furthermore, the test outcomes for durability factors like drying shrinkage and rapid chloride penetration in steel fiber reinforced fly ash-based lateritic concrete mixes with a 50% replacement rate adhere to the prescribed standards, verifying their designed performance over the designated structural lifespan. However, after multiple regression analysis, it is found that the error related to the correlation between experimental and analytical value strength is about 5%. Microstructural studies of the ideal mix were performed at 28 days to further understand the morphology of the laterized concrete containing fly ash and steel fiber.

Coarse synthetic fibers (PP and POM) as a replacement to steel fibers in UHPC: Tensile behavior, environmental and economic assessment

Ultra-high performance concrete (UHPC) has excellent compressive strength and ductility. Nevertheless, the extensive utilization of UHPC has been impeded by factors including the exorbitant cost, substantial carbon emissions, and vulnerability to corrosion associated with steel fibers. This study explores an innovative approach by introducing polypropylene fibers (PPF) and polyoxymethylene fibers (POMF) as replacements for steel fibers (SF) in the preparation of hybrid fiber-reinforced ultra-high-performance concrete (HUHPC), with a total fiber content of 3% vol. The influence and mechanism of different PPF/POMF replacement ratios for SF on the flowability, compressive performance, and tensile behavior of HUHPC were investigated. An axial tensile static constitutive model for HUHPC considering the PPF/POMF replacement ratio was established, and a comprehensive environmental benefit assessment index and economic benefit assessment index considering mechanical performance were proposed. The results showed that using PPF and POMF with low modulus as replacements for high-modulus SF significantly improved the flowability of HUHPC. Notwithstanding there is a decrease in compressive and tensile strength of HUHPC resulting from the utilization of low-modulus and low-strength PPF and POMF as substitutes for SF, it modified the axial tensile stress-strain behavior of conventional UHPC and notably improved its tensile toughness. The established axial constitutive model for HUHPC in this study effectively predicted the tensile stress-strain behavior of HUHPC. Importantly, the comprehensive environmental assessment index reveals that HUHPC offers superior environmental and economic benefits compared to traditional UHPC, leading to substantial cost reductions. The development of HUHPC through fiber hybridization presents a promising strategy for the low-carbon and cost-effective production of UHPC, holding significant implications for the broader adoption and application of UHPC.

Effects of Al addition on the microstructure and mechanical properties of AlxCoCrFeNi2.1 high-entropy alloys

To investigate the effect of Al content on the microstructure evolution and properties of AlxCoCrFeNi2.1 high-entropy alloys, the AlxCoCrFeNi2.1 high-entropy alloys (=0.5, 0.8, 1.0, 1.2 and 1.5) were prepared by vacuum arc melting. The results show that all the designed alloys are composed of single face-centered cubic (FCC) and ordered body-centered cubic (B2) phases. With the increase of Al content, the volume fraction of FCC phase decreases while that of B2 phase increases. In addition, the increasing Al content leads to the sequential increase of the hardness and yield strength of the alloys, while both the plasticity and compressive strength decrease. And the corresponding wear rate decreases from 312.9 × 10−5 mm2 N−1 to 55.3 × 10−5 mm2 N−1. It is revealed that the wear mechanism transforms from initially dominant abrasive wear with adhesive wear as a supplement to the mechanism dominated by adhesive wear with abrasive wear as a supplement, and finally to the oxidation wear plus abrasive wear. The experimental results show that the Al1.2CoCrFeNi2.1 alloy has the most excellent comprehensive performance, with an average hardness of 441 HV, compression ratio of 36.4%, compressive strength of 2618 MPa and wear rate of 68.0 × 10−5 mm2 N−1.

PENGARUH SERAT BUAH PINANG TERHADAP KUAT TEKAN BETON

Concrete material innovations are no emerging more and more and are something that is really needed, one of which is material innovation with the addition of fiber. Fiber concrete is a mixture of concrete plus fiber. The fiber material can be asbestos fiber, plastic fiber (poly-propyline), or pieces of steel wire, plant fibers (hemp, coconut fiber, bamboo, palm fiber). The purpose of adding fiber is to improve or increase the mechanical properties of concrete in the form of tensile strength, compressive strength and flexural strength. This research uses areca nut skin fiber, the skin and seeds are separated, then the betel nut fiber is spread apart so that it does not clump when mixing, then the betel nut fiber is mixed little by little into the concrete mixture. This research aims to determine the effect of adding Areca nut fiber on the compressive strength of concrete aged 7, 14 and 28 days. The percentage of areca nut shell fiber used in this research as 1.6%, 2.4% and 4%. The research used test objects in the form of cubes measuring 15 x 15 x15 cm, with a sample of 12 pieces of concrete, including 9 pieces of concrete with a mixture of betel nut fiber according to each type of concrete aged 7, 14 and 28 days, and 3 pieces of concrete without mixed/normal. The test carried out on the concrete mixture is the compressive strength of the concrete. From the research results obtained, the results of testing the compressive strength of fiber concrete with a percentage of Areca fruit fiber of 1.6% at concrete ages of 7, 14, and 28 days obtained an average compressive strength result of 7.65 MPa, for testing the compressive strength of concrete with a percentage 2.4% for concrete ages of 7, 14 and 28 days experienced a decrease in average compressive strength of 5.88 MPa and for concrete compressive strength testing with a percentage of 4% for concrete ages of 7, 14 and 28 days there as an increase in average concrete compressive strength. The average is 11.43 MPa.

Experimental Study on Mechanical and Thermal Properties of Backfill Body with Paraffin Added

Based on phase-change heat storage backfill, paraffin microcapsules were selected as the phase change material and were directly mixed with backfill materials for preparing backfill specimens. The mechanical and thermal properties of specimens with different paraffin percentages and slurry concentrations were tested and analyzed. The results show that compressive strength gradually decreases with an increasing paraffin percentage while it significantly increases with increasing slurry concentration, thermal conductivity decreases with increasing paraffin percentage and specific heat capacity increases with an increasing paraffin percentage and slurry concentration. For a paraffin percentage from 0% to 10%, compressive strength decreases by an average of 22.5%, thermal conductivity decreases by an average of 43.8% and specific heat capacity increases by an average of 8.7% at a phase-change temperature of 30 °C. For a slurry concentration from 68% to 72%, compressive strength increases by an average of 4.12 times, and specific heat capacity increases by an average of 3.5% at a phase-change temperature of 30 °C. The weakening effect of phase-change materials on compressive strength can be effectively improved by the increase of slurry concentration, and the increases of paraffin percentage and slurry concentration can both improve the sensible heat storage capacity of backfill materials.

Thermomechanical Properties of a Concrete Composed of Cherry Tree Resin and Expanded Clay (Exclay) Aggregate

Expanded clay (exclay) aggregate and cherry tree resin are used in this study to produce a lightweight construction material. Based on the grain diameter, exclays are classified as d = 2–4 mm and d = 4–6 mm. Cement is added to each group as the binder material. The exclay ratios vary as 10%, 20%, 30%, 40% and 50% of the total volume in the samples. The cherry tree resin is poured into the concrete mixture with a ratio of 1% and 1.5% of cement + exclay mixture in order to form artificial pores in each sample group. The produced samples are subjected to some tests, such as thermal conductivity, water absorption and compressive strength. It is determined that due to the increase in exclay ratios and particle diameter, there is an increase in porosity along with water absorption, but there is a decrease in density, thermal conductivity and compressive strength. Hence, these newly produced concretes are recommended for panel walls, brick, concrete briquettes, inner and outer plaster and concrete partition elements.

EXPERIMENTAL STUDY ON BEHAVIOR OF RECYCLED AGGREGATE IN CONCRETE

Concrete is one of the most widely used construction material in the world. Increase in population growth is leading to increase in various demands like cultivation, transportation, construction etc. Nowadays, there is a tremendous increase in the demand for construction works like residential buildings, bridges, dams, roads etc. and because of this increase in demand the availability of sources for concrete ingredients is getting difficult. Hence people are looking for alternative sources for the concrete ingredients in order to full fill their requirements. This dissertation work deals with the study of strength of concrete incorporating Recycled Aggregate concrete(R.A.C).The main objective of this investigation is to find out up to what percentage the Natural Coarse Aggregate(N.C.A) can be replaced by recycled coarse aggregate(R.C.A) in the concrete mix and to find out the extra quantity of cement to be added for each percentage replacement byR.C.A. to achieve its target mean strength. In this ongoing project work it is concentrated only on the use of R.C.A. A series of tests were carried out to determine the compressive strength, split tensile strength, flexural strength with and without recycled aggregates. Natural coarse aggregates in concrete were replaced with 0%, 20%, 40%, 60%, 80% and 100% of crushed concrete coarse aggregates. For the strength characteristics, the result showed a gradual decrease in compressive strength, split tensile strength, flexural strength and modulus of elasticity as the percentage of recycled aggregate is increased. Key Words: Natural Coarse Aggregate, Recycled coarse aggregate, compressive strength, split tensile strength, flexural strength.