Compressive Strength Characteristics Research Articles

Physical Properties of an Eco-Sustainable, Form-Stable Phase Change Material Included in Aerial-Lime-Based Mortar Intended for Different Climates.

The aim of this experimental investigation was to produce a form-stable phase change material (PCM) able to reduce the need for nonrenewable energy resources required for the heating/cooling of buildings located in regions characterized by different climatic conditions. The innovative PCM must also be sustainable and must be produced according to the principles of the circular economy. To achieve such ambitious goals, a form-stable, sustainable PCM was produced through vacuum impregnation. The form-stable PCM was produced starting from a low-toxicity, low-flammability polyethylene glycol of medium molecular weight (PEG 800), which was included in porous stone granules obtained as waste products of the cutting/processing of local (Lecce) stone. The thermal properties and thermal stability of PEG 800 and of its PCM-composite were evaluated by employing differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). The appropriate parameters to perform the impregnation procedure were identified through rheological and calorimetric analyses. A simple leakage test was performed to assess if the PEG polymer can leak from the stone flakes. Finally, the new PCM was added as an aggregate in aerial-lime-based mortars, and the mortar’s properties were analyzed in fresh (workability) and hardened (flexural and compressive strength and thermal characteristics) states for potential applications, particularly in ancient buildings.

Compressive Strength Characteristics of Long Tubular Bones after Hyperthermal Ablation

Thermoablation is used in the treatment of tumorous bones. However, little is known about the influence such thermal treatment has on the mechanical properties of bone tissue. The purpose of this work was to study the influence of thermal treatment in a range of 60–100 °C (in increments of 10 °C) on the structural properties of pig femurs using an original approach that involved a periosteal arrangement of heating elements providing gradual dry heating of the bone from its periphery to its center. Heating of freshly extracted bone tissue segments was performed ex vivo using surface heaters of a Phoenix-2 local hyperthermia hardware system. Mechanical testing followed the single-axis compression scheme (traverse velocity of 1 mm/min). In the 60–90 °C range of heating, no attributes of reduced structural characteristics were found in the samples subjected to thermoablation in comparison to the control samples taken from symmetric areas of adjacent cylinders of healthy bones and not subjected to heat treatment. The following statistically significant changes were found as a result of compressing the samples to 100 °C after the heat treatment: reduced modulus of elasticity and increased elastic strain (strain-to-failure), mainly due to increases in plastic deformation. This finding may serve as evidence of a critical ex vivo change in the biomechanical behavior of bone tissues at such temperatures. Thus, ex vivo treatment of bone tissue in the thermal range of 60–90 °C may be used in studies of thermoablation efficiency against tumor involvement of bones.

Effect of volcanic ash as partial replacement of ground-granulated blast-furnace slag based alkaline activated mortar

Volcanic ash obtained from Mount Sinabung is an aluminosilicate material that is generally available deposited in the land of Sinabung. The study focuses to investigate the effect of volcanic ash as partial replacement of ground-granulated blast-furnace slag (GGBFS) based alkaline activated mortar (AAM) in varying six ratios from 10 wt.% to 60 wt.% in terms of the compressive strength (CS) and structural characteristics. The six-mixture design of AAM was conducted with addition of alkaline activator solution (AAS) to solid material. The AAS were prepared from a combination of 10 M NaOH and Na2SiO3, whereas, solid materials consisted of GGBFS, VA and fine aggregates. The results of the experiments were analysed by CS at the age of 7, 28, and 56 days and supported by SEM characterization for the optimum mixture. The results have revealed that the least significant factor in terms of compressive strength value is the addition of volcanic ash content whereby the highest value of 93.50 MPa produced by Va 10% and the lowest of 35.80 MPa from Va 60% for all of ages day. In addition, the regression linear values show the overall compressive strength decreased slowly over the ages. Contrastingly, the addition of volcanic ash higher than 40% exhibited an increment of compressive strength. Based on SEM observation dense and continuous microstructure was observed which reflects a high degree of polymerization reactions. At the same time, no cracks were observed in the surface microstructure that shows proper aggregate-binder bonding that influences the compressive strength results finding.

Effect of Biopolymeric Stabilization on the Strength and Compressibility Characteristics of Cohesive Soil

Sustainable engineering discourages the use of conventional soil stabilizers such as lime and cement owing to their higher carbon emission rates. To address these challenges, many researchers considered biopolymer stabilization, a promising green technique in geotechnical engineering practice for treating expansive soils. This study evaluated the performance of two biopolymers, xanthan gum (XG) and guar gum (GG), in improving the unconfined compressive strength (UCS) and consolidation characteristics of an expansive soil subjected to different testing conditions. The dosage of the biopolymers (XG and GG) was maintained at 0.5%, 1%, 2%, and 4% by weight of dry mass of soil mass. Biopolymer treated samples were subjected to desiccator and natural curing conditions (i.e., specimens were exposed to different temperature and relative humidity conditions) for 7, 14, 28, 45, and 60 days. Results showed that the UCS of biopolymer-treated soil increased with increased dosage up to 2% and 1% for XG and GG, respectively; strength significantly improved during the first 28 days of curing under controlled conditions. Improvement of strength was due to increased adhesive strength between gum strands and soil particles. One-dimensional fixed-ring oedometer consolidation test results indicated that the compressibility and swelling characteristics of biopolymer-treated soil increased due to the hydrophilic nature of gum and an increase in the repulsive forces between negatively charged clay particles and the respective functional groups of XG and GG. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were performed on both untreated and biopolymer-treated soil to evaluate the interaction mechanism between soil and biopolymer strands. The microlevel studies confirmed the crosslinking of soil particles by gum strands, which aids in the strength improvement.

Use of Waste Ceramic as Aggregate in Concrete

Abstract: This research paper represents the experimental study on use of ceramic waste material as an aggregate in concrete. To reach the goal of sustainable development utilization of waste materials in concrete production is very much useful. The ceramic aggregate used in this study was recycled from industrial ceramic tile waste in India. From the results it can be seen that it is possible to produce a concrete with good strength by using ceramic waste as an aggregate in .It is also seen from the results that the compressive strength characteristics of ceramic aggregate concrete met the required criteria set by various international standards and codes, which shows the ability of ceramic waste to be used as a substitute to the conventional aggregates in concrete. We replaced the coarse aggregate in concrete by 100% to thewaste ceramic aggregate of size 10mm. The water cementratio taken was 0.30 for concrete production and compared it with normal aggregate concrete of M20 grade. By the decrease in water/cement ratio, high strength concrete canbe obtained. But it is found that the workability will be very low. In our project the required workability was achieved by the use of maximum water-cement ratio .To overcome this use of several admixtures like super-plasticizers and silica fume are recommended to add in the mixing so that the workability can be improved. Keywords: Sustainable development, Ceramic waste as aggregate

Performance of Cement Mortar Containing Micro and Ultrafine Metakaolin Binders

Research into the usage of locally available construction material is essential and beneficial in ensuring a cost-effective construction project. One of the natural resources that be used as supplementary cementitious material is metakaolin. This research aims to investigate the performance of mortar reinforced with micro- and ultrafine metakaolin based on compressive strength and water absorption tests. Locally sourced metakaolin was mixed in cement mortar after calcined at 800C with a variation amount of 0%, 5%, and 10% by wt. The tests were conducted on the 50mmx50mmx50mm cube specimens after water curing at 7 and 28 days, following the ASTM-standards. Results show that specimens containing 10% of micro- and ultrafine-metakaolin (MK-10 and UM-10) exhibited the highest compressive strength and better water-resistance characteristics when compared to control mortar. In this case, the addition of 10% ultrafine metakaolin (UM-10) reached the highest compressive strength value with approximately 121% and 100% higher than the compressive strength of control mortar on the 7th and 28th day, respectively. Additionally, the water absorption of UM-10 at 28 days was found to be 86% and 30% lower than PCC and MK-10, respectively. Furthermore, X-Ray Diffraction (XRD) and Thermogravimetric graphs of pastes with micro- and ultrafine-metakaolin indicate a reduction of CH; therefore, the production of more CSH gel. The densification of cement paste with ultrafine-metakaolin is also confirmed by nitrogen adsorption analysis indicating ultrafine-metakaolin's inert filler effect in forming a denser matrix.

Unconfined Compressive Strength and Microscopic Structure Characteristics of Cement Treated Peat Subjected to Crushing and Re-Constitution

Unconfined Compressive Strength and Microscopic Structure Characteristics of Cement Treated Peat Subjected to Crushing and Re-Constitution

Experimental Investigation of Unconfined Compression Strength and Microstructure Characteristics of Slag and Fly Ash-Based Geopolymer Stabilized Riverside Soft Soil.

To solve the issues of insufficient early strength of cement stabilized soil and high resource cost, high reduction cost, and high environmental cost induced by the application of cement, the slag and fly ash-based geopolymer was adopted as the stabilizer to treat riverside soft soil. This study mainly investigated the effects of stabilizer content, slag-to-fly ash ratio, and alkaline activator content on the strength of geopolymer stabilized soils with different curing ages. Unconfined compressive strength (UCS), scanning electron microscope (SEM), and X-ray energy spectrum analysis (EDS) tests were carried out. The results show that the stabilizer content, slag–fly ash ratio, and alkaline activator content have a decisive influence on the UCS of geopolymer-stabilized soil. The mix-proportions scheme of geopolymer stabilized riverside soft soil, with a geopolymer content of 15%, a slag–fly ash ratio of 80:20, and an alkaline activator content of 30%, is considered optimum. It is proven by SEM that the uniformly distributed gelatinous products formed in the geopolymer-stabilized soil bind the soil particles tightly. Moreover, the EDS analysis confirms that the gelatinous products are mainly composed of C-S-H gel and sodium-based aluminosilicate (N-A-S-H).

Measuring Compressive Strength Characteristics of Soil-Dobak-Glue Mixtures over Curing Time

The building materials used by mankind in the past, such as stone, soil, and wood, have been environment-friendly. However, the various building materials invented over time with the development of the industrial age pose problems such as environmental hormone generation and waste generation/disposal. To overcome these problems, building materials based on soil, a traditional building material, are being developed by researchers. However, the improvement in soil’s structural characteristics is insufficient as it excessively emphasizes efficacy and function only. In this study, lime and Dobak-glue were mixed with soil to solve the structural problems and improve the strength of soil, and water content and change in strength in accordance with curing time were tested. In order to understand the change in strength, a compaction test was performed by preparing a standard specimen based on the optimum water content and maximum dry density. The lime mix required optimum water content and quantity of lime equal to 3% of soil weight, while the Dobak-glue mix was prepared by soil mixing in the same weight ratio as optimum water content. Changes in water content and compressive strength were measured over curing time of 3, 7, and 28 days. Three specimens, lime mixed specimen, Dobak-glue mixed specimen, and standard specimen, were prepared, and their water content and compressive strength values were averaged. Although the change in water content according to the curing period differed depending on the material mixed with soil, there was no significant difference between 7.12% and 2.82% after 7 days. As for the change in compressive strength, the initial compressive strength in lime mixed specimen was excellent, but the Dobak-glue mixed specimen displayed the greatest strength after 7 days. To conclude, Dobak-glue is an eco-friendly material, and it can be very useful in compensating for the structural shortcomings of soil.

Characteristic concrete compressive strength of existing structures—Evaluation of EN 13791:2019 for small sample sizes

AbstractIn the sense of resource‐efficient handling of existing structures, conversion should be given priority over demolition and reconstruction of buildings. Accordingly, the assessment of existing structures is becoming increasingly important. Until now, the characteristic concrete compressive strength as one of the most important factors for the evaluation of existing structures has been determined at European level according to EN 13791:2007. Today, the new EN 13791:2019 replaces EN 13791:2007. Especially for small sample sizes of drill cores (3 ≤ n ≤ 7), the introduction of EN 13791:2019 results in significant changes for the determination of the characteristic in situ concrete compressive strength. In addition, there is only limited background information available for the statistical robustness of the new methods. Therefore, the methods for the determination of the characteristic concrete compressive strength of existing structures according to EN 13791:2019 have been evaluated with the help of an existing drill core database established at the TU Kaiserslautern.

Quarry dust as river sand replacement in cement masonry blocks: Effect on mechanical and durability characteristics

Natural sand or river sand constitutes as major fine aggregate in cementitious construction. Especially, masonry block production requires 70–90% sand as raw material. While the demand for river sand increases rapidly, the supply of good quality river sand is limited due to the restrictions in sand mining in river beds. Because excessive extraction of river sand to cater the increasing demand has brought undesirable environment-related consequences. The persisting issues encouraged the researchers to find a sustainable alternative for river sand. Quarry dust is one of the alternatives as it has some advantages over river sand such as better contribution to the strength of the cementitious material, better workability, lesser cement consumption and eco-friendly. The present study explored the feasibility of using quarry dust as fine aggregate in manufacturing cement blocks. Cement blocks with four different quarry dust composition levels 0, 33.3%, 66.7 and 100%, were prepared and tested. The testing included determination of mechanical characteristics (compressive and flexural strength) and durability aspects (sorption, evaporation, wet and dry cycle, resistance against salt, alkaline and acid solution). The test results exhibited that mechanical characteristics and resistance against wet and dry cycles improved when quarry dust completely replaced river sand as fine aggregate. When quarry dust content increased, the cubes subjected to severe environmental conditions exhibited higher strength reduction rates compared to that of normal environmental condition. The final strength, however was higher than the corresponding cubes with river sand. In addition to strength improvement, quarry dust replacement yielded lesser cost and sustainable benefits, which would promote the deployment of quarry dust in cement-sand block production.

Impacts of Water Content and Temperature on the Unconfined Compressive Strength and Pore Characteristics of Frozen Saline Soils

Frozen saline soils have complex components and are sensitive to temperature, water content, salinity, and pressure, resulting in complicated mechanical properties and pore characteristics. In this paper, laboratory investigations were carried out to measure the compressive strength, porosity increment, and failure modes of frozen saline soils under five water contents (10, 15, 20, 24, and 26%) and five freezing temperatures (−5, −10, −15, −20, and −25°C). Results indicated that with the increase of water content and the decrease of freezing temperature, the compressive strength and peak strain of frozen saline soils become larger, and the brittle failure characteristics become more significant. When the temperature is below −15°C, the degree of freezing will dramatically increase as temperatures drop. Besides, the porosity increment of frozen saline soils shows a linear change with the water content and temperature. According to the results, this increment increases by 0.48–0.55% for every 1% increase in initial water content, and by 0.20 – 0.28% for every 1°C decrease in freezing temperature. In addition, the splitting failure caused by tensile stress is the primary failure mode of frozen saline soils. The results are useful in designing, constructing, maintaining, and upgrading the tundra engineering in China.

ПОСТРОЕНИЕ ДИАГРАММЫ СЖАТИЯ ДЛЯ БЕТОНА С КОСВЕННЫМ АРМИРОВАНИЕМ В РАМКАХ ТЕОРИИ ПРЕДЕЛЬНЫХ СОСТОЯНИЙ

When constructing a stress-strain compression diagram for concrete with indirect reinforcement within the framework of the theory of limit state design, it is necessary to assign the strength values of materials with the required security. To do this, a transition is made from average strength value obtained from the results of experiments to reduced characteristic compressive strength and the design value of strength. In view of this, a contradiction arises due to the fact that initially the formulas for determining the deformations corresponding to the top of the compression diagram were obtained for experimental value of strength, and in the calculations of structures it is proposed to use reduced characteristic compressive strength and the design value of strength, which can lead to incorrect results. The article compares the calculated values of strains with experimental data and notes a significant overestimation when calculating by the characteristic compressive strength and the design value of strength.

Experimental investigation of high carbon steel MMC for crown pinion gear

The implementation of high carbon steel composite is growing continuously in the field of automotive and manufacturing industries because of their superior physical, mechanical and tribological properties as compared to normal steel. In automobiles, the differential plays major role to power transmission from engine to wheel. However, failure of crown pinion observed that the gear teeth have been sheared off by heat failure and edge of pinion gear is worn down caused by lubricant failure. So, this high carbon steel composite (high carbon steel + silicon carbide) could be proposed for crown pinion gear to control material wear and fracture. In this paper, the various proportions of high carbon steel composites were investigated and evaluated the characteristics of material hardness, compressive strength and material wear. The material proportions were 100–0 %, 99–1 % and 97.5–2.5 % of high carbon steel with silicon carbide. By observing experimental results, the high carbon steel with 2 % of silicon carbide have better material characteristics than other proportions and this also suggested to crown pinion gear production.

Investigating the fresh state performance of concrete containing iron slag and recycled concrete aggregates

Iron slag (IS) is a major industrial waste produced in the iron and steel manufacturing industry and is widely generated around the globe in significant quantities. A large amount of IS usually dumped in open lands poses a serious ecological threat. Also, construction and demolition waste generated from the construction sector posed similar threats to the environment. The growing concern of land abuse can be minimized with the utilization of such industrial by-products in the production of concrete which is one of the most demanding construction materials. The current experimental study orients towards understanding the workability as well as compressive strength and water penetration characteristics of concrete containing IS and recycled concrete aggregates (RCA). The natural coarse aggregates (NCA) were replaced by 25% and 50% with RCA and fine natural fine aggregates (NFA) were substituted with 30% of IS. Three different tests (Slump Flow, Vee-Bee Consistometer, and Compacting Factor Test) were performed for evaluating the performance of fresh state concrete containing IS and RCA at different percentages. Compressive strength tests were also performed on cylindrical specimens after 7, 28, and 56 days of curing. Water Penetration test was also conducted to assess the permeability characteristics of IS-RCA based mixes. The inclusion of IS enhanced the workability, compressive strength development, and permeability characteristics of RCA-based concrete as concrete prepared with 30% of IS and 25% RCA exhibited higher workability, compressive strength, and water penetration resistance in comparison with the control mix and mix prepared with RCA. Thus, the present results encourage the use of IS and RCA (up to a particular replacement level) in concrete manufacturing to maintain appropriate workability conditions.

Statistical Characteristics of compressive strength of Normal & High strength concrete and concrete made with recycled aggregate

The paper presents the statistical analysis on the compressive strength of concrete with strength ranging from 30 MPa to 130 MPa. To obtain these concrete strengths, concrete mixes with virgin aggregates were prepared with four different wate r to cementitious content (w/c) ratios i.e., 0.45, 0.36, 0.24, and 0.18. With w/c ratio of 0.45, a mix is also designed using recycled construction and demolition coarse aggregate to compare statistical characteristics with respect to concrete made using virgin aggregates. The presented statistical analysis includes measure of central tendency, dispersion of the data, distribution shape properties, and precision of the mean. A normal and a log-normal distribution has been established and validated for the experimental data set of all the mixes. A correlation has also been established for the compressive strength of 100mm cube and 150mm cube. Analysis shows an increase in dispersion of data with increase in the mean compressive strength of the mix. The mix with Construction and demolition waste aggregate shows a higher standard deviation than the mix with virgin aggregates at the same w/c ratio. The correlation curve for the compressive strength of 100 mm and 150 mm size cubes, shows a conversion factor of 1.04, suggesting an insignificant difference of the compressive strength values of 100 mm and 150 mm cubes for the mix studied.

Analysis of the Accuracy of In-Situ Concrete Characteristic Compressive Strength Assessment in Real Structures Using Destructive and Non-Destructive Testing Methods

Analysis of the Accuracy of In-Situ Concrete Characteristic Compressive Strength Assessment in Real Structures Using Destructive and Non-Destructive Testing Methods

Unconfined Compressive Strength Characteristics of Treated Peat Soil with Cement and Basalt Fibre

So far many studies have focused on the mechanical behavior of fibre reinforced soils and stabilized soils with conventional chemical stabilizers such as cement and lime; however, very limited researches were conducted on the unconfined compressive strength characteristics of fibre reinforced cement stabilized peat soils. Fibre-reinforcement of a stabilized soil resulted in a significant improvement in the ductility and strength characteristics of weak or soft soils. The main objective of the current study is considering the effects of cement content, fibre content, fibre length and curing time on the unconfined compressive strength (UCS) of peat soil. The study finds that adding basalt fibre or cement causes a remarkable increase in the UCS values of peat soil. The UCS value of the cement-stabilized sample is observed significantly more than basalt fibre-reinforced ones. However, the sample reinforced with basalt fibers showed more ductile behavior compared to the stabilized sample with cement. The results showed that the increase in UCS values of combined basalt fibre and cement inclusions was more than the increase caused by each of them, individually.

Compressive strength of SF and FA based self curing HSSC: An experimental study

Typical High-strength concrete (HSC) mixtures are characterized by low water-cementitious material ratio, high content of cementitious material, and the incorporation of admixtures. Concrete needs a favourable atmosphere by providing moisture for a minimum base period of 28 days for hydration and to attain targeted strength. In the present scenario of water scarcity, the water required for curing concrete is a troublesome constraint. Self-curing concrete is one of the peculiar concretes for coping with insufficient curing caused by human error. The prime goal of this study is to identify the self-curing compound’s optimum dosage for High Strength Self-Compacting Concrete (HSSC). Likewise, it is aimed to investigate the compressive strength characteristics of HSSC. For the study, a self-curing agent namely “PEG-400” with varying percentages (0.5%, 1%, 2% & 3% by weight of cement) was investigated. An attempt was made to identify the effect of the self-curing compound on the fresh and hardened properties of HSSC, workability tests and compressive strength tests were conducted. The tests on hardened concrete were conducted after curing for 28 days for conventional HSC specimens and ambient curing for HSSC. It was observed that with the addition of 1% of PEG-400 self-curing compound, the compressive of HSC was found to be increased by 1.86% in comparison with the conventionally cured HSC. It was observed that with the addition of 1% of PEG-400 self-curing compound, the compressive strength of HSSC was found to be increased by 1.87% in comparison with the conventionally cured HSSC.

Study on the Compressive Properties and Factors of Recycled Mixture with High Content of Iron Tailings Sand

This paper focuses on the disposal of iron tailings sand (ITS) and recycled aggregate of inorganic (RAI) and proposed the “ITS plus RAI” solid waste treatment methods, which uses ITS and RAI as a new base course material to replace new aggregates by 100% to apply in the pavement renovation project of national and provincial roads in Linfen city, Shanxi Province. In this paper, the compressive strength characteristic of recycled mixture with different ratios is studied for the dual waste treatment methods, and the influence factors are analyzed by multiple regression analysis. Results show that the strength of the recycled mixture composed of a high content of ITS (the mass ratio to RAI exceeds 60 : 40) ups to 7 MPa, which can meet the pavement requirements of 7d unconfined compressive strength of inorganic stabilized base material under various traffic load conditions. The factors affecting the strength of recycled materials include the content of various components, while the particle size of iron tailings sand is the most significant influence factor. Therefore, the proportion of iron tailings sand in the recycled mixture can be further improved by screening coarse iron tailings sand so as to maximize the content of iron tailings sand, which will lead to an excellent engineering value.