Compressive Strength Of Concrete Samples Research Articles

The Effect of Adding Slag, Achieved from Wastewater Sludge Incineration in Fluidized-Bed Furnace, on the Quality of Concrete

Abstract Due to a constant increase in generating the amount of sewage waste it is necessary to find an alternative method of its use or disposal. One of such methods can be utilization of sewage sludge in construction materials industry, particularly in concrete technology and other materials based on cement. It allows using waste materials as a passive additive (filler) or also as an active additive (replacement of part of bonding material). The article aims at presenting the analysis of the effect of adding slag, achieved from wastewater sludge incineration in sewage treatment plant, on properties and quality of concrete mix and hardened concrete. Using an experimental method, the researcher designed the composition of the control concrete mix, which was then modified by means of slag. For all concrete mixtures determined – air content with the use of pressure method and consistency measured by the use of concrete slump test. For all concrete series the following tests were conducted: compressive strength of concrete after 7, 28 and 56 days of maturing, frost resistance for 100 cycles of freezing and thawing, water absorption. The use of slag, ground once in the disintegrator, causes a decrease of in compressive strength of concrete samples in relation to the control concrete series as well as bigger decrease in compressive strength after frost resistance test.

Experimental and microstructural study of the compressive strength of concrete samples containing low volumes of expanded polystyrene beads

The partial replacement of aggregates with expanded polystyrene (EPS) beads is a common technique to produce lightweight concretes. Much research have been already conducted on the compressive strength of EPS concretes containing high volumes of EPS beads. In the current study, however, specimens with low EPS volume contents are also examined. The results show that all the strength versus EPS volume content graphs initiate with a nearly plateau region. The length of this plateau region is found to be an increasing function of W/C ratio. It is also observed that the replacement of redundant water with the EPS beads initially improves strength but the trend is reversed beyond a critical volume content. Finally, the new empirical findings are interpreted and justified based on the underlying microstructural failure mechanisms. The results of this study can lay fresh grounds for the development of more realistic micromechanical and numerical models for EPS concrete.

Влияние пластифицирующих добавок на процесс твердения бетона в условиях сухого жаркого кли-мата

The negative impact of a dry hot climate on the strength characteristics of heavy concrete is considered. At elevated air temperatures, significant evaporation of moisture from the solidified concrete mix may subse-quently lead to the formation of cracks and other deformations in the concrete body. The abovementioned problems can be prevented by introducing plasticising additives into the concrete mix. The compressive strengths of concrete made of concrete mixtures with different percentages of plasticising agents and ex-posed to elevated temperatures are determined in the study. The compressive strength of the studied sam-ples was determined in accordance with GOST 10180-2012 “Concretes. Methods for determining the strength of the control samples." The optimum amount of the additive CentramentAir 202 in concrete is 0.25% by weight of cement, while the increase in compressive strength of concrete is 11.5% at the age of 14 days and 1.7% at the age of 28 days, in relation to the compressive strength of the control composition. The in-troduction of the hyperplasticiser MC-PowerFlow 2695 in the amount of 0.4 to 0.6% by weight of cement reduces the compressive strength of concrete samples by an average of 29% at the age of 14 days and by 39.4% at the age of 28 days. Superplasticiser CentramentN 101 in an amount of from 0.6 to 1% by weight of cement reduces the compressive strength of concrete samples by 11.5% ÷ 35% at the age of 14 days and by 19–37.4% at the age of 28 days. The optimal amount of MC-Techniflow 70 additive in concrete is 1.2% by weight of cement, while the compressive strength of concrete is increased by 2.1% at the age of 14 days and by 0.6% at the age of 28 days. According to the results of the experiments, a highly plasticis-ing additive MC-Techniflow 70 with an optimal dosage in the amount of 1.2% by weight of cement was acknowledged as effective, allowing to obtain high strength characteristics both at 14 days of age (29.2 MPa) and at 28 days of normal hardening (35.0 MPa).

Influence of Water Reducer on Concrete Compressive Strength under Wind Erosion

In this paper, using flow sand jet erosion, erosion tests were performed on concrete samples of the same strength grade with standard and retardation type water reducing agent respectively, study the erosion rate and the impact of compressive strength of concrete samples with erosion time and wind speed during erosion.

Parameters of Concrete Modified with Glass Meal and Chalcedonite Dust

Additives used for production of concrete mixtures affect the rheological properties and parameters of hardened concrete, including compressive strength, water resistance, durability and shrinkage of hardened concrete. By their application, the use of cement and production costs may be reduced. The scheduled program of laboratory tests included preparation of six batches of concrete mixtures with addition of glass meal and / or chalcedonite dust. Mineral dust is a waste product obtained from crushed aggregate mining, with grain size below 0,063μm. The main ingredient of chalcedonite dust is silica. Glass meal used in the study is a material with very fine grain size, less than 65μm. This particle size is present in 60% - 90% of the sample. Additives were used to replace cement in concrete mixes in an amount of 15% and 25%. The amount of aggregate was left unchanged. The study used Portland cement CEM I 42.5R. Concrete mixes were prepared with a constant rate w / s = 0.4. The aim of the study was to identify the effect of the addition of chalcedonite dust and / or glass meal on the parameters of hardened concrete, i.e. compressive strength, water absorption and capillarity. Additives used in the laboratory tests significantly affect the compressive strength. The largest decrease in compressive strength of concrete samples was recorded for samples with 50% substitutes of cement additives. This decrease is 34.35%. The smallest decrease in compressive strength was noted in concrete with the addition of 15% of chalcedonite dust or 15% glass meal, it amounts to an average of 15%. The study of absorption shows that all concrete with the addition of chalcedonite dust and glass meal gained a percentage weight increase between 2.7 ÷ 3.1% for the test batches. This is a very good result, which is probably due to grout sealing. In capillary action for the test batches, the percentage weight gains of samples ranges from 4.6% to 5.1%. However, the reference concrete obtained the lowest water absorption as compared to other batches.

Feasibility Study of the Potential Use of Drill Cuttings in Concrete

Increasing the need of energy and its high price tempts companies to drill more oil wells every day and create more drilling waste. Most of these drilling wastes are managed to be disposed but they will always have many environmental impacts. Therefore, this study investigates the potential of using drill cuttings in concrete as a partial replacement of cement. The innovation of this study is not only to produce a new and cost-effective material from drill cuttings, but also to mitigate its negative environmental impacts. To achieve this objective, laboratory studies carried out to quantify the compressive strength of concrete samples and to determine the chemical composition of drill cuttings. Results showed that replacing 5% of cement with dried drill cuttings reduces the compressive strength of concrete by 10%. However, comprehensive strength of concrete samples decreases by 20% when replacing 10, 15, and 20% of cement with drill cuttings. Furthermore, the effect of some additives such as fly ash and silica fume on the compressive strength of the concrete samples containing drill cuttings was studied. It was concluded that adding these additives have a significant influence on the compressive strength of concrete samples containing 20% drill cuttings.

A Study on the Effect of Time Duration by Vibrating or Tamping Fresh Concrete on the Compressive Strength of C-25 Concrete

Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In Ethiopia, there is no enough knowledge by the laborers, while the site engineers ignored the correct application due to some constraints. The agreement of acceptable vibration level in fresh concrete to which tamping time duration is optimum is an issue to obtain the desired specific compressive strength. This research study aims to evaluate the maximum time length and techniques used to the Vibrating or Tamping fresh concrete and its effect on the compressive strength of C-25 Concrete through internal Rodding. Therefore, to study the effects of the period by vibrating or tamping, the needle type internal vibrator was used to test new concrete cubes based on ACI309R-96. The quality of concrete is important to make physical tests on materials used before any actual experiments to perform. The fresh concrete samples tested by using internal vibration methods and techniques of compaction with different time duration of 1sec, 2sec, 3sec, 4sec, and 5sec. These tests performed by using steel rod in fresh concrete to know the Optimum time of compaction by internal vibration on the cube test of new concrete. Laboratory experiments had been conducted to check the methods and techniques applied to construction sites, as well as site observation on the effects of the vibration time of fresh concrete on the compressive strength and flexural strength of C-25 Concrete with varying vibration time duration and steel rod tamping. Based on the results of cube tests of compressive strength of Concrete Samples have been checked at 3rd day, 7th day and the 28th day. This research study found out that the Optimum period of compaction was 3sec to produce an acceptable right quality of the concrete mix. Likewise, the flexural strength of Concrete Sample, when it tested in the laboratory at 7th day and 28th day, the results revealed that the flexural strength improved when vibration time increased, but the amount of water has to be reduced to obtain the desired strength. Finally, Tamping is needed to place fresh concrete in the mold correctly. Furthermore, new concrete produced should match the properties and avoid improper tamping or vibration applications. This situation must not cause differences in compressive strength of concrete.

Estimating of Compressive Strength of Concrete with Artificial Neural Network According to Concrete Mixture Ratio and Age

Compressive strength of concrete is one of the most important elements for an existing building and a new structure to be built. While obtaining the desired compressive strength of concrete with an appropriate mix and curing conditions for a new structure, with non-destructive testing methods for an existing structure or by taking core samples the concrete compressive strength are determined. One of the most important factors that affects the concrete compressive strength is age of concrete. In this study, it is attempted to estimate compressive strength, modelling Artificial Neural Networks (ANN) and using different mixture ratios and compressive strength of concrete samples at different ages. In accordance with obtained data’s in the estimation of concrete compressive strength, ANN could be used safely.

A survey of the mechanical properties of concrete for structural purposes prepared on construction sites

Abstract This paper aims to study the concrete dosage conditions for structural purposes in construction sitesl, and the impacts of non-compliance of structural concrete for structural safety, having as study case the city of Angicos / RN. Were analyzed the dynamic elasticity modulus, static elasticity modulus and the compressive strength of concrete samples. Was conducted to collect the survey data, a field research aiming to gather information about dosage of concrete used in the works, as well as the collection of cylindrical specimens of 150 mm diameter by 300 mm of height, prepared according to practice of those professionals. The study indicated a clear necessity to reflection on the subject, since there is no concern, or even, a lack of knowledge by the interviewed professionals regarding the care and procedures necessary for the production of concrete with satisfactory quality, once at least 50% of evaluated construction sites presented compressive strength lower than 20 MPa, minimal strength to structural concrete, as recommended by ABNT-NBR 6118:2014.

Temperature Reduction of Concrete Pavement Using Glass Bead Materials

In this study, different proportions of glass beads used for road marking were added into the concrete samples to reduce the temperature gradient through the concrete pavement thickness. It is well known that decreasing the temperature gradient reduces the risk of thermal cracking and increases the service life of concrete pavement. The extent of alkali–silica reaction (ASR) produced with partial replacement of fine aggregate by glass bead was investigated and compressive strength of concrete samples with different proportion of glass bead in their mix designs were measured in this study. Ideal results were obtained with less than 0.850 mm diameter size glass beads were used (19 % by total weight of aggregate) for C30/37 class concrete. Top and bottom surface temperatures of two different C30/37 strength class concrete slabs with and without glass beads were measured. It was identified that, using glass bead in concrete mix design, reduces the temperature differences between top and bottom surfaces of concrete pavement. The study presented herein provides important results on the necessity of regulating concrete road mix design specifications according to regions and climates to reduce the temperature gradient values which are very important in concrete road design.

Concrete with organic mineral admixture based on fine grinding cooper slag

The problem of applying copper manufacturing wastes locating in Chelyabinsk region as a component of organic mineral admixture for concrete with industrial wastes production is considered in this article. Also, organic mineral admixture consisting of superplasticizers, based on esters with carboxyl groups, has not yet been sufficiently studied due to the diversity of species and the complexity of chemical structure. This trend is current for today’s science because of the growing rates and scales of building production, in particular, concrete works. Using new complex admixtures processed of industrial by-products showed their effectiveness. Copper slag dumps located in Urals federal district haven’t been widely used in building production or in other industrial production up to the present time. Efficient utilization of copper production waste materials will help to solve the ecological problems in most regions of Russia. The structure formation period of cement stone with organic mineral admixture, based on fine grinding cooper slag and superplasticizer, is also studied in the article. The thermal variation diagram of concrete mixture with organic mineral admixture during 22 hours of hardening under normal condition are shown and the results of ultrasound of concrete forming structure period during 6 hours of hardening are presented in this article. The strength development process diagram of concrete with organic mineral admixture during 28 days of hardening under normal condition and the research results of the compressive strength of concrete samples are also presented. The obtained characteristics confirm the prospects of applying this kind of non-ferrous metallurgy wastes in the concrete. Also, the obtained results allow us to conclude the significant advantages of using this kind of complex admixture for concrete production with different purpose and in different fields of application.

The effects of using Micro-SiO2 with Ground Granulated Blast-Furnace Slag of Esfahan Steel Company in Concrete

In this study, the properties of concrete with different amounts of Ground Granulated Blast-Furnace Slag (GGBFS) has been studied. In another part, the test deals to assess the properties of concrete containing GGBFS with micro-SiO2. The results show that the slag has pozzolan properties and its use up to 20% in the concrete, has no harmful effect on concrete properties. The simultaneous use of micro-SiO2 with blast furnace slag have little effect, as well as micro-SiO2 covers the defects caused by the use of slag. The results indicate that the use of micro-SiO2 and slag has good effects on the strength of concrete up to a certain age, so that its compressive strength is increased. Water-cement ratio was 0.42 and 12.5 mm for maximum size of aggregate and cement content in concrete was 425 kg per cubic meter. Compressive strength of concrete samples was measured at ages 7, 28, 56 and 90-day and flexural and tensile strength and water absorption after 28-day and 90 days also was measured.

Feasibility Study of the Potential Use of Drill Cuttings in Concrete

Increasing the need of energy and its high price tempts companies to drill more oil wells every day and create more drilling waste. Most of these drilling wastes are managed to be disposed but they will always have many environmental impacts. Therefore, this study investigates the potential of using drill cuttings in concrete as a partial replacement of cement. The innovation of this study is not only to produce a new and cost-effective material from drill cuttings, but also to mitigate its negative environmental impacts. To achieve this objective, laboratory studies carried out to quantify the compressive strength of concrete samples and to determine the chemical composition of drill cuttings. Results showed that replacing 5% of cement with dried drill cuttings reduces the compressive strength of concrete by 10%. However, comprehensive strength of concrete samples decreases by 20% when replacing 10, 15, and 20% of cement with drill cuttings. Furthermore, the effect of some additives such as fly ash and silica fume on the compressive strength of the concrete samples containing drill cuttings was studied. It was concluded that adding these additives have a significant influence on the compressive strength of concrete samples containing 20% drill cuttings.

Investigation of Composite Deflocculant Influence on the Properties of the Refractory Castable with Chamotte Aggregate

The influence of different types of deflocculants, PCE and sodium tripolyphosphate, on the rheological properties of the cement matrix was studied. It was established that composite deflocculant consisting of sodium tripolyphosphate and PCE Castament FS 20 provides the best rheological properties of the cement matrix and affects the composition of the hydration products. During the drying process of matrix with composite deflocculants mineral stratlingite additionally formed, which contributes to increment of strength properties. Comparative studies of refractory castable strength properties with chamotte aggregate showed that the compressive strength of concrete samples with composite deflocculants after hardening and after drying and burning is almost two times higher than the strength of samples with separate deflocculants.

The effect of cure conditions and temperature changes on the compressive strength of normal and fly ash-added concretes

The aim of this study was to examine compressive strength of fly ash-added concrete and normal concrete cured in water and air and to compare their compressive strength on the 7th, 14th, 21st and 28th days. In addition, the study investigated temperature-induced changes in the compressive strength of concrete samples which completed 28 day cure period. While the compressive strength of concretes cured in air was observed to be higher in early days, it was detected to be higher in concretes cured in water in later days. It was also determined that the compressive strength of fly ash-added concrete was lower than that of normal concrete. In addition, no significant change was observed in the strength of both concrete types at the temperatures up to 400°C, but significant changes were noted over 600°C and the compressive strength of both concrete types decreased by 80% at 800°C Key words: Fly ash, concrete, cure conditions, compressive strength, elevated temperature.

Application of Results of Nondestructive Testing Methods in the Investigation of Microstructure of Refractory Concretes

The aim of this investigation is to establish the correlation between concrete porosity, compressive mechanical strength, and microstructure using the results of nondestructive testing methods, i.e., ultrasonic pulse velocity (UPV) and image analysis. Researchers and engineers usually use results of standard laboratory procedures in order to obtain mechanical properties of a material. That process is long and it requires large number of samples, i.e., a lot of time and lot of material. Image Pro Plus (IPP) and UPV are methods which can provide equally accurate results. These methods are much more simple, rapid, and cheaper. Nondestructive test methods were applied on the corundum and bauxite based refractory concretes. Investigated concretes are varying in chemical and mineralogical composition. Mechanical compressive strength of concrete samples after thermal treatment at various temperatures (110, 800, 1,000, 1,300, and 1,500°C ) was investigated using standard laboratory procedure and afterward with UP...

“Effect of Magnetic Water on Engineering Properties of Concrete”

mail: - E Abstract This research investigates the influence of magnetic water on compressive strength and workability (consistence) of concrete. Results show that the compressive strength of concrete samples prepared with magnetic water increases 10-20% more than that of the tap water samples. In the present study, increasing in compressive strength of concrete is achieved when the magnetic strength of water is 1.2 T, and velocity of water current that passes through magnetic field is of 0.71 m/s. It is also found that magnetic water improves the workability (consistency) of fresh concrete.