Physical Properties Of Concrete Research Articles

Effect of recycled coarse aggregate treated with recycled binder paste coating and accelerated carbonation on mechanical and physical properties of concrete

Construction and demolition waste (CDW) is a viable source of recycled aggregates for the production of concrete. However, recycled concrete aggregate (RCA) usually has inferior properties compared to natural aggregates (NA) mainly due to the mortar bonded to its surface, which directly affects the mechanical and physical properties of concrete. Therefore, in this work it is proposed to strengthen the bonded mortar of low-quality coarse recycled aggregate (CRA) through a combined treatment of coating with a slurry of recycled binder paste (RBP) and accelerated carbonation. Mechanical and physical tests were carried out for concretes with replacements of 50% and 100% CRA and the results obtained were compared with a control series. The results showed an effective improvement in the mechanical and physical properties of the concretes with treated recycled aggregate, achieving in some cases values close to those of the control, even considering the high replacement percentages.

Effect of Cow Dung Ash and Recycled Concrete Aggregates on the Mechanical and Physical Properties of Concrete: Central Composite Design (CCD) Optimisation

Globally, concrete constructions are dependable due to their performance under diverse conditions and the availability of concrete components. However, the potential for waste concrete is high as a result of changes in human needs. For the concrete industry’s sustainable development, the ability to use recycled concrete is very important. This study aimed to investigate the effect of blending cow dung ash (CDA) with cement and waste concrete aggregates with natural coarse aggregates on concrete’s mechanical and physical properties. The approach adopted involved natural coarse aggregates (NCA) substitution with recycled coarse aggregates (RAs) derived from demolished concrete fragments as well as the use of CDA as a fractional replacement for Portland cement in the production of concrete. Response surface methodology with the central composite design (CCD) option was employed in the establishment of the effect of varying the CDA and RA on the mechanical and physical properties of concrete. Results revealed that while embedding elevated amounts of CDA lowered concrete’s compressive strength, a smaller percentage of less than 10% enriched the concrete strength past that of normal concrete. Furthermore, increases in the RA proportions from 20% to 30% translated to increases in the concrete compressive strength. The 5% CDA and 20% RA, 5% CDA and 30% RA and 10% CDA and 30% RA registered 0.88, 7.67 and 3.54% respectively greater than compressive strengths in the control experiment. In relation to water absorption, increases in proportions of CDA and RAs translated in 3.2% to 5.9% greater than water absorption rates in the control experiment. Therefore, optimised concrete of 8.80% CDA and 31.69% RA gives concrete with compressive strength of 36.82 MPa, 2315.4 kg/m3 bulk density, and 5.18% water absorption. However, CDA/RA concrete should not be used in areas where water accumulates and/ or structures that are in contact with water

Prediction of complex strain fields in concrete using a deep learning approach

Stress-strain analysis is pivotal in high-performance concrete composite design, which has traditionally relied on experiments and numerical simulations. However, these approaches are inefficient due to the astronomical number of possible combinations. This paper thus proposes a high-efficient surrogate model utilizing generative deep learning (DL) for complex strain field prediction to address this research topic. A dataset containing 2000 samples with randomly distributed geometries and corresponding strain fields is built as ground truth. A DL model is constructed, trained, and validated to capture the intricate geometry-strain relationships within the dataset. The predictions to material properties demonstrate astonishing accuracies of 0.54% MAPE in strain fields and of 0.96 R2 in deformability ranking. Furthermore, the proposed approach offers remarkable adaptability and extensibility to varied geometries and failure modes, supported by real-world tests. This method significantly enhances the efficiency of evaluating concrete physical properties by leveraging the geometry for direct strain field analysis.

Impact of Sugar Cane Molasses to Concrete Strength and Concrete Retardation

The impacts of sugar cane molasses to the strength and retardation of concrete was investigated in this study. A total of 15 concrete cylinder of size 150mm diameter x 300mm Height with a mix ratio of 1:2:4 were cast with different percentages of sugar cane molasses replacing some proportion of water in the concrete mix. The concrete cylinder was prepared by reducing water by 10-20% with sugar cane molasses in the following percentage, 0.3% by weight of cement of molasses, 0.6% of molasses, 1.2% of molasses and 1.5% of Molasses. The concrete cylinder was cured, tested and the physical properties of concrete were determined. The slump values of the concrete increased by 10mm when the percentage of molasses increases. A decrease in compressive strength was noticed when the percentage of molasses increases. The highest final setting time of 240 minutes occurred at 1.50% of molasses. The increased in retardation of concrete was noticed when the percentages of molasses increases.

A review of GGBS use in the UK and its role in reducing embodied carbon

The current approach to the carbon assessment of concrete uses a system boundary limited to a given project. Where cement replacements such as ground granulated blast-furnace slag (GGBS) are used to reduce carbon, the benefit to the project relies on the assumption that GGBS was a waste product. However, estimation of the historical production and use of GGBS in the UK shows that it has been used in concrete to its maximal extent for two decades or more, mainly due to its low cost and beneficial effects on the physical properties of concrete. Therefore, while specifying GGBS on individual projects gives a carbon saving within the project boundary, it does not reduce emissions at a national level. Given the importance of GGBS from a technical perspective, it is proposed that its use should be focused on these technical benefits, rather than as a low-carbon cement replacement. This, along with likely future supply issues, illustrates the urgency of moving past our dependency on GGBS and focusing on alternatives such as calcined clays, pozzolanas and limestone fines to reduce the carbon intensity of concrete.

Experimental and factorial design of the mechanical and physical properties of concrete containing waste rubber powder

The application of waste rubber in the Civil Engineering is considered one of the most effective solutions for managing this waste. Therefore, the aim of this study is to analyze the effect of rubber substituted in cement on the physical and mechanical properties of concrete using the general full factorial design method, and compare the laboratory results with the results of the JMP pilot test program, and find out if there is a match between the results. The rubber powder is used as a mass substitute in cement at rates of 0%, 2%, 4%, 6% and 8%. The fresh properties were evaluated through workability, air content, and fresh density tests, whereas the hardened properties were assessed using tests of compressive strength, flexural strength, and ultrasonic pulse velocity. These concretes have the workability from 8 to 14.5 cm, fresh density from 2.20 to 2.38 (g/cm3). The air content ranged from 1.2 to 1.9%. Furthermore, the compressive strength ranged from 22.85 to 43.97 MPa, while the flexural strength ranged from 4.86 to 7.03 MPa. In addition, ultrasonic velocity from 3831.42 to 4098.36 (m/s). Accordingly, it was concluded that the concrete with 2% of rubber represented significantly better compressive strength compared to the ordinary concrete. The numerical modeling is assessed to have an appropriate determined coefficient R2 close to 1 for the workability, fresh density, air content, compressive strength, flexural strength, and ultrasonic pulse velocity.

Influence of Water with Oxygen and Ozone Micro-Nano Bubbles on Concrete Physical Properties.

In this study, the possibility of using mixing water containing O2 and O3 micro-nano bubbles (M-NBs) in concrete technology was investigated. In particular, the effect of micro-nano bubbles on the durability and frost resistance of concrete was analyzed. Concretes with two types of micro-nano bubbles were studied. The physical properties of both the modified concretes and the reference concrete were determined, i.e., specific and apparent density, porosity, weight absorption and coefficient of water absorption. Mechanical parameters based on compressive and flexural strength were tested after 14 and 28 days of curing. Concrete durability was determined on the basis of frost resistance and resistance to salt crystallization. The pore distribution in the cement matrix was determined based on porosimetry studies. The use of water with micro-nano bubbles of O2 and O3, among others, contributed to a reduction in the water absorption coefficient from 42.7% to 52.3%, in comparison to the reference concrete. The strength characterizing the concrete with O3 increased by 61% after 28 days, and the frost resistance after 150 F-T cycles increased by 2.4 times. Resistance to salt crystallization improved by 11% when water with O3 was used.

A comparison between mechanical and physical properties of concretes containing superabsorbent polymer and polymers

A comparison between mechanical and physical properties of concretes containing superabsorbent polymer and polymers

Gum Arabic as an Admixture in Modified Concrete Mixed with Calcined Kaolin

The use of calcined kaolin (CK) as a cementitious material in construction has attracted the interest of various researchers due to its environmental, mechanical, and physical qualities, all of which contribute to the lowering of cement usage. Studies have reported numerous problems associated with its use in concrete, apart from the ecological benefit that CK can provide. For instance, there is an issue of increased water demand due to smaller particle size, which generates much more heat in concrete, which has a detrimental effect on the mechanical and physical properties of concrete. This paper presents the analysis of an investigation aimed at using gum Arabic (GA) as a biopolymer admixture and calcined kaolin as a partial replacement of cement to improve the mechanical properties and durability of concrete. GA proportions ranged from 0 to 1% by weight of cement. Calcined kaolin (CK) was used to replace 5, 10, 15, 20, 25, and 30% of the cement content, respectively. Compressive strength, splitting tensile strength, density, strength loss, and weight loss tests were all performed to validate the structural performance of the modified concrete. The compressive tests, performed after 28 days from the time the mixture was made, demonstrated that the maximum percentage of CK that could replace cement without affecting the mechanical properties of concrete was 20%. Beyond 20%, concrete does not exhibit good compressive strength properties. The results also revealed decreased compressive strength and splitting tensile strength tests as the percentage of CK increased. After 56 days, compressive strength at 5% CK and 10% CK increased slightly by 0.743% and 1.162 %, respectively, compared to the control sample. The inclusion of 0.8%GA increased the compressive strength by 8.94% compared to the control sample (0%CK + 0%GA + 100%OPC) after 56 days. The results of durability tests showed that 0.6% GA had a higher compressive strength than other percentages containing GA. Doi: 10.28991/CEJ-2022-08-05-010 Full Text: PDF

Overview of the effect of aggregates from recycled materials on thermal and physical properties of concrete

The effect of adding different aggregates on thermal and mechanical properties of concrete is investigated. The materials used as aggregates are crushed rubber results from wasted tiers, recycled plastics, organic, and inorganic wastes. The mechanical and thermal properties of concert investigated are density, compressive strength, and thermal conductivity. Moreover, data of the drying rate of concrete with compressive strength are shown. The study shows a comparison between modified concrete and traditional one is shown. Results shown that rubberized concrete showed a drop in the compressive strength, thermal conductivity, and density. For example adding 10% of rubber aggregates the compressive strength dropped by 8 MPa for 7 days of drying and 10 MPa for 28 days of drying. The average reduction of thermal conductivity between the three mixes was 0.11W/m.K. The average decline in the concrete density between the three mixes was 122 kg/m3.

Microstructure and physical properties of concrete containing recycled aggregates pre-treated by a nano-silica soaking method

In this work, the properties of nano-silica improved recycled aggregates (NS-RAs) and concrete containing these aggregates have been examined. First, RAs were soaked in nano-SiO2 solutions with five different concentrations (0, 1.0, 1.5, 2.0, and 2.5 wt%), after which the crushing indices and water absorptions of the resulting NS-RAs were determined to identify the optimal soaking conditions. The obtained results showed that the optimal concentration of nano-silica was 2%, which reduced the NS-RA crushing index by 28% as compared with that of untreated RAs. After adding this content of NS-RAs to concrete during preparation, its compressive strength was increased by 20%. Thus, the nano-silica soaking method was proven to effectively heal the defects of RAs and compensate for the loss of the compressive strength of RA-modified concrete.

The Effect of Addition of Ash from Burning Wood Powder to the Mechanical and Physical Properties of Concrete

The wood powder is the waste from woods industry that further used as a mixture of plant soil. Scientist have used the powder of wood to make a particle board. This research, We used the ash of wood powder as an additive thing in the concrete mixture. The test is done for physics and mechanics of the concrete. The sample is made from the ingredients 1 cement : 2 sand : 3 pebble. In variation add to ash of the wood powder for cement is 5%, 10%, and 15%. The result of the researching show that the used of the ash of wood powder can build the impact of the concrete is 9.54% from normal concrete with the mixture of the ash of wood powder is 15%. Orther side for the physics, the water absorption and porosity with the ash of the wood powder is from 4.94% to 14.35% and from 4.16% to 14.89% higher than the normal concrete.

Study on Metakaolin Impact on Concrete Performance of Resisting Complex Ions Corrosion

The main purpose of this study is to determine the metakaolin (MK) impacts on the concrete durability when the concrete is subjected to joint corrosion of SO42−,Mg2+ and, Cl−. Four groups of concrete test samples, which contained different MK contents, were designed and tested in order to see their physical property changes and macro-morphology differences during the cyclic corrosion process. And a series of approaches, including XRD, FTIR, SEM, and EDS, were applied to study the concrete phase composition changes and the micro-morphology features of all groups. According to the test results, when reaching 20 cycles, the concrete sample with 10% MK showed the best concrete physical properties; when reaching 120 cycles, the concrete with 5% MK content showed the best durability, produced similar amount of corrosion products to ordinary concrete, and presented relatively compacted micro-structure and small internal porosity. Mg2+ actually has a great impact on metakaolin. The corrosion product quantity increased significantly when MK admixture reached 15%. Due to the great number of produced M-S-H, the corrosive ions damaged the concrete for a second time, leading to serious aggregate peeling-off, powder surface of test samples, and porous micro-structure.

Investigation of the Effect of Microcapsule Additive on Mechanical and Physical Properties of Concrete

Cracks are a fundamental problem in concrete, so this research investigates an experimental study of the effect of adding SiO2 on the self-healing behaviour of concrete. The study is done by studying the physical properties, microstructure, and mechanical properties of concrete. Microcapsules were prepared to contain (cement and nano SiO2) in a (palettization (fluidize bed coating) method) with (5,10, and 15) % of cement weight. The ratio of the prepared concrete mixture was (1: 2: 4) and the ratio of water to cement (W / C) 0.45 by the weight of cement was also added as 0.6% Superplasticizer to all concrete mixtures. SiO2 MC is added with (2.5) % of the cement weight in the concrete mixture. In this study, porosity, density, and water absorption tests were performed to study the physical properties, compressive and bending strength to study mechanical properties. So, referring to the results, (SiO2 MC) was used as an effective effect in the self-healing cracking mechanism, and in improving the bending strength and compressive strength. Also, 10 % wt. was recorded as the best addition because it has a positive effect on properties to be applied in construction.

Mixing of Sugar in Concrete of M20 Grade

The objective of this paper is to experimentally study the effect of sugar doses on the physical properties of concrete. Effect of sugar at concentrations of 0,0.5.0.75, and 1% by weight of cement-on-cement paste and M20 grade of concrete cured at 3,7,14, and 28 days was studied using Portland cement in the laboratory. The main function of sug-ar is it is used as an admixture to increase the initial setting time of concrete. After the study, it was concluded that the workability and compressive strength of concrete get enhanced when admixture like sugar is added into the concrete mix.

Assessment of the reliability of concrete evaluation by multi-physical inversion of NDT measurements – A probabilistic approach

The evaluation of the spatial variability of concrete properties is an important issue for a better diagnosis of reinforced concrete structures. The combination between destructive techniques and nondestructive techniques (NDT) is a common practice to establish relationships between concrete properties and NDT measurements. Concrete properties can then be estimated at each test location using the corresponding NDT values on the basis of the calibration and inversion of these relationships. However, NDT measurements include many sources of uncertainties that can lead to biased or even inaccurate estimation. Thus, the improvement of the reliability of this estimation requires to specify and control the principal influencing factors on these uncertainties. The main objective of this paper is to propose a calibration methodology of conversion models and to study the reliability of concrete properties assessment considering the effect of the number of measurements, the uncertainty of NDT measurements and the combination of NDT techniques. Three conversion models linking the ultrasonic pulse velocity, the electrical resistivity, and the dielectric permittivity to two physical concrete properties, the porosity and saturation degree, are considered. The results show that the inversion of the proposed analytical models enables an accurate evaluation of concrete properties. In addition, it has been shown that there is a minimal number of measurements needed for an efficient non-destructive evaluation of concrete properties considering their variabilities.

The Effect of Sulfate Attack on Physical Properties of Concrete

The effects of different concentrations of sulfate for erosion age on compressive strength, flexural strength, weight analysis, density loss and visual appearances for concrete specimens of different grades were investigated. Experimental studies were carried out on different grades of concrete (M-25, M-30 and M-35). Concrete specimens were immersed in different concentration of sulfate solution i.e. 4.0pH, 5.0pH and 6.0pH. Reduction in compressive strength loss was noticed when the grade of concrete is increased from M-25 to M35. The results of weight analysis and density analysis also confirm the compressive strength loss and flexural strength. Discoloration of concrete was noticed on the concrete blocks when left immersed in sulfate solution at 4.0pH, 5.0pH and 6.0pH for 75days and 90days. It appeared like flakes of concrete and resembled like mold growth.

Physical and mechanical properties of concrete containing PET wastes as a partial replacement for fine aggregates

In this study, the influence of using polyethylene terephthalate (PET) wastes as a partial replacement of natural sand is investigated to study the mechanical and physical properties of concrete. Fine aggregate (sand) is partially replaced by equivalent weight percentages of PET waste particles while maintaining all other proportions. Mechanical tests for compression, splitting, flexure, modulus of elasticity, energy absorption, and axial strain as well as physical tests for density, shrinkage, and absorption, are performed. In addition, the ultrasonic pulse velocity is presented. All specimens are observed for 7, 14, and 28 days. The tests results presented that the presence of PET particles changed the physical and mechanical properties of produced concretes. Physical properties (density and ultra sound velocity) gradually decreased as PET ratios increased, while an increase in absorption rate was observed. Furthermore, for strength-related properties, the results showed that the specimens containing partial substitution ratios ranging within 5 %–12.5 % displayed 26.8 %–43.64 %, 18.6 %–26.9 %, and 18.1 %–30.2 % increments in the compressive, tensile, and flexural strengths, respectively, compared with the reference specimens. The findings also revealed an increase in energy absorption and axial strain of the specimens with 5%–20 % replacement percentages, while the modulus of elasticity decreased as the PET content increased. The results further indicated that the strength parameters decrease when the PET content exceeds 15 %. In conclusion, replacing sand with waste PET particles positively affects the strength-related values of concrete specimens as long as the replacement ratio is less than 15 %.

The Effect of Hybrid Fibers Reinforcement on the Mechanical and Physical Properties of Concrete

Background: Hybrid fiber reinforced concrete is the use of two or more than two fiber textures in a single concrete matrix to improve the overall properties of concrete. Materials and Methods: In this study, the ductility of medium strength concrete was observed to improve by incorporating steel and polypropylene in a ratio of 50:50 as a hybrid fiber. Four proportions of Volume fractions (Vf) were used (0.25, 0.5, 0.75, 1%). The changes in the mechanical properties and density occurred due to the addition of these hybrid fibers. Results: The features examined include bulk density, compressive strength, and flexural strength by using thirteen concrete mixtures with various volume fractions of steel and polypropylene fibers. Discussion: The results showed a significant increase in compressive and flexural strength due to the addition of steel fibers. On the other hand, polypropylene fibers exhibited minor changes in the mechanical properties of hardened concrete exclusively in the mixtures made with both steel and polypropylene fibers in which the strength increased in comparison to plain concrete by 4.4% and to steel fiber group having the optimal strength and other properties. Conclusion: These remarks provide a clear view of the importance of using different fiber reinforcing systems to improve the mechanical performance of concrete, which is considered quasi-brittle.

The Study of the Strength Properties of Galvanized Iron (GI) Fiber Reinforced Concrete

The use of concrete with randomly distributed metallic or non-metallic fiber is now prominent in concrete engineering and metallic fiber has been reported to have a better contribution to concrete mechanical properties. The utilization of locally available galvanized iron or metallic fiber as a bridging material which is a new technique in Bangladesh has the ability to surprisingly improve concrete physical properties. This research was, therefore, conducted to compare the concrete performance of GI fiber and steel fiber using previous literature as well as the suitability of GI fiber as a supplant to steel fiber in the concrete industry. This was achieved through the evaluation of the compression, tension, and brittleness of concrete with ‘Galvanized Iron’ fiber using several cutting lengths of 20 mm and 40 mm with multiple mix proportions including 1.0%, 1.5%, 2.0%, and 2.5% by volume of the concrete. The results showed the fiber with a large cut length of 40 mm and proportion lesser than 2.5% performed well than 20 mm with proportion 2% in reference to the plain concrete. Moreover, the incorporation of a 2.0% proportion of galvanized iron fiber with 40 mm length was observed to have exhibited crowning increment for both concrete compression and tension by 16.1% and 89.2% correspondingly contrasted to the control specimen. A further increase in the percent of fiber content 2% led to a reduction in the compression and tension for both 20 mm and 40 mm lengths while a significant reduction in brittleness for galvanized iron fiber reinforced concrete was observed in contrast to the control specimen. Furthermore, the inclusion of 1.0%–2.5% GI fiber with a 40 mm length reduced concrete brittleness by 56.9% - 65.5 % in comparison with the control specimen. Therefore, the inclusion of galvanized iron (metallic) to enhance the physical properties of concrete was deduced to be one of the startling stratagems