Performance of Cement Mortar Exposed to Different Temperature and Curing Methods

Curing is an important process to achieve the specified concrete strength and durability. The objectives here is to determine the effect of four curing regimes on the development of mechanical properties for mortar specimens with mix proportions of 1:2.75 cement to sand by mass with W/C of 0.46, and with standard cube and prism dimensions, using OPC and SRPC; specimens tested under curing temperatures at 25 °C and 45 °C; to simulate the seasonal climatic conditions in Iraq. Curing methods adopted were: 1st: immersion in water, 2nd: wetting by using saturated covers, 3rd: curing by using wax-based compound, and 4th: by air curing. The specimens were examined at the ages of 3, 7, 14, and 28 days for density and mechanical properties. The study highlights that fully-saturated specimens in water is the recommended curing; as test results indicate that the highest mechanical properties were obtained. Considering the compressive strength as the criterion, curing by using wax-based compound came 2nd; and curing by saturated covers in 3rd position. This is true for temperatures at 25 °C and 45 °C; however, the experiments carried on OPC mortar show that increasing the temperature from 25 °C to 45 °C increases the early strength at 3 and 7 days by 16% and 22%, respectively; while the strengths at 14 and 28 days indicate an opposite manner; as the strength decreases when comparing the testing results at those ages by 23% and 17%. This is also valid for SRPC mortar and water-immersion curing for the same temperatures and corresponding ages; 25% and 19% increase at 3 and 7 days, respectively; but the results show that there was a continuous increase in strength at 14 and 28 days, by 29% and 33%, respectively. The study points out that immersion-curing in high temperatures is not recommended for OPC mortars after the age of 7 days; while it could be used for SRPC mortars.

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Investigation of the Mechanical Behavior of Partially Precast Partially Encased Assembled Composite Beams

Advances in Civil Engineering ◽

10.1155/2019/2762846 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Liufeng Zhang ◽

Yinghua Yang

Keyword(s):

Mechanical Properties ◽

Composite Beam ◽

Low Cost ◽

Concrete Strength ◽

Composite Beams ◽

Test Results ◽

Structural Form ◽

Heavy Load ◽

Grade Steel ◽

Good Agreement

In view of the characteristics of a high floor and the heavy load of logistics buildings, a partially prefabricated partially encased assembled composite beam (PPEC) is proposed in order to achieve the low cost construction of such buildings. In this research, the mechanical properties of PPEC beams were studied experimentally. The effects of the concrete strength grade, steel content, shear span ratio, and fabrication methods on the mechanical properties of the PPEC beams were analyzed. The results showed that the proposed structural form of the PPEC beams was generally feasible. Based on the test results, a practical shear formula for PPEC beams was proposed, and the calculated results were in good agreement with the test results.

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The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

Applied Sciences ◽

10.3390/app10103570 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3570

Author(s):

Romualdas Kliukas ◽

Ona Lukoševičienė ◽

Arūnas Jaras ◽

Bronius Jonaitis

Keyword(s):

Mechanical Properties ◽

Reinforced Concrete ◽

Concrete Strength ◽

Concrete Structures ◽

High Strength ◽

Reinforcement Ratio ◽

Transverse Reinforcement ◽

Reinforced Concrete Structures ◽

Test Results ◽

Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

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Analysis of fly ash from PLTU Asam-Asam as a construction material in terms of its physical and mechanical properties

MATEC Web of Conferences ◽

10.1051/matecconf/201928004013 ◽

2019 ◽

Vol 280 ◽

pp. 04013

Author(s):

Irfan Prasetia ◽

M. Fahmi Rizani

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Construction Material ◽

Concrete Strength ◽

Coal Ash ◽

Physical And Mechanical Properties ◽

Pozzolanic Reaction ◽

Test Results ◽

Replacement Ratio ◽

Slump Test

Nowadays, PLTU Asam-Asam produced enormous amounts of combustion waste in the form of coal ash. On the contrary, only a little effort has been made to utilize coal ash from PLTU Asam-Asam, especially from the research side. In fact, due to its siliceous material, when reacting with CH in concrete, will form CSH hence improves concrete strength. In this study, in order to analyze the physical and mechanical properties of concrete using fly ash from PLTU Asam-Asam, 54 concrete samples were prepared according to SNI-03-2834-2000. The examination of concrete samples workability was conducted based on the slump test according to SNI 1972:2008. Moreover, the compressive tests were carried out in accordance with SNI 1974:2011. The slump test results show that the pozzolanic reaction of fly ash contributes to the improvement of concrete workability. Furthermore, the variation in w/b ratio was also affecting the results of the slump test. As for the compressive strength, in general speaking, the replacement ratio of 30% of cement with fly ash in concrete could produce concrete strength up to 30 Mpa. It is also important to note that due to the pozzolanic reactions tends to delayed, it is expected that at later ages (above 28 days) concrete with fly ash will gain much more strength compared to ordinary concrete.

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Optimization of Sulfur Soaking Water on Mechanical Properties and Physical Properties of Woven Petung Bamboo (Dendrocalamus asper Backer ex Heyne) Strips

E3S Web of Conferences ◽

10.1051/e3sconf/202019000031 ◽

2020 ◽

Vol 190 ◽

pp. 00031

Author(s):

Rahab Martini Bako ◽

Farid Sariman ◽

Christian Wely Wullur ◽

Klemens Alrin Rahangmetan ◽

Cipto Cipto ◽

...

Keyword(s):

Mechanical Properties ◽

Impact Test ◽

Bending Strength ◽

Mechanical Test ◽

Bending Test ◽

Strength Increase ◽

Test Results ◽

Dendrocalamus Asper ◽

Fracture Shape ◽

Strength And Durability

There are about 60 species of bamboo belonging to family gramineae found in Indonesia, which is one of them is Petung bamboo (Dendrocalamus asper). Bamboo has the potential to produce environmentally friendly engineering materials. The strength and durability of the material can be increased through the immersion process using chemical or natural solutions, such as sulphur water because it is known to contain carbon elements high enough to support strength increase. The research was started by making thick bamboo slats 1 mm thick, 250 mm long, 10 mm wide, and then woven in plain shapes of 250 mm × 250 mm, then dried at 110 °C for 60 min then immersed in sulfur water. For tensile test using the ASTM D638-02 standart, ASTM D790-02 bending test, ASTM D5942-96 impact test. The test results show the tensile strength increased 89.17 %, bending strength increased 59.90 % and impact strength increased 1.59 %. The highest value of the mechanical test results occurred in sample 1 AB3, while the lowest mechanical test value occurred in 1 TP sample. The microstructure of the 1 TP sample shows a pointed and smooth fracture shape while the sample 1 AB3 has an increasingly blunt fracture shape with fine threads.

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A Comparative Study on the Mechanical Properties and Microstructure of Cement-Based Materials by Direct Electric Curing and Steam Curing

Materials ◽

10.3390/ma14237407 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7407

Author(s):

Zhihan Yang ◽

Youjun Xie ◽

Jionghuang He ◽

Fan Wang ◽

Xiaohui Zeng ◽

...

Keyword(s):

Mechanical Properties ◽

Energy Consumption ◽

Hydration Degree ◽

Steam Curing ◽

Cement Based Materials ◽

Curing Methods ◽

Temperature Controlled ◽

Stable Growth ◽

Curing Method ◽

Curing Regimes

Direct electric curing (EC) is a new green curing method for cement-based materials that improves the early mechanical properties via the uniform high temperature produced by Joule heating. To understand the effects of EC and steam curing (SC) on the mechanical properties and microstructure of cement-based materials, the mortar was cured at different temperature-controlled curing regimes (40 °C, 60 °C, and 80 °C). Meanwhile, the mechanical properties, hydrates and pore structures of the specimens were investigated. The energy consumption of the curing methods was compared. The results showed that the EC specimens had higher and more stable growth of mechanical strength. The hydration degree and products of EC samples were similar to that of SC samples. However, the pore structure of EC specimens was finer than that of SC specimens at different curing ages. Moreover, the energy consumption of EC was much lower than that of SC. This study provides an important technical support for the EC in the production of energy-saving and high early-strength concrete precast components.

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A Comparative Study on the Mechanical Properties and Microstructure of Cement-Based Materials by Direct Electric Curing and Steam Curing

10.20944/preprints202110.0418.v1 ◽

2021 ◽

Author(s):

Zhihan Yang ◽

Youjun Xie ◽

Jionghuang He ◽

Fan Wang ◽

Xiaohui Zeng ◽

...

Keyword(s):

Mechanical Properties ◽

Energy Consumption ◽

Pore Structure ◽

Steam Curing ◽

Cement Based Materials ◽

Curing Methods ◽

Stable Growth ◽

Curing Method ◽

Curing Regimes ◽

Better Than

Direct electric curing (EC) is a new green curing method for cement-based materials that improves the early mechanical properties via the uniform high temperature produced by Joule heating. To understand the effects of EC and steam curing (SC) on the mechanical properties and microstructure of cement-based materials, the mortar was cured at different temperature-controlled curing regimes (40°C, 60°C and 80°C). Meanwhile, mechanical properties, hydrate phase and pore structure of specimens were investigated. The energy consumption of two curing methods was compared and analyzed. The results show that the EC specimens have better and more stable growth of mechanical strength. The pore structure of EC specimen is also better than that of SC specimen at different maintenance ages. However, the hydration degree and products of samples cured by EC are similar to that SC samples. The energy consumption of EC is lower than SC. This study provides an important technical support for the EC in the production of energy-saving and high early-strength concrete precast components.

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PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

Jurnal Sains dan Teknologi Indonesia ◽

10.29122/jsti.v12i3.863 ◽

2013 ◽

Vol 12 (3) ◽

Author(s):

Sudarmadi Sudarmadi

Keyword(s):

Compressive Strength ◽

Concrete Strength ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Test Results ◽

Concrete Compressive Strength ◽

Strength Assessment ◽

Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

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Sunlight exposure: the effects on the performance of paragliding fabric

Industria Textila ◽

10.35530/it.069.05.1406 ◽

2018 ◽

Vol 69 (05) ◽

pp. 381-389

Author(s):

MENGÜÇ GAMZE SÜPÜREN ◽

TEMEL EMRAH ◽

BOZDOĞAN FARUK

Keyword(s):

Mechanical Properties ◽

Aging Process ◽

Air Permeability ◽

Sunlight Exposure ◽

Test Results ◽

Coating Materials ◽

Strength Tests ◽

Before And After ◽

The Relationship ◽

Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

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The effects of ENSO, climate change and human activities on the water level of Lake Toba, Indonesia: a critical literature review

Geoscience Letters ◽

10.1186/s40562-021-00191-x ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Hendri Irwandi ◽

Mohammad Syamsu Rosid ◽

Terry Mart

Keyword(s):

Climate Change ◽

Water Level ◽

Human Activities ◽

Southern Oscillation ◽

Climatic Conditions ◽

Water Levels ◽

Dominant Factor ◽

Climate Projections ◽

Continuous Increase ◽

The Future

AbstractThis research quantitatively and qualitatively analyzes the factors responsible for the water level variations in Lake Toba, North Sumatra Province, Indonesia. According to several studies carried out from 1993 to 2020, changes in the water level were associated with climate variability, climate change, and human activities. Furthermore, these studies stated that reduced rainfall during the rainy season due to the El Niño Southern Oscillation (ENSO) and the continuous increase in the maximum and average temperatures were some of the effects of climate change in the Lake Toba catchment area. Additionally, human interventions such as industrial activities, population growth, and damage to the surrounding environment of the Lake Toba watershed had significant impacts in terms of decreasing the water level. However, these studies were unable to determine the factor that had the most significant effect, although studies on other lakes worldwide have shown these factors are the main causes of fluctuations or decreases in water levels. A simulation study of Lake Toba's water balance showed the possibility of having a water surplus until the mid-twenty-first century. The input discharge was predicted to be greater than the output; therefore, Lake Toba could be optimized without affecting the future water level. However, the climate projections depicted a different situation, with scenarios predicting the possibility of extreme climate anomalies, demonstrating drier climatic conditions in the future. This review concludes that it is necessary to conduct an in-depth, comprehensive, and systematic study to identify the most dominant factor among the three that is causing the decrease in the Lake Toba water level and to describe the future projected water level.

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Effect of Water Ingress on the Mechanical and Chemical Properties of Polybutylene Terephthalate Reinforced with Glass Fibers

Materials ◽

10.3390/ma14051261 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1261

Author(s):

Catarina S. P. Borges ◽

Alireza Akhavan-Safar ◽

Eduardo A. S. Marques ◽

Ricardo J. C. Carbas ◽

Christoph Ueffing ◽

...

Keyword(s):

Mechanical Properties ◽

Water Absorption ◽

Water Uptake ◽

Significant Influence ◽

Water Immersion ◽

Water Diffusion ◽

Polybutylene Terephthalate ◽

Chemical Changes ◽

Water Ingress ◽

Effect Of Water

Short fiber reinforced polymers are widely used in the construction of electronic housings, where they are often exposed to harsh environmental conditions. The main purpose of this work is the in-depth study and characterization of the water uptake behavior of PBT-GF30 (polybutylene terephthalate with 30% of short glass fiber)as well as its consequent effect on the mechanical properties of the material. Further analysis was conducted to determine at which temperature range PBT-GF30 starts experiencing chemical changes. The influence of testing procedures and conditions on the evaluation of these effects was analyzed, also drawing comparisons with previous studies. The water absorption behavior was studied through gravimetric tests at 35, 70, and 130 °C. Fiber-free PBT was also studied at 35 °C for comparison purposes. The effect of water and temperature on the mechanical properties was analyzed through bulk tensile tests. The material was tested for the three temperatures in the as-supplied state (without drying or aging). Afterwards, PBT-GF30 was tested at room temperature following water immersion at the three temperatures. Chemical changes in the material were also analyzed through Fourier-transform infrared spectroscopy (FTIR). It was concluded that the water diffusion behavior is Fickian and that PBT absorbs more water than PBT-GF30 but at a slightly higher rate. However, temperature was found to have a more significant influence on the rate of water diffusion of PBT-GF30 than fiber content did. Temperature has a significant influence on the mechanical properties of the material. Humidity contributes to a slight drop in stiffness and strength, not showing a clear dependence on water uptake. This decrease in mechanical properties occurs due to the relaxation of the polymeric chain promoted by water ingress. Between 80 and 85 °C, after water immersion, the FTIR profile of the material changes, which suggests chemical changes in the PBT. The water absorption was simulated through heat transfer analogy with good results. From the developed numerical simulation, the minimum plate size to maintain the water ingress unidirectional was 30 mm, which was validated experimentally.

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