scholarly journals The Reinforced Spun Concrete Poles under Physical Salt Attack and Temperature: A Case Study of the Effectiveness of Chemical Admixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5111
Author(s):  
Romualdas Kliukas ◽  
Arūnas Jaras ◽  
Ona Lukoševičienė
Keyword(s):  
Transmission Lines ◽  
Environmental Conditions ◽  
Experimental Program ◽  
Initial Water ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Admixtures ◽  
Spun Concrete ◽  
Physical Salt Attack

The present paper focused on the investigation of the effectiveness of using various chemical admixtures and their effect on the strength and deformability of the reinforced spun concrete members—the supporting poles of the overhead power transmission lines—under the unfavorable long-term combined action of the aggressive salt-saturated groundwater and the temperature changes. According to the long-term experimental program, 96 prismatic spun concrete specimens were subjected to multi-cycle (25-50-75 cycles) processing under the combined aggressive environmental conditions. It has been found that chemical admixtures which decrease the initial water-cement ratio produce a considerable positive effect on the mechanical properties of spun concrete used in hot and arid climates and exposed to physical salt attack (PSA). Superplasticizers decrease the initial water-cement ratio the most, and, due to a unique concrete compaction method used, they produce the most homogeneous and dense concrete structure. They can be recommended as most effective in increasing the durability of spun concrete used under the above-mentioned aggressive environmental conditions.

scholarly journals The Impact of Long-Term Physical Salt Attack and Multicycle Temperature Gradient on the Mechanical Properties of Spun Concrete

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4811
Author(s):  
Romualdas Kliukas ◽  
Arūnas Jaras ◽  
Ona Lukoševičienė
Keyword(s):  
Mechanical Properties ◽  
Temperature Gradient ◽  
Ambient Conditions ◽  
Chemical Admixtures ◽  
Cyclic Temperature ◽  
Spun Concrete ◽  
Physical Salt Attack ◽  
The Impact ◽  
Positive Effect

The article is focused on spun concrete made with different chemical admixtures under long-term exposure to aggressive salt-saturated ground water and a cyclic temperature gradient. Over a long-term experimental investigation, 64 prismatic spun concrete specimens were subjected to multicycle (75–120) processing under combined aggressive ambient conditions. Prismatic specimens were soaked in water or saline and dried at a temperature of 45–50 °C. The long-term multi-cycle effect of the temperature gradient and physical salt attack on the compressive strength, Young’s modulus and durability of concrete was found to be negative. Chemical admixtures, though, improved the structure of spun concrete, thus having a significant positive effect on its physical-mechanical properties and durability.

Experimental Research on the Influence of Humidity on the Moisture Diffusion in Cement-Based Materials

2010 ◽  
Vol 168-170 ◽  
pp. 1806-1809
Author(s):  
Qing Su ◽  
Tie Jun Zhao ◽  
Fan Xiao ◽  
Tao Cui
Keyword(s):  
Moisture Diffusion ◽  
Moisture Loss ◽  
River Sand ◽  
Moisture Migration ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Sea Sand ◽  
Cement Based Materials ◽  
Main Factor

The migration of ion dissolved in water is known to be main factor inducing the deterioration of porous cement-based materials in aggressive environment. Long-term tests have been carried to study the moisture diffusion in mortar with water cement ratio of 0.5 and 0.6 in different humidity, and then the inverse analysis has been done to determine the moisture diffusion coefficient D. The results indicate that the bigger water cement ratio, the faster moisture migrating in same humidity, and the moisture migration process is longer for the mortar under lower humidity. Furthermore, the results of controlled experiments carried on mortar specimens with sea sand show that the moisture migration is longer for sea sand mortar than that of river sand, and the moisture loss is bigger.

scholarly journals Durabilidad del concreto con agregados de alta absorción

2019 ◽  
Vol 20 (4) ◽  
pp. 1-13
Author(s):  
Rómel Gilberto Solís Carcaño ◽  
Miguel Ángel Alcocer Fraga
Keyword(s):  
Electrical Resistivity ◽  
Environmental Conditions ◽  
Mechanical Resistance ◽  
Concrete Durability ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Porosity And Permeability ◽  
High Absorption ◽  
Durability Of Concrete

Durability of concrete constructions is equally important as mechanical resistance, since it determines the capacity to withstand the environmental conditions to which the construction will be subjected for several decades. Most of concrete durability problems are associated with its porosity and permeability, properties on which the ability to allow the flow of liquids and gases depends. The aim of the present work was to evaluate the durability of the concrete manufactured with limestone aggregates of high absorption and water/cement ratio in a range of 0.40 to 0.70, by means of the resistance to the compression, the porosity, the permeability to the air, the sorptivity and the electrical resistivity. Results showed that this type of concrete can have a good durability in aggressive environments with an A/C of 0.40, and in environments of moderate aggressiveness with an A/C of 0.50.

Experimental Study on Engineering Performance of Portland Cement Stabilization of Soil-Bentonite

2011 ◽  
Vol 179-180 ◽  
pp. 978-982
Author(s):  
Xiao Yong Li ◽  
Zhi Gang Zhang
Keyword(s):  
Hydraulic Conductivity ◽  
Portland Cement ◽  
Cement Content ◽  
Expansion Ratio ◽  
Wall Material ◽  
Experimental Program ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Cement Ratio ◽  
Water Cement Ratio

Slurry trench cutoff walls, constructed using self-hardening cement-bentonite (SCB) are the most common form of in-ground vertical contaminant barrier in the world, and are increasingly being used in China. As a kind of vertical anti-seepage wall material， SCB slurry is requently used for the containment of contaminated groundwater and other envirofunental Protection Projeets abroad. Domestie applieation of cement-bentonite slurry walls is not extensive. The objective of this study was to evaluate the effect of water-cement ratio and cement content on the hydraulic behavior of SCB and soil–bentonite (SB) mixtures permeated with water. The experimental program included unconfined compression tests, expansion ratio tests and hydraulic conductivity tests. The test results indicated changes in hydraulic conductivity take place due to the variation of the water-cement ratio and permeant fluid. Cement is a main material in effecting the CSB strength of unconfined compression. Cement greatly influenced the CSB permeability coefficient. Addition of Portland cement to the SB mixtures increased their hydraulic conductivity when permeated with water. The hydraulic conductivity of the SCB specimens permeated with water was inversely related to the cement content.

scholarly journals Effects of selected chemical admixtures on physical and mechanical properties of cement mortar

2020 ◽  
Vol 30 (3) ◽  
pp. 305-310
Author(s):  
SS Bethe ◽  
MN Haque ◽  
MR Islam
Keyword(s):  
Mechanical Properties ◽  
Cement Mortar ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Admixtures ◽  
Super Plasticizer ◽  
The Difference

This study was aimed to determination of appropriate dosage of selected chemical admixtures to reduce water cement ratio for mortar mix also to determine its effects on physical and mechanical properties of cement mortar. Amount of water used in concrete is very important for the physical and mechanical properties. Less amount of water increase the strength but reduce the workability. Water retarding admixture can reduce the water cement ratio with desired workability. In this experiment plasticizer (master pel 707) and super plasticizer (master polyheed 8632) was used. The used dosages of admixture were 0.5%, 1% and 1.5% according to cement weight. The test was done at 3 days, 7 days, 28 days and 91 days. 2.76″ cube mold was used for the work. The experiment was done to find the difference between with and without admixture used in mortar. Water used reduced with add of plasticizer and super plasticizer. In the experiment the workability of normal mortar and admixture used mortar remain same. The compressive strength is high for 1.5% super plasticizer used sample. So 1.5% super plasticizer is recommended for high strength. Progressive Agriculture 30 (3): 305-310, 2019

scholarly journals Long Term Compression Strength of Mortars Produced Using Coarse Steel Slag as Aggregate

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Erika Furlani ◽  
Stefano Maschio
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Compression Strength ◽  
Steel Slag ◽  
Alkali Silica Reaction ◽  
Steelmaking Slag ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Long Time

The paper reports on some experimental results obtained from the production of mortars prepared using a commercial cement, coarse steelmaking slag, superplasticizer, and water. The behaviour of this reference composition was compared to that of some others containing further additives in order to investigate materials compressive strength after long time ageing. It has been demonstrated that an optimized water/cement ratio coupled with slag particles of size lower than 2.5 mm and proper protocol of preparation leads to the production of materials with good mechanical properties after 28, 90, and 180 days of ageing. The resulting materials therefore appeared as good candidates for civil engineering applications. However, the present research also demonstrates that the mortar samples of all of the compositions prepared suffer from decay and compressive strength decrease after long time ageing in water. In the present paper the results are explained taking account of materials residual porosity and alkali silica reaction which occurs in the samples.

Key Techniques of Self-Compacting Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 394-397
Author(s):  
Shu Hua Liu
Keyword(s):  
Thermal Properties ◽  
Limestone Powder ◽  
Self Compacting Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Expansive Agent ◽  
Chemical Admixtures ◽  
Dimension Stability ◽  
Key Techniques ◽  
Temperature Crack

Self-compacting concrete (SCC) is a new style of concrete with high workability. The key techniques of SCC including workability, strength, dimension stability, thermal properties and durability were investigated in this paper. High workability can be achieved at low water-cement ratio by adding superplasticizer. After adding inert powder such as limestone powder, the low strength SCC can be produced. The dimension stability of SCC can be improved by using expansive agent. Mineral and inert admixture can reduce the hydrate heat of binder and avoid temperature crack of concrete. The durability of SCC can be improved by controlling water-cement ratio, adding chemical admixtures and fibre.

scholarly journals The Study of Flowability and The Compressive Strength of Grout/Mortar Proportions for Pre- placed Concrete Aggregate (PAC)

2019 ◽  
Vol 280 ◽  
pp. 04010
Author(s):  
Nursiah Chairunnisa ◽  
Arie Febry Fardheny
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Concrete Aggregate ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Admixtures ◽  
Test Result

This experimental study is focused on the performance of appropriate grout/mortar for pre-placed aggregate concrete (PAC) incorporating superplasticizer in the mortar mixture regarding the flowability and strength of grout or mortar. Twenty-one samples of specimens were prepared. The parameter tests consist of water-cement ratios, cement sand ratios and variation dosages of superplasticizer. To examine the flowability/fluidity of grout or mortar, the flow cone test was applied. The flow cone test result indicated that there were three proportional grout that can meet the requirement for fluidity according to ASTM C-939. The compressive strength of specimens was tested. It was concluded that the composition of grout with containing the percentage of 0.7% by weight of cement of superplasticizer as chemical admixtures at a water-cement ratio of 0.6 and a cement-sand ratio of 0.5 is the proper composition of grout for pre-placed aggregate concrete (PAC).

scholarly journals ASSESSMENT OF THE RELIABILITY OF THE REINFORCED CONCRETE LAYER IN STRUCTURES

2020 ◽  
Vol 12 (0) ◽  
pp. 1-4
Author(s):  
Andrius Patapavičius
Keyword(s):  
Reinforced Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Reliability Indices ◽  
Effect Of Water ◽  
Concrete Layer ◽  
Quality Assessments

An urgency to use probability-based methods and probabilistic reliability indices in long-term quality assessments and predictions of reinforced concrete products and structures is under consideration. Carbonation nature and depth of protective concrete covers of reinforcement bars and stirrups are analysed. Effect of water-cement ratio on the carbonation rate of protective concrete covers is discussed. Analyzes of reliability of structures reinforcement with composite as spiral (transverse) usage and influence. Presented applied equations and the calculation example demonstrate a simplicity and necessities of probability-based methods.

scholarly journals Effectiveness of Locally Available Superplasticizers on the Workability and Strength of Concrete

2018 ◽  
Vol 4 (12) ◽  
pp. 2919 ◽  
Author(s):  
Ashfaque Ahmed Jhatial ◽  
Samiullah Sohu ◽  
Muhammad Tahir Lakhiar ◽  
Jam Shahzaib ◽  
Ahsan Ali Buriro
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Water Content ◽  
Research Work ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Optimum Dosage ◽  
Chemical Admixtures ◽  
Compressive And Flexural Strengths

Though superplasticizers (SP) are well-known chemical admixtures which are added into concrete to enhance the workability and achieve higher strength while reducing the water content. But the rapid increase in different SP in Pakistan has created confusion on the effectiveness of SP. This experimental study was carried out to study the effect of locally available SP on the workability and compressive strength of M15 grade concrete. Three different SP were utilized, with dosage ranging from 0.5% to 2.5% with an increment of 0.5%. The water-cement ratio remained constant at 0.5 for all samples. Based upon the results, all three SP increased the workability as well as strength of concrete. The optimum dosage was determined to be 1.5% to 2.00% for all three SPs used in this research work. BASF 561 was determined to be more effective, as it achieved the maximum workability as well as compressive and flexural strengths.

Sign in / Sign up

Export Citation Format

Share Document