scholarly journals The Effect of Accelerators and Mix Constituents on the High Early Strength Concrete Properties

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
V. M. Sounthararajan ◽  
A. Sivakumar
Keyword(s):  
Fly Ash ◽  
Research Study ◽  
High Strength ◽  
Dosage Level ◽  
Test Results ◽  
Strength Gain ◽  
Strength Concrete ◽  
Concrete Properties ◽  
Different Types ◽  
Early Strength

The present research study focused on the high early strength concrete properties that can be produced with large replacement of cement by fly ash. Also, the effects of adding fibres on the compressive strength gain and early age strength gain properties are determined. Tests were conducted on different high strength concrete specimens, where fly ash was substituted for cement up to 50%. Different types of concrete specimens were casted and tested for different fine-to-coarse aggregate ratio, metallic fibre content, cement-to-total-aggregate ratio, and accelerator dosage. The test results indicated that high early strength concrete (50.7 MPa at 7 days) was obtained for higher F/C ratio of 0.8, C/TA ratio of 0.24, and higher dosage level of steel fibre at 1.5%.

Effects of Nano-CaCO3 on the Compressive Strength and Microstructure of High Strength Concrete in Different Curing Temperature

2011 ◽  
Vol 121-126 ◽  
pp. 126-131 ◽  
Author(s):  
Qing Lei Xu ◽  
Tao Meng ◽  
Miao Zhou Huang
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
High Strength Concrete ◽  
High Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Strength Concrete ◽  
Calcium Nitrite ◽  
Orientation Index ◽  
Early Strength

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Progressive Increase ◽  
Test Results ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Chopped Basalt Fiber

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

Research on Mechanical Properties of C100 High-Strength Concrete Used for Frozen Shaft

2012 ◽  
Vol 598 ◽  
pp. 388-392
Author(s):  
Hong Qiang Chu ◽  
Lin Hua Jiang ◽  
Ning Xu ◽  
Chuan Sheng Xiong
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Poisson's Ratio ◽  
Strength Concrete ◽  
Tensile Elastic Modulus ◽  
Early Strength

The mechanical properties of C100 high-strength concrete used for frozen shaft were studied in this research. The results demonstrate that: The cementitious materials 570kg/m3 concrete 28 strength is only 104.5MPa, which is lower than the C100 requirements; the early strength (3d) of the concrete doped with 30% admixture is less than 20% admixture concrete, but with the age increase, its strength gradually reaches close to concrete doped with 20% admixture, and eventually exceeds the concrete doped with 20% admixture.The tension-compression of high strength concrete doped with 15% fly ash and 15% slag is the smallest, while the tension-compression of the concrete doped 10% fly ash and 10% slag reaches the maximum.The Poisson's ratio of C100 concrete is between 0.20 and 0.24; the compressive elastic modulus is about 50GPa; and the tensile elastic modulus is about 110GPa.

scholarly journals Mechanical Properties of Fly Ash Polymer Concrete with Different Fibers

2018 ◽  
Vol 55 (3) ◽  
pp. 405-409 ◽  
Author(s):  
Marinela Barbuta ◽  
Alexandru Timu ◽  
Liliana Bejan ◽  
Roxana Dana Bucur
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Polymer Concrete ◽  
Test Results ◽  
Material Industry ◽  
Split Tensile Strength ◽  
Building Material Industry ◽  
Concrete Properties ◽  
Different Types ◽  
General Demand

The experimental results obtained by studying the influence of different types of fibers on the mechanical properties of fly ash polymer concrete are presented in the paper. The general demand of using wastes found applicability in building material industry because some of them are beneficial in improving concrete properties. The waste additions type fly ash and fibers were incorporated in polymer concrete. The study focused on fibers type glass, polyester, metallic and cellulose. The mechanical properties such as compressive strength, flexural strength and split tensile strength were investigated having in view the type, dosage and length of fibers. The results show that fibers improved mechanical properties in comparison with that of polymer concrete without fibers, the test results being differently influenced by the factors which were considered.

scholarly journals The Effect of Heat Treatment on the Properties of Ultra High Strength Concrete

2015 ◽  
Vol 1 ◽  
pp. 22 ◽  
Author(s):  
Girts Bumanis ◽  
Nikolajs Toropovs ◽  
Laura Dembovska ◽  
Diana Bajare ◽  
Aleksandrs Korjakins
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Water Absorption ◽  
High Strength Concrete ◽  
High Strength ◽  
Early Age ◽  
Strength Gain ◽  
Strength Concrete ◽  
Heat Treated ◽  
Early Strength

The influence of heat treatment during curing process of ultra high strength concrete (UHSC) was researched. Four different heat treatment temperatures ranging from 50 to 200 °C were studied and compared to the reference temperature regime (20 °C).  Two series of heat treatment were applied: (a) at the early age of UHSC (3 days) and (b) after 27 days of standard curing regime in water at 20 °C. Concrete compressive strength was tested at the early age (4 days) and at the age of 28 days. The water absorption and water penetration under pressure were tested for heat treated and untreated UHSC specimens. SEM and XRD investigations of the studied samples were performed. UHSC with the strength of 123 MPa at the age of 28 days was tested at the standard curing conditions. Results indicate that early age curing at elevated temperature increases early compressive strength from 123 to 189% while at the age of 28 days the compressive strength was only 95 to 117% from reference and depends on the heat treatment regime. The heat treatment of UHSC at the age of 27 days was beneficial with regard to the strength development. Heat-treated UHSC provided compressive strength gain from 112 to 124% from reference. The water absorption for all UHSC specimens was from 2.6 to 3.2 wt.% and it was not affected by the heat treatment. The calcite was detected with XRD in heat treated UHSC samples which indicates the carbonization of Portlandite. This could explain the strength gain of heat-treated samples and the reason for slow compressive strength increase in the case of early heat treatment application. SEM images reveal dense structure and unreacted silica fume particles. The early heat treatment initiated high early strength but the strength of concrete reduced at the age of 28 days comparing to the early strength; therefore late heat application was beneficial for strength gain of the UHSC.

Effect of Emulsified Waste Oil on Micro-Structure and Autogenous Shrinkage of the High Strength Concrete

2014 ◽  
Vol 919-921 ◽  
pp. 1899-1902 ◽  
Author(s):  
Cheon Goo Han ◽  
Min Cheol Han ◽  
Jin Guang Huang ◽  
Tae Cheong Kim
Keyword(s):  
High Strength Concrete ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Waste Cooking Oil ◽  
Test Results ◽  
Strength Concrete ◽  
Cooking Oil ◽  
Different Types ◽  
Reduction Effect ◽  
Shrinkage Reducing Agent

This paper presents an investigation of the effect of emulsified waste cooking oil on the porosity, EDEX results and the reduction of autogenous shrinkage of the high strength concrete with W/B of 20% incorporating 20% of fly ash and 10% of silica fume. Two different types of shrinkage reducing agents, the existing glyeol based shrinkage reducing agent (SR) and the waste cooking oil (WCO) were applied and compared. The effect of emulsification of the WCO with two emulsifying speeds, 2000 rpm and 4000 rpm were also investigated. It is found that the emulsified WCO has desirable shrinkage reduction effect than un-emulsified WCO and existing SR. Test results also indicated that emulsified WCO could also reduce pore volume due to saponification reaction

Study on Strength Development of High Strength Concrete Containing Alccofine and Fly-Ash

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Development ◽  
Strength Concrete
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