Early Strength of Self-Compacting Concrete

2000 ◽  
Vol 1698 (1) ◽  
pp. 61-69
Author(s):  
David J. Mukai ◽  
Simten Altan ◽  
John Q. Ehrgott
Keyword(s):  
Fly Ash ◽  
Primary Objective ◽  
Strength Characteristics ◽  
Strength Gain ◽  
Slag Cement ◽  
Self Compacting Concrete ◽  
Steam Curing ◽  
External Vibration ◽  
Early Strength ◽  
Congested Areas

The researchers’ primary objective was to evaluate the early-strength characteristics of self-compacting concrete (SCC), which is a type of concrete that can be placed without external vibration, even in congested areas. Two unique characteristics of SCC are its high-percentage substitution of cement with fly ash or slag cement, or with both fly ash and slag cement and a relatively high superplasticizer dosage. Both of these characteristics retard early-strength gain. The impetus was to develop self-compacting concrete with an early strength suitable for precast applications. The major findings are that it is possible to proportion SCC mixtures with high early strength (30 MPa at 16 h under steam curing) and that high slump does not necessarily correlate with self-compaction.

Effect of Gypsum on Strength Development of Steam-Cured Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1085-1088
Author(s):  
Zhi Min He ◽  
Xiao Ju Shen ◽  
Jun Zhe Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Development ◽  
Early Age ◽  
Strength Gain ◽  
Fly Ashes ◽  
Steam Curing ◽  
Gain Rate ◽  
Early Strength ◽  
Chemical Activator

The use of fly ashes for cement-replacement purposes, especially in high volumes, decreases rate of early strength development of the steam curing concrete. To resolve it, this paper developed a new steam-cured concrete incorporating fly ash and a chemical activator (gypsum). Experiments were conducted to investigate the mechanical properties at early and later ages of steam and standard curing concretes. The corresponding mechanism was also discussed by testing the microstructure of concretes. Results indicate that the demoulding compressive strength of steam curing concrete with 4% gypsum dosage can meet production requirements, and compressive strength of this concrete at later ages increase well. Compared with that of ordinary pure cement steam-cured concrete, concrete with 4% gypsum has a higher compressive strength gain rate. At an early age, addition of the gypsum can distinctly accelerate the extent of hydration of the steam curing fly ash cement systems, and thus the microstructure of concrete becomes denser. However, in standard curing condtion, the effect of gypsum is not distinct.

Empirical Prediction Models for Strength Gain Properties of Fly Ash Based Concrete Subjected to Accelerated Curing

2018 ◽  
Vol 1150 ◽  
pp. 73-90
Author(s):  
Vallarasu Manoharan Sounthararajan
Keyword(s):  
Fly Ash ◽  
Prediction Models ◽  
Pulse Velocity ◽  
Hot Water ◽  
Experimental Investigations ◽  
Strength Gain ◽  
Steam Curing ◽  
Empirical Prediction ◽  
Accelerated Curing ◽  
Water Curing

Experimental investigations on the early age, strength gain properties of fly ash blended cement concretes containing low and high volume fly ash replacement were studied. Concrete mixes were prepared with two different fly ash contents and varying concrete ingredients with water to binder ratio (w/b), fine to coarse aggregate ratio (F/c) and accelerator dosage. Five different curing techniques, namely controlled humidity curing; hot air oven curing, steam curing, hot water curing and normal water curing were adopted for curing the fly ash based concretes. Test results showed evidence the influence of accelerating admixtures and accelerated curing for obtaining the high early strength properties in fly ash mixed concrete. Most notably a maximum 1 day compressive strength of 40.20 MPa and 34.60 MPa with low (25%) and high (50%) volume fly ash concretes were obtained respectively in this study. Experimental results clearly indicated that the improvements on the strength gain properties with the careful selection of mix ingredients; accelerator addition and accelerated curing in fly ash based concrete mixes. Also, significant improvements on the flexural strength, elastic modulus, dynamic modulus and the ultrasonic pulse velocity test were noticed.

Study of Sleeper Concrete early Strength Based on Orthogonal Experiment

2013 ◽  
Vol 448-453 ◽  
pp. 1316-1320
Author(s):  
Hai Chao Wang ◽  
Ke Qiu ◽  
Shu Ling Gao
Keyword(s):  
Fly Ash ◽  
Design Method ◽  
Orthogonal Experiment ◽  
Orthogonal Design ◽  
Steam Curing ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Early Strength ◽  
The Difference ◽  
Railway Sleeper

Using orthogonal design method of four factors and three levels, make a mix ratio experiment on sleeper concrete of China's railway sleepers, used steam curing concrete early compressive strength (stripping strength) as evaluation index. Study on different experimental factors of water-cement ratio, sand ratio, fly ash and admixture differently influenced on the early strength of sleeper concrete and analyze the difference impact of each factor and level for the orthogonal experiment. The result shows that the admixture is the main factor for early strength of concrete, followed by fly ash, water-cement ratio and sand ratio. It can provide technical guidance for railway sleeper field and has practical value.

scholarly journals Influence of Calcined Flue Gas Desulfurization Gypsum and Calcium Aluminate on the Strength and AFt Evolution of Fly Ash Blended Concrete under Steam Curing

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7171
Author(s):  
Yueran Zhang ◽  
Heng Zhang ◽  
Xiong Zhang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Aluminate ◽  
Flue Gas ◽  
Flue Gas Desulfurization ◽  
Steam Curing ◽  
Formation Kinetic ◽  
Fgd Gypsum ◽  
Active Calcium ◽  
Early Strength

In order to improve the early strength of fly ash blended cement concrete under steam curing conditions, fly ash was partly substituted by calcined flue gas desulfurization (FGD) gypsum and active calcium aluminate. The effect of the composition and curing condition on the workability, mechanical property, and volume stability was systematically evaluated. The variety of hydration products and the evolution was determined by XRD to explore the formation kinetic of ettringite. Results show that the addition of calcined FGD gypsum and active calcium aluminate is able to improve the early compressive strength but using more FGD gypsum and a high sulfur aluminum ratio leads to a reduction in compressive strength from 28 to 90 days due to the increment of ettringite and crystallization of dihydrate gypsum. Both the free expansion ratio and limited expansion exhibited a continuous increasement with time, especially in the first 14 days of testing. Cracks were not observed on the surface of samples immersed in water for a year. The improvement of strength and shrinkage resistance is mainly due to the formation of ettringite generated before 14 days and the precipitation was highly limited from 14 to 28 days. Moreover, the characteristic peak of gypsum appeared after 28 days, indicating the conversion of partial of calcined FGD gypsum. The work presented here provides a new solution for improving the early strength of fly ash concrete without reducing the later strength and consuming extra energy.

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%.

Fresh and mechanical characteristics of roselle fibre reinforced self-compacting concrete incorporating fly ash and metakaolin

2021 ◽  
Vol 290 ◽  
pp. 123209
Author(s):  
R. Prakash ◽  
Sudharshan N. Raman ◽  
N. Divyah ◽  
C. Subramanian ◽  
C. Vijayaprabha ◽  
...  
Keyword(s):  
Fly Ash ◽  
Mechanical Characteristics ◽  
Self Compacting Concrete

scholarly journals Cements with calcareous fly ash as component of low clinker eco-self compacting concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 196-201
Author(s):  
Jacek Gołaszewski ◽  
Grzegorz Cygan ◽  
Tomasz Ponikiewski ◽  
Małgorzata Gołaszewska
Keyword(s):  
Fly Ash ◽  
Hardened Concrete ◽  
Self Compacting Concrete ◽  
Basic Properties ◽  
Ecological Self ◽  
Different Types ◽  
Hardened State ◽  
Main Component ◽  
New Generation ◽  
Good Workability

AbstractThe main goal of the presented research was to verify the possibility of obtaining ecological self-compacting concrete of low hardening temperature, containing different types of cements with calcareous fly ash W as main component and the influence of these cements on basic properties of fresh and hardened concrete. Cements CEM II containing calcareous fly ash W make it possible to obtain self-compacting concrete (SCC) with similar initial flowability to analogous mixtures with reference cement CEM I and CEM III/B, and slightly higher, but still acceptable, flowability loss. Properties of hardened concretes with these cements are similar in comparison to CEM I and CEM III concretes. By using cement nonstandard, new generation multi-component cement CEM “X”/A (S-W), self-compacting concrete was obtained with good workability and properties in hardened state.

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