Early strength behaviour of fly ash concretes

1994 ◽  
Vol 24 (2) ◽  
pp. 277-284 ◽  
Author(s):  
K. Ganesh Babu ◽  
G. Siva Nageswara Rao
Keyword(s):  
Fly Ash ◽  
Early Strength

Experimental Study on Mechanical Property of Concrete Based on Seawater and Sea Sand

2013 ◽  
Vol 641-642 ◽  
pp. 574-577 ◽  
Author(s):  
Ying Tao Li ◽  
Ling Zhou ◽  
Mao Jiang ◽  
Yu Zhang ◽  
Jun Shao
Keyword(s):  
Mechanical Property ◽  
Experimental Study ◽  
Fly Ash ◽  
Raw Materials ◽  
Growth Trend ◽  
Sea Sand ◽  
Significant Strength ◽  
Dry Conditions ◽  
Early Strength ◽  
Better Than

In this paper, the mechanical property experiments of concrete based on the seawater and sea sand have been carried in different raw materials preparation and different conservation environments. The results show that the early strength and late strength of concrete based on seawater and sea sand are better than concrete based on freshwater and sand. There is no significant strength decreased for concrete based on seawater and sea sand under accelerated alternating wet and dry conditions. For concrete based on seawater and sea sand mixed with admixture, the downward trend of late strength is significantly delayed, the late strength of concrete based on the seawater and sea sand mixed with slag gets the most obvious growth trend, while the late strength of seawater and sea sand concrete mixed with fly ash gets the largest increment.

A trial construction of high durability railway viaducts with local aggregates

2019 ◽  
Author(s):  
Kotaro Kawamura ◽  
Joe Takemura ◽  
Shigenobu Iguchi ◽  
Tsutomu Yoshida ◽  
Masashi Kobayashi
Keyword(s):  
Fly Ash ◽  
Side Effects ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
The Other ◽  
Strength Concrete ◽  
High Durability ◽  
Sound Barrier ◽  
Early Strength ◽  
Structural Measure

<p>We are carrying out a construction project of new railroad viaducts. These new railroad viaducts are constructing using about 110,000 m<span>3</span> volume concrete. In this construction place, it is difficult for us to get low ASR-reactive aggregates and it is expected to be supplied with snowmelt water on the viaducts in winter. Then we tested ASR-reactive these local aggregates and found an effective mixed ratio of fly-ash is 20% of cement. On the other hand, various side effects were also expected by using fly-ash. For example, initial cracking due to contraction, early strength concrete, bleeding, etc. Therefore, we repeated various tests and examined and carried out a method that could ensure the same construction method and quality as when using ordinary Portland cement, even with fly-ash. Also, we adopted a structure that is unlikely to be affected by rainwater as a structural measure. For example, the entire adoption of a ramen type viaduct that has eliminated bearings, adoption of FRP sound barrier, etc. Then we made it possible to build highly durable railway viaducts by these various measures of materials and structures.</p>

scholarly journals Experiment and application of ceramsite concrete used to maintain roadway in coal mine

2020 ◽  
pp. 002029402094713
Author(s):  
Ying Chen ◽  
Qianjia Hui ◽  
Hongwei Zhang ◽  
Zhijie Zhu ◽  
Cunwen Wang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Water Absorption ◽  
Scientific Basis ◽  
Raw Material ◽  
Social Benefits ◽  
Particle Sizes ◽  
Optimal Scheme ◽  
Underground Coal Mines ◽  
Absorption Performance ◽  
Early Strength

This paper presents a scientific basis and reference for the application of ceramsite concrete in underground coal mines. Taking fly-ash ceramsite as raw material, a variety of mix proportions of C20 ceramsite concrete were proposed by changing the sand rate of concrete. The results showed that: (1) fly-ash ceramsite has different water absorption performance with different particle sizes. The water absorption stopped after soaked for 48 h. So, the ceramsite should be soaked for more than 48 h to prevent the cement from hydrating insufficient which affects the mechanical properties of the concrete. (2) Seven mix proportions of C20 ceramsite concrete were designed by changing the ceramsite proportion. The ceramsite proportion of 43% was determined as optimal scheme whose 28-day strength was 29.60 MPa and elastic modulus was 12.45 GPa. (3) The optimal scheme was applied and verified in the field. The early strength of ceramsite concrete promotes quickly, 3-day strength was 16.8 MPa, and the 28-day strength was 29.9 MPa. Compared with ordinary pebble concrete, ceramsite concrete can provide faster, higher strength support to the roadway. Meanwhile, ceramsite concrete have properties of lightweight, and its application will bring economic and social benefits.

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.

Effect of fine fly ash and calcium hydroxide on air void structure in very-early-strength latex-modified concrete

2015 ◽  
Vol 42 (10) ◽  
pp. 797-807
Author(s):  
Pangil Choi ◽  
Sung Il Jeon ◽  
Kyong-Ku Yun
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Bridge Decks ◽  
Time Frame ◽  
Early Age ◽  
Freeze Thaw ◽  
Void Structure ◽  
Early Strength ◽  
Air Void ◽  
Air Void Structure

Very-early-strength latex-modified concrete (VES-LMC) was developed for rapid repairs of distresses in concrete bridge decks and pavements, with the emphasis on early-age strength gain so that the repaired bridges and pavements can be opened to traffic within the time frame required in the specifications. However, there are two main concerns in the use of VES-LMC — early-age cracking and poor air void structure. The main objective of this study was to further improve VES-LMC to minimize early-age cracking and improve freeze–thaw durability, which included the use of fine fly ash (FFA) and calcium hydroxide (CH). Laboratory experiments were conducted on VES-LMC materials with cement replaced with FFA as well as CH, and various tests performed. Early-age drying shrinkages of VES-LMC containing both FFA and CH in the amounts evaluated in this study were smaller than that of VES-LMC with no replacements. It is expected that the use of FFA and CH in the range evaluated in this study will reduce the cracking potential of VES-LMC. Overall, the replacement of cement with FFA and CH improved the characteristics of entrained air void system, which will enhance the durability of VES-LMC against freeze–thaw damage. Scanning electron microscope and energy dispersive spectroscopy analysis indicate the primary mechanism of the generation of small sized air voids in concretes containing adequate amount of FFA and CH is the gas formation reaction between citric acid solutions and CH during concrete mixing. It is expected that the inclusion of adequate amounts of FFA and CH in VES-LMC will improve the performance of repaired bridge decks and pavements in terms of reduced cracking and improved freeze-thaw durability.

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.

Study on the Strength of Sea Sand Concrete in Ningbo

2011 ◽  
Vol 250-253 ◽  
pp. 262-265
Author(s):  
Jun Zhe Liu ◽  
Guo Liang Zhang ◽  
Jian Bin Chen ◽  
Zhi Min He
Keyword(s):  
Fly Ash ◽  
Influence Factor ◽  
Concrete Strength ◽  
Chloride Ion ◽  
Strength Development ◽  
Term Strength ◽  
Two Phase ◽  
Sea Sand ◽  
Early Strength

This paper mainly explain and expounded folding compressive strength of the different types of sea sand mortar , fly ash to the sea sand concretes mortar intensity influence as well as the chloride ion content to the sea sand concretes mortar intensity influence. The pulverized fly ash has the postponement function to the sea sand concretes early strength, the chloride ion has the promoter action to the sea sand concretes early strength. 20% pulverized fly ash be good to the sea sand concretes long-term strength development influence, can achieve the goal which enhances the sea sand concretes the long-term strength . The chloride ion is greater to the concretes early strength influence, especially in previous 3 days. Along with the time development, the chloride ion influence weakens, but the pulverized fly ash enlarges to the concretes intensity's influence factor. A two-phase arrived, the final concrete strength values close to each other.

Characterisation of Fly Ash Hydration Reactions from Microstructure

1985 ◽  
Vol 65 ◽  
Author(s):  
R. H. Mills
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Distilled Water ◽  
Reaction Products ◽  
Early Strength

ABSTRACTReaction products of high lime fly ash (FA), mixed with distilled water and hydrated in contact with Portland cement (PC), and in hardened PC/FA pastes of various mix proportions, were examined by SEM and EDX. Structures contributing to early strength originated mainly through solution depositions of ettringite, and portlandite. Some evidence of ettringite instability suggested gypsum deficiency in PC/FA mixtures.

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