EFFECTS OF CLAY ON PROPERTIES OF CONCRETE

Concrete is a versatile and most prevalent construction material. Its long-term performance depends on its interactions with the surrounding environment. The standards limit the ratio of the clay in aggregates due to its harmful effect on the concrete properties. This research paper presents the effect of different levels of clay addition on the concrete properties. Various levels of clay addition for different mixes were used in this experimental study. The effect of clay addition on workability, compressive strengths permeability and acid attack of concrete mixes was investigated. It has been seen that workability decreased by increasing the clay content to the mix. A drop in compressive strength of concrete up to 12% was observed by adding clay as compared with that of control samples. An adverse effect on resistance to permeability and acid attack of concrete was noted by increasing the clay content.

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Long-term performance of mechanically post-installed anchor systems

Advances in Structural Engineering ◽

10.1177/1369433216649396 ◽

2016 ◽

Vol 20 (3) ◽

pp. 288-298 ◽

Cited By ~ 2

Author(s):

Minho Kwon ◽

Jinsup Kim ◽

Hyunsu Seo ◽

Wooyoung Jung

Keyword(s):

Pullout Test ◽

Reduction Factor ◽

Test Method ◽

Test Results ◽

Freeze And Thaw ◽

Comparison Results ◽

Compressive Strength Of Concrete ◽

Long Term Performance ◽

Term Performance

A mechanically post-installed anchor, which is one of the most widely used post-installed anchors in South Korea, was selected to evaluate long-term usage through a pullout test. Two types of specimens were constructed: the original specimens and freeze and thaw specimens. Mechanically post-installed anchors were installed in both of them. A freeze and thaw test method was utilized to consider the long-term usage. The compressive strength of concrete during the freeze and thaw test method is reduced by about 20% compared to that of the original concrete. From the pullout test results, the pullout strength of the freeze and thaw specimen was smaller by about 50% than that of the original specimens. Furthermore, the failure mode of the freeze and thaw specimens was changed. Cone shape destruction of anchors and anchor pullout destruction occurred in the original specimens; concrete pullout destruction occurred dominantly in the freeze and thaw specimens. Based on the comparison results, the reduction factor ( λ) for long-term usage of the mechanically post-installed anchor was derived using a probability function and was proposed to modify the concrete capacity design equation.

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Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

The Scientific World JOURNAL ◽

10.1155/2013/547615 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 13

Author(s):

A. H. Vakili ◽

M. R. Selamat ◽

H. Moayedi

Keyword(s):

Portland Cement ◽

Cement Content ◽

Construction Material ◽

Curing Time ◽

Clay Sample ◽

Optimum Amount ◽

Simultaneous Treatment ◽

Long Term Performance ◽

Term Performance

Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

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Practical Recycling Application of Power Plant Coal Ash for High Performance Shotcrete Material

Materials Science Forum ◽

10.4028/www.scientific.net/msf.620-622.251 ◽

2009 ◽

Vol 620-622 ◽

pp. 251-254

Author(s):

Cheol Woo Park ◽

Kyung Nam Kim

Keyword(s):

Silica Fume ◽

High Performance ◽

Power Plants ◽

Construction Material ◽

Coal Ash ◽

Test Results ◽

Replacement Ratio ◽

Long Term Performance ◽

Term Performance

This study intends to increase the consumption of coal ash which is an industrial by-product from power plants. The coal ash used to be deposited in the ground and its recycling has been very poor comparing to the produced amount. This study aims to enhance practical application of coal ash as a shotcrete construction material. Derived were optimum mix proportions for high performance shotcrete using coal ash. In order to enhance long term performance, silica fume was also added. Experimental variables included replacement ratio of silica fume and coal ash. Compressive strength and potential hazardous contamination to soil were the primary factors in the performance evaluation. From the test results, when fly ash was replaced up to 10% of the cement, most required specifications were satisfied. Hazardous material content was shown to be well below the specifications. Therefore, when appropriate caution in handling is given in the field, it is strongly anticipated to increase the coal ash recycling as a shotcrete construction material.

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