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Effect of selected parameters on agg...

Math, Sujay.

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Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers./
作者:	Math, Sujay.
面頁冊數:	123 p.
附註:	Source: Masters Abstracts International, Volume: 49-05, page: 3270.
Contained By:	Masters Abstracts International49-05.
標題:	Chemistry, General. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1492677
ISBN:	9781124651019

Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers.
Math, Sujay.

Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers. - 123 p.

Source: Masters Abstracts International, Volume: 49-05, page: 3270.

Thesis (M.S.)--Clemson University, 2011.

Alkali Silica Reaction (ASR) is a chemical reaction between reactive siliceous aggregates and the alkali hydroxides present in the pore solution of hydrated cement paste in concrete. The chemical reaction produces ASR gel that is hygroscopic in nature and is volumetrically unstable in the presence of moisture. Expansion resulting from the swelling of the gel creates tensile stresses in the concrete leading to cracking and distress.

ISBN: 9781124651019Subjects--Topical Terms:

1021807
Chemistry, General.

Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers.
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245 1 0 $a Effect of selected parameters on aggregate reactivity in Accelerated Mortar Bar Test method: Aggregate size & deicers.
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500 $a Source: Masters Abstracts International, Volume: 49-05, page: 3270.
500 $a Adviser: Prasad Rangaraju.
502 $a Thesis (M.S.)--Clemson University, 2011.
520 $a Alkali Silica Reaction (ASR) is a chemical reaction between reactive siliceous aggregates and the alkali hydroxides present in the pore solution of hydrated cement paste in concrete. The chemical reaction produces ASR gel that is hygroscopic in nature and is volumetrically unstable in the presence of moisture. Expansion resulting from the swelling of the gel creates tensile stresses in the concrete leading to cracking and distress.
520 $a The first objective of this study is to study the impact of processing coarse aggregate (i.e. crushing, sieving and washing) on its reactivity. One of main factors that could be affecting the reliability of the AMBT method is the aggregate gradation. When coarse aggregates are to be evaluated in this method, it needs to be crushed and processed. In processing the coarse aggregates, the distribution of the reactive siliceous phases in the aggregate can be significantly altered relative to the surface of the aggregate particles, thus affecting the reactivity of the aggregate.
520 $a To investigate the effect of aggregate size in the AMBT method 4 different reactive aggregates were used representing a wide variety of mineral composition. SEM and EDX mapping techniques were employed to confirm the presence of variety of elements in the mineral structure and the variation between different aggregates. Each of the aggregates were crushed, sieved and batched according the standard ASTM C 1260 gradation. Each fraction of the ASTM C 1260 gradation was replaced with 20% reactive aggregate and 80% non reactive to meet the total mass requirements for the test. The cement to aggregate ratio was increased to 1: 1.75 for ease of workability. The mortar bars were prepared and kept in 1N NaOH soak solution at 80'C for 28 days and expansion readings were measured at regular intervals. The results showed that each individual aggregate size had different levels of expansion and the size factor is predominant in evaluating ASR potential of aggregates.
520 $a The second objective of this study is to evaluate the effect of deicers on aggregates in the AMBT method 16 different aggregates were used that represent aggregates with different mineralogy. In this study, the standard ASTM C 1260 test method was adopted along with 3 different versions of the deicer-modified AMBT methods. These included AMBT protocols with three different soak solutions --- 6.4M potassium acetate soak solution, 3M potassium acetate soak solution and combination of 3M potassium acetate + 1M sodium hydroxide soak solution. Of the 3 methods evaluated the combination solution of 3M potassium acetate + 1M sodium hydroxide proved to be most effective test method to evaluate aggregate reactivity in the presence of deicing chemicals. SEM and EDX were used to confirm the presence of ASR gel and study the deleterious behavior of ASR gel. The third objective of this research study is to investigate the possibility of decreasing the duration of CPT method by pre-saturating the aggregates with alkali solutions to increase the pace of reaction mechanism. However, in order to investigate the concept of pre-saturating the aggregate, ASTM C 1260 test method was considered due to its shorter test duration.
520 $a In this study, the standard ASTM C 1260 test method was modified by pre-saturation of aggregates with 1N sodium hydroxide for 24 hrs and then the standard procedure was followed in preparing and using the aggregates. The results from this study indicate that the modification of aggregates by pre-saturation with 1N sodium hydroxide did not provide any better results at 14 days age compared to the standard ASTM C 1260 test. However for some highly reactive aggregates 3 and 7 day mortar bar expansions were higher compared to standard test. The pre-saturation of aggregates with deicer solution was also adopted, but the presence of deicing chemicals did not allow the cement hydration reaction and the mortar bars were not cured and set. (Abstract shortened by UMI.)
590 $a School code: 0050.
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650 4 $a Engineering, Civil. $3 783781
650 4 $a Petrology. $3 535210
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710 2 $a Clemson University. $b Civil Engineering. $3 1018744
773 0 $t Masters Abstracts International $g 49-05.
790 1 0 $a Rangaraju, Prasad, $e advisor
790 1 0 $a Putman, Bradley $e committee member
790 1 0 $a Klotz, Leidy $e committee member
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