Browsing by Author "ABDULLAH SAID ABDULLAH ALMAKRAB"

Now showing 1 - 2 of 2

Restricted
Assessment of Various Mitigation Strategies of Alkali-Silica Reactions in Concrete and Implementing Outlier Detection Method in Industrial Applications
(Saudi Digital Library) ABDULLAH SAID ABDULLAH ALMAKRAB; Dr. Ahmed Ibrahim
The mitigation of Alkali-Silica Reaction (ASR) has become more urgent than ever before due to the high demand for concrete in an increasingly industrialized world with expanding urban infrastructure. This study investigates the efficacy of additives in cement mixtures as an effort of stopping or mitigating Alkali-Silica Reactions that damage the structural integrity of concrete members. While there is existing research on certain supplementary cementitious materials (SCMs) and their role in stopping ASR in concrete, the present study is distinguished by using various binary supplementary cementitious materials (SCMs) such as Metakaolin and waste glass powder as replacement for cement. A new cement product called NewCem Plus was also investigated as a cement replacement at various percentages. In addition, the effectiveness of other materials and admixtures such as basalt fiber and lithium were also examined. The ASTM C1260 14-day accelerated mortar bar test was used for this study, and all supplementary materials were tested separately according to ASTM standards. Moreover, concrete properties such as compressive strength and concrete flow test were also evaluated in order to complement the test results. Our preliminary findings showed that Metakaolin could effectively be implemented in concrete mixtures as an ASR mitigation waste-by-product. In the samples with 10%, 20%, and 30% where Metakaolin was added as cement replacement, the expansion was 79%, 84%, and 88% less than that of the control mixture. The glass powder decreased the expansion of control specimens by 20%, 43%, and 75% at the 10%, 20%, and 30% replacement levels, respectively. The addition of lithium to the Metakaolin mitigated the ASR. Lithium by itself was effective when added to the Metakaolin and glass powder mixtures, where it reduced the expansion below the threshold limit, which is 0.1%. The cement replacement of 10% with glass powder + lithium resulted in 0.209% expansion (51% reduction). However, the reduction for the 20% and 30% was not enough to pass the ASTM test, and the total expansion went iv above the 0.1% total expansion safe limit of the test. The mixtures of NewCem Plus (NCM) and Lithium were not an effective solution for ASR reduction in concrete. The test results of the other two materials, glass powder, and basalt fibers, showed variations between reducing and increasing the expansion level based on their percentages of cement replacements. Although the concrete expansion was slowed, it was not kept under the safe level of 0.10% as recommended by ASTM 1260. Finally, the experimental results point positively to the simultaneous addition of multiple SCMs and additives in cement mixtures to further increase its numerous properties. In addition, a comprehensive cost analysis of all the ingredients used in all mixtures was performed. The results showed that the cost would be 50% less compared to the control mixtures (100% cement) to 655% more when basalt fibers were used. The manufacturer shall perform a life cycle assessment before the final decision of the inclusion of such materials. This study showed the feasibility of using binary and ternary blends of SCMs in mitigating ASR in concrete, and it shows a comprehensive representation of how those materials should be included in concrete moistures for future applications. The second topic of this dissertation was focused on the application of data mining in detecting outliers in concrete testing results and how that is important to stakeholders and decision makers. The rapid development in the construction industry has induced a large amount of concrete data over the years, which are usually measured and analyzed every day. Concrete is made from numerous ingredients that have huge variability either at the design stage or at the testing stage. The main
4 0
Restricted
BEHAVIOR OF HIGH STRENGTH REINFORCED CONCRETE BEAMS WITH VARIOUS REINFORCEMENTS
(Saudi Digital Library) ABDULLAH SAID ABDULLAH ALMAKRAB; Dr.Ahmed Ibrahim
7 0