Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 2Citation - Scopus: 2Effects of Mix-Design Variables on the Workability, Rheology and Stability of Self-Consolidating Concrete(Pontificia Universidad Catolica de Chile, Escuela de Construccion Civil, 2022) Alami, Mohammad Musa; Erdem, T.K.This study investigates the effects of basic mix design variables such as water/cement ratio (w/c), slump flow, coarse-to-total aggregate ratio (CA/TA), and maximum aggregate size (Dmax) on the main characteristics of self-consoli-dating concrete. The w/c of the mixtures was either 0.42 or 0.50. The CA/TA ranged between 0.45 and 0.53. Slump flow was adjusted to 550, 650 or 720 ±20 mm by varying the superplasticizer content. Dmax was varied as 10, 15 and 20 mm. V-funnel, L-box, rheometer, sieve segregation tests and a new test method, recently developed by the authors, for dynamic segregation resistance were performed. The effect of each variable on the test results were effectively summarized in a table. Increasing the w/c, CA/TA and Dmax decreased the superplasticizer demand and increased the flowability. When the slump flow, w/c and CA/TA were higher, viscosity was found to be lower. Higher values of CA/TA and Dmax were found to reduce the passing ability. Increasing the slump flow (or superplasticizer content), CA/TA and Dmax disturbed the sta-bility. Generally, the effects of w/c and slump flow on the SCC characteristics were more pronounced when compared to those of CA/TA and Dmax. Good correlations were obtained between several test results © Copyright (c) 2022 Alami, M. and Erdem, T. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivatives 4.0 International LicenseArticle Citation - WoS: 10Citation - Scopus: 11Meteorological Drought Analysis for Helmand River Basin, Afghanistan(TMMOB İnşaat Mühendisleri Odası, 2022) Alami, Mohammad Musa; Tayfur, GökmenThis study evaluates drought at Lashkargah, Farah, Adraskan, and Gardandiwal stations in Helmand River Basin (HRB) in Afghanistan to determine appropriate drought indices for the basin. Thirty seven years of monthly recorded precipitation data from 1979 to 2015 are employed with different drought index (DI) methods which include the Standardized Precipitation Index (Normal-SPI, Log-SPI, and Gamma-SPI), the Percent of Normal (PN), and the Deciles. All the methods are applied to the annual long term precipitation data. The log-SPI and the gamma-SPI predict extreme drought conditions, whereas, the normal-SPI determines wet and less dry conditions. The results emphasize that the PN and the Deciles methods predict more drought years in comparison to the SPI methods. The Deciles method shows longer period of extreme and severe drought than other methods. The five methods indicate various drought intensities in 1985, 1987, 1994, 1997, 1999, 2000, 2001, 2002, 2003, and 2004 at all the stations. The extreme drought condition in 2001 at all the stations confirms to the recorded drought reports for the same region. It is noted that since the log-SPI and the gamma-SPI capture the historical extreme and severe drought periods successfully, these are recommended as the drought monitoring indices for Helmand River Basin.Conference Object Citation - WoS: 6Development of a New Test Method To Evaluate Dynamic Stability of Self-Consolidating Concrete(RILEM Publications SARL, 2016) Alami, Mohammad Musa; Erdem, Tahir Kemal; Khayat, Kamal H.Although many different test methods have been proposed to evaluate the static stability of self-consolidating concrete (SCC), limited test methods have been developed to determine dynamic segregation of SCC. In this study, a new apparatus was developed for testing the dynamic stability of SCC. The new method was called as "Dynamic Sieve Segregation Test" (DSST) which provides a numerical result referred to the "dynamic segregation ratio" (DSR). Higher DSR values indicate dynamically less stable mixtures. Several correlations were successfully established between the test results. SCC mixtures with higher slump flow, higher coarse aggregate-to-total aggregate ratio or higher maximum aggregate size (Dmax) resulted in higher DSR values. A maximum DSR value of 30% was proposed for a dynamically stable SCC. The repeatability of DSST was found to be high with a COV value of 5.30%. Based on the results, DSST was found to be a suitable method to evaluate the dynamic stability of SCC.