Journal of Materials and Engineering Structures

167-184

Authors: Qasim M. Shakir, Ruqyia Alliwe

An experimental study has been conducted to explore the response of self-compacting RC drop in- beams retrofitted with NSM steel bars under short-term static loading. Eleven specimens have been tested in this program, each of (200x400x1600 mm) dimensions with two values of (a/d), namely (1.0 and 1.5). Two of these beams have been considered as reference beams (efficiently reinforced). Three beams with reduced reinforcement, two with deficient main nib steel, while the third with reduced steel in hanger. The rest have been upgraded with different arrangements to retire the expected drop in strength. It was found that reduction of nib reinforcements to the half, results in decreasing load failure of about (11% & 5%) for (a/d) values of (1 and 1.5) respectively. Also, it is observed that retrofitting the nib region with horizontal NSM steel bars led to increase the failure load capacity by about (28.7%) for (a/d) =1. While, the enhancement in strength for specimen with (a/d) =1.5 was about (24%). The increase in the strength capacity for upgraded hanger regions vertical and inclined bars for a/d (1) was about (21.4% and 14.2%) respectively.

203-2014

Authors: Taghreed Kh. Mohammed Ali

In this paper, the behavior of hybrid short columns made from low strength reinforced concrete core and an outer skin made from high strength concrete was studied. For this purpose, laboratory tests were carried out on ten small-scale column specimens. For bonding, the outer skin portion to the main column epoxy resin was used. Results revealed that bonding low strength concrete core with high strength outer skin was successful and able to produce a hybrid section. For the same section area, load capacity increased by 28% to 80% depending on the compressive strength of the provided outer skin, for concentrically loaded columns. In general, the behavior of eccentrically loaded hybrid specimens was good, indicating that the process of making hybrid columns according to the technique presented in this paper is successful and can be used in practice.

227-240

Authors: K. Ayed, D.E. Kerdal, N. Leklou

The effect of natural pozzolan and local waste siliceous fines on the durability of SCC was studied in this paper. Three self-compacting concretes were made with the following three additions, namely limestone fillers (SCC LF), pozzolanic fillers (SCC NP) and siliceous fillers (SCC SF). Durability tests, such as the porosity accessible to water, capillarity, carbonation, permeability to oxygen gas and diffusion of chloride ions, were carried out on these concretes in order to study the influence of these fillers on the transfer properties and durability of SCCs. The results obtained indicate that the SCC LF and SCC NP generally have the same transfer properties; these properties are significantly influenced by porosity and carbonation. In addition, the capillarity is nearly similar for all three SCCs. Moreover, it is worth noting that SCC NP gives permeability and diffusion coefficients of chloride ions slightly lower in comparison with those of the other SCCs. These finding suggest that the incorporation of Algerian natural fines and industrial waste as mineral additions into the SCC may have a positive environmental impact and can promote the development of local materials that are available in large quantities and whose production cost is low.

253-265

Authors: El-Hadj Meziane, Said Kenai, Bensaid Boulekbache, Abdelkader Bougara

This study investigate the influence of limestone fines (LF) on the mechanical properties, hydration heat and durability (acid and sulfate environments) of mortars made with crushed sand (CS) and different rate replacement of limestone fines of the CS (0%, 5%, 10%, 15%) using three types of cement, that is, ordinary Portland cement, limestone cement and pozzolanic cement. The obtained results show that the limestone fines increase the compressive strength and generate more hydration heat for all the used cements. Mortars made with blended cements, limestone or pozzolan, with 5% and 10% limestone fines, have low expansion when imerged in 5% Na2SO4 solution. In addition, when immerged in acids environment, the mortars with limestone fines exhibit negative effect at long-term durability. However, the mortar manufactured with ordinary Portland cement containing 15% of limestone fines will be strongly affected. It was found that no benefit can be gained from eliminating limestone fines fraction from the CS.

277-291

Authors: Raghubir Singh, Rizwan Ahmad Khan

This paper reports the results of an experimental study on the high performance concrete made with copper slag as fine aggregate. The percentage of Copper Slag(CS) added by weight in a range viz. 0, 25, 50, 75 and 100% as a replacement of sand used in concrete and cement was replaced with 15% Metakaolin. The properties studied include compressive strength, splitting tensile strength, Sorptivity, Rapid Chloride Permeability Test (RCPT), Accelerated Carbonation test and Microstructural properties. The test results showed that the compressive strength increases up to 50% copper slag as replacement of sand, beyond which decrease in strength was observed. The results of RCPT and sorptivity with different proportions of copper slag at 28, 90, 120 days of curing period showed the lowest value for the mix containing 25% and 50 % copper slag at each curing age. Carbonation results show that concrete mixes with 85% cement and MK 15% with increasing percentage of copper slag, the carbonation depth decreases slowly especially for 75% and 100%. The microscopic view from Scanning electron microscopy (SEM) demonstrated more voids, capillary channels, and micro cracks with the increment of copper slag as substitution of sand as compared to the control mix, profoundly visible at 100% replacement of sand which is due to the presence of free water.

307-324

Authors: Mohamed Zaoui, Slimane Himouri, Tahar Kadri, Charef BENAOUINA

Decision-making involves the selection from various possible alternatives and generally implicates huge financial resources. In addition, one characteristic of a territory making it difficult to make a decision is its multi-criteria aspect. These multi-criteria generally have antagonistic effects and analytical methods are most congruent for solving this kind of difficult decision-making situation. The work presented in this article focuses on the problem of decision-making in order to identify the most favorable road alignment with regard to a series of topographical, geometric, geological and economic criteria. The main goal of this study is to select the best road alignment project to replace part of the road section of the CW 42 connecting the city of Sidi Belattar to National Road 90 (RN 90) using GIS and AMC tools. This road section has been blocked several times in recent years during rare winter flooding. The proposed approach deals with the following points: First, determination of the relevant criteria using GIS, then evaluation and classification of the various alternatives by applying the AHP method using AMC Expert-choice software and PROMETHEE-GAIA algorithms (laboratory-developed web.d-sight software, coded SMG, ULB). Four variants were recommended to replace the vulnerable section. From these four variants a classification was made, according to the two methods AHP and PROMETHEE. The calculated consistency of the results confirms the effectiveness of the proposed approach. Finally, Alternative 2 and Alternative 1 were ranked first by both AHP and PROMETHEE methods and are therefore a recommended choice. This work aims at helping decision makers to rank four road projects of the study area in order to replace the most vulnerable section.