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1

Mechanical properties and microstructure of alkali activated mortar containing unexpanded clay

Nasser I.F., Ali M.A., Kadhim M.J.

Archives of Materials Science and Engineering

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2022

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Vol. 113, nr 2

56--68

EN

Purpose: In building constructions, due to the decrease of local raw materials and for sustainability purpose, beside the need of light pieces to be used in roofing and false ceiling; an alkali-activated mortar is the new development where pozzolanic material is used instead of cement and activated by an alkaline solution. Therefore, in this research, alkali-activated mortar containing unexpanded clay as a fine aggregate with a dry density of 1652 kg/m3, compressive strength of 3.2 MPa, and thermal conductivity of 0.4 (W/m.K) was produced ,also boards were performed in a dimension of 305×152×12 mm as to use them in false ceiling, and reinforced with 0.25 and 0.5% steel fibre to improve their toughness by 370.8% and 1146.1% compared with reference boards, which made them good choice to used them in roofing and secondary ceiling. Design/methodology/approach: For preparation of alkali-activated mortar, low calcium fly ash (FA) was used as a source binder material. In addition, super-plasticizer and unexpanded clay as a fine aggregate (produce from the crushed artificial aggregate) in the ratio of 1:2.75 fly ash/fine aggregate. The paste was prepared by mixing fly ash with an alkali silicate solution, in a solid-to-liquid ratio of 0.4. Alkali silicate activator was prepared by mixing the NaOH and Na2SiO3 solutions at the mass ratios of 2.5. The concentrations of the NaOH was the same molarity of (14M).To improve the mechanical properties of the reference mortar mixture ,steel fibre with 0.25 and 0.5% content were added to the mix .The specimens were tested for water absorption, dry density, compressive strength, flexural strengths, flexural toughness, and thermal conductivity, in addition to the Scanning Electron Microscope test (SEM) for all mortar mixes. Alkali-activated mortar boards with (305×152×12 mm) were prepared and tested for flexural strength and toughness. Findings: The results indicated that the modulus of rupture for mortar boards reinforced with 0.25 and 0.5% steel fibre exhibits an increase of (3.68-12.10)%. In comparison, the toughness is increased by about 370.8% and 1146.1%, respectively, as compared with the reference mortar (without fibre) which made them resistance to accident, in addition to use them in roofing due to their thermal insulation. Research limitations/implications: Further research is needed to make a similar board using another sustainable material. We can examine the thermal insulation that we can get from these board, especially in the building in Iraq which the weather faces high temperatures. Practical implications: There is a by-product that we could get from the electricity station in Iraq. We must study how we get rid of it. Originality/value: This paper investigate how to produce a new light board using artificial aggregate made from unexpanded clay, which has many benefits in building insulation roofing.

2

Studying the effect of some parameters on the stability of shallow tunnels

Abdellah W. R., Ali M. A., Yang H.-S.

Journal of Sustainable Mining

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2018

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Vol. 17, iss. 1

20--33

EN

Several factors have crucial impact on the serviceability of underground openings including: the quality of rock mass; the presence of rock joints and their geometrical properties; the state of in-situ stress ratio; the depth below surface and opening geometry. This paper only investigates the effect of two parameters on the stability of underground shallow tunnels, namely: the presence of rock joints in the rock mass matrix and the shape of the excavation. A series of two-dimensional elasto-plastic finite-element models has been constructed using rock-soil, RS2D, software. Consequently, parametric stability analysis has been conducted for three different tunnel shapes (e.g. circular, square and horseshoe) with/without joint inclusion. Four reference points have been assigned in the tunnel perimeter (e.g. back, sidewalls and floor) to monitor the state of stress-displacement in the rock mass around them. The results indicate that the weak performance of a tunnel opening occurs with a square-shaped opening and when joints exist in the rock mass. In addition, the normal stress along joints sharply drops in the vicinity of a tunnel opening. Moreover, the direction of shear stress is reversed. Thus, it causes inward shear displacement.

3

Dual Frequency Triangular Slotted Microstrip Patch Antenna for Ku Band Applications

Samsuzzaman M., Islam M. T., Yatim B., Ali M. A.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1a

275--279

EN

A single feed, compact, new shaped, dual band microstrip patch antenna has presented in this paper. Here three equilateral triangular slots are introduced in the three edges of the patch and a small feed line has used another edge of the patch to obtain the dual band. The antenna has a condensed structure where patch dimension is about 8.5mm by 7.96mm by 1.905mm leading to good bandwidths covering 13.15 GHz to 13.72 GHz and 16.04 GHz to 16.58GHz. The return loss of -19.00dB is achieved at the first resonant frequency at 13.61 GHz and -28.69dB is at second resonance frequency at 16.33GHz. Stable average peak gain that is observed across the operating band in both lower and higher frequency is almost 3.53dB and 5.562dB respectively .The radiation patterns are nearly omnidirectional with moderate gain in both these operating bands. Good results have been established in dual frequencies at 13.62GHz as downlink and 16.33GHz as uplink. This low profile nature and simple configuration of the proposed antenna show the way to easy fabrication and make it adaptable for the application in wireless and satellite communication.

PL

W artykule przedstawiono dwupasmową prostokątną antenę mikropaskową o jednym doprowadzeniu i nowym kształcie. W trzech rogach znajdują się trzy szczeliny w kształcie trójkąta równobocznego, a w czwartym doprowadzenie linii. Antena posiada pasmo 13,15-13,72GHz oraz 16,04-16,58GHz. Niski profil oraz prosta konfiguracja wskazują na łatwą metodę produkcji oraz możliwość zastosowania w aplikacjach bezprzewodowych i komunikacji satelitarnej.

4

Trends and Differences of Applying Intelligence to an Agent

Elmahalawy A. M., Ali M. A., Harb H. M.

Journal of Telecommunications and Information Technology

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2011

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nr 4

119-123

EN

The agent technology has recently become one of the most vibrant and fastest growing areas in information technology. On of the most promising characteristics of agent is its intelligence. Intelligent agent is the agent that percepts its environment, collects all information about its environment that it needs, processes these information and then generate proper actions according to these information. This paper discusses trends and differences between two main types of intelligence that can be applied to agent: accumulative intelligence and dynamic intelligence. Accumulative intelligence is discussed with its two perspectives: moment perspective and historical perspective. Auto-vehicle driver is also discussed as an application example of accumulative intelligence. Also, MOSAIC, Mimesis, and MINDY models are reviewed as the pioneering works of dynamic intelligence.