Abdoullah Namdar

Bearing capacity of mixed soil model

The main objective of this research is the improvement of red soil by the addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to characterize the behavior of red soil when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC). Safe bearing capacity of all models have been calculated to identify the best and worst soil mixed model.

Effect of flexural crack on plain concrete beam failure mechanism A numerical simulation

The flexural failure of plain concrete beam occurs along with development of flexural crack on beam. In this paper by using ABAQUS, mechanism failure of plain concrete beam under three steps have been simulated. The cracking moment has been analytically calculated and applied on the both sides of the fixed beam, and flexural crack has been simulated on beam. Displacement, von Mises, load reaction, displacementcrack length, von Mises-crack length and von Mises-displacement of beams have been graphical depicted. Results indicated that, the flexural crack governs beam mechanism failure and its effects on beam resistance failure. It has been found that the flexural crack in initial stage it developed slowly and changes to be fast at the final stage of collapsing beam due to reduction of the flexural resistance of beam. Increasing mechanical properties of concrete, collapse displacement is reduced.

Effect of Seashell Powder on Flexural and Compressive Strength of Cement Mortar in Early Age

The several structures have been failed due to low flexural and compressive strength of OPC paste. Many waste materials are applicable for modify flexural and compressive strength of cement mortar. Among the additives, a natural additive has been selected. The effect of seashell powder on flexural and compressive strength of cement mortar has been investigated. The result indicated that with replacement of 1% seashell, the deflection, time to failure and maximum load to failure of concrete beam has been improved. And the strain, time to failure and compressive modulus elasticity of cubic specimen has not considerably been changed. The more investigation on macro and micro property of OPC is necessary to obtain better results.

An Investigation on Effect of Oil Palm Shell Ash on Flexural Strength and Compressive Strength of Cement Mortar

One of waste agriculture materials is oil palm shell ash. It has been producing in high quantity in palm oil mill, and for storage of that an investment requires. In this paper, an attempt has been made to analysis effect of oil palm shell ash on compressive and flexural strength of cement mortar. The compressive strength and flexural strength of cement mortar has been measured. To improve accuracy of work 50% cement and 50% fine sand has been proposed in cement mortar mix design. The results have been indicated that the effect of OPS ash on flexural and compressive strength of cement mortar is not same. The deflection, load sustainability and time to failure for compressive strength have independent fluctuation of flexural strength. The positive and negative effect of OPS ash on mechanical properties of cement mortar has been observed. The morphology of crack failure has not been investigated. The work can be continued with many waste agriculture materials. Keywords: waste agriculture, deflection, load sustainability, time to failure.

An experimental study on flexural strength enhancement of concrete by means of small steel fibers

Cost effective improvement of the mechanical performances of structural materials is an important goal in construction industry. To improve the flexural strength of plain concrete so as to reduce construction costs, the addition of fibers to the concrete mixture can be adopted. The addition of small steel fibers with different lengths and proportion have experimentally been analyzed in terms of concrete flexural strength enhancement. The main objectives of the present study are related to the evaluation of the influence of steel fibers design on the increase of concrete flexural characteristics and on the mode of failure. Two types of beams have been investigated. The force level, deflection and time to failure of beams have been measured. The shear crack, flexural crack and intermediate shear-flexural crack have been studied. The steel fiber content controlled crack morphology. Flexural strength and time to failure of fiber reinforce concrete could be further enhanced if, instead of smooth steel fibers, corrugated fibers were used.

Tsunami numerical modeling and mitigation

The numerical modeling and wave theory are used in tsunami mitigation analysis. It is assumed sea forest is simulating offshore structure submitted to wave loads. The sea forest acts simulate break waves in conservation of coastal territory and facility installed over there. The result reveal that mathematical modeling and numerical simulation can be used to understand tsunami ability in design and urban construction, the research indicates reduction of water deep by sea forest resulted in reducing geometry and all wave ability.

Behaviour of Oil Palm Shell Reinforced Concrete Beams Added with Kenaf Fibres

The present article reports the findings of a study into the behaviour of oil palm shell reinforced concrete (OPSRC) beams with the addition of kenaf fibres. This work aims at examining the potential of kenaf fibres to improve the strength and ductility of the OPSRC beams as well as observing its potential in serving as part of shear reinforcement in the beams. Two different arrangements of the shear links in OPSRC beams with a selection of kenaf fibres content (10kg/m3 and 20kg/m3, respectively) were tested under monotonic loading. The results show that the addition of kenaf fibres enhances the load carrying capacity, ductility apart from altering the failure mode of the beams from brittle shear mode to flexural ductile mode. Furthermore, the study shows that kenaf fibres are compatible with OPSRC with desirable results.

The Effect of Nanoparticles of Ordinary Portland Cement (OPC) on Compressive Strength of Concrete

The quality of a construction material satisfies stability of structure. Several additives have been innovated for improve quality of compressive strength of concrete. In this paper for enhancement of compressive strength of concrete, a simple method has been proposed. The kaolin and bentonite have been treated by heat for duration of 1 hour, with constant temperature. For kaolin 200 oC, 400 oC, 600 oC, 800 oC, 1000 oC and 1200 oC of heat, and for bentonite 200 oC, 400 oC, 600 oC, 800 oC of heat has been subjected. The kaolin and bentonite treated by heat have been proposed as additive for concrete. The objective is to introduce an additive to improve compressive strength of concrete. The microstructure of modified Ordinary Portland Cement (OPC) paste has been investigated by using Field Emission Scanning Electron Microscopy (FESEM) and X-ray diffractometry (XRD). The results indicate that the best level of heat for produce additives from kaolin and bentonite, and illustrate quantity of additives for replace a portion of cement in concrete application. Modification of nanoparticles of cement paste during hydration has been discussed.

Using High Temperature for Improve Compressive Strength of Ordinary Portland Cement Paste (OPC) – A New Approach

Cement paste was replaced with kaolin-bentonite. The specimens were exposed to elevated temperature for 3 hours in a ceramic furnace and cooled down to room temperature. After cooling, the effect of kaolin-bentonite (particles sized of < 45μm) on hydration, rehydration, surface roughness and compressive strength of ordinary Portland cement (OPC) paste were investigated. Atomic Force Microscopy (AFM) was used to study surface roughness of OPC paste-additive mixture. The application of fire on OPC paste was analyzed. The results showed imposed heat (500 oC for 3 hours) accelerates the hydration process of OPC, and reduces setting time. Increased heat to 1000 oC, leads to zero compressive strength of specimens, the compressive strength of OPC continuously reduces after specimen has fully cooled down. A method for recovery of compressive strength of OPC after offing fire has been suggested. The method of offing fire has important effects on the compressive strength of concrete. The best results for specimen content are cement-kaolin-bentonite paste, exposure to 500 o C, after 90 days of curing, and cooling down in water. In this case the compressive strength has been increased around 60 % compared to not using additive and not exposing to heat.

Modification of Kaolin Mineralogy and Morphology by Heat Treatment and possibility of Use in Geotechnical Engineering

This paper presents an experimental work on the effect of heat treatment on the mineralogy and morphology of kaolin. Kaolin, which is moderately expansive, was preheated at temperatures ranging from 200°C to 800°C by increment of 200°C and cooled at room temperature before it was mixed with peat. Peat represents a compressible soil and has low bearing value. The main aim of the work is to study the effect of heat treatment on shear strength parameters of peat-kaolin mixture. The mixtures are prepared at different proportions, and at each proportion triaxial samples were prepared and tested in the undrained condition to study the shear strength parameters. Untreated kaolin-soil mix was also prepared to provide a comparison between the treated and untreated soil mix in terms of the shear strength behaviour. XRD and FESEM were also carried out to investigate the change in soil micro-structure due to heat treatment. The tests showed that there was a slight improvement in the strength of peat-kaolin mixture when kaolin was preheated to a temperature of up to 400°C. Finally results were discussed and conclusions were made for the preheated kaolin-peat mixture.