Abstract: The shearing strength and volumetric relationship of granular materials change notably with a variation of confining pressure. In this study the effect confining pressure on the mechanical behavior of granular materials were observed using discrete element method (DEM). The triaxial tests were conducted on seven specimens covering a range from extremely low to high confining pressures. Each isotropically compacted specimen contains similar number spherical particles for same porosity. The strength and deformation characteristics show a good agreement with the experimental behavior of granular materials. At low to high confining pressures, there is a decrease in the peak angle of shearing resistance and dilation with the increase of confining pressures. However, the dependency of peak friction angle, dilatancy index and deformation characteristics on extremely low confining pressures are negligible. A unique relationship was also observed between normalized work and axial strain under different confining pressures. Microscopic parameter such as coordination number increases with the increase of confining pressure both for extremely low and low to high confining pressures. However, the tendency of evolution of the coordination number is quite different in extremely low and low to high confining pressures.

Abstract: The use of timber as structural member have come under serious review and study recently as good quality logs are alarmingly becoming scarce besides the chronic problems of traditional sawn timber. Several technologies, like plywood, OSB, glued laminated timber (glulam) and laminated veneer lumber (LVL) have been developed to improve the properties of timber. This paper present the results of a preliminary investigation on the bending strength behavior of glulam manufactured from selected Malaysian tropical timber namely, resak and keruing in accordance with MS 758. Tests were carried out on four isolated simply supported beams according to procedure set forth in BS EN 408:2003. The bending strength of glulam was compared with the permissible strength of the timber under bending in accordance with MS 544 Part 3. The results shown that the glulam produced passed the required allowable strength value.

Abstract: In this study, the experimental results on the simply supported PFRP channel beams subjected to three-point loading are presented. The aims of this paper are to investigate the effects of the span on the structural behaviors, the critical buckling loads and the modes of failure of the beams, and to compare the obtained deflections with those obtained from the Timoshenko’s shear deformation beam theory equation in order to check the sufficiency of the equation. The beam specimens have the cross-sectional dimensions of 152 43 10 mm with span-to-depth ratio ranging from 13 to 33. A total of sixteen specimens were tested. Based on the experimental results, it was found that the loads versus mid-span vertical deflection relationships of the beam specimens are linear up to the failure, but the load versus mid-span lateral deflection relationships are geometrically nonlinear. The general modes of failure are the flexural-torsional buckling. Finally, the Timoshenko’s shear deformation beam equation can adequately predict the vertical deflection of the beams.

Abstract: Waste concrete aggregate (WCA) refers to aggregates that have been used previously in cement concrete structures. After many research it had been concluded that WCA can be used in bituminous concrete. In bituminous concrete mix, there is a wide scope for varying the gradation of aggregate to obtain a good mix without affecting the durability of pavement. Bituminous concrete mixes with WCA in accordance with different gradations were studied. Behavior of bituminous concrete mixes with WCA is also investigated with two different compactive energy, one for medium traffic and another for heavy traffic. The research program concentrated on the Marshall design criteria for bituminous mixes. A dense grading with 25 mm maximum size is found to give the most satisfactory result from the stand point of stability, stiffness, deformation and voids characteristics. Test results reveal that the bituminous concrete with WCA can give satisfactory results when they are constructed using dense gradation and medium compaction.

Abstract: Problems of rigid pavement can be due to two basic causes. The first is deterioration or deficiency of the pavement itself. The other category deals with the structural adequacy of the pavement-base-subgrade structure. To minimize these problems, a rigid pavement called “Nailed Slab System” was proposed. The interaction of concrete slab, piles and soils creates a stiffer pavement structure and more resistant to traffic load. This paper aims to show the method to determine the deflection of the slab supported by piles due to point load. For this purpose, loading tests on small scale models of piles supporting slab were performed in the laboratory. The deflections along the slab observed from loading test were compared to those calculated using the theory of beam elastic foundation. The results of analysis showed that the proposed method to estimate deflections is fairly in accordance with the data observed.

Abstract: This paper presents the results of an experimental study on the durability properties of self compacting, high-volume fly ash concrete mixes (SCC-HVFC) mixes. Five self-compacting concrete mixes with a higher cement replacement at 60% of cement with fly-ash, are designed and their performance is compared with two normally-vibrated concrete mixes (NCs) of equivalent M30 strength grade. The durability properties are evaluated in terms of chloride-ion penetrability as measured by RCPT tests . The results indicate that the SCC-HVFC mixes would have lesser permeable voids than the normally-vibrated concrete mixes of comparable strengths. The experimental results also show that large improvements against chloride penetration can be realized with self- compacting high-volume fly-ash concrete mixes additionally admixed with GGBFS, silics fume, metakaolin and rice husk ash.

Abstract: Soil stabilization with cement is a good solution for the construction of subgrades for roadway and railway lines, especially in transition zones between embankments and rigid structures, where the mechanical properties of supporting soil are very influential. In order to optimize the design of cement-mixed soil structures, their behaviors need to be well understood; especially the strength and deformation characteristics at very small strains are of great importance. Similar to concrete material, the strength of cement-mixed soil continues to increase with time, thereby improving its strength and deformation properties with time. On the other hand, in the field cementation bonds in cement-mixed soils are formed under stress in case of in-situ soil. However, in the past researches the cementation bonds under stress was considered only by a few researchers. This is an underestimation of the stress-strain behavior of cement-mixed soil. This study investigates the influence of long curing period (e.g. up to 180 days) and the stress condition during curing stage on the strength and deformation characteristics of cement-mixed sand. A series of consolidated drained (CD) triaxial compression (TC) tests were performed along with the small strain cyclic loading and bender element tests at intervals during monotonic loading to determine the elastic Young's modulus (Ev) at extremely small strain range and shear moduli (Ghh, Ghv and Gvh) respectively. The test results show that the curing stress and curing period both have a significant influence in the peak strength, stiffness, Ev, and Gvh value. Curing period also influences the value of shear moduli in the two horizontal directions Ghh and Ghv. However, the influence of curing stress on the Ghh and Ghv is not very clear. The degradation phenomena of cementation bond were discussed according to the test results obtained from the cyclic loading and bender element test during shearing of cement-mixed sand.

Abstract: This study is carried out to evaluate the effectiveness of lime as a modifier and also a replacement of stone filler in the road paving asphalt concrete mixtures. The control optimum Asphaltic Concrete (AC) mix without lime and the modified AC mixes with lime in varying percentage as substitute to crushed stone filler by the same amount in the mineral aggregate were prepared in laboratory for fabrication of the test specimens. Design asphalt content was obtained 5.8 % from Marshall Method of mix design. The same asphalt content was used for AC control mix and modified AC mixes with lime in 1.0%, 1.5%, 2.0% and 2.5% for preparation of test specimens. Marshall Stability and Indirect tensile strength tests were conducted on unconditioned and conditioned test specimens of AC Mix without lime and modified AC mixes with lime for evaluation of loss of stability and Tensile Strength Ratio. The results obtained from modified AC mixes with lime shows a reduction in loss of stability and increase in tensile strength ratio. The increase in tensile strength ratio was found 3.3%, 5.3%, 6.5% and 8.1% and loss of stability are 14.8%, 28.1%, 45.0% and 51.5% against the addition of 1.0%, 1.5%, 2.0% and 2.5% lime respectively in modified AC mixes. The tensile strength ratio and loss of stability are the parameters for assessing the effect of water susceptibility of AC mixes. Results of this study shows that the addition of lime up to 2.5 % in AC mixes produced with Bolaganj stone aggregate increased the resistance to adverse effect of water.

Abstract: In many regions around the world groundwater serves as the only reliable source for fresh water making it extremely important natural resource. The quality of many groundwater aquifers is threatened by various types of pollution including leaking under ground storage tanks. When such tanks leak, they introduce a liquid organic substance that is usually less dense than water frequently called LNAPL. Usually such source of contamination is not discovered until significant subsurface pollution takes place. To overcome such problem once it exists, proper assessment related to aquifer properties and extent of pollution becomes necessary over which the success of the whole cleanup process depends. The natural heterogeniety is expected to have a big effect on the above attempts. The various processes that influence the fate and distribution of organic contaminants in groundwater after a leak and the transport process itself are presented indicating the complexities that will exist as one attempt to develop flow, transport of dissolved contaminants, and multiphase flow models to come close to representing real life problems indicating the degree of modeling reliability. The role of heterogeneity is examined through the use of a physical model and an idealized heterogeneity. Experimental spills were conducted and experimental observations were compared with model predictions in order to assess the reliability of the mathematical modeling process. The difficulties associated with aquifer remediation from residual LNAPLs are also examined by considering a hypothetical natural heterogeneity and the often low success rate of aquifer restoration programs due to heterogeneity is explained.

Abstract: The increasing demand for producing durable construction materials which is essential for green environment. Supplementary cementitious materials have been proved to be effective to meet most of the requirements of durable concrete. Rice husk ash is found to be good performance to other supplementary materials like silica fume and fly ash. The objective of this research is to present the use of Bangladeshi RHA as partial replacement of cement in concrete production. Three different replacement levels namely 0%, 10% and 20% are chosen for the study concern. Long range of curing periods starting from 7 days, 14 days, 28 days, 90 days and 300 days are considered in the present study. Permeability of concrete is measured in terms of current passing through it at 14 days curing. The compressive strength of the concrete with 10% RHA has been increased significantly and for up to 20% replacement level could be beneficially without adversely affecting the strength. In addition, it can be noted that the permeability of concrete was decreased up to 6% in presence of 10% replacement of RHA and for 20% replacement it was decrease up to 14%. Rice husk ash (RHA) added to concrete influences the pH of the samples. In this study it was observed that addition of 10% & 20% RHA with OPC to the concrete, the time required for the equal pH in the anodic and cathodic compartment is more than the control sample which was indicated that rich cement mix exhibits better resistance of water with respect to normal and lean cement concrete.