Investigation of linearity between mechanical properties of wood using graphical method

Some basic requirements are set for small clear specimen data to incorporate Malaysian timbers into equivalent European timber strength classes. In general, the correlation between structural and small clear specimen test results must be established for every timber group regardless of origin. This paper introduces a sort-plot technique for analysing the correlation of some mechanical properties of timber in selecting appropriate parametric model. Bending test was conducted on mixed species hardwoods for the determination of strength and stiffness values of both structural and small size specimens. The results showed that the sort-plot diagrams demonstrate an obvious linearity pattern between timber properties despite having poor regression values. The technique verified that properties of timber in structural and small size specimens correlated linearly

High strength lightweight aggregate concrete using blended coarse lightweight aggregate origin from palm oil industry

The benefits of using structural lightweight concrete in construction industry, particularly in high rise buildings, over normal weight concrete are numerous. The main method of producing structural lightweight concrete is the use of lightweight aggregates instead of ordinary aggregates in concrete. Due to the limited resources for natural and artificial lightweight aggregates, the alternative sources for lightweight aggregates should be discovered from industrial wastes. Oil palm shell (OPS) and oil-palm-boiler clinker (OPBC) are two solid wastes from palm oil industry and are available in abundance in tropical regimes. The use of just OPS as coarse lightweight aggregate in concrete mixture has some drawbacks for concrete. The aim of this study was to investigate engineering properties of a lightweight concrete containing both of these aggregates. For this purpose, in this study, 50% (by volume) of OPS was replaced with OPBC in an OPS lightweight concrete. The test results showed that when OPS was substituted with OPBC, significant improvement was observed in the compressive, splitting tensile and flexural strengths. In addition, initial and final water absorption as well as drying shrinkage strain of blended coarse lightweight aggregate concrete were significantly less than OPS concrete

Problems associated with plate bonding methods of strengthening reinforced concrete beams

This paper reviews works on problems associated with plate bonding or plating methods of strengthening reinforced concrete beams. Every structural element should be designed for a particular type of loading. However many civil structural elements, like reinforced concrete beams are often required to be upgradedor strengthened due to increased load requirements. Strengthening is becoming both environmentally and economically more preferable than replacement. Different types of materials and methods such as sprayed concrete, ferrocement, steel plate and fibre reinforced polymer (FRP) are available for strengthening existing reinforced concrete beams. However, plating methods of steel plate and FRP laminate are the most popular methods amongst the other methods. In this paper, strengthening of plating methods by using steel plate and fibre reinforced polymer (FRP), and the methods of applying these materials are reported. The advantages and disadvantages of these materials are also reported. Furthermore the problems associated with this plating methods by using two these two materials (steel and FRP) are briefly discussed in this paper

Strengthening of RC beams using externally bonded plates and anchorages

This paper presents a study on strengthened reinforced concrete beams using externally bonded plates and anchorages. Strengthening materials and methods, failure modes of strengthened beams, effect of end anchorages and effect of intermediate anchorages are reviewed. An experimental programme to evaluate the structural behaviour of anchored steel plate and CFRP laminate flexurally strengthened reinforced concrete beams is also reported. A total of five beams, each 2300 mm long, 125 mm wide, and 250 mm deep, were fabricated and tested. One beam was left un-strengthened to act as the control beam, two beams were strengthened with steel plate and another two beams were strengthened with CFRP laminate. From each of the steel plate and CFRP laminate strengthened beams, one beam was left unanchored and another beam was anchored at the end and shear spans (intermediate anchored) by L shape plates to avoid premature failure. The experimental results overall showed that the strengthened beams had higher failure loads and good failure modes over the control beam. Results also illustrated that the end with intermediate anchored strengthened beams

Mix design and mechanical properties of oil palm shell lightweight aggregate concrete: a review

To build environmentally sustainable structures, especially in developing countries, the possibility of using some agricultural wastes and industrial by-products from different industries as construction materials will be highly desirable and has several practical and economic advantages. Oil palm shell (OPS) is a form of agricultural solid waste in the tropical regimes. Research over the last two decades shows that OPS can be used as a lightweight aggregate for producing structural lightweight aggregate concrete. The density of OPS concrete is around 20 - 25 lower than normal weight concrete. Generally, mechanical properties of OPS concrete are slightly lower than the other types of lightweight aggregate concrete. It seems that from the summary and analysis of the existing information concerning OPS concrete and comparing it with other lightweight aggregate concrete it appears that significant achievements can be attained

Review on bonding techniques of CFRP in strengthening concrete structures

Selecting appropriate bonding technique is crucial for strengthening and repairing concrete structures as different bonding techniques have different performances. A state-of-the-art review of different bonding techniques that is epoxy bonding technique, prestressed strengthening technique, unbonded anchored technique/mechanically fastened technique using CFRP is dealt and the corresponding advantages and disadvantages are highlighted in this review. Existing unbonded anchored techniques/mechanically fastened techniques are critically reviewed and compared to the other conventional strengthening techniques which will help in selecting the appropriate bonding technique for strengthening and repairing concrete structures. Future recommendations in this field are also indicated in this paper

Structural performance of reinforced concrete beams repairing from spalling

The effectiveness of a repair work for the restoration of spalled reinforced concrete (r.c.) structures depends to a great extent, on their ability to restore the structural integrity of the r.c. element, to restore its serviceability and to protect the reinforcements from further deterioration. This paper presents results of a study concocted to investigate the structural performance of eight spalled r.c. beams repaired using two advanced repair materials in various zones for comparison purposes, namely a free flowing self compacting mortar (FFSCM) and a polymer Modified cementitious mortar (PMCM). The repair technique adopted was that for the repair of spalled concrete in which the bond between the concrete and steel was completely lost due to reinforcement corrosion or the effect of fire or impact. The beams used for the experiment were first cast, then hacked at various zones before they were repaired except for the control beam. The beam specimens were then loaded to failure under four point loadings. The structural response of each beam was evaluated in terms of first crack load, cracking behavior, crack pattern, deflection, variation of strains in the concrete and steel, collapse load and the modes of failure. The results of the test showed that, the repair materials applied on the various zones of the beams were able to restore more than 100 of the beams' capacity and that FFSCM gave a better overall performance

Development of lightweight concrete using industrial waste material, palm kernel shell as lightweight aggregate and its properties

Abstract-Agricultural industrial wastes produced after extracting palm oil from palm fruits known as palm kernel shell (PKS) are available in large quantities in Indonesia, Malaysia, Nigeria and other tropical countries. Malaysia is the second largest palm oil producing country in the world. This paper reports the results of an investigation conducted to utilize the PKS as lightweight aggregate to produce grade30 concrete with density of about 1850kg/m3. The properties of both PKS and crushed granite aggregates were compared. The concrete produced using PKS referred to here after as palm kernel shell concrete (PKSC) and its properties were compared with properties of normal weight concrete (NWC) of grade 30 produced using crushed granite aggregates. The fresh and hardened concrete properties such as density, workability, compressive strength of PKSC and NWC were compared. Further, structural behavior through flexural test was investigated. It has been found that PKSC has produced workable concrete and compressive strength of about 35MPa was obtained within 90 days. The addition of 10 silica fume has effect on both workability and strength. The as-cured density of PKSC was found 22 lower than the NWC. Further, the moment capacity of PKSC beams was found higher than NWC beams. In addition, the mode of failure observed in PKSC was ductile compared to the brittle failure of NWC beams

Failure reliability and damage detection of ferrocement composite slabs

This paper introduces suitable features and methods to define hazard rate function by acoustic emission parameters to develop robust damage statement index and reliability analysis. AE signal energy was first examined to find out relation between damage progress and AE signal energy so that a damage index based on AE signal energy was proposed to quantify progressive damage imposed to composite slabs. Moreover by using AE signal strength, historic index was utilized to develop a modified hazard rate function through integration bathtub curve and Weibull function