Payam Shafigh

Behavior of Channel Shear Connectors in Normal and Light Weight Aggregate Concrete (Experimental and Analytical Study)

This paper describes five push-out tests carried out at the University of Malaya using channel shear connector. The tests study experimentally and analytically, the behavior of channel shear connectors embedded in normal and light weight aggregate concrete (LWAC). Limited push-out tests are used to measure the accuracy of a proposed nonlinear finite element model for typical push-out test specimens. Using this model, an extensive parametric study performed to arrive at prediction for shear capacity of channel connectors in LWAC. An equation is suggested for the shear capacity of these connectors in LWAC.

Development of Self-Consolidating High Strength Concrete Incorporating Treated Palm Oil Fuel Ash

Palm oil fuel ash (POFA) has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC). POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties.

Structural Lightweight Aggregate Concrete by Incorporating Solid Wastes as Coarse Lightweight Aggregate

Structural lightweight aggregate concrete offers several benefits as compared to the normal weight concrete. Most common methods of producing structural lightweight concrete is by using artificial lightweight aggregates. However, the cost of the production of artificial lightweight aggregates is high due to energy and raw materials consumption. The use of waste and by-product materials as lightweight aggregate in concrete can provide a better solution to reducing the negative impact of the concrete industry. This paper reports an investigation to produce structural lightweight aggregate concrete by utilizing the locally available solid waste materials, namely oil palm shell (OPS) and oil-palm-boiler clinkers (OPBC) as coarse lightweight aggregates. Two different mix proportions were studied. In the first concrete mix, just OPS was used as coarse aggregate. However, 40% of OPS (by volume) of the first mix was replaced with OPBC in the second mix. The test results showed that by replacing OPS with OPBC, it directly affects the characteristics of the lightweight concrete. The 28-days compressive strength of the blended coarse lightweight aggregate concrete was significantly increased compared to OPS concrete.

An experimental study on shear reinforcement in RC beams using CFRP-bars

Fibre reinforced polymer (FRP) as an alternative to steel in reinforced concrete (RC) beams has become increasingly popular. The merits of FRP include high strength to weight ratio and corrosion resistance, and its advantages cannot be ignored in civil engineering. Consequently, FRP has attracted considerable interest from researchers. In this research, the effects of using CFRP bars as shear reinforcement instead of stirrups in RC beams have been investigated. All beams were cast using a high strength concrete (HSC), which was also a self-compacting concrete (SCC). For this new idea, modes of failure for seven laboratory specimens, including a comparison of the ultimate moment capacity of beams, load-deflection control, load of first crack, crack width and position of the neutral axis (N.A.) were analysed. The results show that using carbon fibre reinforced polymer (CFRP) shear reinforcement can be an acceptable alternative for normal stirrups in RC beams.

Flexural Behaviour of Concrete Beams Bonded with Wire Mesh-Epoxy Composite

This paper investigates the flexural performance of plain concrete beams bonded with wire mesh-epoxy composite. A total of four beam specimens were prepared and tested. Three specimens were bonded with same amount of wire mesh-epoxy composite with varying composite width and one plain concrete specimen was used as a control. The effect of wire mesh-epoxy composite on enhancing the flexural behaviour of concrete beams as well as the effect of different configurations of composite was studied. Test results showedthat the wire mesh-epoxy composite increased the flexural strength of concrete beams. The increase in energy absorption of bonded beams was remarkable. In addition, specimen with large composite width showed better behaviour with respect to energy absorption capability.

Structural Lightweight Aggregate Concrete Containing High Volume Waste Materials

The use of waste and by-product materials as aggregate or cement replacement in concrete can provide a solution to reducing the negative impact of the concrete industry. This paper reports an investigation to produce green concrete by using oil palm shell (OPS) as coarse lightweight aggregate as well as ground granulated blast furnace slag (GGBFS) as supplementary cementing material subjected to different curing conditions. Test results show that it is possible to produce green structural lightweight aggregate concrete containing 50% waste materials (by volume of concrete) with 28-day compressive strength of about 33 MPa. Data show that OPS concrete is very sensitive to curing, especially when GGBFS is used as a supplementary cementitious material.

Production of high-strength lightweight concrete using waste lightweight oil-palm-boiler-clinker and limestone powder

Oil-palm-boiler clinker (OPBC) is an agricultural solid waste from the incineration process of solid wastes in palm oil industry. The OPBC that is highly porous and lightweight in nature is suitable to be used as a lightweight aggregate. This paper presents a method to produce high-strength lightweight aggregate concrete using OPBC. The workability, density, cube compressive strength in different curing conditions, splitting tensile strength, modulus of elasticity and water absorption were measured. Test results showed that a high-strength lightweight aggregate concrete with the 28-day compressive strength in the range of 50–60 MPa with an oven dry density of 1875–1995 kg/m3 could be produced. OPBC high-strength lightweight concrete under air-drying condition showed equivalent compressive strength compared to full water curing condition, showing that OPBC lightweight concrete is not sensitive to the lack of curing. The initial water absorption test result showed that OPBC high-strength lightweight concrete can be categorised as good concrete.

The Effect of Palm Oil Fuel Ash as a Cementreplacement Material on Self-Compacting Concrete

In this study ground palm oil fuel ash (POFA) has been used as cement replacement in percentages of 0%, 10%, and 20% in a self-compacting concrete (SCC). Fresh properties such as slump flow, T50, V-funnel, J-ring, L-box and segregation index; concrete properties such as drying shrinkage strain, initial surface absorption test (ISAT) as well as compressive strength were investigated. Test results showed that substitution of cement with POFA up to 20%, the fresh properties of the concrete fulfilled the requirements of a self-compacting concrete. The results revealed that concrete has higher compressive strength, lower drying shrinkage, and lower initial surface absorption than control mix. The results indicated that POFA can be used up to 20% as a cement replacement material for producing self-compacting concrete.

Oil palm shell as an agricultural solid waste in artificial lightweight aggregate concrete

The aim of this study was to produce a sustainable construction material by incorporating an agricultural solid waste, namely oil palm shell (OPS), in an artificial lightweight aggregate concrete. For this purpose, in a structural lightweight aggregate concrete made of expanded clay, the lightweight aggregate was substituted with OPS in 0, 25 and 50% by volume. Properties such as compressive strength under different curing conditions, as well as density, splitting tensile and flexural strengths, modulus of elasticity and drying shrinkage of expanded clay–OPS concretes were measured and discussed. The test results showed that partial substitution of expanded clay by OPS increased the density, compressive strength, specific strength (compressive strength to weight ratio), as well as splitting tensile and flexural strengths of lightweight concrete. However, it was observed that the modulus of elasticity decreased by about 4 and 13% in the 25 and 50% substitution levels, respectively. The expanded clay–OPS concretes showed greater drying shrinkage strain compared to expanded clay lightweight concrete. In addition, it was found that the sensitivity of compressive strength of concretes containing OPS to the lack of curing is due to high drying shrinkage and consequently micro-cracks formation in the interfacial transaction zone of the concretes.

Quality control of lightweight aggregate concrete based on initial and final water absorption tests

Water absorption test is used to evaluate overall performance of concrete in terms of durability. The water absorption of lightweight concrete might be considerably higher than the conventional concrete due to higher rate of pores in concrete and lightweight aggregate. Oil palm shell is a bio-solid waste in palm oil industry, which could be used as lightweight aggregate in the concrete mixture. The present study aims to measure the initial and final water absorption and compressive strength of oil palm shell lightweight concrete in order to evaluation of quality control and durability performance. Total normal coarse aggregates were substituted with coarse oil palm shell in a high strength concrete mixture. The quality of concrete was then evaluated based on the compressive strength and water absorption rates. The results showed that fully substitution of normal coarse aggregates with oil palm shell significantly reduced the compressive strength. However, this concrete with the 28-day compressive strength of 40 MPa still can be used as structural concrete. The initial and final water absorption test results also showed that this concrete is not considered as a good concrete in terms of durability. Therefore, it is recommended that both compressive strength and waster absorption tests must be performed for quality control of oil palm shell concretes.