The concrete technology has been growing significantly since years ago especially in Indonesia’s construction. Therefore, Indonesia needs new innovation of concrete technology to solve the problem for the availability of concrete material. Indonesia is known as the largest producer of crude palm oil (CPO) in the world. Oil palm shell (OPS) is one of the solid wastes produced in crude palm oil industry that can be used as concrete materials. This paper presents the experimental results of a research project to produce structural lightweight concrete using oil palm shell (OPS), as a coarse aggregate. This experimental was investigating the effects of adding silica fume, fly ash, and superplasticizer for the compressive strength and flexural strength of the OPS lightweight concrete. It was found that OPS lightweight concrete has compressive strength up to 23.90 MPa in 28-days and flexural strength up to 2.54 MPa in 28-days. This experimental concluded that OPS lightweight concrete has a good potential as a lightweight coarse aggregate and low-cost housing construction in Indonesia.

The shear key is an important part of a precast segmental concrete bridge. Aside from its function of contributing to the distribution of shear force from one concrete segment to another, it helps to join precast concrete segments to become a complete bridge structure and provide continuity of movement for vehicles and pedestrian traffic. This numerical study discusses the behavior of a full-scale shear key connection without epoxy joining two concrete blocks representing segmental precast concrete at which two external forces load the blocks. Ferro Casting Ductile (FCD) is used as the metal shear key material where the shear key consists of two parts, a male and a female shear key. Numerical simulation is conducted using the ANSYS academic package, with nonlinear analysis implemented accordingly. The appropriate constitutive materials in relation to the numerical program, both for concrete and FCD, are taken from the appropriate literature. Two criteria are employed in the study; failure of the concrete block and yielding of the shear key that follows the von Mises criterion. Shear key connection system capacity is evaluated by applying different magnitudes of horizontal force. The validation of two numerical simulation studies is conducted by two experimental programs that cover laboratory experimentation of full-scale shear keys connecting two concrete blocks. The numerical and experimental results produce an almost similar relation of shear stress at the male shear key and vertical displacements of the upper block relative to the lower concrete block. Finally, a contour of shear key shear stress as a function of the different magnitudes of equivalent prestressing and different quality of concrete compressive strength is proposed.

Abstract. The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken's et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca 2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can't accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.

The columns of a building must be stronger than the beams. The aim of this study is to obtain the cause of the long-term deformation difference by shrinkage between the beams and columns of high performance concrete with compressive strength of 60 MPa. This research was done experimentally in Indonesia during 410 days. Specimens measuring 150 mm × 150 mm × 600 mm were used, 3 pieces for the beams and 2 pieces for the columns. Deformation was obtained by using an embedded vibrating wire strain gauge for each specimen. The difference of long-term deformation in columns and beams is in their autogenous deformation behavior. This is because during the autogenous phase, swelling abnormally occurs in the column before shrinkage occurs. The abnormal swelling is caused by the press of its own weight. This phenomenon does not occur in beams. In the age range of 1 to 200 days, the behavior of the beam deformation has a similar pattern to the deformation behavior of the column with a high deformation rate. After that, at 200-410 days, column deformation changes to a very slow deformation rate. Long-term deformation in columns is lower (64%) than in the beams at 410 days age.

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