Papers by Author: Iswandi Imran

Abstract: Nowaday, we require higher capacity and ductility of structural member particulary in reinforced concret column in construction world. One way to improve the ductility and carrying capacity of concrete is confining the concrete. To investigate the effects of external confinement on column capacity, an analytical study is carried out. A steel ring external confinement is used in this study. The stress-strain diagrams design for confined concrete are developed by considering different proposed confined models based on width variations of the steel ring. The test results showed that steel ring are effective as external confinement in confining the concrete. Capability of concrete to support load simultaneously is increasing along the width of the ring. Its effect on column capacity is studied in terms of load – moment interaction diagram of column. The presence of external reinforcement expands the interaction diagram of the column particularly when it is in the compression-controlled region.

Abstract: Research on concrete material in many countries resulted a concrete type of Ultra High Performance Concrete (UHPC) which has a high performance in terms of compressive strength, ductility, durability, and modulus of elasticity using Reactive Powder Concrete (RPC). Research on structural engineering using RPC material shows better performance than normal concrete (NC) to resist gravity and cyclic loads. In this study, the experiments were conducted under the combination of constant axial and cyclic loads on the structure of the partial prestressed interior and exterior beam-column subassemblages with partial prestressed ratio value of 31.72% on the beam. The application of cyclic loading was conducted by displacement control based on the ACI 374.1-05. The purpose of this study was to determine the performance of structures based on three moment frame acceptance criteria presented in the ACI 374.1-05. From the test results, the interior and exterior beam-column subassemblage structure systems showed performance that adequated all of these criteria at the drift ratio of 3.50% and 2.20%, respectively.

Abstract: Deformability of concrete decreases as its strength increases. The higher the concrete strength, the lower it’s failure strain which shows increase of brittleness. One way to improve the ductility and carrying capacity of concrete is by doing confinement of the concrete. A steel ring external confinement was used in this study. The steel ring is made of a steel cylindrical tube that is cut with a specific width (a) so similar to the ring. The steel ring is placed at a specific distance between the ring (b). With ring width variation (a = 28, 45 and 73 mm) and the distance between the steel ring is constant (b = 40 mm), gave the variation of the volumetric ratio which will afffect the confinement on the concrete. The test results showed that the steel ring was effective as external confinement of the concrete. The capability of concrete to support load increases in line with the width of the ring. Increased carrying capacity of concrete for 28, 45 and 73 mm ring width is respectively 115.382%, 131.792%, 150.253% and the maximum strain of concrete increases to 389.474%, 368.421% and 366.667%, respectively.

Abstract: The development of construction materials technology, particularly concrete is growing very rapidly in the presence of nanotechnology. One material that deserves the attention of researchers is nanosilica. Silica has been used on concrete, starting from silica sand as a filler to microsilica (silica fume) as a reactive pozzolan. Based on previous research, silica fume is proven effective to improve the mechanical properties and durability of concrete. A novel nanotechnological process allows producing amorphous nanosilica with high reactivity from locally available silica sand. In this study a locally available nanosilica is used on mortar and concrete thereby limiting the use of commercial nanosilica materials from semiconductor industry waste. To obtain sustainable concrete, the mix is design to have high strength as well as low permeability using as much possible local sources. This study also make use of commercial, regular silica fume combined with the locally produced nanosilica. The results show that combined use of nanosilica with silica fume can increase the compressive strength and durability.

Abstract: Keywords: High Performance Concrete, mix proportions, compressive strength , and durability Abstract. The use of concrete materials to date, remain a key ingredient in such construction work on the construction of building, bridges and infrastructure. One indicator is the increased production of readymix concrete which is nearly 16 billion tons in 2010. But the increased used of concrete, apparently bring the impact of environmental damage. This is due to the fact that production of raw materials contributes greatly to CO2 in the air. One effort to reduce such impact is to use of high performance concretes. Mix proportion of High Performance Concrete are strongly determined by the quality and availablity of local materials. The implications of research result from other countries can‘t be directly used. Therefore is need to the research on development of High Performance Concrete mix using locally available materials. In this research the mix proportions for f’c : 60 and 80 MPa are developed using local materials that are commonly used by readymix producers. The high Performance Concrete is developed based on compressive strength and durability. The result is expected to be applied to readymix industry particularly for construction use in Indonesia.

Abstract: Bauxite tailing waste or commonly known as red mud is considered to be a very hazardous material. The using of red mud to make alternative building material has been widely studied for many years. Geopolymer as one of the breakthrough in the searching of ordinary portland cement/concrete substitution provides many options and possibilities of using different types of pozzolanic or alumina-silica materials. In this study, the using of red mud in metakaoline-based geopolymer paste has been studied in three different curing conditions for 7 days of sample age. Each sample then characterized both, macroscopically and microscopically including compressive strength testing, SEM photograph, XRD and FTIR spectroscopy

Abstract: Based on data from Indonesian Directorate General of Mineral and Coal Technology, popular sources of silica sand in Indonesia can be found: Bangka Belitung, Pangkal Pinang,South Sumatra, Lampung, West Kalimantan, South Kalimantan, West Java, and East Java. Unfortunately, the use of silica sand in concrete mix is still limited as filler material. The challenge is then to explore the use of such silica sand, for instance in the form of nano silica. This research work explores silica sand from: Bangka Belitung, Pangkal Pinang, Lampung, West Java, East Java, West Kalimantan and South Kalimantan. The selected silica sand are then processed by the novel method developed by Indonesia Center for Ceramics using Polishing Liquid Milling Technology. The result is expected to contribute in the development of increased added value of locally available silica sand and to advancing application of nano silica for concrete.