Asian journal of civil engineering
Volume:17 Issue: 3, May 2016

Self compacting geopolymer concrete (SCGC) is becoming an innovative sustainable engineered material in the construction industry that doesn’t require both compaction and cement. In this study, SCGC mixes were manufactured using class F fly ash (FA) and ground granulated blast furnace slag (GGBS) in 50:50 proportions with 100% manufactured sand (MS). All mixes had a fixed water-to-geopolymer solids ratio of 0.4 by mass and a constant total binder content of 450 kg/m3. The present investigation is mainly focused on the fresh and compressive strength properties of SCGC by varying the molarity of sodium hydroxide (NaOH) from 8 M to 12 M. Test methods such as slump flow, T50cm, V-funnel and L-box were conducted to assess the fresh properties. Compressive strength of SCGC was determined after 7, 28, 56 and 90 days of curing at ambient room temperature. The contribution of GGBS helps the SCGC mixes to attain significant compressive strength development during all curing periods at ambient room temperature itself. Studies also revealed that the increase in NaOH molarity decreased the fresh properties, however it increased the compressive strength of SCGC.

In this paper, a study on experimental and numerical investigation of the flexural strength and behavior of cold-formed steel built-up closed section with intermediate web stiffener is presented. Totally, nine built up beams with various cross section geometries are experimented under simply supported end condition with two-point loading. The section geometries are chosen such that all types of buckling modes are met with. A finite element model is developed using ANSYS and verified with experimental results and found to be in good agreement. The material and geometric nonlinearities are included in the finite element model. The results indicate that flange width and depth of intermediate stiffener is significantly affecting the strength and buckling behavior of the member. The experimental and finite element analysis results are compared with the strength predicted from the North American Iron and Steel Institute Specification for the cold-formed steel structure and suitable recommendations are made based on the results. The accuracy of the proposed design equation is established by comparison with an experimental results reported by other researchers.

This paper presents most recent meta-heuristic algorithm, symbiotic organisms search (SOS), for optimum design of structures. The SOS simulates the symbiotic interaction strategies adopted by organisms to survive and propagate in the ecosystem. Due to some difficulties on finding optimum design of frame structures and grillage systems, this problem is known as one of benchmark examples in the field of structural optimization. Therefore, the new algorithm is adapted to find optimum design of structures. The performance of the algorithm is then evaluated by comparing with some other methods. The results confirm the validity of the new algorithm.

Life cycle cost (LCC) analysis is currently a most valuable tool in the civil engineering construction industry and will be inevitable as resources become scarce. Selection of materials for fabricating components of any civil engineering structures will be based on LCC analysis. It is due to significant reduction in lifetime cost of construction, maintenance, repair and rehabilitation. In this paper, cost benefit analysis of three types of beam namely Glass Fiber Reinforced Polymer (GFRP) reinforced, epoxy coated and steel reinforced beam was done. It includes the calculation of total lifetime cost, overall system cost and calculation the Net Present Value (NPV). Beams with over reinforced section and under reinforced section were considered in the cost analysis to have better understanding. A comparison was made between steel reinforced beam and GFRP reinforced beam to assess the benefits based on the economic aspects. From the results, it was found that good amount of cost-saving to an extent of 20% at initial stage and 40% with increase in age for GFRP reinforced beam over steel reinforced beam. The trend in variation of total cost for GFRP reinforced beam was consistent throughout its lifetime, whereas for steel reinforced beam and epoxy coated beam it was not so. Hence with the combined advantages of structural performance, serviceability, suitability for aggressive environments and economy, GFRP reinforced beam was strongly recommended from this study.

This paper deals with the experimental results on wind pressure distributions at all four faces of a rectangular tall building with 1:1.5:7 ratio. The model is made up of acrylic sheet with a geometric scale of 1:300 having plan dimension of 10 cm x 15 cm and height of 70 cm. The model is tested using a Boundary Layer Wind Tunnel (BLWT) facility at CSIR- SERC, Chennai for twelve angles of wind incidence (0°, 5°, 10°, 15°, 25°, 33.5°, 45°, 56.5°, 60°, 75°, 87.5° & 90°) under sub urban terrain condition. Mean pressure coefficients, mean value of drag, lift and torsional coefficients along the wind direction and perpendicular to the wind direction are calculated from the pressure measurement on the model. The value of mean drag coefficient is obtained from IS: 875 for 0° and 90° are 1.4 and 1.5 and experimental values obtained are 1.4 and 2.1. The difference could be due to the effect of boundary layer. The mean values of lift coefficient for 0° and 90° are zero, as expected could be due to symmetry.

Insulated paper board saw dust waste from paper board industries is used to develop composite materials for its application as door shutter. Physical and mechanical analysis of the developed composite is carried out and presented along with optimized process parameters. Developed composite is analysed for its density, porosity, water absorption, compressive strength, tensile strength and screw withdrawal properties. Observed behaviour is explained and it is found that this waste can be successfully used for the development of composites. This has its potential application as door shutter in building industry, and can be used as a substitute to natural wood.

The development of alternate material to replace cement by new eco friendly materials such as fly ash, rice husk ash, silica fume slag etc., by method of alkali activation under thermal curing process forms a new binder called geopolymer. These materials not only increases the strength but considerably decreases the emission of carbon dioxide gas to the atmosphere and also these mineral admixtures also can be used as a replacement material for cement to meet the future demand. In this study an attempt has been made to produce ground granulated blast furnace slag (GGBFS) based geopolymer concrete and to find out its compressive strength characteristics by considering the parameters such as ratio of alkaline liquid (AL) to (GGBFS), ratio of silicate to hydroxide (SiO3/OH) and the age of geopolymer concrete with different temperatures of thermal curing has been adopted. Detailed experimental investigations were carried out to assess the effect of the above mentioned parameters on compressive strength. From the results it was understood that with AL/GGBFS = 0.30, SiO3/OH= 1.5, for thermal curing temperature of 100C, for curing period of 56 days yielded better compressive strength when compared to conventional concrete under normal curing. Hence use of GGBFS based geopolymer concrete is recommended for construction.

Urban Heat Island (UHI) is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. In this study, effects of the variation of physical and geometrical properties of the urban fabric (i.e. cool roofs including green and white roofs and perviousness of paving materials) on the urban micro-climate and outdoor thermal comfort were investigated using 3dimentional urban micro-climate model, ENVI-met. Based on the predicted results, increasing the amount of vegetation and permeable pavements can cool the air temperature down by up to 3 K.

In this investigation, broiler hen egg was used as natural admixture (NAD) to study the effect on fresh properties and compressive strength of Conventional Concrete (CC) and class C Fly Ash (FA) blended concrete. Cement was replaced by fly ash at various levels of 0%, 25%, 35% and 45% and broiler hen egg mixed sample (white albumen and yellow yolk) was added to concrete at different replacement dosages of 0%, 0.25%, 0.5%, 1.00%, 1.5% and 2.0% in water content and liquid to binder ratio was maintained at 0.5. For all replacement levels of NAD and FA, the fresh properties and compressive strength of mixes were studied at 7, 28 and 56 days. From the results, it was concluded that 0.25% of NAD dosage was considered as optimum dosage for both CC and class C fly ash blended concrete.

In this study, four scaled circular-shaped bridge columns were established, three of which were retrofitted using three different strengthening methods to wrap or confine the columns. Specimens were subjected to a constant axial load and a cyclically reversed horizontal force. Results of the investigation on experimental phenomena and data, showed that the three reinforcement materials served a significant function in confining the core concrete of columns for strength improvement of core concrete, thus resulting in enhanced ductility compared with an unstrengthened column. Among the three strengthening materials, the column is strengthened by Aramid fiber-reinforced polymer (AFRP) exhibited the best performance in seismic events.