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This paper investigates the performance of plain cement concrete (PCC) and fiber reinforced concrete (FRC) with silica fume (SF) and ultra-fine TiO2 (UFTiO2) as mineral admixtures. The size of UFTiO2 was analyzed using Zeta size analyzer. Concrete with a characteristic compressive strength of 50 MPa was chosen. Cement was partially replaced with SF in three different percentages namely 4.5, 9.5 and 14.5 and constant UFTiO2 percentage of 0.5 to have a total replacement level of 5%, 10%and 15%. Steel fibres were added in 0.5% by volume of concrete. Specimens were for various parameters like resistance against compression, water absorption and sorption. In addition, tests on Split tension, flexure and impact were done to study the characteristics of the concrete with fibre. The results were compared with conventional concrete. Concrete with 9.5% SF, 0.5% UFTiO2 was found to be an optimum mix among all the combinations tested in both plain cement and fibre reinforced concrete.

Self compacting concrete (SCC) has an ideal fluid character at the fresh state and becomes solid once it sets/hardens completely when poured on the desired shape of the mould. The increase of workability and the control of segregation were taken care by super plasticizer (SP) and viscosity modifying agent (VMA) dosages. In this paper an attempt was made to study the flexural behaviour of ternary SCC beams. Cement was replaced with two different combinations viz metakaolin (mk) + ground granulated blast furnace slag (ggbs) and silica fume + ggbs. The experimental results of these ternary beams were compared with Conventional Vibrated Concrete (CVC) & SCC control concrete (SCC 0). Fresh properties of SCC like slump flow, spread were studied in accordance with EFNARC guidelines. Flexural strength of concrete was tested at the age of 28 days. Load-deflection characteristics were studied at mid span of the beam (L/2). From the results it was observed that SCC ternary blended beams have higher flexural strength and better ductile performance compared to CVC and SCC0 beams.

High performance concrete (HPC) in three different forms were used in the present research and they were made with mineral admixtures, air entraining agent (AEA) and light weight aggregate (LWA). This paper deals with compressive strength, sorptivity, porosity, corrosion resistance and load carrying capacity of HPC. Experimental results reveal that, HPC with ground granulated blast furnace slag (GGBFS) (20%) and Quartz powder (10%) gave 68.4 MPa (for fck = 70 MPa) the maximum compressive strength among three different forms used. In terms of durability the same mix showed a reduction of 60% in voids compared to control concrete. The load carrying capacity of that mix was only 6% less than control concrete. Performance of HPC made with LWA and AEA was inferior to HPC with mineral admixture. Hence HPC with GGBFS (20%) and Quartz powder (10%) was an optimum mix among the various mixes used.

The exposure of alumino silicate materials such as fly ash, ground granulated blast furnace slag will undergo thermal activation along with alkaline environment and forms an environment friendly material called geopolymer. These materials not only reduce emission of carbon dioxide gas in the atmosphere but also act as a substitute for cement to meet with the future demand. In the present work a sincere attempt was made to produce ground granulated blast furnace slag (GGBFS) based geopolymer concrete (GPC) and to assess its performance by conducting parametric study such as magnitude of temperature, Alkaline liquid (AL) to GGBFS ratio, SiO3 to OH ratio and age of concrete on compressive strength. All the experiments were conducted with a constant sodium hydroxide (NaOH) molarity of 14. Detailed experimental investigations were carried out to assess the effect of the above mentioned parameters under thermal curing with three different curing temperatures of 60, 80 and 100 °C. From the experimental results it was understood that geopolymer concrete with AL/GGBFS = 0.30, SiO3/OH = 1.5 and curing temperature of 80 °C, yielded better compressive strength when compared to all the other combinations used in the present work. Hence use of GGBFS based geopolymer concrete could be feasible for any engineering construction and most preferred for precast construction.

Ground granulated blast furnace slag (GGBFS) in the present research work was commercially available ultra fine slag of size 5 μm meter was used which fills micro voids. This paper deals with compressive strength, porosity and sorptivity characteristics of commercially available ultra fine slag based high strength concrete (HSC) (with a characteristic compressive strength of 50 MPa). The results were compared with similar characteristics of precursor slag and ultra fine slag obtained by grinding (Sharmila and Dhinakaran, 2015). Ultra fine slag replaces cement with three different percentages viz 5, 10, and 15% to study the compressive strength, porosity and sorptivity. Performance of commercially available ultra fine slag was found to be inferior than ground one and concrete with 10% ultra fine slag was found to be optimum.

The utilisation of recycled coarse aggregate obtained from demolished concrete has gained momentum in recent years due to its contribution towards sustainability by minimising the use of artificially produced materials and eliminating environmental problems due to dumped waste materials. The present research exploited the possibility of producing high-volume fly ash (HVFA)-based recycled aggregate (RA) high-strength concrete. It was found that 50% of desired strength could be achieved even with 50% replacement of cement with fly ash and 50% of natural aggregate (NA) with RA. An attempt was thus made to study the effects of RA and HVFA on durability characteristics. The parameters considered were resistance to chloride ion penetration, acid attack, sulfate attack and sorption. It was found that replacement of NA with RA and cement with fly ash in higher volumes showed a way of considering economy and environmental effects as criteria, given a little bit of compromise towards strength and durability criteria but still falling well within an acceptable limit.

In the present research work, investigations were carried out to improve the performance of concrete in terms of strength and resistance to chloride-ion-penetration by incorporating metakaolin (MK) as mineral admixture in concrete. Parametric study was carried out by considering w/cm ratio, various percentage of MK and age of concrete as parameters to understand the effect of each parameter. The study was conducted for different water-to-cement metakaolin ratio (w/cm) ratios of 0.32, 0.35, 0.4 and 0.5. The MK proportion was varied from 0 to 15% with an increment of 5% and ages of concrete from 3 to 90 days were considered and experiments performed accordingly. The effects of above said parameters on the various properties of concrete such as workability, compressive strength, chloride penetrability (Rapid chloride permeability test as per ASTM C 1202), pH of concrete and depth of penetration of chloride ions were investigated, and the results of MK concrete were compared with the conventional concrete. From the results, it was observed that MK concrete showed greater strength for higher w/cm ratios (0.4 and 0.5) and its resistance to chloride ion penetration was more or less consistent for all w/cm ratios and the optimal amount of MK resulted significant reduction in chloride ion penetration. A Multiple non-linear regression analysis was used to develop a statistical model to predict the strength and found to have good correlation between the observed and predicted values. It was concluded that the concrete developed in this study have significant potential for use on real time projects.

Scientists and researchers are currently focusing considerable attention on the hydrodynamic characteristics of semicircular breakwaters worldwide, particularly in Japan and the People’s Republic of China. A semicircular breakwater is a composite breakwater made of prestressed concrete and has several merits over a conventional rubble mound breakwater, e.g. it is technically advanced, economically viable and aesthetically pleasing. At low water levels, it serves as a rubble mound breakwater and, at high water levels, it acts as a composite breakwater in the emerged condition. It reduces the considerable magnitude of dynamic forces if constructed in front of a vertical wall (the main structure) under the submerged condition and also reduces coastal erosion along the shoreline. Many research studies are being carried out all over the world to evaluate the performance of a semicircular breakwater in the laboratory and in the field. The authors of this review paper have also conducted a large number of experiments to study the hydrodynamic characteristics of a semicircular breakwater and to optimize the parameters such as the rubble mound height, the water depth and the size of perforations. The experiments were conducted for both the emerged condition and the submerged condition subjected to regular and random waves with various wave heights and periods to find the suitability of a semicircular breakwater in the field, and the optimum parameters were recommended in their previous publications. Hence, a sincere attempt has been made in this review paper to present the ongoing research on semicircular breakwaters, which has been carried out all over the world to facilitate the studies of researchers and to provide related information to people working in the area of semicircular breakwaters.

Recycled aggregate (RA) obtained from crushed concrete rubble, instead of being stored, can be reused in building industry. An attempt has been made to study the possibility of reusing the recycled concrete aggregate from demolished structures in the place of fresh aggregate. Four series of mixes of control concrete with fresh aggregate and recycled concrete aggregate with three different ages of 5, 10, and 15 years were prepared for the present study and used with three different combinations, 0% fly ash, 20% fly ash, and 20% fly ash with super plasticizer. The basic properties of aggregates, such as water absorption and specific gravity, mechanical properties, such as abrasion resistance, effect, and crushing values were considered. Workability of fresh concrete and strength parameters of hardened concrete, such as compressive strength and tensile strength, were studied. The preceding properties were tested for three different periods of curing of 7, 14, and 28 days. All these mixes were designe...

The Andaman Sea is known for the genesis of many severe cyclones that traverse the Bay of Bengal. The Andaman Islands face the surge disaster threat as their north-south orientation comes across the eastward path of severe cyclones moving from the Andaman Sea and western Pacific Ocean. In this study, we investigated the potential of a storm-induced surge—a natural disaster due to short-duration sea-level rise—to affect the Andaman Islands. A two-dimensional hydrodynamic model was employed to simulate storm surge characteristics and demarcate the coastal flooding extent of the highly inhabited Port Blair region of the Andaman Islands in the case of the severe cyclone of November 1989. A storm surge disaster mitigation plan is also proposed for the group of Andaman Islands.

The semicircular breakwater (SBW) is a composite breakwater consisting of a semicircular caisson resting on a rubble mound. The SBW function as a barrier dissipates the incident wave energy and creates tranquility on its leeside. The dynamic pressures due to regular waves exerted on seaside perforated SBWs with 7 and 11% of exposed surface area with perforations were measured. The measured pressures are compared with those exerted on impermeable SBWs. In addition, the forces exerted on the caisson alone are measured. The reflection coefficient, measured total forces on the caisson of the models, and the pressures are presented as functions of relative water depth. The effect of the water depth and the percentage of perforations on the above stated variables are examined, details of which are reported in this paper. ? 2002 Elsevier Science Ltd. All rights reserved.