Advanced Materials Research Vols. 374-377

Abstract: ABSTRACT It is a very well known fact that the use of fly ash in masonry and concrete make the structures durable. Properties of Fly Ash depend upon coal source. For acceptability of fly ash in cement, mortar and concrete various specifications and standards are available. The Indian standard IS 3812: 2003(Part I and Part II) expects some physical and chemical properties similar to world standards, while differs in some, like lime reactivity test. As a part of research activity the authors have collected 23 different fly ash samples from various hoppers of three power stations near Nagpur. The samples were tested as per most of the provisions of IS 3812 and tests specified in IS 1727. Test results are compared with major world standards and specifications. Gain of strength is the most important character of fly ash, especially from the usage in cement and concrete. The paper discusses comparison of various standard specifications and interpretation of pozzolanic reactivity.

Abstract: Solute (pollutant) and sediment transports directly relate to controlling water quality in water environment (e.g. river, estuary and reservoir). An understanding of turbulent diffusion is the key for improving water quality in rivers and estuaries. Many studies on turbulent diffusion have been carried out in open channels, compound channels and estuaries for different flow conditions in the past. This paper reviews the past research mainly carried out by the author and includes flow structures, solute concentration distributions, mixing parameters in simple open channel, compound channel, rivers and estuaries. Sediment transport rates and bedforms in meandering channel for flooding are also included.

Abstract: Compared with natural gypsum, the basic properties of FGD gypsum are studied based on the test results and then the influence of FGD gypsum’s chemical constituents, impurities and particle size distribution on its products is analyzed. The results indicate the impurities play an important role on the FGD gypsum behavior. Finally, the differences between FGD gypsum and natural gypsum are summarized.

Abstract: Carbon dioxide curing was adopted to accelerate the hydration of foam concrete samples with a lower bulk density level of around 450 kg/m³ and a higher level of around 1150 kg/m³. The bending strength, compressive strength and ultrasonic transmission velocity of carbonated harden foam concrete were tested, the hydration products were analyzed by means of XRD and TG/DSC. The results show as: (1) By comparing with standard curing samples, there are more than 47% increments of specific strengths of carbonated foam concrete with the higher density level at a certain curing time before 14d. However, for the lower density level one, there is just a significant improvement of specific bending strength obtained before 7d. (2) The carbonated foam concretes with the lower density level show lower ultrasonic transmission velocity than standard curing ones. The velocities have hardly difference for both carbonated and standard curing samples with the higher density level. (3) Vaterite can’t be found in carbonated foam concrete with the lower density level at curing time before 28d, while it becomes a common phase in 3d’s carbonated sample with the higher density level. Vaterite was considered to be an important factor that influences the ultrasonic transmission velocity.

Abstract: The added mass has significant effect on the vibration of the membrane structures, which can not be ignored during their vibration analysis. The added mass is significant and depends on the mode shape. The solution of the wave equation can derive the mode shapes of the circular membrane. The added mass of the circular membrane is investigated by Numerical analysis, both in Fluent and in the theory of dipole configuration. An existing test result is employed to verify the proposed methods.

Abstract: This paper offers a model that can estimate the 28-day compressive strength of concrete containing fly ash (FA) using the concept of cementing efficiency. Using various statistical analyses, the prediction model was derived from a wide range of mix proportions and a number of strength test results of concretes used in eight construction sites. A strength prediction model was proposed in terms of a function of the modified cement-water ratio reflecting the equations for cementing efficiency. This prediction model that has R² of 0.88 and root mean squared error (RMSE) of 1.6MPa is capable of properly predicting the 28-day compressive strength within strength variation of FA concrete.

Abstract: Modern concrete is now common to use admixture (chemical or mineral), pozzolana’s for modifying different properties of concrete in fresh and hardened state. This paper presents the salient features of the development of Phosphogypsum(PG) Cement Concrete and discuss the improvements affected in the properties of concrete with the use of PG as an admixture compared to the plain or conventional cement concrete. This was accomplished by an experimental study by preparing different grades of cement concrete mix M20, M25 and M30 using PG as an admixture by replacing 5% of OPC and few durability parameters were investigated. This includes studying the compressive strength, workability, air entrainment and moisture movement by wetting and drying method. Study were conducted for modifying the properties of the concrete, controlling the concrete production cost, to overcome the scarcity of cement, and finally the advantageous disposal of industrial wastes.

Abstract: Predictive Technique Audits, one of the types of environmental audit, is considered to have greatest potential role in strengthening the Environmental Impact Assessment practice in India. Many predictive techniques which rely upon the use of mathematical or computer models have also been subject to an audit. There is a need for strengthening the understanding on which environmental attributes can be predicted in a quantified manner, and which predictive techniques may be applied to provide predictions within an acceptable range of error, recognizing that this will be influenced by the significance of the attribute under consideration. With this backdrop, the present paper outlines the concepts of predictive techniques in Environmental Eco-Audits.

Abstract: In this paper, we gave a clear concept of environmental performance (EP), and proposed an estimating method of environmental performance indicator (EPI) for concrete, based on an integrated life cycle impact assessment. The environmental burden (EB) factors of concrete were also discussed. In order to well evaluate the environmental benefits of waste utilization, land use change and nature environmental resource loss caused in the production stage of concrete were also taken as the EB factors and their estimating methods were given, besides air emissions, waterborne releases, and exhaustible resource consumption. Furthermore, An EB intensity database was constructed for concrete’s raw materials and processes such as transportation. An environment-conscious mix design method was suggested for maximizing EP of concrete, while still meeting the usual property requirements such as consistency, strength and durability. Finally, as an application example, mix proportions of a retaining wall concrete were designed.

Abstract: Subgrade resilient modulus (MR) is very important for effective design of pavements. Several methods to estimate the resilient modulus were suggested in the past years. The main objective of this paper was to validate the correlation of MR with other physical properties of the subgrade soils. Cohesive soils representing major soil types in Shanghai were selected. The resilient modulus tests were conducted with UTM. Additional analysis was then performed to develop correlations between the model parameters and other soil properties. To verify the prediction models independently, laboratory MR tests were conducted on new subgrade soils. It was observed that the predicted MR values compared well with the laboratory measured values for the soil samples.