Utilisation of flyash as cement replacement material to produce high performance concrete

Disposal of fly ash, a waste product from thermal power plants, is a major problem in India.Many R&D and academic institutions are actively involved in the effective utilisation of flyash in Civil Engineering applications. The Structural Engineering Research Centre (SERC),Chennai has carried out extensive research on utilisation of fly ash in concrete as partial cement replacement material (CRM) since 1975 . Recently, SERC has carried out extensive R&D work on development of High Performance Concrete (HPC) mixes using flyash(FA),ground granulated blast furnace slag(GGBS) and silica fume(SF) as mineral dmixtures,especially to improve the durability characteristics of cement concrete. This paper presents the mechanical and urability properties of different HPC mixes containing fly ash. HPCs using flyash as mineral admixture have been used to evelop precast concrete products such as, non-pressure pipes and heavy duty paver blocks and these developments are eported in this paper

Strength characterisation of self cured concrete using AI tools

Civil engineering experimentation process is termed to be a costly process when it involves destructive testing of materials to obtain their strength and durability. Testing of materials through destructive process is century old procedure, but recent decade science involves the prediction of strength and durability using alternative methods. One such method to predict the strength in nondestructive method is employment of Soft computing technologies, this process is gaining impetus in the recent decade due to its accuracy, reliability, and versatility. In this research, we had employed artificial intelligence tool to predict the compressive strength of concrete with available real time laboratory-based data. AI tools require a greater number of data to predict the results but in this work and attempt is made to predict using a smaller number of data with more accuracy. Compressive, flexure and tensile strength of concrete is predicted using ANN techniques (Levenberg-Marquardt (L-M) process and Bayesian regularization (B-R)). Two input parameters were only employed to check the real time accuracy with a model that has 12 input layers and 18 hidden layers incorporated. Model output shows regression values of 0.97428, 0.92865 and 0.96772, concerned with L-M algorithmic model and 0.96573, 0.95625 and 0.91787 for BR based model. Also, its observed that while using L-M algorithm the best performance was obtained at 1.3287 at epoch 2 for compressive strength and 0.12417 is achieved at epoch 1 for tensile strength and 0.021578 at epoch 3 concerned with flexural strength. Also with B-R algorithm provided best performance of 2.1488 at epoch 4 for compressive strength, a value of 0.43468 at epoch 3 for flexural strength and 0.015279 for tensile strength reached at epoch 30. Thus we propose the usage of ANN even with less number of data using this method for predicting the values of compressive strength of concrete. � 2020 The Authors. Published by Elsevier Ltd

An Investigation of Bond Strength of Reinforcing Bars in Fly Ash and GGBS Based Geopolymer Concrete

Geopolymers are amorphous aluminosilicate materials. Geopolymers are binders formed by alkali activation of Geopolymer Source Materials (GSM) using an alkaline activator solution. Concretes made using Geopolymer binders are excellent alternative to the Ordinary Portland Cement concretes from strength, durability, and ecological considerations. Especially, usage of industrial waste materials such as Fly Ash and Slags as GSMs considerably lower the carbon footprint of concrete and mitigate the damage due to the unscientific dumping/disposal of these materials. To use the Geopolymer concrete (GPC) for reinforced structural members, the composite action of reinforcing bars with Geopolymer concrete i.e. the bond behaviour should be well understood. This paper describes the bond behaviour of 12mm and 16mm dia. bars embedded in Fly ash and GGBS based Geopolymer concrete and conventional Portland Pozzolana cement concrete specimens investigated using the pull-out tests as per Indian Standard Code IS:2770(Part-I); the bond stresses and corresponding slips were found out. The bond stress increased with increase in compressive strength. The peak bond stress was found to be 4.3 times more than the design bond stress as per IS:456-2000. The Geopolymer concretes possess higher bond strength compared to the conventional cement concretes

Fire Related Temperature Resistance of Fly Ash Based Geopolymer Mortar

The study presented in this paper is on the effect of heat treatment on fly ash based geopolymer mortar synthesized from fly ash (Class F –Low lime) using alkaline binary activator solution containing sodium hydroxide (18 M) and sodium silicate solution (MR 2.0), cured at 80oC for 24 h. 7 days aged specimen heated at elevated temperature (200°C, 400°C, 600°C and 800°C) for the sustained period of 2hrs. The TGA/DTA analysis and thermal conductivity measurement as per ASTM C113 were carried out besides the compressive strengths. The thermal stability of the fly ash mortar at elevated temperature was found to be high as reflected in the observed value of f800°C/f30°C being more than 1 and this ratio was raised to about 1.3 with the addition of 2% Zirconium di oxide (ZrO2). No visible cracks were found on the specimens with and without ZrO2 when 800°C was sustained for 4 hrs in smaller specimens of size: 50 mm diameter x 100 mm height and in also bigger size specimens: 22 cm × 11 cm × 7 cm) specimens. TGA/DTA analysis of the geopolymer paste showed that the retention of mass was around 90%. The addition of ZrO2 improved thermal resistance. The micro structure of the matrix found to be intact even at elevated temperature that was evident from the FESEM studies

Fire Related Temperature Resistance of Fly Ash Based Geopolymer Mortar

The study presented in this paper is on the effect of heat treatment on fly ash based geopolymer mortar synthesized from fly ash (Class F –Low lime) using alkaline binary activator solution containing sodium hydroxide (18 M) and sodium silicate solution (MR 2.0), cured at 80oC for 24 h. 7 days aged specimen heated at elevated temperature (200°C, 400°C, 600°C and 800°C) for the sustained period of 2hrs. The TGA/DTA analysis and thermal conductivity measurement as per ASTM C113 were carried out besides the compressive strengths. The thermal stability of the fly ash mortar at elevated temperature was found to be high as reflected in the observed value of f800°C/f30°C being more than 1 and this ratio was raised to about 1.3 with the addition of 2% Zirconium di oxide (ZrO2). No visible cracks were found on the specimens with and without ZrO2 when 800°C was sustained for 4 hrs in smaller specimens of size: 50 mm diameter x 100 mm height and in also bigger size specimens: 22 cm × 11 cm × 7 cm) specimens. TGA/DTA analysis of the geopolymer paste showed that the retention of mass was around 90%. The addition of ZrO2 improved thermal resistance. The micro structure of the matrix found to be intact even at elevated temperature that was evident from the FESEM studies

ORIENTAL JOURNAL OF CHEMISTRY Evaluation of the Role of Cetyltrimethylammoniumbromide (CTAB) and Acetylenicglycol (AG) Admixture on Fly Ash Based Geopolymer

ABSTRACT Alkali activation of fly ash with proper mix design and correct formulations can exhibit very good strength and chemical resistance and other potentially valuable characteristics similar or even better than conventional Portland cement. Utilization of fly ash activated system as binder material in construction industry can limit the consumption of virgin materials required for the production of cement as well less energy intensive process in the manufacturing stage leads to lower greenhouse gas emission. Goeopolymeric products with characteristic properties can be achieved on a laboratory scale level by optimizing the process conditions using selected source material with the addition of admixture. On contrary, Usage of variable source material in a large scale preparation, issues like flow ability, control of setting time are always present that need to be studied. This study was conducted on leaching of fly ash by hybrid activator solution namely sodium silicate, sodium hydroxide, for preparing geopolymer matrix wherein geopolymer (GPC) mortar was made with the addition of organic admixture Cetyltrimethylammonium bromide (CTAB), Acetylenic glycol (AG) as flow ability enhancer with dosage ranging from 0-2% by keeping the Liquid/Solid as 0.45.The Compressive strength of the mortar in the order 30 Mpa was achieved with good flow property by the addition acetylenic glycol and the zeta potential value was found to be similar in the order of control specimen (-15.4mv). Analysis of SEM microstructure of the matrix revealed that binding gel of type Na-S-H are found to be more on AEG added matrix than that of CTAB

ANALYSIS OF SOLAR REFRIGERATION SYSTEM USING THERMO ELECTRIC COOLING (TEC) MODULE

A refrigerator is a common house hold appliance that consists of a thermally insulated compartment and a heat pump that transfer heat from the inside of the refrigerator to its surrounding so that the inside of the refrigerator is cooled to a temperature below the ambient temperature of the room. Thermoelectric Cooling (TEC) solar refrigerator runs on energy provided by sun, which includes photovoltaic or solar thermal energy. Peltier Jean (1834) discovered the Thermoelectric (TE) property about two centuries ago;thermoelectric device havecommercialized during recent years. The applications of TE vary from small to large refrigerators. The Thermoelectric module refrigerator work on the principle of Peltier effect. Recently, the application of TEC modules in an industry is dramatically increased. Theyhave been adopting the solar refrigeration, widely recognized as alternative to the conventional vapourcompression system for their merits of energy saving and being eco-friendly. The paper presents a design of TEC solar refrigeration using thermoelectric cooling. The objective of this paper is to establish an alternative eco-friendly refrigeration cycle for producing a temperature usually encountered in a conventional refrigerator. By designing and manufacturing such type of refrigerator adds new dimension to the world of refrigeration. The proposed solar refrigeration system using TEC module is a feasible alternative for local refrigeration system. Briefly,the paper presents an economical and feasible model of solar refrigeration system