Lightweight Structural Concrete

Using of Lightweight concrete (LWC) amounts to a lower cost and a better thermal performance due to its unique properties and light density. The main disadvantage in using lightweight concrete is that its mechanical properties are relatively poor. An effective method to improve the mechanical properties of lightweight concrete is using a dosage of nano-silica in the concrete mix. The gained enhancement of mechanical properties promotes a more serious discussion of structural applications of lightweight concrete. There exists an optimum dosage of nano-silica by which the mechanical properties enhancement is maximized. Increasing the nano-silica content beyond the optimum dosage degrades the mechanical properties. However, a fixed optimum dosage is not agreed upon in literature. This paper investigates the optimum dosage of NS to enhance the mechanical properties and microstructure of a lightweight concrete made with lightweight expanded clay aggregates (LECA). The results concluded that a dosage of 0.75% of nano-silica is optimum for the studied lightweight concrete mixes.

Decolourisation of Sewage using Commercial Tannin-Based Coagulant

In this work, the effectiveness of removing colour and total suspended solid (TSS) from complex organic particulate artificial sewage (COPAS) via the coagulation process was studied. Organo-floc (OF), a tannin-based coagulant derived from the plant was used as a coagulant. OF was applied in a jar test experiment at the various dosages at 57 rpm for 5 min, and 30 min sedimentation time to find out the optimum dosage for colour and TSS removal. Zeta potential, pH and conductivity were also analysed. Experiment with tannin dosage of 125 ppm resulted in the highest colour and TSS removal of 94% and 79%, respectively. Organo-floc showed promising results in decolourisation and TSS removal from artificial sewage.

Polyelectrolytes as a Material of Value in Water Treatment: A Review

The use of polyelectrolytes in the treatment of water/wastewater has been studied with special emphasis on the characteristic impurities, which should be removed and the types of polyelectrolytes commonly available. Much attention is being on using polyelectrolyte as primary coagulation, their application as a coagulant aid, including the use of dual polyelectrolytes in the treatment of complex industrial wastewater. The optimum dosage of polyelectrolytes in all kinds of water and wastewater is very low when they are used as coagulant aids in conjunction with inorganic polyelectrolytes. Hence, the quantification of remaining polyelectrolytes in the water after their treatment is ruled out in this case. Polymer toxicity in aquatic animals has been assessed and the presence of residual polyelectrolytes in the treated water has been discussed. Keeping in view the applicability of these polyelectrolytes for the removal of contaminants, it is expected that this technique can be applied for further investigation in various types of water from different origins.

Sustainable soil stabilization using combination of geotextile, fly-ash and saw dust for pavement subgrade

Purpose: This paper investigates the combined effect of fly ash, sawdust and geotextile in stabilizing the soil. Design/methodology/approach: A thorough geotechnical testing was carried out in order to study the potent characteristics of soil and soil mixes. The present investigation was set up in two stages. In the first stage, effects of fly ash (5, 10, 15 and 20%), sawdust (2.5, 5 and 7.5%) and layers of geotextile placed at different depths were studied separately to determine their effect on soil stabilization. In the second stage, fly ash, sawdust and geotextile were mixed with soil sample in order to obtain the optimum dosage which can be used for stabilization of soil i.e. their combined effect as stabilizer on soil stabilization. Findings: It was observed that by introducing fly ash, sawdust and geotextile to the soil, the CBR values increase and thickness of pavement layer decreases. It also decreases the amount of stress on subgrade leading to enhancement of pavement stability with cost effectiveness. Research limitations/implications: Economical use of industrial waste has been proposed in the present research which otherwise prove to be a malady to climatic change and human health. From the study, an optimum dosage of fly ash (2.5%) and saw dust (5%) and depth for geotextile (6 cm) has been proposed. Originality/value: The article explores the possibility of a ternary blend, i.e., geotextile, flyash and saw dust on effectively stabilizing pavement subgrade. Limited literature was available to address the issue of utilizing the industrial wastes that otherwise pose disposal issues.

Potensi Pemanfaatan Ulang Sampah Plastik Menjadi Eco-Paving Block

Eco-paving block is a product used for construction consisting of sand and plastic mixes. In order to produce eco-paving blocks, the mixture of sand and concrete was substituted in part with sand and plastics. In order to properly mix plastics to create eco-paving blocks, a plastic smelter was used to generate heat and melt the plastic materials. The plastic material types used in this case was PETE or PETE, which has the characteristics of being flexible and high adhesive properties; along with ABS which can stand pressures. Based on the tests conducted with the plastic smelter using PET, ABS, and the combination of PET and ABS, the most promising result was shown with the combination of PET and ABS. This combination required 8 minutes 21 seconds for the plastics to become fully melted, and a temperature of 278oC. The combination of PET and ABS resulted in a mixture of plastics with strong adhesive properties and durability. This product could potentially be developed into eco-paving blocks. Additional studies regarding the optimum dosage combinations of PET and ABS plastics in eco-paving blocks can potentially be established in order to further optimize the usage of these plastics in eco-paving blocks.

Comparative study of Conplast SP 430 and Polycarboxylic Ether based super plasticizer on M50 grade PVA-FRC

The properties of conventional concrete is improved by addition of fiber in it. By addition of these fibers ductility of concrete is enhanced and brittleness of concrete reduced. In this study Polyvinyl alcohol (PVA) fibers are used as a reinforcing material. Polyvinyl alcohol is a high resistance nonreactive material. It will not oxidize when exposed to aggressive whether conditions and having good affinity with cement. Polyvinyl alcohol fibre of size 6 mm added in five proportions of 0%, 0.125%, 0.25%, 0.375% and 0.5%. the workability of concrete decreased by addition of PVA fibers in it. So, the superplasticizers are used to improve the workability. In this study two different plasticizers Conplast SP 430 and Polycarboxylic Ether (PCE) are used and their performance on the workability and strength of concrete was worked out. The main reason for conducting this study is to find out the optimum dosage of PVA fibers, optimum dosage of super plasticizer and suggest which super plasticizer is more suitable for preparation of Polyvinyl alcohol fiber reinforced concrete.