scholarly journals A COMPARITIVE STUDY ON CONCRETE WITH PARTIAL REPLACEMENT OF HYPO SLUDGE AND MANUFACTURED SAND IN CEMENT AND FINE AGGREGATE EXPOSED TO ELEVATED TEMPERATURES

Author(s):  
G.Nagendha Reddy .

Construction and Demolition wastes(C&D wastes) are generated in all cities of the world due to rapid urbanization. Disposing C & D waste these days is a costly affair, and raises environmental issues. Hence an attempt is made to reuse the demolished concrete as a partial replacement of natural coarse aggregates. Also due to ban of sand mining by local authorities, the cost of natural fine aggregate is very high and itself becoming a scarce material. Hence crushed stone aggregates called manufactured sand (m sand) is used, totally replacing natural fine aggregates. This concept is found to be cost effective, minimizes disposal of C & D wastes, and leads towards Green Building Concepts. Compression test on M40 concrete cubes of size 150mmx150mmx150mm are conducted at end of 7 days and 28days. Mix design for M40 concrete is made in accordance to IS: 10262-2019 with water cement ratio of 0.45 using 53 Grade Ordinary Portland cement. Superplasticizer (LIQUIFIX) is used to enhance workability. Nano Silica (NS)(1.5% by weight of cement),Wollastonite powder(WP)(10%by weight of cement) and Basalt fibres(BF)(1% by weight of cement) are added as additives. It is observed, that compressive strength of 7 days and 28 days cured samples is 25% more with the addition of all three additives compared to samples without additives. Hence the loss of compressive strength obtained by using demolished concrete as aggregates and m sand in concrete is regained with the addition of additives.


Abstract. Continuous extraction of sand is having a huge impact on the natural river beds which has resulted in lowering of water table and a decrease in the amount of sediment supply. Despite the quantity of sand used in our day-to-day activities, our dependence on sand is significantly increasing. The use of manufactured sand as a fine aggregate in concrete draws the attention of many investigators and researchers. The present investigation includes the study of soundness and EDAX .The test results depicted that for M-sand substituted concrete the loss of weight, when subjected to alternate cycles of freezing and thawing when tested with magnesium and sodium sulphate solution was found to be less when compared with natural sand. The important observation is that the inclusion of manufactured sand in concrete reduces the pores present in concrete resulting in matrix densification and makes the concrete impermeable and substantially reduces the rate of oxygen diffusion and reduces the corrosion process as well. This paper also focuses on the effect of manufactured sand as a fine aggregate in the elastic and bond characteristics of concrete.


Crusher sand or Manufactured sand (M-Sand) obtained from stone aggregate quarries is widely used as fine aggregate in concrete to avoid the depletion of natural river sand. To avoid air and land pollution due to direct dumping of wastes in open land area from granite processing industries and thermal power stations, the behavior of reinforced concrete beam without waste (RC beam) and with waste (RCW beam) materials like granite powder (10%) and bottom ash (10%) as combined partial replacement for M-Sand was carried out. The parameters like load carrying capacity, ductility, energy absorption capacity and stiffness degradation were evaluated. The behavior of all the parameters of both the beams was similar and there was slight decrease (10%) in strength parameters due to increase in fine pore particles. Hence, the granite powder and bottom ash can be used as partial replacement for fine aggregate in building constructions


Author(s):  
Sindhu Vaardini U ◽  
Pon Soundarya M

Disposal of large quantity of plastic causes land, water, and air pollution etc.., so a study is conducted to recycle the plastic in concrete. This work investigates about the replacement of natural aggregate with non-biodegradable plastic aggregate made up of mixed shredded plastic waste in concrete. Several tests are conducted such as compressive strength of cube, compressive strength of cylinder, flexural strength test of prism to identify the properties and behavior of concrete using shredded plastic aggregate. Replacement of fine aggregate weight by 0%, 5%, 10%, 15%, 20% with shredded plastic fine (PF) aggregate and manufactured sand (M-Sand). Totally 30 cubes, 30 cylinders and 30 prisms are casted to identify the compressive strength, cylindrical compressive strength, and flexural strength respectively. Casted specimens are tested at 7, 14 and 28 days. The identified results from concrete using shredded plastic aggregate are compared with conventional concrete. Result shows that initially there is increase in mechanical properties then there is reduction in mechanical properties due to addition of shredded plastic aggregate added concrete. This reduction in strength is mainly due to poor bond strength between cement and shredded plastic aggregate.


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