Sand and cement, which go into making concrete, is in great demand because it is a crucial building material. Due to this demand, environmental degradation is rising during the production of cement and river basins are running out of sand. Concrete is being updated with suitable substitutes without sacrificing its durability and strength. Fly ash and M sand are used in this study as alternatives to cement and fine aggregates, respectively. Fly ash is by product of combustion process; hence utilizing this product in concrete can be advantageous to both the environment and cost considerations. Whereas M sand is obtained by crushing aggregates into desirable sizes which can benefit workability of concrete .The percentage of these alternatives for which partial replacement results in higher test values is indicated in this study. Super plasticizer was used in testing on newly laid concrete. M 45 grade concrete mix design as per IS 10262:2019 is calculated. Testing was done on M45 grade fresh concrete for workability: slump cone test, compaction factor test, vee bee consist-meter test, as well as hardened concrete for compression strength, tensile strength, and flexural strength. The tests were conducted for variable percentages of fly ash and M sand by weight of cement and natural sand replacement. In this study natural sand is replaced with M sand in 0, 10, 20, 30, 40 & 50% for every 0%, 10% & 15% replacement of fly ash with cement. Satisfying results were found for 10% fly ash and 40% M sand mix for both workability tests and strength tests conducted in the specimen.
Concrete is an essential building material that you can use to enhance the strength of your building.The major raw material for concrete production is limestone & natural sand which are coming with cost to both environmentally & financially. Due to rapid urbanization of developing nations and the upkeep of structures in developed nations, there is a high demand for high-quality concrete at the same time. Therefore, the production of concrete can be made more sustainable by substituting some concrete constituents with industrial waste, since these substitutes are already produced but still disposed. On the other hand, the addition of discussed industrial wastes has been shown to improve the properties of concrete: strength and workability. Sand is currently very expensive. Large-scale market introductions of materials like artificial sand have significantly lessened the cost burden of river sand on concrete. It makes sense for the world to use industrial wastes, such as slag, fly ash, etc., to partially replace fine aggregates.
II. FLY ASH
When lignite or pulverised coal is burned, a significant amount of by- product is formed in thermal power plants, due to the high burning temperature of the coal, the fragmented particles that become molten and then solidify are generally spherical particles known as Fly ash. Fly ash is fine spherical silt sized (10-100 μ) solid residual, which could be transported easily by flue gases and deposited at electro- filters. About 80% of the ash residue produced is carried by flue gases and subsequently collected by electrostatic precipitators that are installed in chimneys to decrease air pollution. The remaining 20% of the residual is at the bottom forming bottom ash. Fly ash, hopper ash, or chimney ash are all terms used to describe the ash that is collected at the top of the chimney. Fly ash is made up of organic components like unborn carbon and inorganic substances like silica and alumina. The fly ash's mineral makeup and particle sizes have a big impact on its pozzolonic properties.
A. Properties of Fly ash
Improved workability: The shape of particles is spherical hence they act as small ball bearings in concrete as lubricants.
Lowered water demand: Fly ash, which accounts for around 20% of the cementitious material, reduces water demand by about 10%.
Reduced heat of hydration: Concrete's hydration heat can be reduced by using fly ash.
Improved ultimate strength: Fly ash concrete gains strength over time as a result of growing binder resulted by the interaction of the fly ash with available lime.
Reduced permeability: Because of the improved binder produced by the interaction between the fly ash and easily accessible lime, fly ash concrete gets stronger over time.
Improved resistance to corrosion: The corrosion resistance is increased by the decrease in permeability.
III. MANUFACTURED SAND
M Sand is manufactured sand used in cement or concrete construction that is made by crushing rocks or granite. Natural sources for sand such as river sand, stream sand, pit sand, sea sand and other sands, for use as aggregate in construction are becoming scarce and exhausted as a result of environmental deterioration. M Sand was developed in response to a rising need in the building sector for alternative aggregates. Another argument in favour of its utilisation is the active availability of M sand, which cuts down on pollutants and transit times. M Sand is a better option than river sand since it is manufactured by machines in the correct ratios of particle size.
???????A. Properties of M-Sand
Greater Durability: M Sand can withstand challenging environmental conditions and has balanced physical and chemical characteristics.
Higher Strength: M Sand doesn't contain any elongated or flaky particles and has a smooth surface texture thanks to the usage of a VSI shaping machine.
Greater Workability: Mortar has outstanding workability due to its cubical shape and correct gradation, which calls for particles to range in size from 150 microns to 4.75 mm.
Economy: Waste is nonexistent because M Sand doesn't have any contaminants like river sand does. Given that it is easily accessible, the cost of transportation also decreases.
IV. OBJECTIVE OF THE WORK
The goal is to determine the strength parameters to efficiently utilize fly ash and M sand in the mix as it decreases the environmental effect and also can be made cost effective as well as not compromising with the durability and strength parameters. In this study natural sand is replaced with M sand in 0, 10, 20, 30, 40 & 50% for every 0%, 10% & 15% replacement of fly ash with cement. Tests such as compressive strength test, split tensile test & flexural strength test are conducted. Workability tests such as vee bee consist-meter test, compaction factor test and slump cone test are as well conducted on fresh concrete. Both fly ash & M sand have been studied as potential partial replacements in concrete. In the current study, the behaviour of concrete is made by swapping out traditional components for the right proportion of these alternates is examined. Tests for workability and strength are used to see the impact of the fly ash and M sand.
A. Workability goes on increasing up to 40% replacement of natural sand by M sand & 10% replacement of OPC by fly ash. Beyond this replacement level workability reduces.
B. Workability of concrete produced by replacing natural sand by M sand & OPC by fly ash is higher as compared to reference concrete.
C. Higher compressive strength can be obtained when the 40% replacement of natural sand by M sand & 10% replacement of OPC by fly ash.
D. Higher split tensile strength can be obtained when the 40% replacement of natural sand by M sand & 10% replacement of OPC by fly ash.
E. Concrete produced by replacing natural sand by M sand & OPC by fly ash exhibit higher split tensile strength as compared to reference concrete.
F. Higher flexural strength can be obtained when the 40% replacement of natural sand by M sand & 10% replacement of OPC by fly ash.
G. Concrete produced by replacing natural sand by M sand & OPC by fly ash exhibit higher flexural strength as compared to reference concrete.
 Rafat Siddique “effect of fine aggregate replacement with class f fly ash on the mechanical properties of concrete” 33 (2003) pp 539–547
 Patil S L Kale J N Suma S “fly ash concrete a technical analysis for compressive strength” (2007)
 Wolfe, Michael Hayse “Bond strength of high volume fly ash concrete” University of Science and Technology (2011)
 AnandKumar B .G” Effective Utilization of Fly Ash and Supplementary Cementitious Materials in Construction Industry”
 Venkatachalapathy Venkitasamy Srinivasan Gopala Krishnan, B.P.C Rao “ Performance of fly ash blended crushed sand concrete”
 IS 456-2000 Specifications for plain and reinforced concrete.
 IS: 10262 – 2019 Specifications for plain and reinforced concrete.
 IS: 8112 - 1989 Specifications for plain and reinforced concrete.
 IS: 383-1970 Specifications for plain and reinforced concrete.