Mechanical Properties of Partial Replacement of Cement with Sugarcane Baggase Ash

Current study focuses on mechanical properties of Sugarcane Baggase Ash (ScBA) as a cementetious material and as pore filling material in concrete. With depleting natural resources these industrial waste materials not only helps as replacement material but also provides in numerous alternate benefits such as protecting environment, land fill compounds, saving energy etc. Difficulty of disposing of ScBA is already an environmental hazard. ScBA imparts high strength in early replacements and also reduces concrete permeability, also presence of silica in chemical composition imparts high chloride resistance and corrosion resistance. Mechanical properties were studied for 5%, 10%, 15% and 20% replacement with cement, compressive strength, split tensile and workability were studied and optimum was found to be at 10% replacement. Also durability studies were performed by conducting Rapid Chloride Penetration Test (RCPT) and durability is found to be higher than conventional concrete.


Introduction
With growing economy and rapid increase in construction, there is high requirement of alternate materials in construction inorder to save the natural resources and thereby reducing impact on environment. In engineering materials applicable in construction concrete is considered as the most dynamic material. In this context there is high need for replacement in concrete mix with natural wastes such as Fly Ash, ScBA, Rice-husk etc [1]. ScBA is considered as waste material in current study as it is widely used in construction industry. it can be used in variety of building materials such as ceramic tiles, cement replacement, fine aggregate replacement etc. due to good pozzolanic properties of ScBA it can be chosen as alternate material in replacement in concrete mixes [2]. India is rich in its agricultural produce and natural fibers, has a large production of sugarcane, these natural fibers provide excellent increase in physical and mechanical properties upon replacement [3]. Baggase waste generated from indian sugar mills is produced in huge proportions and several ways of converting waste to usable material is being studied [9]. Researchers all around world are focusing on various ways of utilizing either industrial or agricultural wastes as raw materials, these waste reusing, ScBA is among such wastes in sugar refining [4]. Baggase Ash was already used to improve the strength parameters of flexible pavements [8] although results may differ when applied the same for structural concrete. Chloride penetration of concrete specimens can be determined by RCPT  [7]. RCPT tests were conducted to assess the durability aspect of present study as per [6,7].
Current study aims to evaluate mechanical properties with main focus on strength parameters such as compressive strength, split tensile strength. The workability aspect is also presented in the work. It is focused on 5%, 10%, 15%, 20% replacement of ScBA. Finally durability aspect was studied by performing RCPT on cylindrical specimens.

Material Tests
Preliminary tests on all materials Water, Fine Aggregate, Course Aggregate, ScBA were conducted as per codalprovisons.

Cement &ScB
Ordinary Portland Cement 43 grade is used in current study for replacement studies. Tests on cement were conducted as per guidelines followed by IS 269-2015. Similar tests were conducted on ScBA for obtaining parameters. Table 1 represents the material properties of ScBA where Specific gravity, mean particle size, density, min specific surface area, particle shape and color determined in the preliminary laboratory tests. Specific gravity 2.2 3.
Colour Black Chemical composition of ScBA is taken from [2], Table 2 represents the Chemical composition of ScBA. Main composition is Silicon dioxide comprising of 78.34% of total volume, and other compounds as in Table 2. OPC 43 grade cement when mixed with ScBA with various percentages (5%, 10%, 15%, 20%) with particle size distribution represented in form of graph shown in Figure 1. with all proportions.Tests on cement for OPC 43 grade were performed and the results were presented in table 3.

Fine Aggregates
Fine aggregates are tested as per IS 383 -2016 and the results were represented in table 5. Fine aggregate was confined to Zone III based on sieve analysis tests. Also the bulk density (loosely compacted and closely compacted), Specific gravity, Fineness modulus were given and values are found to be within limits of codal provisions. It can be seen that maximum percentage of weight passing lies in Zone III.   Table 6.

Concrete Mix Preparations
As per 10262-2019 mix for M30 concrete was prepared, cubes of 150x150x150mm dimensions, cylinders of 150mmdia and 300mm height for split tensile strength and durability studies were conducted in accordance with ASTM C1202 (2012). Mix was designed with 5%, 10%, 15%, 20% ScBA to evaluate the strength parameters. Concrete proportions for all five mixes were shown in Table 7. Water cement ratio and other weights were obtained from weight batching from mix specifications.

Workability
Slump for conventional concrete is found to be higher results in higher workability and with different percentages of ScBA slump decreased with increase in ScBA content which results in lower workability for higher percentages of ScBA. Table 8 represents the values of Slump obtained with corresponding replacement of ScBA.   Figure 2 of Compressive strength, it is observed that maximum strength with respect to 7 days curing was found with no replacement of ScBA whereas with age of concrete increasing it is found that strength at 10% replacement of ScBA showed significant improvement and immediate declination in strength with greater percentages of ScBA.

Split Tensile Strength
Split Tensile Strength was determined by casting cylindrical specimen of 150mm diameter and 300mm height. Results obtained were represented in Figure 3.

Rapid Chloride Penetration Test
Rapid Chloride Penetration Test (RCPT) was conducted on 28 and 56 days old concrete in accordance with ASTM C1202 (2012) codal specifications.Test results were represented in below, which the overall chloride ion permeability decreases with increase in ScBA content, from the table it can observed that penetration of chloride ions decreases with increase in ScBA content. It might be due to high amount of Silicon dioxide present in the composition. Also it can be seen that durability is slightly better than conventional concrete. Table 9 represents the chloride ion charge passed.

Conclusions
Mechanical properties and durability based on chloride ion permeability were studied for 0, 5%, 10%, 15%, 20% replacement of ScBA. High compressive strength, Split tensile strength were observed at 10% replacement of ScBA and strength immedietly declined at higher percentages of ScBA. Workability decreases with higher replacement of ScBA although strength decreased. Durability also increases with higher ScBA content compared with durability of Conventional concrete, durability is said to be slightly higher than conventional concrete.
Although it is established that ScBA has decent durability and higher strength at 10% replacement further need to study with closer percentages around 10% which gives the optimum replacement percentage.