Table 1. Mix Design and Proportion of M20 & M30 Grade Concrete
Natural Sand is a common form of fine aggregate used in the preparation of concrete. However, due to rapid urbanization and large scale depletion of river bed, natural sand has become very expensive. Many non-conventional resources such as Stone Dust, Carbonate Sand, Fly ash, Copper Slag etc. with larger % of Silica (SiO ) have been tried out as an alternative to 2 river sand as fine aggregate in preparation of concrete. Copper Slag which is an industrial waste in the metal smelting process of copper production has shown promising result to be used as an alternative to sand in preparation of concrete. The use of copper slag in construction activity will also resolve the issues of disposing the industrial waste which is a major concern these days. This paper studies the behavioral aspects of Copper slag admixed concrete while it is subjected to both destructive and non destructive tests. It proposes to study the behavioral aspects by adding Crimped steel fibres with varying percentages from 0 to 1.5 in the mixes of M 20 and M 30 .
Large scale depletion of river bed has created huge demand for alternative material of river sand which is the most common form of fine aggregate in preparation of concrete. Several non-conventional resources such as Fly-ash, Stone Dust, Carbonate Sand, Copper Slag etc. having larger percentage of Silica (SiO2) have been tried out, as a substitute to river sand as fine aggregate in concrete preparation. Many studies have shown good results in terms of various strength properties of concrete by partially replacing sand with copper slag in the preparation of concrete and the optimum percentage of copper slag replacement has been found to be 40 %. Low tensile strength and low strain at fracture are the main deficiencies of plain cement concrete which can be removed by the inclusion of crimped steel fibres in it.
The paper proposes to study the behavioral aspects of Copper Slag admixed concrete by adding crimped steel fibres with varying percentages from 0 to 1.5 in the mixes of M 20 and M 30. The objective is to study various strength properties such as Compressive Strength (CS), Ultrasonic Pulse Velocity (UPV) and Rebound Hammer (RH) of Copper slag admixed fibre reinforced concrete using Destructive and Non-Destructive method.
Brindha and Nagan [1] studied the durability properties of copper slag admixed concrete and found that the concrete with copper slag has less resistance to the H So 2 4 solution than the control concrete. Saveria Monosi [2] et. Al studied the impact of Foundry Sand in Mortars and Concrete and found that the structural mortar and concrete can be manufactured with UFS as partial replacement of natural sand. A suitable recycling of the discarded foundry sand as building construction material was suggested. Chandana Sukesh et. al [3] investigated the impact of using quarry dust as a partial replacement of sand in concrete and found an improved performance of concrete in terms of compressive strength. Sreekrishna perumal Thanga Ramesh et. al [4] used welding slag and furnace slag as partial replacement for sand and found a better performance towards compressive strength. As per the experimental result, 10% of furnace Slag & 5% of welding Slag as sand replacement was very effective. Ion Dumitru et. al [5] did field trials using recycled glass as natural sand replacement and powdered glass as cementitious materials replacement in concrete pavement and found that the recycled sand glass can be used to partially replace the natural sand in concrete, producing concrete with at least equivalent fresh and hardened properties. Omar M. Omara et. al [6] used marble powder and limestone waste as partial replacement material for sand and found that compressive strength of the concrete increases with the increase in the percentages of M.P additions at all curing ages. Binaya et. al [7] reported that, sand can be partially replaced with copper slag in concrete manufacturing process and for M20 Grade mix, the maximum strength can be attained with 40 % of Copper slag replacement. Seshadri Sekhar et.al [9] discussed the behavior of Copper slag for variable mixes in concrete with variable percentage of fibres and copper slag.
53 grade OPC with normal consistency of 32%, fineness modulus of 4.62% and specific gravity of 3.094 was used. The quality of the cement was established as per IS 4031- 1988 and all the quality tests were done according to specifications of 12269-1987.
River sand having water absorption of 1.20%, Bulk Density in compacted state of 1700kg/m3 and in loose state of 1597 kg/m3, fineness modulus of 2.4 and specific gravity of 2.6 was used.
20 mm angular crushed granite metal having water absorption of 1.1%, Bulk Density in compacted state of 1550 kg/m3 and in loose state of 1414 kg/m3, fineness modulus of 7.1 and specific gravity of 2.6 was used.
Rounded crimped steel fibres of diameter 0.5 mm X length 30 mm (Aspect ratio = 60) with various volume fractions (0%, 0.5%, 1% & 1.5%) have been used for this study. The Ultimate Tensile Strength of the crimped steel fibres was found to be 1020 MPa.
Glassy, air cooled, irregular and black copper slag with fineness modulus 3.3 and specific gravity 3.47 was used. Water absorption was 0.24%. Bulk Density in loose state was found to be 1898 kg/m3 and in compacted stage of 2024 kg/m3.
Table 1 gives the proportions of M20 and M30 grade of concrete mixes used confirming to IS 10262-1978.
Table 1. Mix Design and Proportion of M20 & M30 Grade Concrete
Figure 1 shows the test results based on destructive and non-destructive testing of copper slag admixed concrete of grade M20 and M30 with varying percentage of crimped steel fibre (0%, 0.5%, 1% and 1.5%) at different ages.
Figure 1. Relation between Destructive and Non- Destructive values of Copper Slag Admixed Conctere
Out of various M20 grade mixes, the maximum percentage increase in compressive strength at 90 and 180 days observed in the case of normal concrete were found to be 20.49 % and 25.54 % respectively. The similar observation was found in the case of M30 grade mixes. The maximum percentage increase in compressive strength at 90 and 180 days observed in case of normal concrete were found to be 24.59 % and 29.86 % respectively.
Out of various M20 grade mixes, the maximum percentage increase in UPV at 90 and 180 days observed in case of C40S0 mix are found to be 2.01% and 6.94% respectively. The similar observation was found in case of M30 grade mixes. The maximum percentage increase in UPV at 90 and 180 days observed in case of C40S0 mix are found to be 4.68% and 7.35% respectively.
Out of various M20 grade mixes, the maximum percentage increase in RH number at 90 and 180 days observed in case of normal concrete are the found to be 4.6% and 6.05% respectively. Similar observation was found in case of M30 grade mixes. The maximum percentage increase in RH number at 90 and 180 days observed in case of normal concrete were found to be 1.73% and 3.12% respectively.
Figure 2 shows the behavior of Copper slag admixed crimped steel fibre reinforced concrete subjected to Destructive and Non-Destructive tests.
Figure 2. Relationship between Compressive Strength and ultrasonic pulse velocity
The relationship between compressive strength and Ultra Sonic Pulse Velocity for copper slag admixed concrete with crimped steel fibres at 180 days is given by CS = 0.176e1.214upv
The relationship between the CS and UPV is in correlation with the formulae given by earlier researchers which is given as fc = aebv where fc is compressive Strength, V is the velocity and a, b are the constants. The relationship is given as,
RH*UPV=[(62*10^-5)CS*CS]+[(70.17*10^-2) CS] + 168.5
The Compressive Strength, Rebound Hammer value and Ultra sonic Pulse Velocity value of Copper slag admixed fibre reinforced concrete is attained with 1% steel fibre and on further increase of crimped steel fibre, the compressive strength decreases. However, in case of fibre reinforced concrete without copper slag, the values are found to be increasing linearly with the increase in crimped steel fibre content (0% to 1.5 %) and the maximum compressive strength is observed with 1.5% of crimped steel fibre.