Utilization of Iron Ore Waste and Tailings in Concrete Pavements

Abstract

With the augmenting infrastructure, the need for construction materials is increasing in various applications viz., buildings, bridges and pavements. The quantity of materials required for pavement construction is huge. At present scenario, in a few states within India, sand mining is banned due to which it is affecting the construction industry. So, many research works are being focussed on utilization of indusial waste in pavements. A systematic research study is taken up to utilize iron ore mine waste and iron ore tailings in concrete pavements. The main objective of this research study is to evaluate the properties of concrete mixes with marginal materials derived from mine waste i.e., iron ore waste rock (WR) and iron ore tailings (IOT) as coarse and fine aggregates with suitable admixtures for M40 grade concrete based on requirement. The fresh and hardened properties of concrete determined were workability, compressive, splitting tensile and flexural strength. Rapid Chloride Permeability Test (RCPT) was conducted to determine its durability property. Experimental investigations were carried out for three different material compositions. Firstly, two different mixes were considered, one set of concrete mixes with WR as coarse aggregates and other set of concrete mixes with IOT as fine aggregates were replaced partially by 10%, 20%, 30%, 40% and 50% for 3, 7 and 28 curing days with varying water-cement (w/c) for each composition by 0.35, 0.40 and 0.45. Around 162 cubes, 54 cylinders and 54 beams were casted for each mix composition and tested for their strength properties. Optimum strength was obtained at 40%, 30% and 20% replacement of WR in concrete and at 30%, 20% and 10% for IOT concrete for 28days cured specimens, for 0.35, 0.40 and 0.45 w/c. Concrete mix with IOT was workable with higher w/c compared to 0.35 and 0.40 w/c; this is due to the high specific gravity of IOT. In case of WR concrete, workability was found to satisfy the design criteria. Flexural strength observed for IOT and WR concrete mixes ranged between 4.50 to 5.10 MPa. Similar trend was observed in case of compressive and splitting tensile strength.ii To enhance the strength properties of concrete mixes with WR and IOT replacement, alccofine was used as a binder replacement by 10%. Similar to the first case, two different mixes with WR and IOT as coarse and fine aggregates respectively in concrete were considered with 10% alccofine at 10%, 20%, 30%, 40% and 50% for 3, 7, 28 and 56 days curing. Water-cement (w/c) ratio varied for each composition by 0.35, 0.40 and 0.45. Around 216 cubes, 108 cylinders and 108 beams were casted for each mix composition and tested for their strength properties. Similar to WR and IOT concrete mixes, optimum strength obtained for 0.35, 0.40 and 0.45 w/c were at 50%, 40% and 30% replacement of WR-alccofine concrete and in case of IOT-alccofine concrete, optimum strength obtained were at 40%, 30% and 20% respectively. Here, compressive strength ranged between 55 to 75 MPa, splitting tensile strength ranged between 3.8 to 5.0 MPa and flexural strength ranged between 5.80 to 7.30 MPa for WR-alccofine and IOT-alccofine concrete mixes. In this case, density of concrete increased due to the high specific gravity of WR and IOT aggregates. To reduce the density of WR-alccofine and IOT-alccofine concrete respectively and make it a light weight concrete, expanded perlite (EP) was added as partial replacement for fine aggregate by 0%, 2.5%, 5.0%, 7.5% and 10.0% for 3, 7, 28 and 56 days curing with varying w/c of 0.35, 0.40 and 0.45. In this case, control concrete mix with optimum percentage obtained from WR-alccofine and IOT-alccofine were considered for their respective w/c and later EP was replaced as fine aggregates for varying percentages. Based on the results obtained for EP-concrete, density reduced drastically and ranged between 2,600 Kg/m3 to 2,300 Kg/m3 making it a light weight concrete. Due to addition of EP in WR-IOT-alccofine concrete, strength also reduced due to its fineness and porous nature which absorbs water. However, the strength achieved from 5% EP concrete are still higher than the target strength requirement as per IS codes. Compressive strength varied between 58 MPa to 49 MPa. Similar results were obtained in the case of splitting tensile and flexural strength of concrete. Based on all the above experimental investigations, it can be concluded that, for light weight concrete the optimum mix is with 5% replacement of EP concrete for all the w/c considered. For 0.35, 0.40 and 0.45 w/c the optimum percentage of mix consistsiii of WR-IOT-alccofine-EP of 50-40-10-5 percent and 40-30-10-5 percent and 30-20- 10-5 respectively. Whereas, for high dense concrete applications, the optimum percentage of WR-alccofine for 0.35, 0.40 and 0.45 w/c is at 50%, 40% and 30% respectively. Similarly for IOT-alccofine concrete, the optimum percentage was found to be for 0.35, 0.40 and 0.45 w/c is at 40%, 30% and 20% respectively. A statistically fitted multiple regression analysis was performed for all the mechanical properties to evaluate the significant level of concrete containing WR-alccofine, IOTalccofine and EP-concrete mixes. These prediction models developed have high accuracy and low bias. The validation process presented that the equations can perform in a better way in predicting the WR-alccofine, IOT-alccofine and EP concrete properties.