This article was originally written by (Ram Chandar et al., 2022).
Concrete is one of the most basic and critical components for any type of construction and plays an important role in building the nation’s infrastructure. Concrete is a composite material which is composed of coarse and fine aggregates embedded in a matrix and bound together by a binder, which fills the space or voids between the aggregates (Mindess et al. 2003).
Basically, concrete is a mixture of binder, water, aggregates and additives. The binder generally used in concrete production is OPC, which is mainly responsible for the mechanical strength. Utilization of a few industrial wastes as binder material could result in higher strength compared to OPC concrete strength.
One of the major construction projects includes road construction which develops the country’s infrastructure. Research on replacement of sand with IOTs to prepare Ultra High-Performance Concrete (UPHC) was conducted (Zhao et al. 2014). When the replacement level was not more than 40% for 90 days standard cured specimen, mechanical behaviour of tailings was comparable to that of control mix and the compressive strength decreased by less than 11% and flexural strength increased by 8% in comparison to control mix for specimen that were steam cured for 2 days.
Recent trends in autoclaved aerated concrete (AAC) have increased the requirement of waste utilization during the production of AAC. Much research was carried out on the utilization of waste materials, such as fly ash, air-cooled slag, coal bottom ash, efflorescence sand, copper tailings and carbide slag, for the possibility of using them as AAC production (Zhao et al. 2014; Huang et al. 2013; Kurama et al. 2009; Mirza and Al-Noury 1986; Mostafa 2005).
Further, AAC production was carried out using coal residues and IOT. Bulk density and compressive strength of prepared AAC were 609 kg/m3 of 3.68 MPa, respectively. This AAC mainly com posed of 20% CGC, 40% IOTs, 25% lime, 10% cement, 5% desulphurization gyp sum and 0.06% aluminium powder (Wang et al. 2016).
Preparation of lightweight tailings AAC block was recommended by Ma et al. (2015). AAC block has bulk density of 490 and 525 kg/m3, compressive strength higher than 2.5 MPa with the composition consisting of cement, quicklime siliceous materials, gypsum and aluminium powder. Results for leaching test showed that AAC blocks with IOT were not a threat to environment.
Kumar (2014) studied on utilization of IOTs as replacement to fine aggregates in cement concrete pavements. In this study, IOT used as partial replacement to fine aggregates at levels of 10%, 20%, 30%, 40%, 50% and the basic material properties, strength parameters are studied. It is found that as the IOT percentage increases in the mix, workability is reduced.
The cube specimens were tested in Compression Testing Machine after specified curing period for different percent of IOT replacement Mix1(10%IOT), Mix2(20%IOT), Mix3(30%IOT), Mix4(40% IOT) and Mix5(50%IOT) and for normal concrete mix. At 40% replacement level for 28 days, compressive strength is more than the reference mix (Normal concrete mix) and other replacement percentage mixes. Flexural strength is observed maximum for reference mix.
Quality of concrete mixes is found good from Ultrasound Pulse Velocity test. Flexural fatigue analysis is carried out on mix with 40%. IOT replacement at stress ratios 0.65, 0.70 and 0.75 compared with IRC model for number of repetitions using log normal distribution, up to 0.7 stress ratio, it showed more number of repetitions than IRC and at higher stress ratio mix with IOT achieved failure earlier.
Prahallada and Shanmuka (2014) studied on stabilized IOT blocks showing an increasing trend in the erosion resistance with increase in curing period. Stabilized IOT blocks showed decrease in liquid absorption with increased stabilizer percentage and curing period, i.e. 1.35% on 21 days curing of 7% cement stabilization. Maximum dry compressive strength of IOT blocks with 7% cement stabilization on 21 days curing is 8.5 MPa, and the ratio of wet to dry compressive strength lies between 0.50 and 0.73.
Prem Kumar et al. (2014) experimented by replacing 0%, 10%, 20%, 30%, 40%, 60%, 80% and 100% of sand by IOT. There is an increase in the compressive strength due to sand replacement by IOTs. The maximum increase in compressive strength for about 40% of sand replacement, and there is no reduction in flexural strength of reinforced concrete beams. Ugama and Ejeh (2014) studied the suitability of IOT as fine aggregate for replacement of sand in masonry mortar and found compressive, tensile and flexural strength of 36.95 MPa, 1.76 MPa and 5.73 MPa, respectively, for optimum level of 20% of IOT replacement.
Abdulrahman (2015) produced sand concrete blocks with mix ratio of 1:6 (one part of cement to six parts of sand) where sand portion was replaced by IOT with different percentages like 10%, 20% and 30% at 28 days curing; compressive strength approached the recommended strength for 230 mm blocks and proved that there is a way for waste disposal (IOT) and development of eco-friendly sand Crete blocks.
Kshitija et al. (2015) studied the use of IOTs as a construction material. In the study, IOTs are used as a partial replacement of the fine aggregates. In this study, 15%–20% replacement of IOTs is recommended which can save up to 20% of fine aggregates, thereby reducing the cost of production and also pollution of environment by using IOT and marching towards sustainable construction.
Concrete with IOTs is a sustainable solution as it reduces sand by as much as 15% by IOTs in concrete. Nagaraj et al. (2016) have conducted exploratory study on compressed stabilized earth blocks (CSEB) utilizing various proportions of mine spoil waste (MSW) (accumulated at up stream of mining area at Sandur region, Karnataka), quarry dust and stabilizers (cement and lime). Mine spoil waste was utilized in three possibilities 30%, 40% and 50% with cement and lime as stabilizer in two combinations like 6% cement + 2% lime and 8% cement + 2% lime in CSEB blocks. It was observed that wet compressive strength for any combination of admixture is more for blocks prepared with 40% MSW, which indicates these blocks can be effectively used as eco friendly bricks in construction industry.
Reference
Ram Chandar, K., Gayana, B. C., & Shubhananda Rao, P. (2022, May 27). Mine Waste Utilization. https://doi.org/10.1201/9781003268499
