Utilization of Iron Slag, Waste Foundry Sand and Rice Husk Ash as Partial Replacement of Cement and Fine Aggregates in Pavement Quality Concrete

Abstract

The construction industry is one of the largest consumers of the natural resources. The main component in the construction industry being concrete consists of 75-85% of natural aggregates. The natural aggregates being non-renewable resource they may undergo extinction some day or even if exists, the form may not be used in the construction products. In order to reduce the consumption of natural aggregates, replacing them by materials possessing similar characteristics is one of the solutions. There are several industrial by-products, which possess characteristics similar / superior to natural aggregates. These industrial by-products can be used as partial replacement for natural aggregates in concrete, thus reducing the consumption of natural resources. Some of the most suitable industrial by-products include iron slag, waste foundry sand and rice husk ash. Rice husk ash (RHA) is a form of ash after burning the husk which is generated during rice milling process by rice milling industries. Further, iron and steel industries produce iron slag which is a by-product. In past studies usage iron slag shows good mechanical properties for concrete. The foundry industries produce large amount of sand by using it till the loss of all the properties for their industry this sand is a waste and generally known as waste foundry sand. Pavement quality concrete (PQC) is a type of harsh concrete, which is mainly used in the construction of rigid pavements. With this increase in share of rigid pavements on Indian highways, the usage of concrete in the road construction has increased tremendously. As per IRC: 58, which is the guideline for design of rigid pavement, recommend 4.5 MPa flexural strength at 28 days for PQC. As above mentioned, industrial wastes can be a good replacement for natural aggregates in concrete, this study focused on replacing partially cement as rice husk ash and on the other hand sand is partially replaced by iron slag and waste foundry sand both in different proportions. The RHA is used as 10 %, 20 % and 30 % replacement by weight of cement. Further iron sag with 20 %, 40 % and 60 % replacement by weight of natural sand and WFS with 10 %, 20 % and 30 % replacement by weight of natural sand. The different proportions comprise to make different mixes using Taguchi method namely CM, M1, M2, M3, M4, M5, M6, M7, M8 and M9. These total of ten mixes have different mix design as per the IRC 44: 2017. Compressive strength test 7

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days and 28 days and flexural strength test is done for 28 days of curing age. These tests done by casting 60 cubes (15 cm×15 cm×15 cm) and 30 beams (15 cm×15 cm×70 cm). These tests are done on M40 PQC concrete. Results shows that mix M1 with (RHA-IS-WFS) as (10%-20%-10%) shows value that is ideal for M40 concrete but decreases as compared to control mix. The economic analysis shows results that the cost of Pavement Quality Concrete reduces by 4.23 % with the only optimum Mix-1. Also, according to the Minitab Analysis the optimum mix would be RHA 10%, IS 20% and WFS 20%.