Industrial Wastes as Alternative Materials to Fine Aggregates in Triple Blend Self Compacting Concrete – a Sustainable Technological Solution
Authors: Divith Kumar R P , Ganesh Bharathi , Bai Sharada , Narendra B K , Venkateswaran N 
Published: July 2019

Self-compacting concrete is a most revolutionary development in concrete constructions for several decades and presently has become a common feature of day to day constructions. The powder content of SCC consists of cement as major binding material. It is a well-known factor that cement production is the major contributor of emission of CO2, One of the methods adopted to reduce the consumption of cement and hence to reduce greenhouse effect is to use the mineral admixtures such as Fly Ash, GGBS, Metakaolin etc., as cementitious materials, replacing cement partially. It is a solution for the management of Industrial by-products as solid waste, reducing the burden on environment. The consumption of depleting natural resources as FA can also be reduced. Encouraging the use of alternative materials in concrete contributing to green and clean environment. The quality and strength criteria of end product, concrete and SCC are maintained as expected. The paper presents the experimental study on use of cementitious materials alternate to cement/powder content replacing cement equally named as Triple Blend and also to replace Natural River sand (FA) with Manufactured Sand and Pond Ash.

The literatures report the studies on rheology and strength parameters of concretes with Supplementary Cementitious Materials (SCM). Few studies on the application of cement, fly ash and GGBS in equal proportion by weight (Triple Blend SCC-TSC) is available. The literature on properties of TSC replacing both cementitious materials and FA are scanty.

This paper is an effort to develop a sustainable concrete (TSC) with alternative materials for Cement and Natural River sand and to assess the suitability in terms of required properties of TSC.

The SCC mixes are designed for a powder content of 400 kg/m3 using Absolute Volume method. The Rheology of mixes namely Slump Flow, Slump T50, V Funnel and L-Box are assessed with 180lts of water and varying the dosage of admixtures as per EFNARC 2005. Specimens are cast and cured (for 28 days) as per standard codal procedure. The properties in fresh state of TSC and strength are assessed and analysed in comparison with that of Normal SCC – SCC with 70% cement, 30% Fly ash as powder content and with 100% Natural River Sand as FA.

Properties in fresh state confirms to the requirement of EFNARC 2005. However, the study showed that the presence of Pond ash as FA makes the SCC mix is sticky due to more inter particle friction. Slight bleeding of mixes can be attributed to the that higher water absorption of Pond Ash in comparison with Natural River Sand and lesser water retentivity of Pond Ash.

The rheological properties of TSC mixes is comparable with that of Normal SCC mixes recommending the use of industrial waste from the point of view of properties of fresh SCC.

The strength reduction of TSC mixes is ranging from 5-10% for the mix in which replacement of M-Sand and Pond ash is carried out in equal proportion by weight. This may be due to the presence of porous, irregular particles of Pond ash which may affect packing density of the mix. Other important observation in the study is that reduction in strength of TSC mix may be attributed to higher water absorption of Pond Ash and lesser water retentivity of Pond Ash.

Hence, the present study recommends the use of alternative materials to both power content of TSC and FA content to produce a sustainable SCC mix contributing to lesser release of CO2 to atmosphere, avoiding the dependency on depleting natural resources (using alternatives as M-Sand and Pond ash) contributing to Green Design Mix of TSC. This may be one of the most appropriate solution for management of huge solid waste from the industry.