Study on Properties of Aerated Concrete with Supplementary Cementitious Materials and Metal Waste

Abstract

Autoclave Aerated Concrete (AAC) Blocks are newly developed light weight substitute for conventional clay bricks. AAC blocks has become specialized solution for making building light weight by reducing weight of infill panels which is beneficiary for tall buildings. AAC blocks are available in various sizes as per its requirement and use. There are two variants available commercial market: flyash based AAC blocks and sand based AAC blocks. The compressive strength of commercially available blocks varies from 4 MPa to 5 MPa and the dry density of blocks varies from 550 kg/m3 to 700 kg/m3.

The metal industries are known to produce billion tons of powder as well as metal waste from various process. The dumping of these waste is a major issue with increase in industrial development. Similarly other fields like agricultural industries also produces tons of waste every year. The industrial waste, metal waste and other waste can be used as replacement of cement and/or flyash as supplementary cementitious material which can make AAC blocks more ecofriendly.

Similarly, large amount of remains of Aluminum AL6061-T6 is produced at SAC-ISRO workshops during manufacturing of various equipment and machineries. This Aluminum AL6061-T6 can be used as replacement of aluminum powder in AAC blocks. In this study Aluminum AL6061-T6 produced in SAC-ISRO, Ahmedabad workshop is used as aerating agent in aerated concrete.

The production of AAC blocks consist of Autoclaving process which is costly as well as tricky. The development of Alkali Activated Aerated concrete (AAAC) blocks can be a solution of the process of autoclaving. The Alkali Activated concrete gains strength by ambient curing or it can be accelerated by heat curing.

In this major project, the basic information related to AAC blocks like various materials, size and shape, strength of blocks and cost of AAC blocks are collected from different manufacturers.

The experimental work consist of development of mixture proportions for AAC blocks as well as Alkali Activated Aerated Concrete. Both type of aerated concrete has been prepared with different supplementary cementitious materials.

The prepared aerated concrete specimen have been tested for compressive strength, dry density, Thermal Conductivity and sorptivity. The specimens of AAAC are tested for compressive strength at 7, 14 and 28 days.

In this study, a multiplying factor has also been established to extrapolate the compressive strength AAC cube having of 100 mm long side to that of cube having 150 mm long side.

Based on investigation, various mixture proportions are suggested for production of commercial AAC blocks as well as alkali activated aerated concrete blocks. For the recommended mixes, the investigation has also been made to analyze effect of variation in autoclaving condition on compressive strength and dry density of autoclave aerated concrete.