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Showing posts from January, 2021

Why the vacuum should be done for AAC Blocks?

  Purpose of Evacuation: Before steam is often entered into the autoclave, the  autoclave must be evacuated by reducing the  pressure within the autoclave with the utilization of  vacuum from the air pump or steam ejector.  Hereby the existent atmosphere within the autoclave  is removed. By keeping the evacuation pressure below the  saturation pressure of water, which is out there within  the green cakes, steam is released from the green  cakes as a desired side effect. Air and hydrogen which are still present within the  green cakes are scavenged from the autoclave by this  self-formed saturated steam. Why the vacuum should be done  for AAC Blocks? The vacuum is mandatory. This will remove the entrapped air from autoclaves. Otherwise, liquid steam marks are going to be visible  after autoclaving. Those blocks are sensitive and have a tendency to  break easily. If it's not broken, please keep the  separate stacking/drying for a couple of days. If there's no vacuum, do the purgi

AAC vs Non AAC Blocks

  Why Autoclaving is required when Non Autoclaved Aerated Concrete Blocks are available in the Market? The matrix and the firmness of the AAC products are made due to autoclaving.  AAC vs Non AAC Blocks Technically, such product will start cracking by itself  when it approaches equilibrium moisture content  after a couple of years. In the case of ordinary concrete products, there are  no shrinkage troubles during the drying operation. But in foamed or aerated concrete the mixture is air  and if manufactured without autoclaving, drying  shrinkage will cause cracking. The calcium silicate hydrates formed during  autoclaving is more stable than the one formed of  cement at room temperature. Autoclaved products have low shrinkage. Cement will need four weeks to achieve its final  strength at room temperature whereas, autoclaving  takes only 12 hours. to get desired strength. The mechanical strength will not be very high and  through the drying, the shrinkage is going to be  excessive. It i

Reactions during Autoclaving of AAC Blocks

Reactions during Autoclaving of AAC Blocks In the first phase, a topochemical reaction takes place during which the lime and silica acid are the reactants.  Water doesn't happen within the actual rejection; it’s only built into the new formulations that are formed.  These reactions occur within the border areas of the raw materials, starting at the active spots (e.g. on the edges) of a crystal. The second phase of the reaction will mainly involve the solvent phase where the lime and silica acid, both of them are dissolved in water, will react into insoluble calcium silicate hydrates.  These hydrates will form a structure. Looking at this in a little more detail from when the  green blocks enter the autoclave, the main reactions  that occur are broadly as follows: Over 2 hours or so, as the pressure and temperature increase, the normal cement hydration products that formed in the green state progressively disappears and the pulverized fly ash becomes reactive.  C-S-H(I) forms, partl

AUTOCLAVING - NUTS AND BOLTS OF AAC BLOCKS MANUFACTURING (By Srinivas Goud Chikati)

 

One and only Book available in the world on this subject - ‘Autoclaving of AAC Blocks'

  7 ReasonsWhy this Book Must Be Read 1. India is full of fake AAC consultants. This book will save lakhs of money spending on them. 2. By understanding the process and following the checklists and log sheets, one can save lots of money. 3. This book is written by one of the five  senior  AAC professionals available in the country with more than 17 years of hands-on experience in AAC Plants. 4. When you are planning the New AAC Plant, this will enable you to choose the right Autoclaves, and the systems connected to it. 5. Most of the plans have no long vision. They hand over the plant to some contractors and ask for the production. They damage everything in 4 or 5 years. This is ok when you want to do business for 4 or 5 years. This book and my next book on Process Control will enable you to choose your own team and manage the plant for a long time. 6. Much attention was given to Safety. If the plant is safe, employees can work without any fear , and productivity will be increase