Aac Block Installation Guide (1) 6i1b4m

AAC Block Installation Guide

CONTENTS________________________________________ 1) Introduction 2) Advantages and Properties of AAC Blocks 3) General Installation Guidelines          

Mortar Usage Bottom Layers Corners Normal Wall Windows/Door Secondary Wall Top Layer Chicken mesh installation Fasteners Chiseling/drilling/ducting

4) Precautions

Introduction_______________________________________ Autoclaved aerated concrete, or AAC It is a lightweight, precast building material that simultaneously provides structure, insulation, and fire and mold resistance. AAC products include blocks, wall s, floor and roof s, and lintels. It is made with the reaction of Aluminum on a proportionate blend of lime, Cement and Fly ash, the hydrogen gas that escapes creates millions of tiny air cells giving it a strong honeycomb structure. In fact, this type of concrete contains 80% air. In the factory where it is made, the material is molded and cut into precisely dimensioned units. Cured blocks or s of AAC are ed with thin bed mortar. Components can be used for walls, floors, and roofs. The lightweight material offers excellent sound and thermal insulation, and like all cementbased materials, is strong and fire resistant. The purpose of this block installation guide is to serve as a reference for the installation of AAC blocks to masons and those seeking experience in AAC block construction.

Properties of AAC blocks_____________________ AAC Block is accepted worldwide due to its properties. The properties of AAC Blocks are as follows:-

Parameter

Value

Density

550-650 kg/ m3

Compressive Strength

>3 N/mm2 (Mpa)

Shear Strength

0.6

Modulus of Elasticity

2040Mpa

Coefficient of Thermal Expansion

8.1*10-6 K-1

Water Absorption

8%

Thermal Conductivity

0.16 w/k

Thermal Resistance (R Value)

0.46 m2-K/w

Drying Shrinkage

0.04%

Fire Rating

4 Hrs

Sound Transmission Class Rating

44 db

Advantages of AAC Blocks___________________________  Sound Proof:-With its closed air pockets, AAC lightweight blocks can provide very good sound insulation /sound absorption with a STC (Sound Transmission class) rating of 44.It can also be used as a sound barrier wall along busy roads. Result, virtually sound interiors.  Earthquake Resistant:-Earthquake forces on structure are proportional to the weight of the building, hence light weight blocks show excellent resistant to earthquake forces.  Thermal Insulation:-Highest thermal rating in an industry R30! Its cellular structure provides well insulated interiors, keeping out warm air in summers and cold air in winters.AAC reduces air conditioning cost by up to 50%.  Fire Resistant:-Its unique cellular structure provides excellent fire rating. Due to this cellular structure AAC Blocks do not disintegrate even in fire. It is best in class fire rating of 4 hrs. The melting point of AAC Blocks is over 1600 degree centigrade, more than twice the typical temperature in building fire 650 degree centigrade.  Ease of Working:-AAC can be drilled, sawed, nailed, and chiselled. Basically, one may work Autoclaved Aerated Concrete like wood, using wood working tools. Unlike standard concrete, AAC yields readily without chipping or cracking.  Water Barrier:-Microscopic structure of lightweight block does not allow for capability action making it impervious to water. Its water barrier properties are further enhanced by adding silicone based additives.  High Strength:-High pressure steam curing autoclaving process gives AAC blocks unmatchable strength to weight ratio, higher than even M 150 concrete, and far exceeds the Indian Building Code Requirements.  Pest Resistant:-With solid wall construction and finishes, there are fewer if any, cavities for insects and rodents to dwell in. Termites and ants do not eat or nest in AAC blocks. Being made up of inorganic minerals, light weight blocks does not promote growth of molds.  Energy Efficient:-AAC is 100% green building material and is a walling material of choice in LEED certified buildings.AAC is most energy and resource efficient in the sense that it uses least amount of energy and material per m3 of product.

Installation Procedure__________________________ Mortar Proportion:- The mortar which is used for the ing of blocks should be mixed up in proper ratio. The amount of ratio in which the sand and cement is mixed should not increase by 1:5. It is however recommended to use the Thin Bed Mortar MagicBond (Block ing Adhesive) which has right proportion of sand cement and additives. The installing procedures of AAC Blocks are as follows:-

1. Mark and level the Slab:Once the foundation is ready it will be necessary to mark the position of the walls, including door openings, in accordance with construction drawing.It is recommended to set the string line level from the “top of leveling course point” to assure the level of first course. The string should be stretched hooking the line blocks properly. At the same time, the line should be checked by using a line level.

2. Bottom Layer or laying the first course:Using a brush, clean block surface before installation. Lay the first course over a semi-dry cementsand mortar leveling bed. Corner blocks are laid first and the first course should be completed before the second course installation. Once the corner blocks are placed, use a brush to clean the next block surface before mortar application.  Ensure that the top level of all blocks is at same height. This can be checked with either a straight rod or simple level-o-meter. Any undulation might led to uneven load and can result in cracks.

3. Begin with Corners Set the first corner block in the sand cementmortar and adjust the t as needed. To achieve the required height, lower or raise the block by tapping down with a rubber mallet. For next block apply mortar to the vertical ts using an appropriate notched trowel. the trowel should be as wide as the block. After installing each unit, plumb and level should be checked immediately by mason’s level. Corner are to be made in alternate fashion as depicted in figure so that both walls fit into each other L shaped corners

T shaped corners

Top view

Side view

Corners ts

NON CORNER AREA / Normal Wall:After setting up the corners, remaining wall is built up with the proper measure so that no space is left between the blocks.The block should be fixed up in a proper way. An overlapping of the block is done with the centre of other blocks. After every 5-6 level of blocks a lentil has to be made with just two 6-8 mm iron rod and a proper measurement has to be done to get the wall completely horizontal.

Center of block overlap

Lintel with 2nos. 8mm steel rods after 5-6 layers. (Recommended not mandatory)

Windows / Doors:Lintel has to be provided on top of doors and windows. Fixing of the door is done as shown in figure. Concrete infill is recommended where door is attached to the wall

Secondary Wall Ideal way to construct is following the installation procedure of making T shaped ts. Incase it is not possible, To construct a secondary wall an L-angle has to be used after every 2 levels to provide a proper strength and to build a secondary wall along with the main wall.

Secondary Wall Connection to Main Wall

If the length of secondary wall is small less than 600 mm then insert 5-6 mm steel rod after every 3 layers. And also ensure the last block is 100mm in length.

Top Level:The top level just connecting an upper beam. The space is filled with smaller block pieces afteratleast 20 days of the removal of Shuttering and the mortar has to be filled with the ratio of sand and cement not more than 1:5.

Chicken Mesh Installation to avoid cracks

Fasteners Anchors used with AAC shall be made of plastic or nylon. Wood, fiber, lead, metal or expansion anchors are not recommended. To make the holes for fasteners power drills are used. The anchor shall penetrate tightly in the hole to avoid rotation when placing the screw. The hole should be removed to allow the anchor to fully penetrate into an AAC element.

Fasteners

Chiseling/Drilling/Ducting:For electrical conduits and piping installation, cut a chase using an electrical router or a chasing tool. A power drill or router can be used to install an electrical box.

Electrical Conduiting

Precautions______________________________________ The precautions have to be taken as it is very important to avoid the cracks in an AAC block wall.  Level:-The level from the base to the top layer should be properly horizontal. There should not be any gap between the ts  Bottom layer perfectly layered:-The bottom layer should be perfectly layered so that no gaps should come in between or the block should not crack.  Centre of Blocks:-The blocks should be properly constructed as the overlapping should be done with the centre of each block.  Corners need to made first using overlapping technique.  Use of chicken mesh while plastering at proper places

 Coping/Lintel: -The coping and lentil should be placed after every 5-6 layer of blocks. Coping beam with 2 nos 8mm reinforcement after 1.2mts height