Our recommendations for masonry as filler walls based on IS 2572, IS 2250 and IS 2185 part I
Dry Units Essential:Concrete Masonry blocks should never be pre-whetted as is customary with bricks as concrete block will give drying shrinkage while the joints mortar is setting, resulting in cracking of the joint mortar. However, water may be sprayed on the joints for curing from the next day.
Mark the courses on the columns:In case of block work in framed structure before starting the block work mark the course on columns and try to adjust the first course in a way as to avoid any gap at the beam bottom. Use a stick which has 20 cm marks on it.
Arrange the blocks in the First Course: After leveling the surface as above start by arranging the blocks between two columns so to arrange the vertical gaps equally or use a half or one fourth block.
Use cement-lime mortar 1:1:6 (1 cement:1 lime: 6 sand):After having adjusted the first course start spreading mortar by lifting one by one block from first course. Lime adds plasticity and makes watertight. Instead of lime one can use Air entraning agent or both for best water tight joints. Prepare mortar strictly that can be consumed in an hour. Keep the gauging water at the minimum. Refer I.S.2250.
Face Shell bedding is enough: The mortar need be applied only on the face shell and not on the full shell because even with face shell bedding the factor of safety of is 4.2 which far exceeds a factor of safety of 2.8 achieved in brick masonry with full mortar bedding this will also break the continuity of passage of rain water to the inner of the block through the joints.
Avoid wastage of mortar & make at least 1cm thick joint of the mortar: By making a "Mason's Float" of the width of the cores with a 25 mm thick plank one can achieve the final thickness of joint as 1cm. & avoid falling of the mortar into the Hollows of the blocks.
Tool the joints to make them water tight: The mortar in the joint has been compacted vertically by the weight of the block by tooling with 16mm rod can compact from the side and make a concave groove making the joint water tight. The Plasticity of the sufficient thickness of the mortar are a perquisite for a water tight joint.
Concealed wiring is possible in PraYoSa's Blocks without any short of grooving or chasing or pre-planning, one can be changed at a later date also without damaging the plaster or paint.
Provide a hexagonal wire mesh or a single leg 3mm stirrups at section of walls: Provide wire mesh or stirrups at every 3rd layer of Intersecting walls and preferable fill those two core with concrete. Also for Load bearing walls provide joint reinforcement at every 3rd layer. This is just indicate the structural Engineers Design is a must for any such use.
Fixing of doors & Windows: This is possible by using special lintel blocks for receiving the hold fasts and then concreting the end cores after placing a 6mm bar.
Protection from Rain:It is recommended to do external plaster preferably with a integral water proofing compound or apply a coat of Silicone based transparent water repellent coat both for protection fro rain water. It is recommended to used inverted Lintel blocks in the closing course at the beam bottom in framed structures.