It is necessary to protect masonry during construction when the mortar is green or when the masonry is not supported afterwards, against damage due to rain, frost, storms, etc. It is also necessary to protect some vulnerable parts of masonry such as jambs, corners and exposed masonry and masonry during construction from damages caused by construction activities.
1. rain protection
Heavy rain falling on freshly laid masonry can leach cement and lime from the mortar used to lay the masonry if the mortar is not sufficiently set. In the first instance, masonry work should be stopped when heavy rain is expected. When some masonry work has been laid anew and rain is imminent, the masonry should be covered with tarpaulin or water-proof canvas and, if these are not readily available, with old gunny bags. These are only the top few courses that need protection. This protection is required more in the case of slow setting lime or cement-lime mortars and less in the case of rapid setting cement mortars.
2. protection against frost
As a general rule, when the ambient temperature is 5 . Masonry work should not be carried out in exposed condition if less than0c, unless special means are adopted for the protection of masonry, material heating and completed work. When frost is likely to occur at night, the first thing to do is to use a mortar which is quick to set, i.e., a mortar of appropriate proportion of Portland cement for masonry. Where deemed necessary, accelerators may be used in cement mortar so that the mortar sets quickly and develops sufficient strength before frosting occurs. As a further precaution, the day’s work should be protected by covering freshly laid masonry with a tarpaulin, canvas or sack. The use of air-permeable admixtures in cement mortar results in increased resistance to repeated cycles of solidification and thawing.
3. storm protection
A masonry wall is able to resist lateral forces due to air pressure when cross walls have been constructed or an RCC floor/ceiling bearing is placed on the wall. Therefore, a high wall can overturn due to wind pressure, if a storm strikes, the wall is tied with cross walls or floor/ceiling slabs. Therefore, it is necessary to protect an unwired wall during construction if there is a possibility of storm surge with the help of sufficient number of bully stays on both sides of the wall.
4. exposed masonry care
In case of masonry, which is not to be plastered and which is to be exposed, care should be taken to remove the mortar drops and surface defects immediately after laying the masonry, i.e. before the mortar sets . It is very difficult and laborious to clean the exposed masonry surface once the mortar droppings have set and the surface is eroded.
5. Protection against damage caused by normal construction activities
Care should be taken that the corners/edges and doorways of openings are not damaged due to material fall, movement of labour, fixing and removal of scaffolding, centering and shuttering etc. In order to prevent this type of damage, it is necessary to issue suitable instructions to the workers and inform them about the need to take proper care.