Basic differences among brick masonry and stone masonry

Masonry belongs to the method of setting out one masonry unit i.e. bricks and stones, concrete blocks etc. over another by applying mortar uniformly to build up a member or an component of the building.

Masonry buildings particularly made of stone masonry have strong resistance capacity against harsh weather and they are not easily injured with physical or ecological forces. Reinforced masonry also protects seismic forces and the hurricane.

Given below, some basic differences among stone and brick masonry

Stone Masonry:

• Stone is extensively utilized for both residential, public buildings as well as historical buildings because of it’s sturdiness, strength and the superior weather-resisting capacities.
• The longevity of brick masonry is less with regard to stone masonry.

Brick Masonry:

• Conversely, Brick contains much less strength, stability and weather-resisting capacities.
• The longevity of stone masonry is greater with regard to brick masonry and if the construction process is accurate it’s durability remains for 100/2000 years.

Stone Masonry:

• Owing to its extreme crushing strength, stone is mostly utilized in the erection of piers, docks, dams, and other marine structure.
• Stones come in irregular shapes and as a result the process becomes complicated to provide perfect bond in stone masonry and the strength is reduced.
• Dead load of stone masonry is higher.

Brick Masonry:

• Bricks are not recommended for the construction of above structures.
• Bricks are homogeneous and standard in shape and consequently exact bond can be provided easily and the strength remains superior.
• Dead load of brick masonry is fewer.

Stone Masonry:

• When uncovered to weather, no dampness occurs on bricks.
• Stones are applicable in sewage devoid of any protective coat.
• Stone masonry does not have good fire resisting strength with regard to brick masonry.
• Stone walls release more quantity of heat and make sitting in the room uncomfortable.
• Stone masonry is good insulation to air-transmitted noise.

Brick Masonry:

• When bricks are uncovered to weather, damp occurs on them and it results in breaking up the masonry and other components of building.
• If specific salts are found in the sewage, they react chemically with uncovered brick and when brick-work comes in contact with sewage, it should properly plastered, otherwise it becomes poor.
• Brick masonry has strong fire resistance capacity with reference to stone masonry.
• Bricks engross less quantity of heat.
• Brick masonry contains low insulation to air-transmitted noise.

Stone Masonry:

• The application of stone is confined to only hilly areas as stones can be easily accessible here.
• The masonry built up with stones requires higher cost if it is away from sources.
• Stones are bigger in size; for this reason the least thickness of a stone wall normally remains greater than 35 cm (14”).
• Thick mortar joints are provided in stone masonry and as a result lager quantity is required for mortar.

Brick Masonry:

• Bricks can be easily accessible in most of the places excluding hilly and rocky areas.
• The masonry built up with bricks requires less cost.
• Bricks walls are easily constructed in small thickness of even 13 cm, 23 cm and so on.
• Mortar joints are thin in brick masonry and for this reason less mortar is needed.

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Published By
Rajib Dey
www.constructioncost.co
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Benefits of joining & pointing in brick masonry

When bricks are not fully uniform in colour and irregular in shape, the joint finishes should be designed to provide correctness and repose to premier facades with formation of the illusion of perfectness.

JOINTING: The finished profile of the original mortar joint is produced instantly since the bricks are placed later in an individual practice called as pointing. Jointing is associated with bricklaying for finishing the joint faces of the bedding mortar as work continues.

Benefits:

• Combined joint
• Consistency of joint in strength and colour, on condition that mortar is properly measured
• Lower labour costs

Drawbacks:

• Less quality control of joint finish (not all bricklayers joint well)
• Complication in retaining consistent colour all through the wall face.

POINTING: Pointing stands for the method of repairing mortar joints among bricks or other masonry elements to resist penetration of rain water or dampness.

Benefits:

• Greater joint finish
• Consistency of colour and strength
• Better choice of joint finishes
• Clean face work

Drawbacks:

• Higher labor and material costs
• Extra construction time
• When improperly performed the compound joint can’t be joined
• Requirement for expert and experienced pointers.

Structural benefits: The bricks consume moisture from the mortar when perfectly dampened prior to laying or pointing. Together with evaporation, it leads to partial de-hydration of the joint towards the joint face. So the purpose of the jointing tool is to solidify the surface of the joints fixing shrinkage cracks and defending from the ingress of driving rain.



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Definition, causes and remedies of efflorescence in masonry & other building surfaces

Efflorescence stands for a fine, white or greyish, powdery deposit of water-soluble salts that is present on brick, concrete, stone, stucco or other building surfaces when the water vaporizes. Besides, efflorescence also exists on floors and walls and requires special attention. It is often mentioned as "whiskers”.

These efflorescent salt deposits is found at the worst times, normally about a month as soon as the building is developed, and sometimes as long as a year after finishing of structure.

Efflorescence is found in both indoors and exterior, and it can differ in frequency and intensity because of the existence of moisture and temperature.

The efflorescence happens for the following three factors :-

• Existence of water-soluble
• Salts are converted into a soluble solution because of moisture content.
• The transmission of salts through a material to its surface that leads to vaporization of the moisture and cause the salts to crystallize and thus efflorescence is formed.

Moisture is mainly formed due to water, rain and snow and may affect the extent of efflorescence. Condensation, groundwater tapering and interior activities also may influence the extent of moisture formation.

In several cases it is found that efflorescence may happen throughout home construction. If masonry units are left behind all through the night during construction, they can consume moisture from damp soil and rain. It is recommended that masonry units should be wrapped and left in pallets to reduce the risk of efflorescence during a construction project.

The following installation issues associated with building surface result in creating efflorescence

• Improper application of through-wall flashing
• Utilization of masonry devoid of adequate ventilation
• Utilization of masonry in areas where a perfect moisture barrier does not exist
• Joint material failure
• Imperfect ground storage

How to get rid of efflorescence - The following measures should be taken to avoid efflorescence:

1) Hydrophobic Sealant: Use a saturating hydrophobic sealant to a building material surface to resist the immersion of water. The sealant also will resist water from passing through a building material.

2) Capillary Breaks: Set up capillary breaks like polyethylene sheeting among a building material and soil to reduce the risk of salt penetrating the material.

3) Standard Masonry Construction: Apply overhanging copings, eaves and flashings will help in reducing the risk of entering water into a wall.

4) Better Emphasis on Landscaping and Sprinklers: Give concentration to landscaping and sprinklers will guarantee to avoid water from reaching permeable building materials.

5) Set up Grout with Mechanical Vibration: Compile grout with mechanical vibration will control the occurring of voids in the grout.

6) Apply Dense Tooled Mortar Joints: Provide dense tooled mortar joints to minimize the permeable nature of a wall, making it strong for salts to pass through it.

7) Utilizing Grout Admixtures: Various grout admixtures like chemical additives should be used since they can make flow of a grout mix better and minimize its water content all together to lessen voids in grout.

8) Preserve Masonry Materials Properly: Retain masonry materials off the ground and wrap them with water-resistance materials to safeguard these materials from groundwater and precipitation.

Article Source: www.nitterhousemasonry.com




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Published By
Rajib Dey
www.constructioncost.co
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Types and properties of bricks

Bricks is produced from well clay molding, that is dried and then burnt. The size of the brick varies from 90 mm × 90 mm × 90 mm and 190 mm × 90 mm × 40 mm. With mortar joints, the size of brick varies from 200 mm × 100 mm × 100 mm and 200 mm × 100 mm × 50 mm.

Types of Bricks: Bricks are categorized as -

(i) Building bricks, (ii) Paving bricks, (iii) Fire bricks, (iv) Special bricks.

Properties of Bricks: The standard quality bricks should contain the following properties -

(i) Colour: The color should have been identical and clear.

(ii) Shape: Shape of the bricks should have been sharp and genuine rectangular angles.

(iii) Size: There should be standard dimensions for bricks with adherence to codes.

(iv) Texture: A standard brick should contain a fine, solid and consistent texture. They should be free from fissures, cavities, loose grit and unburned lime.

(v) Virtue: If the brick is hit with another brick, there should be a metal sound.

(vi) Hardness: If scratches are made with finger on a brick, there should not be any mark on the brick.

(vii) Strength: The breaking strength of brick should not be under 3.5 N / mm2. A field test is conducted to check the strength by dropping the brick from a height of 0.9 m to 1.0 mm on a hard surface. If the brick has good strength, the stone should not be broken into pieces.

(viii) Water absorption: Once the brick is drowned in water for 24 hours, the water absorption rate should not exceed 20 percent by weight. For class I bricks, this limit remains 15 percent.

(ix) Efficiency: There should not be any white patches in bricks when they are drenched in water for 24 hours and then allowed to dry in the shade. White stains may appear because of the existence of sulfate of calcium, magnesium and potassium. They retain masonry in wet and humid conditions.

(x) Thermal conductivity: Bricks should contain low thermal conductivity, so the buildings developed with bricks should have cold temperature in summer and warm temperature in winter.

(xi) Sound insulation: Bigger bricks have poor sound insulators whereas light and hollow bricks have superior sound insulation.

(xii) (xii) Fire resistance: Normally, the fire resistance capacity of brick is good. Actually, bricks are utilized to trap steel columns to safeguard them from fire.

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Various types of masonry Mortar

Mortar is extended in among the masonry, grouts, and stuffs the cavities of the masonry units. Mortar belongs to the material that is visible among the bricks. Mortar allows the masonry units to remain jointly. Mortar is very vital in masonry construction. It is always recommended to apply the proper mortar or grout.

The process is complicated to find out the exact mixture for the mortar or grout for maintaining proper strength. The mortar or grout should contain the perfect strength to get rid of over bearing issue (load bearing in this case). Besides, the mixture that retains the masonry sections together should not be considerably stronger that what the masonry units are, because it can transform the load bearing to gain extreme amount of stress.

If the mortar’s mixture is not provided properly it can lead to weighing over the masonry units themselves and results in damaging the structure with cracking and/or spakling.

The categorization is done on the basis of ASTM C 270 (Standard Specification for Mortar for Unit Masonry). Given below, various categories of mortar.

Mortar-Type M: Mortar (Type M) contains a minimum 2500 psi and suitable for areas to withstand a considerable amount of load bearing, wind forces, earthquakes, and etc. This specific type of mortar is normally applied with stone. If the Mortar is formed with any material that contains less strength, it may collapse the structure and its job positioning prematurely.

Application - This type of mortar is normally applied with stone as it closely simulates the strength of stone, it will not collapse prior to the stone itself collapses.

Mortar (Type S): This type of mortar contains a minimum of 1800 psi. It contains medium strength, and defined as (Type S). It is mostly utilized for outside structures like a patio as well as exterior walls which are assessed below grade as it is more durable as compared to (type N). Therefore, it is best suited to perform with mildly withstanding soil pressures below grade.

Applications - Below grade having normal to moderate loading. In some areas where the masonry touches the ground, like paving or shallow retaining walls.

Mortar (Type N) for general purposes: Mortar (Type N) is mostly recognized mortar. This type of mortar is utilized when there exist no other special circumstances which need a specialty for the load bearing of a structure. It has medium strength (minimum 750 psi) and is suitable for reinforced interior and above-grade exterior load-bearing walls. It is perfect for semi-soft stone or masonry as it will bend in excess of a high-strength mortar to resist prevents cracking of the masonry units.

Mortar (Type O): Mortar (Type O) refers to a mortar that contains a low strength (a minimum of 350 psi). This type of mortar is useful for interior usages where non-load bearing exist. It is frequently applied to patch mortar where the wall has strong structure. Type O mortar is occasionally applied with masonry units having a low compressive strength (i.e. sandstone or brownstone) to allow more flexibility for resisting cracks in the units.

Applications: Interior non-load-bearing areas with very restricted exterior use because of its low structural capacity and not suitable for the areas prone to high winds. Type O Mortar mix is perfect when repointing because of its stability. It is applied in above grade, non-load bearing situations preferably in interior environments.

Mortar (Type K): The (Type K) Mortar is not listed under the ASTM C 270 anymore, although it is still applicable to projects which have a pre-historic preservation need. This type of mortar will not produce any damage to a fragile structure, nor to any fragile stones as it contains the lowest compressive strength of any mortar.

Applications : Mortar (Type K) is useful for safeguarding pre-historic structures, which needs the use of a low strength mortar to get rid of any damage. Type K is not recommended for load bearing.

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www.constructioncost.co
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