SPECIFICATIONS AND ESTIMATIONS

MATERIAL- LIME MORTAR ITEM OF WORK – EXCAVATION AND

FOUNDATION

LIME MORTAR

Lime mortar is a type of mortar composed of lime and an aggregate such as sand , mixed with water. It is one of the oldest known types of mortar.

With the introduction of ordinary portland cement (OPC) during the 19th century the use of lime mortar in new constructions gradually declined, largely due to portland's ease of use, quick setting, and high compressive strength. However the soft, porous properties of lime mortar provide certain advantages when working with softer building materials such as natural stone and terracotta. For this reason, while OPC continues to be commonly used in brick and concrete construction, in the repair and restoration  of brick and stone-built structures originally built using lime mortar, the use of OPC has largely been discredited.

Properties

• Lime mortar is not as strong in compression as OPC mortar, but both are sufficiently strong for construction of non-high-rise domestic properties.

• Lime mortar does not adhere as strongly to masonry as OPC. This is an advantage with softer types of masonry, where use of cement in many cases eventually results in cement pulling away some masonry material when it reaches the end of its life. The mortar is a sacrificial element which should be weaker than the bricks so it will crack before the bricks. It is less expensive to replace cracked mortar than cracked bricks.

• Under cracking conditions, OPC breaks, whereas lime often produces numerous microcracks if the amount of movement is small. These microcracks recrystallise through the action of 'free lime' effectively self-healing the affected area.

Properties (conti.)• Historic buildings are frequently constructed with relatively soft masonry

units (e.g. soft brick and many types of stone), and minor movement in such buildings is quite common due to the nature of the foundations. This movement breaks the weakest part of the wall, and with OPC mortar this is usually the masonry. When lime mortar is used, the lime is the weaker element, and the mortar cracks in preference to the masonry. This results in much less damage, and is relatively simple to repair.

• Lime mortar is more porous than cement mortars, and it wicks any dampness in the wall to the surface where it evaporates. Thus any salt content in the water crystallises on the lime, damaging the lime and thus saving the masonry. Cement on the other hand evaporates water less than soft brick, so damp issues are liable to cause salt formation and spalling on brick surfaces and consequent disintegration of bricks.  This damp evaporation ability is widely referred to as 'breathability'.

• Lime mortar should not be used below temperatures of 5 °C (41 °F) and takes longer to set so it should be protected from freezing for three months.

MIX A typical modern lime mortar mix would be 1 part lime putty to 3 parts washed, well graded, sharp sand. Other

materials have been used as aggregate instead of sand. The theory is that the voids of empty space between the sand particles account for a 1/3 of the volume of the sand.

The lime putty when mixed at a 1 to 3 ratio, fill these voids to create a compact mortar. Analysis of mortar samples from historic buildings typically indicates a higher ratio of around 1 part lime to 2 part aggregate/sand was commonly used. A traditional coarse plaster mix also had horse hair added for reinforcing and control of shrinkage, important when plastering to wooden laths and for base (or dubbing) coats onto uneven surfaces such as stone walls where the mortar is often applied in thicker coats to compensate for the irregular surface levels.

If shrinkage and cracking of the lime mortar does occur this can be as a result of either-The sand being poorly graded or with a particle size that is too smallThe mortar being applied too thickly (Thicker coats increase the possibility of shrinkage, cracking and slumping)Too much suction from the substrateHigh air temperatures or direct sunlight which force dry the mortarHigh water content in the lime mortar mixPoor quality or unmatured lime putty

Types of Lime Mortar

It is also called natural lime mortar and should not be confused with the popular type of mortar, Portland cement mortar.

There are two types of lime mortars: • one type hardens when exposed to air, called non-hydraulic lime mortar • the other one hardens when mixed with water, called hydraulic lime

mortar. There are also sub types under the hydraulic lime mortar category.

Non-hydraulic Lime Mortar

• Non-hydraulic lime is so named because it does not require water in order to harden. This type of lime is basically taken from calcium carbonate in its purest forms, i.e. limestone and chalk. The material is burned in a kiln and made to produce quicklime or calcium oxide. Quicklime becomes calcium hydroxide once it is mixed with water. In order to reform calcium carbonate, calcium hydroxide is made to react with carbon dioxide in the air.

• Non-hydraulic lime can be produced in two different forms, i.e. lime putty and hydrated lime. Take note that hydrated lime is different from hydraulic lime, although the words are somewhat similar. Hydrated lime can sometimes be hydraulic when it hardens after being mixed with water, and non-hydraulic when it does not harden after being mixed with water. Lime putty is also considered to be non-hydraulic and is made simply from lime and water.

• When non-hydraulic lime mortar is set in a mason unit, it takes quite a long time to harden. The setting process may take weeks or even months or years to achieve its optimum strength. The slow process is due to the fact that it requires carbon dioxide in the air to reform back to its original state. Lime putty will retain its form as long as it is kept underwater and away from the air. When it is ready for use, it can be taken out of the water and exposed to the air to harden.

Hydraulic Lime Mortars

• Hydraulic lime mortars are designed to harden when they come in contact with water. In the production of a calcium oxide, impurities in the material form aluminates and calcium silicates that cause the material to harden when mixed with water. The calcium oxide is then mixed with a sufficient amount of water in the kiln to produce calcium hydroxide, while allowing the aluminates and the calcium silicates to set. Once the calcium hydroxide is formed along with the aluminates and the calcium silicates, they are bagged to prevent moisture from seeping in and hardening the mortar. Unlike non-hydraulic lime, hydraulic lime can easily harden after it is mixed with water.

• Hydraulic lime is graded depending on the rating and strength of the material. Hydraulic limes are describes as eminently hydraulic, moderately hydraulic, and feebly hydraulic. In modern times, these grades are referred to as NHL 5 for eminently hydraulic, NHL 3.5 for moderately hydraulic, and NHL 2 for feebly hydraulic. NHL stands for Natural Hydraulic Lime.

USES

• Lime mortar today is primarily used in the conservation of buildings originally built using lime mortar, but may be used as an alternative to ordinary portland cement. Portland cement has proven to be incompatible with lime mortar because it is harder, less flexible, and impermeable. These qualities lead to premature deterioration of soft, historic bricks so the traditionally, low temperature fired, lime mortars are recommended for use with existing mortar of a similar type or reconstruction of buildings using historically correct methods.

• Lime is commonly available in the United States as Type S hydrated mason's lime (ASTM C 207). However, this lime product is intended to be added to Portland cement to improve workability and for several other reasons. Type S lime is not reliable as a sole cement because some manufacturers fire the lime above 1,100 °C which begins to cause vitrification of impurities in the lime. This over-burned lime is sometimes called dead-burned because lime fired at these temperatures loses reactivity leading to poor or no bond strength and will not hold up to freeze-thaw weather cycles.

Why Use Lime Mortar

• Buildings made using slaked lime mortars are far more capable of withstanding the vibration from traffic and the movement of the ground beneath them. Lime mortar makes the ideal plaster for timber-frame and straw bale construction. It will even cope well with the movement of green oak, which can be seen in so many early Tudor houses.• Today slaked lime mortars and mortars made with NHL (natural hydraulic

lime) are gaining ground with enlightened architects and contractors, as a better alternative to cement mortar in new builds. It is aesthetically appealing, flexible and far less prone to cracking, it also allows moisture to be released from walls via the mortar bed. Garden designers are finding it superior for hard landscaping for the same reasons• Lime has a much lower carbon footprint as opposed to cement.

SPECIFICATIONS OF EXCAVATION AND

FOUNDATION

EXCAVATION

• EXCAVATION is the preliminary activity of the construction project. It starts from the pits for the building foundations and continues up to the handing over of the project.

• For small buildings, excavation is carried out manually by means of pick axes, crow bars. spades etc. In case of large buildings and deep excavation, mechanical earth cutting equipment can be used like Hydraulic excavator, tractor / trucks.

• Deep excavation or the construction of basements includes the construction of retaining walls, excavation, the installation of struts, the construction of foundations and floor slabs,etc.

DEPTH OF EXCAVATION

• For Isolated footing the depth to be one and half times the width of the foundation.

• For adjacent footings with clear spacing less than twice the width (i.e.) one and half times the length.

• 1.5m in general and 3.5 m in black cotton soils.

• For hard soils when the depth of excavation is less than 1.5 m, the sides of the trench do not need any external support. If the soil is loose or the excavation is deeper, some sort of shoring is required to support the sides from falling. 

EXCAVATION WORKING PROCEDURE

PRIOR TO EXCAVATION PROCESS

Site clearance Before excavation, the area coming under cutting and filling shall be cleared of shrubs, vegetation, trees and saplings of girth up to 30cm measured at a height of one metre above ground level shall be removed up to a distance of 50 metres outside

the periphery of the area under clearance. The trees of girth above 30 cm shall be cut only after

permission of the Engineer-in-Charge. Existing structures and services such as old

buildings, culverts, fencing, water supply pipe lines, sewers, power cables, etc. within or

adjacent to the area if required to be diverted/removed,

In case of archaeological monuments within or adjacent to the area, the contractor shall provide

necessary fencing around such monuments as per the directions of the Engineer-in-Charge

Preservation of Property, Antiques and

Relics Excavating operation shall be conducted in such a manner that all properties, facilities,

utilities and improvements on or near the project site, which are to remain in place, are not

damaged. Any finds of archaeological

interest such as relics of antiquity, coins, fossils or

other articles of value shall be delivered to the Engineer-in-

Charge and shall be the property of the Government.

The Contractor shall layout, and construct one or more permanent bench marks in some central place before the start of the work, from

which all important levels for the excavations will be set.

Setting out

Blasting Where hard rock is met with and blasting operations are considered necessary, the contractor shall obtain the

approval of the Engineer-in-Charge

EXCAVATION METHODS

1.FULL OPEN CUT METHOD can be further classified into:• Slope open cut method• Cantilever methodSlope full open cut method : excavation site is excavated with sloped sides and does not use retaining walls or struts to obstruct excavation . In case of excavation not too deep the cost remains cheap as there is no struts, but when excavation is deep and soil is loose and firm ,a tremendous amount of excavated soil will be needed to backfill that turs whole the process costly.Cantilever method: though requiring the construction of retaining walls , does not necessitate digging the slope and backfilling ,thus cost is low compared to full open cut method.

2.BRACED EXCAVATION METHOD : Installing horizontal struts in front of retaining walls to resist the earth pressure on the backs of walls is called braced excavation method . The bracing system of the braced excavation method includes struts ,wales ,end braces ,corner braces ,and center posts. The function of wales is to transfer earth pressure on the back of retaining walls on to the horizontal struts . End or corner braces can help shorten the span of wales without increasing the number of struts.

3.ANCHORED EXCAVATION METHODS :braced method use struts to offer lateral support against earth pressure. Anchored methods substitute anchors for struts to counteract the lateral earth pressure . The construction procedure as follows:Set out

first excavation stage

Bore for anchors

Insert tendons into the bores

Inject grouts

Preload anchors and lock

them

Proceed to second stage of

excavation

Build the foundati

on of building

Excavation process EXCAVATION IN ALL KINDS OF SOILS/ORDINARY/HARD ROCK

• All excavation operations manually or by mechanical means shall include excavation and ‘getting out’ the excavated materials. In case of excavation for trenches, basements, water tanks etc. ‘getting out’ shall include throwing the excavated materials at a distance of at least one metre or half the depth of excavation, whichever is more, clear off the edge of excavation.

• During the excavation the natural drainage of the area shall be maintained.• In firm soils, the sides of the trenches shall be kept vertical upto a depth of 2 metres from the bottom. For greater depths,

the excavation profiles shall be widened by allowing steps of 50 cms on either side after every 2 metres from the bottom. Alternatively, the excavation can be done so as to give slope of 1:4 (1 horizontal : 4 vertical).

• In case of excavation for foundation in trenches or over areas, the bed of excavation shall be to the correct level or slope and consolidated by watering and ramming.

• Where hard rock is met with and blasting operations are considered necessary, the contractor shall obtain the approval of the Engineer-in-Charge. Where blasting operations are prohibited or are not practicable, excavation in hard rock shall be done by chiseling.

• In ordinary rock excavation shall be carried out by crowbars, pick axes or pneumatic drills and blasting operation shall not be generally adopted.

MEASUREMENTS

• The length and breadth of excavation or filling shall be measured with a steel tape correct to the nearest cm. The depth of cutting or height of filling shall be measured, correct to 5 mm, by recording levels before the start of the work and after the completion of the work.• In case of open footings up to the depth of 1.5 metres, around

excavation of 30 cm. beyond the outer dimension of footing shall be measured for centering and shuttering.• In case of open footings/Rafts at a depth of more than 1.5 metre,

around excavation of 75 cm shall be measured for centering and shuttering.

EARTH WORK BY MECHANICAL MEANS

Excavators • (i) Dipper–shovel• (ii) Backhoe• (Iii) Skimmer• (iv) Dragline• (v) ClamshellTractor–based Equipment• (i) Loaders• (ii) Tractor Shovel• (iii) Trench Digger• (iv) Scraper• (v) Bulldozer and Angle-dozer• (vi) Angledozer

Transporting Equipment(i) Dumpers(ii) Vibratory Roller

BACKFILLING

• The earth used for filling shall be free from all roots, grass, shrubs, rank vegetation, brushwood, tress, sapling and rubbish.

• Filling with excavated earth shall be done in regular horizontal layers each not exceeding 20 cm in depth.

• All lumps and clods exceeding 8 cm in any direction shall be broken.• Each layer shall be watered and consolidated with steel rammer or ½ tonne roller. Where

specified, every third and top must layer shall also be consolidated with power roller of minimum 8 tonnes. Wherever depth of filling exceeds 1.5 metre vibratory power roller shall be used to consolidate the filing unless otherwise directed by Engineer-in-charge.

• The top and sides of filling shall be neatly dressed. The contractor shall make good all subsidence and shrinkage in earth fillings, embankments, traverses etc. during execution and till the completion of work unless otherwise specified.

PLANKING AND STRUTTING

When the depth of trench in soft/loose soil exceeds 2 metres, stepping, sloping and/ or planking and strutting of sides shall be done.

Types: Planking and strutting shall be ‘close’ or ‘open’ depending on the nature of soil and the depth of

trench.• Close Planking and Strutting - Close planking and strutting shall be done by completely covering

the sides of the trench generally with short upright, members called ‘poling boards’. These shall be 250x38 mm in section or as directed by the Engineer-in-Charge. The boards shall generally be placed in position vertically in pairs. One boards on either side of cutting. These shall be kept apart by horizontal wallings of strong wood at a maximum spacing of 1.2 metres cross strutted with ballies.

• Open Planking and Strutting - In case of open planking and strutting, the entire surface of the side of the trench is not required to be covered. The vertical boards 250 mm wide & 38 mm thick, shall be spaced sufficiency apart to leave unsupported strips of 50 cm average width.

CLOSED PLANKING

Excavation for Concrete Culverts Neat trenches shall be excavated for placing aprons, cut off walls and lower portions of headwalls or wingwalls. Excavations that are more than 1.5 metres deep and within a cofferdam in a watercourse shall be shored, sloped and/or stepped A maximum 1:1 slope (angle not greater than 45 measured from the horizontal plane) shall be provided

Excavation for Abutments, Approach Piers and Retaining Walls Excavation shall be kept to a minimum. The limits of the excavation shall not extend more than 1.0 meter beyond the footprint of the footings

Excavation for River Piers Excavation shall be kept to the minimum. The limits of the excavation shall not extend more than 1.0 meter beyond the footprint of the footings. Excavation for river piers shall be isolated from the watercourse using sheetpiling cofferdams. Sheetpiling cofferdams shall be shored

REFERENCE-BHEL SCHEDULE OF RATES(2007)

FOUNDATIONS• Foundation is the lowest part of a structure which provides a base for the

super‐structure and transmit the loads (live load, wing load) on the structure including the dead weight of the structure itself to the soil below.

FOUNDATION

SHALLOW FOUNDATION DEEP FOUNDATION

SHALLOW FOUNDATION

• A shallow foundation is a type of foundation which transfers building loads to the earth very near the surface, rather than to a subsurface layer or a range of depths • According to Terzaghi, a foundation is shallow if its depth is equal

to or less than its width.SHALLOW FOUNDATION

SPREAD FOOTING COMBINED FOOTING

RAFT OR MAT FOOTING

RAFT OR MAT FOUDATION

Why it is used • Base soil has low bearing capacity

or• Column load are so large that more

than 50% of the area covered by conventional spread footing.

• Resist unequal settlement due to earthquake.

• Quickness of construction work.

Consist of a thick reinforced concrete slab covering the entire area of the bottom of the structure (like a floor). This type of foundation is useful for public buildings, office buildings, school buildings, residential quarters etc, where the ground conditions are very poor and bearing power of the soil is so low that individual spread footing cannot be provided

PROCESS

Method of construction of Raft Foundation:• The whole area is dug out to the specified depth and 30 cm more wide than the

area to be covered.• The bed is compacted and sprinkled over with water.• Then a layer of lime concrete or lean concrete ( 1: 8 : 16 ) is laid to a suitable

thickness to act as a bottom cover.• After this, the reinforcement is laid. The reinforcement consists of closely

spaced bars placed at right angles to one another.• Then the cement concrete (1 : 2 : 4 ) is laid and compacted to the required

thickness.• The concrete slab so laid is then properly cured• When loads are excessive, thick concrete beams running under the columns can

also be constructed.

DEEP FOUNDATION If the depth of a foundation is greater than its width, the foundation is known as deep foundation. In deep foundation the depth to width ratio is usually greater than 4 to 5. Deep foundations as compare to Shallow foundations distribute the load of the super structure vertically

rather than laterally. Deep foundations are provided when the expected loads from superstructure cannot be supported on

shallow foundations.DEEP FOUNDATION

PILE FOUNDATION PIER FOUNDATION CASSION

PILE FOUNDATION

Pile foundations are the part of a structure used to carry and transfer the load of the structure to the bearing ground located at some depth below ground surface.  A pile foundation usually consists of a base of spread footing or grillage supported by piles at their bottom. Piles distribute the load of structure to the soil in contact either by friction alone or by friction combined with bearing at their ends.

SUITABILITY :This type of foundation is suitable under the following situations ;When the soil is very soft and solid base is not available at a reasonable depth to keep the bearing power within safe limits.When the grillage and raft foundation are very expansive.When the building is very high carrying heavy concentrated loads.When it is necessary to construct a building along the sea shore or river bed.

Pile foundation

Concrete piles

Cast-in situ piles

Precast piles

Pre-stressed concrete

piles

Steel piles Timber piles Composite piles

CLASSIFICATION

PRE-CAST PILE

PROCESS• Steel form is used for the precast pile

manufacture.• Before pore the concrete in to the form,

mobile or other kind of oil have been used.

• cement, sand ,aggregate ratio is normally 1:2:4 in pre cast pile.

• But to make the foundation stronger mix ratio is used 1:1.5:3

• When the concrete pore in the steel form it would be ramming by the vibrator.

Pre means before & cast means made. So precast pile refers to a pile that has made before it is being used.

Pictures of Processing Precast pile•After 3 days, pile have been covering by the sheet.• After 3 days of casting, steel form would be removed.• Then the piles would be prepare for 4 weeks curing.•Then the piles are transported to the site for driving

CURING

REFERENCES

• IS 1200 (Pt 1) Method of measurement of earth work • IS 1200 (Pt-27) Method of measurement of earth

work (by Mechanical Appliances ) .• IS 4988 (Part IV) Excavators .• https://en.wikipedia.org/wiki/Lime_mortar.• BHEL Schedule of rates(2007).