Lime Cement Aggregates Mortar

Transcription

1 Lime Cement Aggregates Mortar

2 Lime Preparation of lime mortar Cement Ingredients Manufacturing process Types and Grades Properties of cement and Cement mortar Hydration Compressive strength Tensile strength Fineness Soundness and consistency Setting time Industrial byproducts Fly ash Slag Aggregates Natural stone aggregates Crushing strength Impact strength Flakiness Index Elongation Index Abrasion Resistance Grading Sand Bulking.

3 INTRODUCTION:- Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, concrete blocks, cinder blocks, etc. Mortar is mixture of binding material, water and sand. It is similar to concrete but it do not contains coarse aggregates. Mortar becomes hard when it sets, resulting in a rigid aggregate structure.

4 Modern mortars are typically made from a mixture of Fine aggregate, Binder such as cement or lime, and Water.

5 FUNCTIONS OF MORTAR: MORTAR To bind together the bricks or stones properly so as to provide strength to the structure. To form a homogenous mass of the structure so as to resist all the loads coming over it without disintegration. To provide a weather resisting i.e., a durable layer between the different courses of masonry in the structure. To hold coarse aggregate together in any concrete so as to form a solid mass. The mortar used in a concrete is termed as matrix. To do pointing and plastering to the structure. The mortar used for plastering is known as plaster. To fill up empty joints in brick and stone masonry. The mortar used for such purposes is a thin liquid mortar which is termed as grout and the process is known as grouting.

6 Cement,lime,clay Binding materials imparts strength. Sand increases crushing strength of mortar & reduces shrinkage Surkhi economy; for furnishing hydraulic properties to mortar Flyash & cinders used in lime mortar. Water lubricated the surfaces of aggregate; spreads the binding material uniformly so that it can fill the pores in the fine aggregate and cause hydration of cement and hydraulic lime. (ph should not be less than 6).

7 Mobility To indicate the consistency of mortar mix which may range from stiff to liquid. Depends on the composition of mortar Mortar mixes used for masonry work, finishing work, are made sufficiently mobile. Placeability Ease with which mortar mix can be placed with min cost in a thin and uniform layer over the surface depends on the mobility of the mortar. It should be such that a strong bond is developed with the surface of the bed.

8 Water retention A good mortar mix posses the ability of retaining adequate humidity during transportation and laying over the porous bed. If water retention power of mortar mix is low, it separates into layers during transportation and when comes into contact with porous bed such as bricks, wood., it gives away its water to that surface. Thus, the mortar becomes poor in amount of water and the remaining water proves to be insufficient for its hardening. Hence required strength of the mortar will not be achieved with such mortar mix.

9 It should be capable of developing good adhesion with the building units such as bricks, stones, etc., It should be capable of developing the designed stresses It should be capable of resisting penetration of rain water It should be cheap It should be durable It should be easily workable It should not effect the durability of materials with which it comes into contact It should set quickly so that speed in construction may be achieved. The joints formed by mortar should not develop cracks and they should be able to maintain their appearance for a sufficiently long period.

10 Classification of mortar based on Bulk density Kind of binding material Nature of application Special mortars Heavy mortar Lime mortar Brick laying mortars Fire-resistant mortars Light weight mortars Surkhi mortar Finishing mortars Lightweight mortars Cement mortar Packing mortars Gauged mortar Sound-absorbing mortars Gypsum mortar X-Ray shielding mortar

11 Mortar as Binding Material Plastering Pointing Masonry joint Cement Slurry

12 Brick Laying Mortar Finishing works

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14 The progression of stiffening, defined in the European Standard as workable life, refers to the gradual change from fresh or plastic mortar to setting or set mortar. Hardening refers to the subsequent process whereby the set mortar progressively develops strength.

15 Durability of mortar may be defined as its ability to endure aggressive conditions during its design life. A number of potentially destructive influences may interact with the mortar. These includes water, frost, soluble salts and temperature change. In general, as the cement content increases so will durability. Air entrainment of mortars improves resistance to freeze-thaw damage.

16 The use of too much of cement will produce a more rigid mortar which may result in vertical cracking passing through units and mortar joints as stresses are imposed. Use of appropriate mortar should not result in cracking, but any that does occur, (Eg. Due to movement), they will tend to follow the joints, which will be much easier to repair.

17 MIXING THE MORTAR: The sand and the cement have to be by hand or thoroughly mixed in a mechanical mixer before adding any water Do not use dirty water, or water from puddles or ponds, as this could impair the final strength of the mortar. Similarly, keep any sugar- containing liquids, such as soft drinks, well away from the mix - sugar, even in small amounts, seriously impairs the setting ability of the cement.

18 LIME MORTAR: Lime mortar is a type of mortar composed of lime and an aggregate such as sand, mixed with water. Lime mortar is primarily used in the conservation of buildings originally built using lime mortar, but may be used as an alternative to ordinary portland cement. Slaking of Lime When water is added to quick lime in sufficient quantity, lime cracks, swells and falls into powder form due to the chemical reaction thus forming calcium hydrate Ca(OH) 2.

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20 Quick Lime: Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature usually obtained from limestone. A lime kiln is used to produce quicklime through the calcination of limestone (calcium carbonate). CaCO 3 + heat CaO + CO 2 Hydrated lime: It is created by adding water to quicklime in order to turn oxides into hydroxides. Combined with water and sand or cement, hydrated lime is most often used to make mortars and plasters. Its chemical name is calcium hydroxide, or Ca(OH) 2. This is sold in most builders merchants as bags of dry powder. After Soaked in just enough clean water, for at least twenty-four hours, it makes a lime putty. This putty may be of a poor quality due to carbonation of the powder occurring in the bag before use.

21 Hydraulic lime: A specialized form of limestone is used to make hydraulic lime. The limestone is mixed with clay then fired in a kiln to high temperatures. This process removes much of the moisture from the lime and also produces mineral byproducts known as silicates. The remaining limestone and silicates are combined to form hydraulic lime. Hydraulic lime offers a number of benefits over traditional lime mortar blends. The most important is its ability to cure and harden when wet, which means it can be used in many applications where other mortar products would fail.

22 Lime mortar is made by mixing lime, sand and water. Lime used for mortar may be fat lime (quick or hydrated lime) or hydraulic lime. Fat lime has high calcium oxide content. Its hardening depends on loss of water and absorption of carbon dioxide from the atmosphere and possible recrystallization in due course. Hydraulic lime contains silica, alumina and iron oxide in small quantities. When mixed with water it forms putty or mortar having the property of setting and hardening under water. Slaked fat lime is used to prepare mortar for plastering, while hydraulic lime is used for masonry construction and are most suitable for construction of chimneys and lightly loaded superstructure of buildings.

23 Sand in lime mortar is an adulterant, and reduces its shrinkage. Lime mortar becomes porous allowing air to penetrate and helps the mortar in hardening. Lime mortar is not suitable for water-logged areas and damp situations. Lime mortars have plasticity and placability, good cohesion with other surfacing and little shrinkage. They harden and develop strength very slowly continuously gaining strength over long period. Fat lime mortars do not set but stiffen only as water is lost by absorption (by masonry units) and evaporation. The gain in strength is a very slow reaction of lime with carbon dioxide absorbed from air.

24 Manual Mixing Lime and sand in required quantities are placed on an impervious floor or in a tank. The constituents are thoroughly mixed dry by turning them up and down with spades. Water is added and mixing is done again with spades till mortar of uniform colour and consistency is obtained.

25 Mill Mixing Mills used for preparing lime mortars in undeveloped countries may be a chakki or ghanni run by bullocks while a pan mill is used in developed countries. In the case of ghanni the required quantity of ingredients in the form of putty is put in the trench and grinding for 100 to 200 revolutions is carried out by moving stone roller. The operation takes about 2 to 3 hours for each batch of mix; the time required in a Pan mill is much less.

26 Bullock driven mortar mill(ghanni) Power driven mortar mill Precautions: Lime mortar or putty should be kept moist till use and in no case its drying is allowed. The mortar made of hydraulic lime should be consumed within one day and that with fat lime within 2-3 days.

27 Ht: 40 cm 6 9 m Dia Width: 30 cm BULLOCK DRIVEN GRINDING MILL

28 Pivot Roller Roller Revolving Pan CM Dia Power POWER DRIVEN GRINDING MILL