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Difference between nominal mix and design mix of concrete - Concrete is most extensively used mix to achieve desired properties of structure. There are two methods to prepare the concrete mix. 1-Nominal mix 2- Design mix Nominal mix - Nominal mix specifies the fix proportion of the cement , sand and aggregates. Ingredients of concrete are mixed on the basis of volume. It is a site level mixing of ingredients to prepare concrete mix. Such type of concrete mix is generally used in small quantity or where load is not high. There are many grade of nominal mix concrete like M-5, M-7.5, M-10, M-15 and M-20. In above grades of concrete mix  the letter 'M' refers to Mix where as the value like 5,7.5,10,15 etc indicates the compressive characteristic strength of concrete after 28 days in specified conditios. Unit of this compressive characteristic strength of concrete is  Newton /mm 2. The ratio of various grade of concrete is being given below - M-5 

First of all i want to tell you that DBM act as bituminous base course while BC acts as wearing course. LAYING OF DBM(Dense Bituminous macadam) /BC(Bituminous concrete)  Laying of DBM/BC is done with the help of paver. There are following points which clearly indicates detailed process of laying. To know more about the bituminous concrete (BC) ,please click on below link......... bituminous-concrete (BC) specifications 1-Weather and seasonal limitations- Laying shall be suspended: A- In presence of standing water on the surface B-When rain is imminent, and during rain, fog, or dust storm C-When the base/binder course is damp D-When the air temperature on the surface on which it is to be laid is less than 10°C for mixes with conventional bitumen and is less than 15°C for mixes with modified bitumen E- When the wind speed at any temperature exceed the 40 km per hour at 2 m height. 2-Cleaning of surface- The surface on which the bituminous work is to be

Detailed information about the application of tack coat - Tack coat Scope: The work shall be consist of the application of a single coat of low viscosity liquid bituminous material to existing bituminous, cement concrete or primed granular surface preparatory to the superimposition of a bituminous mix, when specified in the contract. Material: The binder used for tack coat shall be either cationic bitumen emulsion (RS 1) complying with IS:8887 or suitable low viscosity paving bitumen of  VG 10 grade conforming to IS:73. The use of cutback bitumen RC:70 as  per IS:217 shall be registered only for sites at sub-zero temperatures or for emergency applications as directed by the engineer. To know more about Dense Bituminous macadam, kindly click on below link  Dense bituminous-macadam-technical specifications as per MORTH and indian standard Weather and seasonal limitations: Bituminous material shall not be applied during a dust storm or when the weather is fog

Prime coat over a granular base- Scope: This work shall consist of the application of a single coat of low viscosity liquid bituminous material to a porous granular surface preparatory to the superimposition of bituminous treatment or mix. Purpose of prime coat over Base course 1- To bond loose material of base course 2- To provide good adhesion between  bituminous layer and granular layer 3- To plug the capillary tubes Material: The primer shall be cationic bitumen emulsion SS 1(slow settling-1)  grade conforming to IS: 8887 or medium curing cutback bitumen conforming to IS: 217 or as specified in the contract.  Quantity of SS1 grade bitumen Emulsion for various types of Granular surface.                               Cutback for primer shall not be prepared at the site. Type and quantity of the cutback bitumen for various types of granular surface shall be given in table. The correct quantity of primer shall be decided by the Engineer and shall be such that