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Quantity & Rate Analysis - Part 1 - Cement mortar

Will be dealing with the very basic form of rate analysis from first principles, this would be part of a series of posts, as I feel it would be better to go step by step rather than fitting in everything at once.

Part 1 - CEMENT MORTAR

Cement mortar as the name bluntly suggests is the combination of cement, sand and water in a prescribed ratio.
This mix ratio is generally determined by the usage of the mortar, that is, if it is used for block work, plastering or a simple flooring etc., the mix proportions used are various i.e, 1:1, 1:2, 1:3 so on and so forth, where the first part of the ratio indicates the quantum of sand and the second part of the ratio in indicative of the quantum of cement i.e., C:S

Let's take this in three simple steps for about 10 cum of cement mortar:

Step 1: DRY VOLUME CALCULATION
Since the mixing of materials is first dry, we need to calculate the dry volume of materials to be used, as a general assumption we consider between 30 to 40% of voids in dry state of cement and sand hence consider 40% of voids for our quantity of 10 cum of cement mortar the dry volume  will result as follows:

Dry volume of 10 cum of cement mortar =
40      
X
10
+
10
100
                                                                    = 14 cum
Step 2: VOLUME OF MATERIALS
As indicated in the details above the cement mortar is represented by a ratio which indicates cement:sand, for the purpose of this example let us consider a ratio of 1: 5.

From Step 1 we have the Dry volume = 14 cum
The total volumetric ratio of the mix = 1+5 = 6
The density of cement = 1440 kg/cum
Weight of 1 bag of cement = 50 kg

Volume of Cement            =
1     
X
14
X
1440
=
67.2
bags
6
  50

Volume of Sand            =
5      
X
14
=
2.3
cum
6
Step 3: RATE ANALYSIS
Application volume = 10 cum
Dry volume = 14 cum
Volume of Cement for 10 cum = 67.2 bags
Therefore, Volume of Cement for 1 cum = 6.72 bags
Volume of Sand for 10 cum = 2.3 cum
Therefore, Volume of Sand for 1 cum = 0.23 cum

Therefore, rate of 1 cum of 1:5 cement mortar
= 6.72 bags x "MARKET PRICE OF  A CEMENT BAG" + 0.23 cum x "MARKET PRICE OF A CUBIC METER OF SAND"

Further you may note that a wastage need not be incorporated additionally since we have considered "dry volume" for the quantity calculations.

This ends the analysis of cement mortar, more posts to follow on the analysis.

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