ENGINEERING TACTICS

How to calculate quantity of Cement and Sand in Plaster? Ex:    Area of plaster = 100 ft × 100 ft    Thickness of plaster = 12mm Step 1) find out volume of plaster:  (Need to all units that is "ft" and "mm" convert into "m" )                   1000mm = 1m So that;        12mm = 0.012m                      3.28ft = 1m So that;        100ft = 30.49m     Volume of plaster = 30.49 × 30.49 × 0.012                                      = 11.15 m³ Step 2) Convert plaster volume wet to dry:              Take 33%     Dry vol = 11.15 × 1.33                   = 14.83 m³ Step 3) Consider wastage:               Take 5%      Total dry vol = 14.83 × 1.05                             = 15.57 m³ Step 4) find out Cement and sand required:               Take;                    Cement : sand                               1 : 6     Cement req = 1/(1+6) × 15.57                           = 2.22 m³             Need to cement in bags  

Derivation of steel weight calculation D²/162 Derivation :     W = c/s area × density of steel × length of steel         = (π/4 × D²) × 7850 ×1         = (3.14 × D²/4) × 7850         = 6162.25 D²         =D²/ 1.6227 × 10-⁴ [ 1m = 1000 mm ]           = D²/ 1.6227 × 10-⁴ × 1000²         = D²/ 162.27     W = D² / 162 https://youtu.be/v3_qNReDvRs

How to calculate target strength of concrete?             TARGET STRENGTH OF CONCRETE Formula;      f'ck = fck + 1.65s  Where;        S = standard deviation Grade of concrete             assumed 'S' N/mm²    M10 to M15                                     3.5    M20 to M25                                     4.0    M30 to M55                                     5.0 From  IS 10262:2009 Ex:      Concrete grade = M25 - fck                           fck = 25 N/mm² at 28 days     That's why,  fck = 17 N/mm² at 7 days    (M25 gain strength 17 N/mm² at 7 days) Solution: 1   Target strength of concrete at 7 days f'ck = fck + 1.65s         = 17 + (1.65×4)         = 23.6 N/mm² Solution: 2    Target strength of concrete at 28 days f'ck = fck + 1.65s         = 25 + (1.65×4)         = 31.6 N/mm² For Proper understanding watch this video https://youtu.be/NyFxv0jU-Ac

There are some Densities of building construction materials are as follows;       DENSITY OF BUILDING CONSTRUCTION                                       MATERIALS ● Cement - 1440 kg/m³ ● Steel - 7850 kg/m³ ● Plain cement concrete - 2400 kg/m³ ● Reinforced cement concrete - 2500 kg/m³ ● Sand - 1600 to 1850 kg/m³ ● Coarse aggregate - 1600 to 1890 kg/m³ ● Cement mortar - 2162 kg/m³ ● Water - 1000 kg/m³ ● Common red brick - 1600 to 1920 kg/m³ ● Concrete block ;    1) Dense concrete block - 1800 to 2100 kg/m³     2) Medium dense block - 650 to 1500 kg/m³    3) Aircrete block - 400 to 900 kg/m³ https://youtu.be/5mp2HTCrdLc

There are some important things site Engineers must know about reinforcement and Steel Bars are as follows;         THINGS SITE ENGINEERS MUST KNOW            ABOUT REINFORCEMENT AND STEEL BARS ● Hooks for stirrups is 9D for one side. ● No.of stirrups = (clear span/spacing ) + 1 ● For cantilever Anchorage length for main steel is 69D. ● 'L' for column main bar in footing is minimum length 300mm. ● For chairs in footing minimum 12mm dia with 1m spacing should be used. ● Lapping of steel bar should not be used for larger than 36mm. ● In steel Reinforcement binding wire required 8kg per MT. ● Weight of rod per meter = D^2/162, (D=dia of bar). ● Main bar in the slab shall not be less than 8mm (HYSD) or 10mm (plain bar). ● Distribution bar in the slab shall not be less than 8mm and not more than 1/8 of the slab thicknes. ● All reinforcement shall be free from loose rust, oil or any other substances.

There are some clear cover to main reinforcement of different structural members are as follow;      CLEAR COVER TO MAIN REINFORCEMENT As pr Indian guidelines only:       There are some clear cover of structural members ; ● Footings - all sides 50mm & bottom 75mm ● Raft foundation - all sides 75mm & top 50 mm ● Staircase - 15mm ● Slab - 15mm or not less than dia of bar ● Flat slab - 20mm ● Retaining wall on earth - 20mm to 25mm ● Beam - 25mm to 40mm ● Column - 40mm (d>12mm), 25mm (d=12) ● Shear wall - 25mm ● Sunshade (chajja) - 25mm ● Water retaining structure - 20mm to 30mm

Types of Concrete:     There are three types of Concrete according to its characteristics strength.                           TYPES OF CONCRETE           1) Ordinary concrete     2) Standard concrete     3) High strength concrete ●These concrete types categories according to       its Grades ;       1) Ordinary concrete - M10 to M20       2) Standard concrete - M25 to M55       3) High strength concrete - M60 to M80 Where;       M stands for mix, and numbers stands for characteristics of strength at 28 days.

Her you can see the Responsibilities of site engineers point wise.This is very important to every civil site engineers.      RESPONSIBILITIES OF SITE ENGINEERS ●Checking plans, drawings, quality of materials with accuracy. ● Site engineer act as a technical advisor on a construction site. ● Proper survey the site and set out the levels with architect engineer. ● Proper co-ordination with consultant, contractor, planners, supervisor, quantity surveyor involved in the project. ●Communicate with clients, architect, RCC consultant regular meeting to keep them informed of progress of the work. ● Ensure that all materials used with proper specification. ● Manage the work of the site and run with planning. ● Maintain quality control and safety matters. ● Resolve any unexpected Technical difficulties on the site. ● Prepare daily progress report. https://youtu.be/x9mIMb4GZRI