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CONCRETE TECHNOLOGY - SHORT NOTES 1. CONCRETE TECHN O free fall > 1.5m. W/C Ratio: Most important for strength & durability. Lower W/C — higher strength, lower workability. Range: 0.40 — 0.60 Segregation: Separation of coarse aggregate due to over-vibration or Bleeding: Water rises to surface > weak top layer & poor bonding. OLOGY | Grade M15 1:2:4 M20 127.5:3 Curing Time: Mini Self-Compacting No vibration; flows Workability (Slump Test): Low slump = dry mix; High slump = wet mix. OPC: = 10 days | Mineral admixture: = 14 days 2. WATER QUALITY FOR CONCRETE O pH Range: 6.0 — 8.5 Impurity Limits: Parameter Limit (mg/L) Organic 200 (max) Inorganic 3000 (max) Sulphates (SO,) 400 (max) Chlorides (Cl) 900 (max) for RCC 2000 (max) for PCC Sugar Contamination: Acts as severe retarder and can prevent setting. mum 7 days Concrete (SCC): under its own weight. "3. pH AND CORROSION IN RCC Fresh Concrete pH: 12.5 — 13.5 Protects steel (passivation). | | Carbonation: CO, in air reduces pH. When pH < 9 - 10 — protective layer “| dissolves — corrosion starts. Adhesive/Coating: Floor coating needs concrete pH < 10. eX / _ B," 4. AGGREGATES (FINE & COARSE) P Classification Shape Effect Silt Content Absorption Alkali-Aggregate i qg™ “Fz Reaction (AAR) Angular Rounded , 1 Fine: < 4.75 mm Better bond, Better workability, a : = pel of ic aka Coarse: > 4.75 mm a a whe lower strength Water-Cement with reactive silica ower workability ratio. — expansion > cracks. \ / A : Ay 5. ESSENTIAL SITE RULES f , Free Fall Limit Common Mix Ratio Cement Storage ji 1:2:3 Store on raised Max (Cement : Sand : Aggregate) ee te 200 mm) 1.5m | ce. seen for moderate # Protect from moisture. \ / A ~ LU * =N [ “y- Good Quality Concrete = Good Materials + Correct Proportion + Good Workmanship + Proper Curing a CALCULATION OF BRICKS IN MASONRY Y W1 Z 4'-0" X 4'-6" Z - L © Z t+ g a W2 x Z 15'-0 d y + D1 7'-0" X 3'-0" 10'-O" RRR Ww2 4'-0" X 4'-6" PLAN (Inside Size) a = + ig oO “1 Iz" | be nae 4' =” 4' =0" 3'-0" FRONT ELEVATION LINTEL DETAILS Window Lintel (2 Nos.) Door Lintel (1 No.) al Se 4'-0 | 5'-0 I 5" WALL THICKNESS = 5" mee BRICK SIZE Brick Face for 5" Wall = 10" X 3" 3" Area = 30 sq.in. ~ = 4.8 bricks oe 40" per sq.ft. STEP BY STEP CALCULATION . Total Length of Walls (Center Line) _ 5 = 2(15 + 10)+4x +3 - 20 = 50 + 13 = 50 + 1.67 = 51.67 ft . Total Wall Area = 51.67 x 10 = 516.70 sq.ft. . Deduct Door & Window Openings Door (1 No.) = 7'x 3’ = 21.00 sq.ft. Window (1 No.) = 4' x 4.5' = 18.00 sq.ft. Window (2 Nos.) = 18.00 x 2 = 36.00 sq.ft. Total Openings = 21.00 + 36.00 = 57.00 sq.ft. . Deduct Lintel Areas Door Lintel (1 No.) = 5" x 5" x 4' = 0.417 x 4 = 1.67 sq.ft. Window Lintel (2 Nos.) = 5" x 5" x 5' x 2 = 0.417 x 5x2 = 4.17 sq.ft. Total Lintel Area = 1.67 + 4.17 = 5.84 sq.ft. . Net Masonry Area = Total Wall Area — Openings — Lintel Area = 516.70 — 57.00 — 5.84 = 453.86 sq.ft. . Bricks per sq.ft. = 144 / 30 = 4.8 bricks per sq.ft. . Total Number of Bricks = Net Masonry Area x Bricks per sq.ft. = 453.86 x 4.8 = 2178.5 = 2180 Nos. TOTAL BRICKS REQUIRED = 2180 Nos. (Including 5% Wastage ~ 2290 Nos.) 
