All post Here - script by vk

[abstract]vk [accelerators]vk [admixtrure]vk [Aggregate]vk [agrregate test]vk [aquifer]vk [Batten]vk [beam]vk [Bitumen]vk [Bolt]vk [Booster]vk [Boussinesq theory]vk [Brick]vk [Bricks]vk [Bricks Study]vk [Building Materials]vk [canal]vk [cast]vk [cement]vk [CIVIL ENGINEERING]vk
[abstract]vk [accelerators]vk [admixtrure]vk [Aggregate]vk [agrregate test]vk [aquifer]vk [Batten]vk [beam]vk [Bitumen]vk [Bolt]vk [Booster]vk [Boussinesq theory]vk [Brick]vk [Bricks]vk [Bricks Study]vk [Building Materials]vk [canal]vk [cast]vk [cement]vk [CIVIL ENGINEERING]vk [Civil engineering amazing]vk [Civil engineering amazing projects]vk [class]vk [coat]vk [concrete]vk [Concrete Technology]vk [construction management]vk [Contra-flexure]vk [Cost]vk [Coulombs Theory]vk [Critical Flow]vk [Cseb]vk [csphcl exam previous year papers and admit cards]vk [docks and harbour]vk [elastic]vk [Electrical and Electronics]vk [electronics]vk [Engineer's-Knowledge]vk [ENVIRONMENTAL ENGINEERING]vk [Ese Civil 2023 questions]vk [estimate]vk [Ethics and Moral]vk [Facts-About-Engineering]vk [ferro cement]vk [first]vk [FlOW-NET]vk [FLUID MECHANICS]vk [FOUNDATION]vk [Frog]vk [Geo-technical-engineering]vk [Glass]vk [good]vk [HEART]vk [high]vk [High density concrete]vk [HIGHWAY ENGINEERING]vk [hydration]vk [Hydraulic jump]vk [important notes]vk [Instruments and Tools]vk [Iron]vk [Irrigation]vk [isochrones]vk [Job Updates & Opportunities]vk [lime]vk [Local shear failure]vk [low]vk [management]vk [mason]vk [Masonry]vk [maturity of concrete]vk [MCQ]vk [medium]vk [Mild steel]vk [mortar]vk [Optimum Compaction]vk [paint]vk [pig]vk [Plastering]vk [plastic]vk [Plasticizers]vk [prime]vk [problem]vk [Project Management]vk [properties]vk [Question-Answer]vk [quick lime]vk [Quick Revision]vk [Quick-Revision]vk [Rankine Theory]vk [RCC]vk [Recommended]vk [Reinforced Concrete Construction]vk [resection]vk [retarder]vk [RING]vk [rock]vk [scope]vk [seasoning]vk [second]vk [Self compacted]vk [sensitivity]vk [SHAKES]vk [Shear center]vk [shear strenght]vk [slope deflection method]vk [Soil exploration and Boring]vk [SOIL MECHANICS]vk [Soil Structure and Clay Mineralogy]vk [SOM]vk [Stability of Slope]vk [STAR]vk [steel]vk [Steel Engineering]vk [stiffeners]vk [stone]vk [Strength of Material]vk [Structural Steel Design]vk [structure analysis]vk [Subjects]vk [surveying]vk [syphon]vk [tack]vk [temperature]vk [templates]vk [Terzaghi Theory]vk [Test]vk [Tests]vk [third]vk [TILES]vk [timber]vk [tpes]vk [TRANSPORTATION ENGINEERING]vk [Tunnel]vk [Types of flow]vk [valuation]vk [value]vk [vee bee]vk [Wall]vk [wastage]vk [Water Supply]vk [Weld]vk [westergaard theory]vk [workability]vk

Table of Contents

  Admixtures

  

  Functions  

  

  Typical compounds

Application

    Disadvantages

Accelerating admixtures

or accelerators

More rapid gain of strength or higher early strength.

More rapid setting.

Calcium chloride Calcium formate Triethanolamine 

(TEA)

Soluble inorganic salts

Sodium nitrite

Sodium sulphate

Sodium aluminate

Sodium silicate

1. Normal rate of strength development at low temperature.

2. To counter retarding effects

3. Shorter stripping times.

4. Plugging of pressure leaks.

5. Sprayed concreting.

1. Possible cracking due to heat evolution.

2. Possibility of corrosion of embedded effects reinforcement.

Retarding admixtures or retarders

Delayed setting

Soluble carbohydrate

derivatives:

starch

Hydroxylated carboxylic acids,

Inorganic retarders

Sugars

1. Maintain workability at high temperatures.

2. Reduce rate of heat evolution.

3. Extend placing times, e.g., ready-mixed concrete.

4. Prevent cold joint formation.

May promote bleeding.

Water-reducing accelerators

Increased workability with faster gain of strength.

Mixtures of calcium chloride and lignosulfonate.

Water reducer with faster strength development.

Risk of corrosion.

Water-reducing retarders

Increased workability and delayed setting

Mixtures of sugars or hydroxylated carboxylic acids and lignosulfonate.

Water reducer, with slower loss of workability.

Air-entraining agents

Entrainment of air into concrete.

Aluminum powders,
Natural wood resins, fats, lignosulfonates, alkyl sulfates, sodium salts of petroleum, sulfonic acids.

Enhanced durability to frost without increasing cement content, improvement in workability, lowered permeability and cellular concrete.

Careful control of air content, water-cement ratio, temperature, type and grading of aggregate and mixing time is necessary.

Damp-proofing or water-proofing agents

1. Water-repellent, i.e. prevention of water from entering cap

2. Reduced water permeability of concrete.

Potash soaps, calcium-stearate, aluminium-stearate, butylstearate, petroleum

1. Reduced permeability.

2. Enhanced durability.

3. Increased freeze-thaw resistance.

4. Reduced drying shrinkage.

5. Reduced surface staining.

6. Water tightness of structures without using every low water-cement ratio.

1. Not efficient under high hydrostatic pressure.

2. Requires low water-cement ratio and full compaction.

Plasticizers (water reducers)-8 to 15 percent water reduction

Higher flowability

Hydroxylated carboxylic acid derivatives Calcium and sodium lignosulfonates.

1. Higher workability with strength unchanged.

2. Higher strength with workability unchanged.

3. Less cement for same strength and workability.

Certain special types of cements like sulphate resistant cement (low C3A content) and expansive cement do not perform well.

Superplasticizers (Super-water reducers) – 15 to 30 per cent water reduction

Greatly enhanced workability.

Sulfonated Melamine formaldehyde resin, sulfonated naphthalene-formaldehyde resin, Mixtures of saccharates and acid amides.

1. Water reducer, but over a wider range.

2. Facilitate production of flowing or self-leveling concrete

1. Tendency to segregate.

2. Flowability is not long lasting.

3. During hot weather the workability retention period decreases fast.


[Job Updates & Opportunities]vk