Purpose of Admixtures

Dear Readers,

In continuation with Admixtures article, let us understand the functions

Functions of Admixtures

Concrete admixtures have various functions and they are as follows:

(a) To  increase  the rate  of strength development at early ages – calcium chloride is the most widely  used accelerator,                              

(b) To retard the initial setting time while pumping concrete over a long distance,

(c) To  increase the workability without changing the water content – pozzolana such as fly ash is used,

(d) To increase the strength,

(e) To  increase  the  resistance  to  freezing  and  thawing  – vinyl  resin  is  an  air entrainment admixture which is used for this purpose,

(f) To decrease heat evolution,

(g) To increase water tightness,

(h) To decrease capillary flow of water, and

(i) To decrease rate of bleeding and segregation. 

Chemical admixtures are various types and they are:

(a) Accelerating admixture – A substance that increases the rate of hydration of hydraulic cement, reduces the setting time, or in other words, increases the rate of strength development.

(b) Retarding admixture – A substance which delays the setting time of cement paste.

(c)   Water – reducing admixture – A substance which either increases the workability of freshly mixed mortar or concrete without increasing water-cement ratio or maintains workability with reduced water-cement ratio.

(d) Air – entraining admixture – A substance that causes air to entrap/Cd in the form of tiny bubbles in mortar or concrete during mixing to increase its workability and resistance to freezing and thawing.

(e)  Super plasticizing admixture   – A   substance that has very high workability with a large decrease in water content (at least) for a given workability. High range water reducing admixture (HRWRA) is also referred to as a superplasticizer.

To Know more about concrete admixtures click Here

Difference Between Sheet and Plate

Dear Readers,

We often used both Sheets and Plates in construction Industry. Let us see the difference between sheet and plate.

Sheet metal and plate metal are different forms of steel. The most notable difference between plate and sheet metal is the thickness of the products. Plate metal is thicker when compared to sheet metal.

Sheet metal is produced on an industrial scale by applying rolling, processing and drying techniques. Eventually it is the process of rolling that will decide whether a particular metal will be classified as sheet or plate. Rolling metal adds pressure which determines the overall thickness of the metal. If the metal is rolled thin then it is considered to be sheet and if it is thick then the metal can be classified as plate.

Sheet metal is made from steel and it is a metal that has thickness less than 6mm.

The only difference between sheet and plate steel is the gauge (thickness) of the metal. They both have very different uses, depending on the varying durability and weight requirements for different projects.

Types of Cement

Dear Readers,

As you are well aware that without Cement modern infrastructure is not possible or even unimaginable now. Cement is a critical component in the construction of buildings, roads and other brick-and-motor creations and it plays vital role in construction Industry. Cement is a grey colored powder that resembles ash in texture. It is a binding substance that is used to harden and set two materials, typical bricks or rocks together. Before using it, cement is mixed with water and other materials in varying ratios and placed between two substances as “glue”. 

It’s time to learn about the many types of cement available in the market to cater to different construction purposes. Cements are broadly classified into two categories – Hydraulic and Non-Hydraulic, depending on how they react to the presence of water.

Hydraulic Cement: This cement gets hardened in a very short span and are widely used in construction industry for saving time and effort.

Non-Hydraulic Cement: They have a very long setting period and can only work in dry conditions. Non-hydraulic is not practical for commercial constructions, as they cannot be used in sites that are open to weather challenges.

Selection of cement based on suitability for different concrete construction is important for durability considerations of structures. Thus, making wise choice of cement type for specific construction site that prevents structure from deteriorating and saves much repair and rehabilitation cost later. 

A wide variety of cement types are available in market, which are suitable for use under certain conditions due to its unique properties. They are as follows.

    1. Ordinary Portland cement (OPC)

    2. Portland pozzolana cement (PPC)

    3. Rapid hardening Portland cement (RHPC)

    4. Low Heat Portland Cement (LHPC)

    5. Portland Slag Cement (PSC)

    6. Sulphate-resisting Portland Cement (SRPC)

    7. Hydrophobic Portland Cement (HPC)

Other Types of cements are based on its either unique property or its application.

    1. High Alumina Cement

    2. Quick-setting Cement

    3. White Cement

    4. Coloured Cement

    5. Air Entraining Cement

    6. Expansive Cement

    7. Extra rapid hardening cement

    8. Super sulphated cement

    9. Oil-well Cement

    10. Ultra-high strength concrete (UHSC)

Ultra-high strength concrete (UHSC) is the latest spectacular development in the domain of Portland cement-based materials.

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