Concrete Engineering

Introduction:
Formwork is a term that refers to temporary or permanent moulds that are used to pour concrete or other comparable materials. The shuttering moulds are supported by the falsework in concrete construction. For all types of construction projects, plastic shuttering is the most often utilised shuttering. Both large and small projects require concrete shuttering. It is suitable for a wide range of construction projects. When concrete is poured into moulds known as formworks, it retains its position. When the moulds are removed, a solid structure will be visible. Shuttering or formwork is the term for the complete process.

Both temporary and permanent moulds can be made with formwork. The concrete is kept in shape thanks to these moulds. The mould is removed once the required strength has been achieved. This mould can also be used again in the future.

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By
Kaushal Kishore
Materials Engineer, Roorkee

Self-compacting concrete (SCC) is a special type of concrete which can be placed and consolidated under it’s own weight without any vibration effort due to it’s excellent deformability, and which at the same time is cohesive enough to be handled without segregation or bleeding.

WORKABILITY:
The workability of self-compacting concrete is measured by the usual slump cone having a base diameter of 200mm, top dia 100mm, and height 300mm. The slump cone is to be placed as usual upon a base plate square in shape is having at least a 700m side. Concentric circles are marked around the center point where cone is to place. A firm circle is drawn at 500mm diameter. Read More

3D printed concrete is an emerging technology that has many advantages like reduced labour cost, less emission of carbon dioxide in the atmosphere, reduced cost, less time consuming, ease of use, ability to change properties as per desire and many more. A case study on building houses using 3D printed concrete and conventional concrete brought into light that cost is effectively reduced using 3D printed concrete which is beneficial for people having low income or for refugees who have nowhere to go and construct houses affordably. Many types of 3D printing can be observed out of which the perfect method is selected based on various criteria. Some admixtures can also be added for better strength and workability that will facilitate ease of extrusion through the nozzle. Compaction or vibration is seen absent here as the process is completely automatic. However, some labours may be needed to move the 3D printed elements from one place to another. Other properties like bond strength, compressive strength and flexural strength are also taken into account for monitoring the effects of standoff distance as well as printing speed on tensile bond strength. Apart from this, some future projects are also expected that can produce homes on other planet and can open an array of opportunities.

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Introduction
Mineral admixtures are not chemically generated and are sourced from other substances. Mineral admixtures include fly ash, blast furnace slag, and silica fume. They have numerous roles in the concrete mix and improve the concrete’s varied qualities. As we all know, we seldom build anything without using concrete additives on the construction site in order to enhance the qualities. The usage of pozzolanic or mineral admixtures can be traced back to the early days of concrete construction. Mineral admixtures change the characteristics of both fresh and cured concrete. Mineral admixtures are sometimes known as concrete additives or extra cementing materials. They have a hydraulic or pozzolanic effect on the hardened concrete’s nature. Natural pozzolans (such as the volcanic ash used in Roman concrete), fly ash, and silica fumes are examples of cementitious materials. They can be used separately or in conjunction with Portland cement or mixed cement.
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INTRODUCTION
The period developed when the mean day to day temperature falls below 4⁰ C for more than three consecutive days is called cold weather and the concreting done in that period is referred to as cold weather concreting. However, special conditions are to be maintained when finishing, placing, curing, and protecting concrete from severe weather conditions. As during winter conditions can change abruptly, better planning in execution of the work is essential.

When concrete is in plastic state and it freezes, then strength reduces by 50% which in turn affects its durability and workability. Hence, it should be protected from freezing until it attains a minimum of 3.5 MPa.

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