Concrete Engineering

What is Vibrator?
On construction sites, vibrators apply to compact concrete. Concrete vibrators come in many different shapes and sizes. Some Concrete Vibrators are smaller, more efficient, and run on battery power, whereas others are much larger and rely on power lines for power. In vibration, compacting is caused by a reduction in internal friction between various concrete particles due to particle oscillation, resulting in a dense and compact concrete mass. Vibrators work for concrete compaction in the roads, trains, and buildings. It compacts fresh concrete by removing trapped air and excess moisture. Its function is to hold the concrete in place in the formwork. And to ensure proper concrete consolidation and the avoidance of product flaws. Vibration frequencies range from 2800 to 15000 pm.

Read More

Introduction
Concrete floors can be extremely slippery when wet or icy, especially in the winter. Slippery concrete can be extremely hazardous, resulting in accidents and injuries. When the concrete floor surface is color hardened, sealed, or polished, this problem is more likely to occur.

The coefficient of friction measures the slickness of a surface. As a result, increasing the coefficient of friction of the surface is required to increase slip resistance. Slip-resistant concrete surfaces are created using anti-slip paints, additives, or silica sand.

Read More

Why are cement concrete pavement road joints useful?
An efficient joint system is critical to the successful operation of a cement concrete road. Tie bars and dowel bars keep the pavement strong at joints and act as load transfer devices. The first reason for jointing concrete pavements is that concrete shrinks over time. This occurs through a variety of mechanisms. Drying shrinkage occurs as a result of water being used for hydration while also being lost to the atmosphere via evaporation. The heat of hydration causes thermal shrinkage in concrete. The mixture becomes hot as cement is mixed with water. Heat is released as the concrete sets and cools and the pavement shrinks. Chemical shrinkage occurs because the cement hydration products (concrete) take up less volume than the reactants (cement and water in addition to aggregates).

Read More

What is Geopolymer concrete?
Ordinary Portland Cement (OPC), which is the main ingredient for concrete production, contributes about 10% of the global carbon dioxide (CO2) emission. Nearly 40% of the world’s construction sector contributes to global emissions. With the rising number of buildings every year, it is reckoned that only 40% of the infrastructure is built at present and the rest 60% is yet to be built which means more pollution is yet to be faced by the world. Thus, there is a requirement to shift industrial dependency from cement to some other alternatives that are environmentally friendly and effective.

On performing extensive analysis to develop alternate binders for the production of concrete that can help curb the CO2 burden on the planet, geopolymer concrete has appeared as a suitable replacement capable enough to replace the conventional concrete. While testing its properties, it has shown a reduction in CO2 emission in OPC production by 80%.
Read More

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.

Read More

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.

Read More

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.
Read More

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.

Read More

INTRODUCTION
Self compacting concrete is a type of concrete that needs no mechanical vibration or any external source for vibration for its compaction. It can be placed under its own weight and it is cohesive much to be handled without bleeding or segregation. However, the circumstances under which it is made should be free from any kind of noise or any kind of vibration that may damage or alter the property of such concrete. Such concrete is used specially in places where compacting is difficult. Hence it has been gaining traction since its discovery and is more used in important works to ensure structural performance and safety. It is widely used in various important project sites, drilled shafts, retaining systems, pipes, conduits, columns, floor finishing and many more.
Read More