Water proofing

civil techniques

Concrete Hacking Procedure

abbu riyaz 7 Aug, 2023

The Concrete Hacking Procedure discuss in this post. The Concrete hacking performs in a specific way in a proper procedure. Hacking executes manually with the help of hacking chisel and hammer. It executes mechanically using grinding machines with the concrete cutting blades. This performs by making a very small groves on the RCC Structures.

Concrete Hacking is a process of making smooth surface rough. It makes on the surface of concrete to provide a strong bond for the plastering. As the finishing surface of concrete is smooth, the plaster wont sticks to it. To create a strong mechanical bonding between them, this process of hacking in concrete performs.

Hacking performs mostly in Reinforced Cement Concrete structures like, the Roof Slab at the bottom of slab. This creates a strong mechanical bonding between the chemicals and the mortar in RCC members on plastering. It sticks strongly and gives a long and durable life to the concrete structures and protects them.

Concrete Hacking Procedure

Concrete hacking performs in a specific way in a proper procedure. Concrete Hacking carries out after removing the shuttering of Reinforced Cement Concrete structures. After De-shuttering the RCC members cures properly to attain its strength. And hacking executes after two to three days from the date of casting, before it attains its harder state.

The surface of concrete surface cleans for shuttering oil, excess slurry, dust, supporting wood materials and other loose particles. Hacking performs on the surface of concrete structures manually with hacking chisel and hammers only on its faces. This should not carries out on the corners as it affects the strength of the concrete structure.

This performs at a depth of two to five millimeter groves in the concrete surface. The length of hacking groves in concrete surface is twenty five millimeters. And hacking performs in a same consecutive lines in a pattern.

This pattern performs in a zigzag series opposite ways. This zigzag series of hacking is known as cross stitching method way of hacking in the concrete surfaces. After this the concrete structure cleans thoroughly and left for curing to attain its design strength. And then plastering performs above the concrete structure.

civil techniques

Concrete Hacking

abbu riyaz 1 May, 2023

Concrete Hacking is a process of making smooth surface rough. It makes on surface of concrete to provide a strong bond for plastering. As the finishing surface of concrete is smooth, plaster wont sticks to it. To create a strong mechanical bonding between them, this process of hacking in concrete performs. This makes on surfaces of beam, column and roof slabs for plastering. And helps to hold mortar with plastering in walls, tile works.

Hacking performs mostly in Reinforced Cement Concrete structures like, Roof Slab at the bottom of slab. And specially in the Walls and roof slabs of underground tanks, sumps for the purpose of water proofing and plastering. This creates a strong mechanical bonding between chemicals, mortar in RCC members on plastering. It sticks strongly and gives a long and durable life to concrete structures and protects them.

Concrete Hacking

Concrete Hacking carries out after removing the shuttering of Reinforced Cement Concrete structures. After De-shuttering the RCC members cures properly to attain its strength. And hacking executes after two to three days from the date of casting, before it attains its harder state. This helps to hold mortar with plastering in walls, tile works.

Hacking executes manually with the help of hacking chisel and hacking hammer. It executes mechanically using grinding machines with concrete cutting blades.This performs by making a very small groves on RCC Structures. The depth of the groves in concrete surface is two to five millimeters.

This carries manually and mechanically. Hacking performs on places where plastering carries out. This creates a mechanical bonding between RCC members and Cementous plastering mortar which applies directly on the surfaces.

The surface of RCC structure where the walls to constructs hacks properly before starting with brick or block work. This makes a strong connection between RCC structure and walls. And mainly in plastering of roof ceilings in super structures.

civil techniques

Causes of Cracks in concrete structures

abbu riyaz 1 May, 2023

Causes of Cracks in concrete structures

There are many Causes of Cracks in concrete structures, they are

Thermal movement
The permeability of concrete.
Corrosion of Reinforcement
Creep
Moisture Movement
Structural design and specifications
Poor Construction practices.
Improper maintenance

1.Thermal movement

All materials expand on heating and contract on cooling. The thermal movement depends on temperature variations, dimensions, a coefficient of thermal expansion and physical properties of materials. The external exposed to direct solar radiation and the roof subject to thermal variation is liable to cracking.

Remedial Measures:

Thermal joints avoid by expansion joints, control joints and slip joints.

2.The Permeability of concrete

Concrete permeability controls by factors like water-cement ratio, water hydration, curing, air voids, micro-cracks and continues exposure to thermal variations.

3.Corrosion of Reinforcement

Concrete provides protection to reinforcing steel. Steel will not corrode as concrete around it is impervious. And does not allow moisture or chlorides to penetrate within the coverage area. A properly designed and constructed concrete is initially water-tight. The reinforcement steel protects by a physical barrier of the concrete cover having low permeability and high density.

Remedial Measures:

Increase the concrete cover with proper materials like plastic, concrete, readymade cover blocks, etc., instead of using stones and wood pieces. Increased concrete cover over the reinforcing bar reduces corrosion.

use concrete with low permeability.

4.Creep

Concrete subjected to loading exhibits a slow time-dependent deformation known as creep. Creep increases with increase in water and cement content, water-cement ratio and temperature. It decreases with increase in humidity of surrounding atmosphere and age of material at the time of loading. Use of admixtures and pozzolanas in concrete increases creep. Amount of creep in steel increases with rising in temperature.

5.Moisture Movement

Shrinkage occurs in all building materials that are cement/lime based. Heavy aggregate concrete shows less shrinkage than lightweight aggregate concrete.

Materials with pores in the structure in the form of intermolecular space expand on absorbing moisture and shrink on drying. These movements are cyclic in nature and causes by increase or decrease in inter pore pressure with moisture changes.

Remedial Measures:

Shrinkage cracks in masonry minimize by avoiding the use of rich cement mortar in masonry.

Plastering of masonry after proper curing.

6.Structural design and specifications

Cracks in concrete forms due to poor structural design and specifications. At the starting of design first, consider the environmental conditions existing around the building site. It is important to determine the type of foundations, the type of concrete materials use in concrete. And the grade of concrete depending on chemicals present in groundwater and subsoil. Closely spaced of reinforcement steel bars due to inadequate detailing causes segregation.

precautions while designing

specification for concrete materials and concrete.

Proper quality and thickness of concrete cover around the reinforcement steel.

proper reinforcement layout and detailing

7.Poor Construction practices

Construction should design and supervise only by civil engineers or persons having proper knowledge and experience in construction practices. People without construction knowledge are engaging nowadays to supervise construction works and to carry out construction works.

Lack of good construction practices due to ignorance, carelessness, greed or negligence.

For a healthy building, it is necessary to ensure good quality materials selection and good construction practices.

Some of the main causes for poor construction practices

Using poor quality materials
improper selection of materials
cheap and nonstandard materials
improper concrete mix
Inadequate control on various steps of concrete products such as batching, mixing, transporting, placing, finishing and curing
Inadequate quality control and supervision causing large voids(honeycomb)
Improper construction joints between
Addition of excess water in concrete and mortar mixes.
Poor quality of plumbing and sanitation materials and practices.

8.improper Maintenance

Buildings should maintain at regular interval of time properly to avoid damages. Attend Leakages as earliest as possible before corrosion of steel inside concrete starts. The external painting of the building helps in protecting the building against moisture and other chemical attacks. Necessary water-proofing and protective coating on reinforcement steel or concrete.

civil techniques

Steel corrosion control methods

abbu riyaz 30 Apr, 2023

Steel Corrosion control methods are essential to prevent damage and the failure of structures. 40% of failure of structures are by corrosion of inner steel. Steel corrosion control methods carry mostly in the structure that locates in coastal areas. And steel structures like tower transmission lines, cell phone towers, etc.

There are many causes of corrosion. It relates to the quality of concrete and quality of construction. The first step in corrosion of steel is to provide good quality of concrete. The quality of concrete materials, mixing and compaction and workmanship help to control the steel corrosion.

Quality in construction reduces corrosion. There are various methods, they are

Steel corrosion control methods

Cement-Polymer Composite Coated Rebars (CPCC)
Fusion Bonded Epoxy Coated Rebars (FBEC)
Corrosion Resistant Steel Deformed Rebars (CRSD)

1. CPCC

It set in concrete surrounds by an alkaline medium. A cement base coating is more useful for steel corrosion control. Apply two coats of cement polymer on rebar.

Products in CPCC are:

De-rusting Solution
Alkaline Powder
Phosphating Jelly
Inhibitor Solution
Sealing Solution

2. FBEC

It produces from 100% solid finely ground fuse powder particles. At heating, it melts to form an adherent film. There is no primer film provide in FBEC rebars. It makes a medium of weakness in the path of a bond between rebar and concrete.

Epoxy coats the rebar by

Melts
Flows
Gels
Cures
Cools
Stick to coat

3. CRSD

Corrosion begins with the formation of an initial layer of rust. On common rust on normal rebars, the CRSD rust is self-renewing. The protective oxide is fine texture, tightly stick and a barrier to moisture, oxygen, carbon dioxide, Sulphur dioxide. And chloride prevents corrosion.

Use corrosion resistance bars to prevent corrosion of concrete structures, damage, and failure of structures. This increases the strength and lifespan of structures.

civil techniques

Screed in concrete construction

abbu riyaz 30 Apr, 2023

Screed in concrete construction

Screed in concrete construction is a process of cutting off the excess wet concrete. And to bring top surface slab to a proper level. And to provide a good smooth floor. A screed is a flat board uses to smoothen the concrete.

Properties and composition of the screed

A screed is a construction element constructs in a range of thickness. Its purpose is to bring the surface of the flooring to the design height. And to provide a suitable surface for installing the specific flooring.

The screed is a flat board or an aluminum tool. It uses to smoothen the concrete after it places over a surface.

A screed makes from pre-blended mortar mixes with binders. They set as guides for straight edges. And helps in bringing the surface of floor concrete to the required level.

The screed is hard in nature. This resists the stresses and the distortion causing on the spreading and leveling of the floor topping.

Specifications of an effective screed

Acts as a substrate, important for fixing the specified flooring
It is laying on schedule
shows durability under various service conditions

The service conditions specify it is external or internal for civil, commercial and industrial flooring purpose.

Composition of Screed

The major components of screed show good performance

Admixtures for mixing it with water, liquid and powdered superplasticizers, cement, and aggregates.
Special binders to mix with water and aggregates.
Mixes of aggregates in a granulometric curve to make the screeds.
Special pre-blended mortars to mix with water.

Advantages

Improve the quality of concrete
Reduce repairs
Lower costs
Improvement of health and safety
Elimination of vibrators
Reduce of noise around the site
Thinner concrete
Good durability and
Quality of concrete
Ease of placing
Reduce equipment and
Labors

civil techniques

Plastic formworks for concrete construction

abbu riyaz 30 Apr, 2023

Plastic formworks for construction is to keep fresh concrete in position to gain strength. With the help of formworks, concrete is easily made into various shapes and size. And the structure constructs.

There is different material uses to make formworks. Mainly timber and steel. Plastic gives a number of advantage compares to other materials. some are durability, cost-effectiveness, and flexibility.

The construction of formworks takes time. And it spent about 20 to 25% of the total cost of the structure. It is a major factor that affects the success of construction in terms of safety, cost, quality, and speed. Using of Plastic formworks reduces the setting time. And it is easy to fix. And remove easily after concrete gets strong. It reduces the time to fixing and removing. It requires low manpower.

Advantages of Plastic Formworks in Concrete Construction

Plastic formworks have many advantages like durability, cost, and flexibility. Formworks expend large labor force and total cost of the project. Efforts have made to introduce a formwork system which is cost-effective. And assembles, dismantle and handle easily by labor.

There are many advantages make by plastic formworks in concrete construction. some of them are as follows,

Cost-effective
Labor-friendly
Eco-friendly
Low maintenance

1. Plastic Formwork

It makes from specific high-grade plastic. Other materials do not stick to it. And no chemical reactions occur between pour material and the plastic. And there are no scratches on the surface. This is the main cause of using Plastic formwork in modern construction.

2. leakages

Leakages are the main factor to consider in the construction of structures. Leakages in formwork lead to segregation. It causes honeycomb in the concrete structures. By using Plastic formwork water and fresh concrete leakages from different parts of the form prevents. It is by the perfect fitness of parts of the Plastic formwork system.

3. labor-friendly

It is the most labor-friendly system. It fits and plugs easily and considerably lightweight compares with other types of formwork systems.

4. Nailing and oiling

Nailing and oiling plates not require. As in the other types of formwork like steel and wood, it is necessary to oil it. And it sets by nailing. The erection of formwork is by nailing. But in this type of Plastic formwork, it does not requires. Auto-leveling of plugging system make plates level automatically. And take less time to install and dismantle. This makes Plastic formwork a major material in modern construction.

5. cleaning

Cleaning of formwork is an important thing.The formworks are clean and neat it gives a long life of the material. As the formworks are in large numbers it’s difficult to clean properly. And cleaning takes more time. It requires more manpower to clean formwork. Plastic forms are clean with water easily. This makes Plastic formwork a major material in modern construction. Plastic formwork to be handled properly. It breaks by bad handling. And using low voltage hot air gun to seal it.

Formwork materials like wood, steel, produce many disadvantages. The use of wood is costly. And it creates environmental impacts of deforestation.

Other formworks cost high makes it not suitable to use. Plastic forms are recyclable. And it is eco-friendly. It reduces handling time. And provides great reusability index.