Sunday, September 12, 2021

Different Types of Concrete




The types of concrete mentioned here are from 7.5 MPa to around 400 MPa. Very specialised plants with management controls are required for handling all such type of concrete. Most the plants may not be able to fulfil the requirements. However, UHPC is available as ready to mix  packs and can be purchased, transported, and used.


Topics Covered


General

Types of Concrete - Nominal Mix Concrete

Types of Concrete -Design  Mix Concrete

Data Required for Design Mix Concrete

Brief description for types of concrete

Summary of Different types of Concrete

Project Concrete Requirements Management

  

General

The types of concrete mentioned here are from 7.5 MPa to around 400 MPa. Very specialised plants with management controls are required for handling all such type of concrete. Most the plants may not be able to fulfil the requirements. However, UHPC is available as ready to mix  packs and can be purchased, transported, and used.


Concrete is a mixture of FA, CA, Cement & SCM and Water with or without chemical admixtures, prepared in proportions as per design requirements.


 

FA - Fine Aggregates

CA – Coarse Aggregates

SCM – Supplementary Cementitious Materials

UHPC – Ultra High-Performance Concrete

NMC – Normal Mix Concrete

 

Types of Concrete  - Nominal Mix Concrete

Indian Standard, IS 456 – Plain and Reinforced Code of Practice, suggests using Nominal Mix Concrete up to M20 (20 MPa) and Design Mix Concrete above M20


NMC is  not designed, and it may use excess quantity of cement and must be use for small quantiles of works  as per direction and approval of Engineer in Charge.

However, if the quality of NMC is in mass, it is advisable to use the design mix concrete.

 

Proportioning of Nominal Mix Concrete

(For small and scattered job and as per approval of engineer in Charge)

 

 



Types of Concrete - Design  Mix Concrete

Designed Mix — Mix for which the purchaser is responsible for specifying the required performance and the producer is responsible for selecting the mix proportions to produce the required performance.

 

Grades of Concrete as per IS: 456, for Ordinary, Normal and High Strength Concrete. 


Data Required for Design Mix Concrete:

  

Attributes

Requirements

Type of Concrete

Such as Ordinary, High strength, High performance, Mass, Self- compacted concrete etcetera.

Grade designation

M 60: or 60 MPa

Type of cement; and grade of cement

OPC or PPC; 43 or 53 or other

Maximum nominal size of aggregate

A40 or A 20

Maximum water-cement / cementitious materials ratio to be adopted

As per Code

Minimum cement / cementitious materials content

Do -

Exposure conditions

Mild, Moderate, Severe, Very Severe, Extreme

Workability required at the time of placement

Very low, Low, Medium, High, Very High

Transportation time

As per site requirement

Means of Transport

Dumpers, TM, other

Concrete placement environment

Over the ground or under the ground etcetera

Method of placing

Bucket, pumping etcetera

Degree of site control

Good / fair or value of established standard deviation if any

Type of coarse aggregate

Angular / sub angular/

gravel with some crushed particles/ rounded gravel / manufactured

Type of fine aggregate

natural sand/ crushed stone or gravel sand / manufactured sand/ mixed sand);

Maximum cement content;

As required for durability requirement

Details of Admixes used

Type of admixture / Manufacturer

Type of pozzolanic material to be used as replacement of cement

Such as Fly Ash, GGBF Slag, Micro Silica

Any other specific requirement like early age strength requirements.

 

 

 

 

 

 

 

 

Brief description for types of concrete

Normal Strength Concrete (NSC) is designated up to 40 MPa.

High Strength Concrete Beyond NSC the concrete was developed as High Strength Concrete (HSC). HSC is used in high rise buildings and in structural members bearing high loads. The member size gets reduced using HSC and performance is better about strength and durability.

HSC provides a high level of structural performance, especially in strength and durability, as compared (NSC).

ACI defines a high-strength concrete as concrete that has a specified compressive strength for design of 6,000 psi (41 MPa) or greater.


High Performance Concrete  High Performance Concrete  up to 150 MPa

High-performance concrete It is a mix of concrete ingredients defined based on  performance criteria that includes  high durability, high strength, and high workability.

 

Ultra-High-Performance Concrete UHPC ( Beyond 150 MPa) - Ultra-High-Performance Concrete is a super concrete which has more strength, durability, and ductility. The UHPC can be used for structural and architectural members, overlays, and many more items through its factory and in situ production. The UHPC is more homogeneous and its design, mixing placing and curing processes are slightly different and need better controls in all stages from design to placement.

Self-Consolidating Concrete SCC

SCC is an innovative concrete that does not require vibration for placing and compaction. It can flow under its own weight, completely filing formwork and achieving full compaction, without segregation, even in the presence of congested reinforcement.

 

Polymer Concrete

Polymer Concrete  - Cement is replaced with polymeric materials.

Polymer Modified Concrete – a mix of cement and polymer is used as cementing material.

Polymer Impregnated Concrete – The top surface of concrete is impregnated with polymers and cured at high temperature

 

          Summary of Different types of Concrete

 

In summary the concrete categories are as follows:

Nominal mix concrete

Design mix concrete

Normal Strength Concrete

High Strength Concrete

High Performance Concrete

Ultra-High-Performance Concrete

Polymer Concrete

Self-Compacting Concrete

 

Main type of concretes is discussed above . However, the concrete is also classified on basis of structural and another requirement, namely

 Under water concrete – concrete placement under water by tremie or other means

Light weight,  porous and nailing concrete – to reduce load, to provide drainage and concrete in which nails can be hammered (soft concrete)

Foam concrete – for light weight bricks or as underlay below tiles.

 

Reinforced Concrete  with steel bars and girders, ribs, and fibber reinforced concrete

Prestressed Concrete

Precast Concrete

Shotcrete

Nominal mix concrete

Design mix concrete

Normal Strength Concrete

High Strength Concrete

High Performance Concrete

Ultra-High-Performance Concrete

Polymer Concrete

Self-Compacting Concrete




Vacuum Concrete – water is sucked out after placement to reduce water cement ratio.




Pumped Concrete – It is associated with placement techniques.





Stamped Concrete – architectural features are stamped for enhanced appearance.




Limecrete-  use of lime instead of cement in concrete

Asphalt Concrete – Asphalt is used as binder instead of cement and supplementary cementitious materials.

 



Roller Compacted Concrete- A near zero slump concrete is consolidated by rollers.

 

 

 

 

 

 


Project Concrete Requirements Management

In general, the project concrete requirements should be oriented and managed on points as given below:

 

Reporting Requirements

Concrete mix design requirements

 Checklist for project  work

Preconstruction conference

Project concrete requirements

Onsite concrete performance and rejection process

 Material management

Laboratory set up.

Field test set up.

Project testing needs

Tests on Fresh concrete

Tests on hardened concrete

 Transportation and storage of test material

Setting up of Processing and Batching Plants

Production of Concrete

Test result communication system

Field Lab vs Main Lab outcomes

Measurement / Acceptance concrete procedures

Concrete placement and Finishing measures.

Concrete placement and pumpability

 

Also please follow the link below, by the same author.

 

 













Monday, September 6, 2021

Understanding Data Flow and Information Gathering in Project Management

 


This writeup covers Raw Data Management and getting the meaningful information out of it. Information sharing is a part of communication management plan, and more than 90 percent project movement depends on communication.

 

Project Management Data and Information Flow

Data - information (such as measurements or statistics) used as a basis for reasoning, discussion, decisions, mentoring, alignment calculation, etcetera.


Data is the basic information source collected throughout the execution of processes of the project

This raw data which needs to be taken carefully, is then analysed qualitatively, aggregated, and transformed into information which is used for reporting purposes. Raw data management is a very important aspect as all the information depends on it. There is technological advancement these days and data can be electronically observed and stored in dataloggers from where real time data transmission can be done to storage device. The automatic data recording is very reliable and given preference over manual data recording.

 

The raw data is recorded for example in following fields

*    Weather station

*    Batching plant operation

*    Drilling and grouting

*    Health and safety

*    Environment

*    Geographical

*    Educational

*    Quality control measurements

*    Earned value management

*    Progress

*    And others

 

 

 Ensure a Strong Data Management Framework

Important principles for successful data management framework may be considered as given below.

*    Data collection is very important and should be done with sincere efforts as it is a source for taking furth3er actions.

*    It is a regular process and as such the resource management for data collection must be adequate

*    Data management is a business need and involvement of Total Quality People should be there.

*    There should be a data management plan suitable for general data management and integrated with custom data management facility Stress should be on real time data management.

*    Data storage management should use digital data facility with required backup facility.

*    The stored data should be analyzed with required data analysis tools to get an output from it.

*    The information obtained from raw data analysis should be transmitted effectively and efficiently for further use to venture stakeholders

 

The detail of data- information -flow is shown below in the chart as an example.


The total information - data stream – use, is as described below.

 

The raw data is gathered during project activities physically or electronically. The nature of information gathering is vital to look for significant data. The information gathered is overseen physically and electronically, and it is called work performance data (WPD). The good practice is that it should be collected with automatic real time data collection, loading, and transportation to the central server for further analysis.


The data analysis is done in project context and accordingly it is aggregated for transformation process. The transformed data is used for getting work performance information (WPI).

 

The significant data is utilized for creating work performance reports (WPR). (WPR are high level reports, progress reports, financial reports, report on change management, stakeholder mange met, risk management, HSSE report, business reports for assessing the alignment of ongoing projects and others).

The WPR have important role to play in project management and    these reports are passed to change control units / boards and to communication units. The communication units compose the reports for the stakeholders and the project team.

Any changes approved based on these reports are informed to process control units and further to project team and the stakeholders.

The desired and approved changes in process control are documented for necessary changes in project plans. The revised project plans are then used for further project execution processes.

 

The flow diagram below has the contents suggested in PMBOK guide of PMI

 



Ultimately the data flow can be managed for

 

*    Data Storage

*    Data Analysis

*    Getting information

*    Sharing Information

*    As Repository of Data and Information

*    For Preliminary Planning of Project

 

“Management is, above all, a practice where art, science, 

and craft meet.” –  Henry Mintzberg

 


Different Types of Concrete

The types of concrete mentioned here are from 7.5 MPa to around 400 MPa. Very specialised plants with management controls are required for h...