Quality Control and Safety Concerns in Construction

Quality control and Construction Safety represent increasingly important concerns for project managers.

Weak quality control leads to defects or failures in constructed facilities, thus result in very large costs. Even with minor defects, re-construction may be required and facility operations impaired. Increased costs and delays are the result. In the worst case, failures may cause personal injuries or fatalities. Accidents during the construction process can similarly result in personal injuries and large costs. Indirect costs of insurance, inspection and regulation are increasing rapidly due to these increased direct costs. Good project managers try to ensure that the job is done right the first time and that no major accidents occur on the project.

As with cost control, the most important decisions regarding the quality of a completed facility are made during the design and planning stages rather than during construction. It is during these preliminary stages that component configurations, material specifications and functional performance are decided. Quality control during construction consists largely of insuring conformance to these original design and planning decisions.

While conformance to existing design decisions is the primary focus of quality control, there are exceptions to this rule. First, unforeseen circumstances, incorrect design decisions or changes desired by an owner in the facility function may require re-evaluation of design decisions during the course of construction. While these changes may be motivated by the concern for quality, they represent occasions for re-design with all the attendant objectives and constraints. As a second case, some designs rely upon informed and appropriate decision making during the construction process itself. For example, some tunneling methods make decisions about the amount of shoring required at different locations based upon observation of soil conditions during the tunneling process. Since such decisions are based on better information concerning actual site conditions, the facility design may be more cost effective as a result.

With the attention to conformance as the measure of quality during the construction process, the specification of quality requirements in the design and contract documentation becomes extremely important. Quality requirements should be clear and verifiable, so that all parties in the project can understand the requirements for conformance. Much of the discussion in this chapter relates to the development and the implications of different quality requirements for construction as well as the issues associated with insuring conformance.

Safety during the construction project is also influenced in large part by decisions made during the planning and design process. Some designs or construction plans are inherently difficult and dangerous to implement, whereas other, comparable plans may considerably reduce the possibility of accidents. For example, clear separation of traffic from construction zones during roadway rehabilitation can greatly reduce the possibility of accidental collisions. Beyond these design decisions, safety largely depends upon education, vigilance and cooperation during the construction process. Workers should be constantly alert to the possibilities of accidents and avoid taken unnecessary risks.

How To Deal With Poor Workers In The Workplace

In order to keep the relevant people informed, you must have regular and complete access to all information about the project: customer needs, objectives, plan, constraints, changes/risks and progress.

PRINCE2TM, the government-standard Project Management methodology, suggests that a system of ‘management products’ (documents used to make management more efficient) is set up.

For example, a Project Quality Plan relies on information about quality expectations provided by the Customer. The Quality Log is a record of quality checks performed by project staff. Both documents are necessary for effective management of product quality.

The PRINCE2TM method also recommends that Project Managers establish regular dates for Checkpoint Reports (detailing the progress of individual teams and team members) and Highlight Reports (documents prepared by the Project Manager, for the Project Board, describing overall project progress).

With disciplined adherence to a system of regular and focused communication, you will avoid the misunderstandings and delays that so frequently lead to project failure and ensure that all your project staff and stakeholders are secure in their knowledge of what has to be done, and who is doing it.

If Situation #2 appears, then you may have to take additional actions, such as:

•  Tell the worker that if their performance does not improve within a given time period, you will work with the line manager and take whatever disciplinary actions are necessary. You are giving them a chance for recovery.
• If the performance does not improve within the given time period, then provide the worker with an on-the-spot performance review and see to it that the functional manager receives a copy.
• Remove the worker from the project team. If you do not have the authority to do so by yourself, then it may be necessary to ask your sponsor for help.

Obviously, there are other issues that can cause poor work performance and there are other ways to handle the situation; this is just one option.

The Importance of Communication in Project Management

Communication is key to successful Project Management.

If project staff do not know what their tasks are, or how to accomplish them, then the entire project will grind to a halt. If you do not know what the project staff are (not) doing then you will be unable to monitor project progress. And if you are uncertain of what the customer expects of you, then the project will not even get off the ground.

Maintaining open, regular and accurate channels of communication with all levels of project staff and stakeholders is vital to ensuring the smooth flow of instructions from customer to factory floor and sufficient warning of risks and changes to enable early assessment and preparation.

•    The Information that You Need to Give

As Project Manager, it is your job to keep a number of people well-informed. It is essential that your project staff know what is expected of them: what they have to do, when they have to do it, and what budget and time constraints and quality specification they are working towards.

It is also your job to keep the Project Board informed of project progress. The Project Board usually includes the Executive (person ultimately responsible for the project), and representatives from the User and the Supplier.

It is important that the Project Manager updates the Project Board regularly on the status of the project, so that any changes or risks can be assessed, project progress can be measured against the original Business Case and a project that is not fulfilling its purpose or matching the value of its investment can be called to a halt.

•    The Information that You Need to Receive

In order to keep the relevant people informed, you must have regular and complete access to all information about the project: customer needs, objectives, plan, constraints, changes/risks and progress.

PRINCE2TM, the government-standard Project Management methodology, suggests that a system of ‘management products’ (documents used to make management more efficient) is set up.

For example, a Project Quality Plan relies on information about quality expectations provided by the Customer. The Quality Log is a record of quality checks performed by project staff. Both documents are necessary for effective management of product quality.

The PRINCE2TM method also recommends that Project Managers establish regular dates for Checkpoint Reports (detailing the progress of individual teams and team members) and Highlight Reports (documents prepared by the Project Manager, for the Project Board, describing overall project progress).

With disciplined adherence to a system of regular and focused communication, you will avoid the misunderstandings and delays that so frequently lead to project failure and ensure that all your project staff and stakeholders are secure in their knowledge of what has to be done, and who is doing it.

Quality control in construction field

Quality control in construction typically involves insuring compliance with minimum standards of material and workmanship in order to insure the performance of the facility according to the design. These minimum standards are contained in the specifications described in the previous section. For the purpose of insuring compliance, random samples and statistical methods are commonly used as the basis for accepting or rejecting work completed and batches of materials. Rejection of a batch is based on non-conformance or violation of the relevant design specifications. Procedures for this quality control practice are described in the following sections.

An implicit assumption in these traditional quality control practices is the notion of an acceptable quality level which is a allowable fraction of defective items. Materials obtained from suppliers or work performed by an organization is inspected and passed as acceptable if the estimated defective percentage is within the acceptable quality level. Problems with materials or goods are corrected after delivery of the product.

In contrast to this traditional approach of quality control is the goal of total quality control. In this system, no defective items are allowed anywhere in the construction process. While the zero defects goal can never be permanently obtained, it provides a goal so that an organization is never satisfied with its quality control program even if defects are reduced by substantial amounts year after year. This concept and approach to quality control was first developed in manufacturing firms in Japan and Europe, but has since spread to many construction companies. The best known formal certification for quality improvement is the International Organization for Standardization’s ISO 9000 standard. ISO 9000 emphasizes good documentation, quality goals and a series of cycles of planning, implementation and review.

Total quality control is a commitment to quality expressed in all parts of an organization and typically involves many elements. Design reviews to insure safe and effective construction procedures are a major element. Other elements include extensive training for personnel, shifting the responsibility for detecting defects from quality control inspectors to workers, and continually maintaining equipment. Worker involvement in improved quality control is often formalized in quality circles in which groups of workers meet regularly to make suggestions for quality improvement. Material suppliers are also required to insure zero defects in delivered goods. Initally, all materials from a supplier are inspected and batches of goods with any defective items are returned. Suppliers with good records can be certified and not subject to complete inspection subsequently.

The traditional microeconomic view of quality control is that there is an “optimum” proportion of defective items. Trying to achieve greater quality than this optimum would substantially increase costs of inspection and reduce worker productivity. However, many companies have found that commitment to total quality control has substantial economic benefits that had been unappreciated in traditional approaches. Expenses associated with inventory, rework, scrap and warranties were reduced. Worker enthusiasm and commitment improved. Customers often appreciated higher quality work and would pay a premium for good quality. As a result, improved quality control became a competitive advantage.

Of course, total quality control is difficult to apply, particular in construction. The unique nature of each facility, the variability in the workforce, the multitude of subcontractors and the cost of making necessary investments in education and procedures make programs of total quality control in construction difficult. Nevertheless, a commitment to improved quality even without endorsing the goal of zero defects can pay real dividends to organizations.

A Sample of Home Construction Contract

This contract sample is for home construction, repair, or remodeling. It was drafted by the Consumer Protection Division of the Maine Attorney General in an attempt to meet the requirements of 10 M.R.S.A.§§ 1486-90, Home Construction Contracts. This contract is required to be used for home construction or repair projects costing more than $3,000. You are free to copy this contract and use it for your home construction project.

The Maine Attorney General does not guarantee that this model contract satisfies all legal requirements.
Contract No. _________________________

1. Parties to This Contract:
A. Contractor

Name:

Phone :
Address:
B. Homeowner or Lessee:

Name:

Phone:
Address:

2. Location of Work:

3. Completion Dates:
A. Estimated date of commencement:

B. Estimated date of completion:

4. Contract Price (if a “cost-plus” formula the cost of labor and materials must be estimated):

5. Method of Payment (initial down payment is limited to no more than 1/3 of the total contract price):

6. Description of the Work:

7. Warranties: The contractor provides the following express warranty:

In addition to any additional express warranties agreed to by the parties, the contractor warrants that the work will be free from faulty materials; constructed according to the standards of the building code applicable for this location; constructed in a skillful manner and fit for habitation. The warranty rights and remedies set forth in the Maine Uniform Commercial Code apply to this contract.

8. Resolution of Disputes: If a dispute arises concerning the provisions of this contract or the performance by the parties, then the parties agree to settle this dispute by jointly paying for one of the following (check only one):
1. Binding arbitration as regulated by the Maine Uniform Arbitration Act, with the parties agreeing to accept as final the arbitrator’s decision (______);
2. Nonbinding arbitration, with the parties free to not accept the arbitrator’s decision and to seek satisfaction through other means, including a lawsuit (______);
3. Mediation, with the parties agreeing to enter into good faith negotiations through a neutral mediator in order to attempt to resolve their differences (______). The parties are not required to select one of these dispute resolution methods. They are optional. If the parties do not select one of these dispute resolution options, check here: ______.

9. Change Orders: Any alteration or deviation from the above contractual specifications that involve extra cost will be executed only upon the parties entering into a written change order.

10. Additional Provisions:

Please note: if this contract is being used by contractors who sell door-to-door it must meet any applicable requirements of the Consumer Solicitation Sales Act, 32 M.R.S.A. §§ 4661-4671, the Door-to-Door Home Repair Transient Sellers Act, 32 M.R.S.A. §§ 14501-14512, and The Credit Home Solicitation Sales Act, 9-A M.R.S.A. §§ 3-501-3-507, including a description of the consumer’s 3 day right to cancel the contract. If this contract includes installation of insulation in an existing residence it must contain a detailed description of the insulation as required by 10 M.R.S.A. § 1482. If this contract includes construction of a new residential building or a new addition to an existing residence, it must contain a statement that 10 M.R.S.A. §§ 1411 -1420 establishes minimum energy efficient building standards for new residential construction, and whether this building or addition will meet or exceed those standards.

11. Contract Acceptance:
Signature:

Date: _____________
(Homeowner or Lessee)
Signature:

Date: _____________
(Contractor)

Each party must receive a copy of this signed contract before work can be started.

Construction Contract

Definition of a construction contract

The term Contract used in the Construction management can be defined as: “An agreement entered into by two parties under the terms of which one party agrees to perform a specific job for which the other party agrees to pay. Contract documents attached to and/or stated in the agreement form integral parts of the contract”.

Essentials of Contract validity

* The parties to the contract must be competent, and legally capable of playing their intended part. The law can not enforce the agreement on someone who has not the legal capacity to enter into an agreement. This could be due to infancy, lunacy, drunkenness, or being restricted from entering into such agreement by a prior in date agreement or scope of authority.
* The subject matter of the contract must be lawful and definite in respect of requirements and duties of each party. For example a contract violating municipal regulation is not binding and is void in courts. Also uncertainty in respect of the what is wanted may result in the contract being not enforceable by law.
* Proposal and acceptance: There must be a proper proposal by one party and its absolute and unqualified acceptance by the other party. The proposal is not binding without a clear acceptance and is not binding beyond its date of validity.
* Free consent of parties to the contract: Consent is said to be free when it is not caused by force, or undue influence or fraud or misrepresentation.

Breach of Contract

Breach of Contract is the failure to perform it. However, not every failure to perform an obligation amounts to a true breach, as there are a number of excuses for non performance. When a contract has been broken without sufficient excuse or justification, the party who suffers by such breach is entitled to receive from the party in default, a compensation for any loss or damage caused by such breach.

Data Required for Preparing an Estimate:

A Contract may be terminated or brought to an end in either of the following ways:

* Full and satisfactory performance by both parties to their obligations under the contract.
* Breach of contract, when the default of one party releases the other party from the contractual obligations.
* Mutual agreement of the parties to terminate the contract.
* Unforeseen circumstances beyond the control of either party render it impossible to perform his duties or obligations stated in the contract.
* Operation of law to terminate a void contract.

Types of contracts commonly used in construction

* Lump sum contract
* Item rate or unit price contract
* Percentage rate contract
* Cost plus percentage rate contract
* Cost plus fixed fee contract
* Cost plus fluctuating fee contract
* Target cost contract.

A Business Coach Can Assist You To Build Your Business

If you give thought to what a coach does, especially for sports teams, it is to prepare a team for a game, then to motivate them, and make changes when they are required. A business coach could show you the things you have to do in launching a business, but it is up to you to do the work. Your coach could point out things that you might be doing wrong and give advice. A great coach will offer you several options but it is up to you if you want to execute or not. It is a great idea to get a coach that matches your style so that you can trust in their guidance.

Many of you could be thinking about whether you should find a business coach to help you put your business on the right track. If you find the right business coach, they can certainly take your personal life and business to a higher level. A coach could help you identify your objectives, so that your life has some direction, and purpose. If you decide that you would like to start a business, then you must figure out what you need and whether you have what it takes.

If you give thought to what a coach does, especially for sports teams, it is to prepare a team for a game, then to motivate them, and make changes when they are required. A business coach could show you the things you have to do in launching a business, but it is up to you to do the work. Your coach could point out things that you might be doing wrong and give advice. A great coach will offer you several options but it is up to you if you want to execute or not. It is a great idea to get a coach that matches your style so that you can trust in their guidance.

The objective of the coach is to help their clients find the right way to work things out by helping them find their own answers. Chances are you’ll realize that finding the answer can come from another person asking the right question to a problem. A great coach will keep you motivated and help you remain focused in addition to hold you accountable for your targets. When you start out, you’re going to be making several mistakes but your coach is going to help you get through them. You may find that in order to improve your business, you may need to make adjustments to your personal life. It is not easy to be two different people at the same time where one is for personal and the other for business.

If you’re wanting to become successful on your own without any help, then getting a business coach is a waste of money. A coach is there to offer you assistance, and help you make adjustments that will make things work a lot easier. If you are obstinate and tend not to take advice from other individuals, then you will not need a coach. If you determine that having a business coach is a great idea, you must do some research and look for a coach that can lead you to success.

If you work with your business coach, then they will be able to help you achieve your targets. You ought to make the time and effort to find the one that is right for you.

Construction Project Engineer

A Project Engineer is, in some cases, the same as a project manager. Project Engineers are considered to be Project Managers but with engineering qualifications. Government organizations might have a Senior Project Engineer at the top of the ladder followed by Project Engineer followed by Project Manager.

In some cases a Project Engineer is responsible for assisting the assigned project manager with regard to design and a project and with the execution of one or more simultaneous projects in accordance with a valid, executed contract, per company policies and procedures and work instructions for customized and standardized plants.

Responsibilities:

1. Schedule preparation and resource forecasting for specific engineering activities relating to the project.

2. Performance management of the architectural and engineering vendor.

3. Assuring accuracy of financial forecasts with tie-in to project schedules.

4. Ensuring projects are completed according to project plans.

5. Managing project team resources and training.

6. They have extensive project management experience & expertise.

7. It is not permissible to call a project engineer a P.E., as this refers to a Professional Engineer.

An similar role is undertaken by a Client’s Engineer or Owner’s engineer, but by inference, these often act more in the interests of the the commissioning company.

Project Finance

Investment in a constructed facility represents a cost in the short term that returns benefits only over the long term use of the facility. Thus, costs occur earlier than the benefits, and owners of facilities must obtain the capital resources to finance the costs of construction. A project cannot proceed without adequate financing, and the cost of providing adequate financing can be quite large. For these reasons, attention to project finance is an important aspect of project management. Finance is also a concern to the other organizations involved in a project such as the general contractor and material suppliers. Unless an owner immediately and completely covers the costs incurred by each participant, these organizations face financing problems of their own.

At a more general level, project finance is only one aspect of the general problem of corporate finance. If numerous projects are considered and financed together, then the net cash flow requirements constitutes the corporate financing problem for capital investment. Whether project finance is performed at the project or at the corporate level does not alter the basic financing problem.

In essence, the project finance problem is to obtain funds to bridge the time between making expenditures and obtaining revenues. Based on the conceptual plan, the cost estimate and the construction plan, the cash flow of costs and receipts for a project can be estimated. Normally, this cash flow will involve expenditures in early periods. Covering this negative cash balance in the most beneficial or cost effective fashion is the project finance problem. During planning and design, expenditures of the owner are modest, whereas substantial costs are incurred during construction. Only after the facility is complete do revenues begin. In contrast, a contractor would receive periodic payments from the owner as construction proceeds. However, a contractor also may have a negative cash balance due to delays in payment and retainage of profits or cost reimbursements on the part of the owner.

Plans considered by owners for facility financing typically have both long and short term aspects. In the long term, sources of revenue include sales, grants, and tax revenues. Borrowed funds must be eventually paid back from these other sources. In the short term, a wider variety of financing options exist, including borrowing, grants, corporate investment funds, payment delays and others. Many of these financing options involve the participation of third parties such as banks or bond underwriters. For private facilities such as office buildings, it is customary to have completely different financing arrangements during the construction period and during the period of facility use. During the latter period, mortgage or loan funds can be secured by the value of the facility itself. Thus, different arrangements of financing options and participants are possible at different stages of a project, so the practice of financial planning is often complicated.

On the other hand, the options for borrowing by contractors to bridge their expenditures and receipts during construction are relatively limited. For small or medium size projects, overdrafts from bank accounts are the most common form of construction financing. Usually, a maximum limit is imposed on an overdraft account by the bank on the basis of expected expenditures and receipts for the duration of construction. Contractors who are engaged in large projects often own substantial assets and can make use of other forms of financing which have lower interest charges than overdrafting.

In recent years, there has been growing interest in design-build-operate projects in which owners prescribe functional requirements and a contractor handles financing. Contractors are repaid over a period of time from project revenues or government payments. Eventually, ownership of the facilities is transferred to a government entity.

Project Management Guide

If you come across the big question of what should project managers do to be able to make a job accomplished easily, then this article will be very helpful to you. The project manager is the one who carries the biggest responsibility in a construction firm. He is the one who holds the success of a company. Once the project is accomplished and the tasks are executed properly, the credit is due to the project manager because he is the one who handles everything in the company.

There are project managers who are inexperienced, it is very risky for a company to have inexperienced project managers in the company. If you would like to have a successful business, it will be best for you to know that there are important things you need to keep in mind:

1. The need to look for help if you have inexperienced project managers is very vital. If you know that you still lack experience to get the job done easily, there is someone in the company that can help you with your training needs. Usually, a company allows newly hired project managers to go through training from someone who is well verse in the field.

2. It is important for you to equip yourself with software to be able to get the job done easily. A lot of companies’ today especially big firms know the importance of software that is why most of them include software for a tool whenever they need to work more efficiently.

3. Learning the details of every project is also important and as a newbie in the industry, it will be best for you to know that taking care of proposals and other things as well will be very helpful to you.

As a project manager, there are lots of responsibilities on your shoulders so you need to be equipped with all the right information so that you will never miss a thing.

Managing Your Website Development ?eight Easy Steps to Project Management

Managing your website development need not cause you sleepless nights providing you learn the secrets of successful project management. Perform the best practices in project management and give your project the best chance of success.


Define objectives-

Objectives guide everyone on the project to your final goals. Are your objectives to sell your product online, to provide customer support, to promote investor relations? Carefully decide and clearly document your objectives.

Decide the critical success factors ?the things at the end of the project which tell you if you’ve been successful. Make them measurable so you know if you’ve achieved them. For example, the website development should result in an increase in online sales of 25% by year end.

Stakeholder analysis-

A stakeholder is someone with an interest in your project’s success (or failure). Decide who they are and whether they support your project. Perform stakeholder analysis by classifying them (high or low) according to how motivated they are in helping (or blocking) your project and how influential (high or low) they are.

Highly influential and supportive people are your allies. Gain their support whenever you can. Aim to reduce the influence of people who are both highly influential and against your project as these people could act to damage your project.

During your stakeholder analysis, draw up strategies for dealing with each group of stakeholders.

Define deliverables-

Deliverables are tangible things produced during the project. Talk with key stakeholders to help define deliverables. Will your website design include web page layouts and sitemap for use by the programming team? What is the content for each page? Write all this down.

Key stakeholders must review and agree the deliverables accurately reflect what they expect to be delivered.

Project planning-

Define how you will arrive at your objectives. This involves planning how many people, resources and budget are required. If delivering this in house, decide what activities are required to produce each deliverable.

For example, you might decide a web designer will develop page layouts and navigation diagrams. You might decide the marketing team will supply all product details and photographs. You might decide the finance manager will set up merchant and payment gateway accounts to enable e-commerce transactions via your website. If outsourcing work, specify exactly what the sub-contractor should deliver.

Estimate the time and effort required for each activity and decide realistic schedules and budget. Ensure key stakeholders review and agree the plan and budget.

Communication planning-

Hold a kick off meeting with the team and explain the plan. Ensure everyone knows exactly what the schedule is, and what is expected of them.

For example, the web designer needs to know that he is to produce page layouts and navigation diagrams based upon the marketing manager’s requirements. He needs to know his expected start and end times.

Share your project communication plan with the team. This should include details of report templates, frequency of reporting and meetings, and details of how conflicts between teams and their members will be resolved.

Project tracking-

Constant monitoring of variations between actual and planned cost, schedule and scope is required. Report variations to key stakeholders and take corrective actions if variations occur. To get a project back on track you will need to juggle cost, scope and schedule.

Suppose your programmer hits technical problems which threaten to delay the project. You might recover time by re-organising or shortening remaining tasks. If that’s not possible, you might consider increasing the budget to employ an additional programmer, or consider reducing the scope in other areas.

Be aware that any adjustments you make to the plan might affect the quality of deliverables. If you need to increase the budget, seek approval from the project sponsor.

Change management-

Once started, all projects change. Decide a simple change strategy with key stakeholders. This could be a committee which decides to accept or reject changes which comprises of you and one or more key stakeholders.

Assess the impact of each change on scope, cost and schedule. Decide to accept or reject the change. Be aware that the more changes you accept the less chance you have of completing the project on time and within budget unless you reduce scope in other areas.

Suppose the marketing manager wants to add a popup window to display full size photographs of products. Assess the impact of this change. You might need to remove some remaining tasks to include this change and stay within budget. Or, it might be impossible to include the change without increasing the budget or schedule.

Don’t blindly accept changes without assessing the impact or your project will overrun.

Risk management

Risks are events which can adversely affect the success of the project. Identify risks to a project early. Decide if each risk is likely or unlikely to occur. Decide if its impact on the project is high or low.

Risks that are likely to occur and have high impact are the severest risks. High impact but unlikely risks, or low impact but likely risks pose a medium threat. Unlikely and low impact risks pose the least threat.

Create a mitigation plan of the actions necessary to reduce the impact if the risk occurs. Start with the severest risks first, then deal with the medium risks. Regularly review risks. Add new ones if they occur.

Suppose the marketing manager cannot decide what he wants from the website. Without knowing what the marketing manager wants, the team cannot deliver a website to meet his expectations. You assess this risk as highly likely to occur and having high impact. Your mitigation plan might be that the web designer develops page layouts to be reviewed by the manager early in the project.

Summary

Performing best practices in project management will give your website development project the best chance of success.

Concrete Mix Design Secrets

In order to make a concrete mix design that works, you should master all the concrete theories in combination with experiences of concreting at work. Here is some important things you need to know when design concrete mixes.

A. What do you need to know before designing concrete?

1. What are the strength requirements?

- Compressive (on cube or cylinder specimen) strength

- Flexural strength

- Tensile strength

2. What is the placing method? By pump or direct pouring?

3. How far is the job site from the batching plant?

4. What is the structure for casting? Pavement, foundation, elevated slab, etc.

5. What are the projects specification?

- Maximum or minimum cement contents

- Maximum water/cement ratio

- Slump or consistency limit

- Minimum Strength requirement @28 days

- Material specifications (what is the maximum size of aggregate?)

6. Latest testing results of materials is needed in the preliminary selection of materials and design calculation

B. What are Design Precautions and Things to Remember when design concrete mixes?

1. Increasing the sand/total aggregate ratio, increases the water requirement at the same consistency.

2. Increasing the water/cement ratio decreases the strength of concrete at the same cement content.

3. Remember that adding 5 liters of water per cubic meter increases the slump by 2.5cm.

4. Remember that adding 5 liters of water per cubic meter decreases strength by approximately 4%.

5. Always follow recommended admixture dosage.

6. Always have “control” when performing trial mixes, always perform trial mixes with another mix using the same materials. This data can be useful in diagnostics if a problem occurs.

7. Always adjust batching quantities to the actual moisture condition of the aggregates.

8. Volume tolerance for 1m3 concrete is 1 ± 0.2m3.

9. Range of normal weight concrete is from 2,200 kg/m3 to 2,400 kg/m3