In this article, we will discuss 15 popular cement test mistakes at site, the reasons why they occur and how they can be prevented to achieve sound construction on the site.
The concrete structure depends on cement. It can be a small residential house or it can be the grand infrastructure construction. cement quality has a direct influence on the strength, durability and safety. This is the reason why site testing of cement is important.
But in field conditions of sites cement testing is not always carried out properly, it may be because of a lack of knowledge, it may be because of time and it may be because of carelessness. Such errors may result in low concrete strength, cracks, and durability, as well as structural failures.
15 Popular Cement test mistakes
Given below are the 15 popular cement test mistakes at site.
1.Omitting Cement Testing because of Brand Trust
A lot of site engineers are under the assumption that thriving cement brands do not require testing. Consequently, cement is consumed without any check.
Why It’s Risky ?
Cement may be old stock. Mishandling at the storage of the supplier. Risk of exposure to moisture.
How to Avoid this cement test mistakes?
Essentially, basic site tests (visual exam, date of production, field tests) should always be done irrespective of the brand name.
2.Failure to Check Date of Manufacture
Cement bags are received without verification of the manufacturing date which is printed on the bag.
Why It’s Risky ?
The cement becomes weak with time. A loss of strength can be 20 to 30 percent after 3 months.Cement can be rendered structural hazards after 6 months.
How to Avoid ?
Consumption of cement within 90 days of production. Discard cement that is above 3 months old without laboratory tests.
3. Unacceptable Visual Inspection of Cement
Observation is not taken seriously or casually. What Should Be Checked
Color: homogenous grey of a light greenish hue. Lumps Cement must not be lumpy. Availability of foreign materials.
How to Avoid this cement test mistakes ?
Train on-site personnel about the importance of doing visual inspection prior to use.
4. Carrying out Field Tests improperly.
Frequent field tests such as hand feel test or float test or smell test are performed improperly or without any knowledge.
Examples:
- When rubbing cement between fingers, it should not be gritty.
- When cement is added to water, it must not rise, but sink.
How to Avoid this cement test mistakes ?
Train the site engineers and supervisors on proper test procedures and interpretation.
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5. Testing on Contaminated Water.
Water to be used in cement test is collected in dirty tanks and curing pits or even muddy water.
Why It’s Risky ?
Test results are affected by impurities. Gives wrong assumptions on the quality of cement.
How to Avoid this cement test mistakes?
These cement tests should always be performed using clean and potable water.
6. Ignoring Fineness Testing
On-site testing of fineness of cement is rarely performed.
Why Fineness Matters?
- Affects rate of hydration
- Influences the development of early strength.
- Low strength is caused by poor fineness.
How to Avoid this cement test mistakes?
Conduct sieve test (90-micron sieve) where necessary. Make sure that cement residue is within acceptable boundaries.
7. Incorrect Setting Time Test Procedure.
There are no standard guidelines followed during initial and final setting time tests.
Common Errors:
- Incorrect water content
- Delayed postmix testing.
- Inappropriate application in Vicat apparatus.
How to Avoid?
Strict adherence to IS 4031 (Part 5) and test should be carried out by trained personnel.
8. Failure to have the right temperature in testing.
There is no correction on cement testing done in extreme temperatures.
Why It’s a Problem?
- Higher temperature- quicker setting.
- Low temperature – retarded setting.
Results become unreliable
How to Avoid this cement test mistakes?
Carry out the tests at normal room temperature. Do not test in the direct sun.
9. Poor Cement Storage Pre-testing.
Testing of cement bags is done on the ground or close to water sources.
Consequences:
- Moisture absorption
- Lump formation
- Reduced strength
How to Avoid?
Pile cement on wooden raised platforms. Clearance at floor must be at less than 150 mm. Wrap up using waterproof covers.
10. Cement Blending with Old Stock to Test.
During testing, fresh cement is added to old or unused cement.
Why It’s Dangerous?
Test results do not reflect real quality cement. Masks defects of poor cement.
How to Avoid?
Test cement batch and do not combine different consignments.
11. Mistaken Analysis of Cement Sample.
Sample of cement is only collected on one bag or surface.
Why It’s Wrong?
Doesn’t represent entire lot Bags can be of different quality.
How to Avoid?
Take a sample out of a variety of bags. Blend well in order to have a representative sample.
12. Omission of Compressive Strength Testing.
Compressive strength tests are often skipped on many sites because it is believed that mix design will make up.
Why It’s Risky?
The strength of cement has a direct impact on the concrete strength. The failure of a cube can be caused by poor cement.
How to Avoid?
Sample compressive strength test is to be done when:
- Cement is old
- Supplier is new
- Project is critical
13. Ineffective Test Result record keeping.
The results of the tests are not documented or documented and are recorded informally.
Problems Caused:
- No traceability
- Hard to detect quality problems at a later stage.
- Audit failures
How to Avoid?
Keep a cement test register which contains:
- Date
- Batch number
- Test type
- Results
- Approval status
14. Failure to address Test Failures under Site Pressure.
Cement is applied even in the case of questionable test outcomes because of schedule pressure.
Why It’s Dangerous?
Results in structural defects in the long run. Costs of repair are much higher than the time lost in testing.
How to Avoid?
Design a quality policy that is non-negotiable and failed cement is not accepted irrespective of pressure.
15. Inadequacy in Training and Awareness of the Cement Testing.
Cement tests are done by untrained assistants or supervisors.
Consequences:
- Incorrect testing
- Incorrect interpretation of findings.
- False pretence of quality assurance.
How to Avoid?
- Hold training regularly.
- Display testing SOPs at site.
- Engage the QA/QC engineers.
Best Practices of Cement Testing on Site.
In order to prevent the above 15 cement tests mistakes, the following are the best practices:
- It is important to always look at date of manufacture.
- Store cement properly
- Carry out simple field tests on a regular basis.
- Send sample to laboratory where necessary.
- Proper documentation is necessary.
- It is better not to sacrifice quality to speed.
Final Thoughts:
Cement testing is not as easy as it may appear since minor errors can lead to huge failure. A majority of the cement construction issues are not caused by cement, but the improper testing in the field.
Knowing how to prevent these 15 most frequent cement test mistakes, site engineers and contractors can help a great deal to enhance the quality, durability, and safety of construction, without raising the cost of the project.
Remember: Good buildings do not get constructed using good materials only; they are constructed with good habits.
Frequently Asked Question(s) on cement test mistakes:
- What is the importance of cement testing on site?
The cement testing will make sure that the material satisfies the strength, setting time, and quality demands before it is utilized and to eliminate structural defects and failures.
- Does branded cement fail quality tests?
Yes. Even branded cement may not work in case it is old, not properly stored or in case it is subjected to moisture before arriving at the site.
- What is the most frequent cement test mistakes?
The most frequent mistake committed on construction sites are not verifying the date of manufacture and omission of basic field tests.
- What is the maximum duration of safe use of cement once it is made?
Cement is preferably to be utilized in 90 days of its production. Strength decreases greatly after this time.
- Is that all that field tests can tell us about the quality of cement?
Field tests provide a rough concept but laboratory tests are necessary when it comes to critical or structural works.
- What IS codes are applied in testing cement?
Depending on the type of cement, Cement testing is regulated by IS 4031 and IS 269 / IS 8112 / IS 12269.
- Who is to undertake cement testing on site?
Cement testing requires standard procedures to be done by the trained site engineers or QA/QC personnel.