Initial and final setting time of cement

 

cement setting time | Initial and final setting time of  cement | What is initial and final setting time of cement | Initial and final setting time of OPC cement | Initial and final setting time of concrete as per IS code

The usability and effectiveness of cement in diverse construction applications are significantly influenced by its initial and final setting times, which are significant features. The initial setting time is the time taken by the cement to lose its plasticity and become hard, while the final setting time is the time taken by the cement to attain its full strength and become completely hard. These properties are influenced by various factors, such as the composition of the cement, water-cement ratio, temperature, and other environmental conditions.

Effects of Initial and Final Setting Time of Cement:

The initial setting time affects the workability of the cement mortar or concrete. If the initial setting time is too short, it may be difficult to work with the cement, while if the initial setting time is too long, the cement may not set properly.

The final setting time affects the strength and durability of the concrete or mortar. If the final setting time is too short, the concrete may not attain its full strength, while if the final setting time is too long, the concrete may become too hard and brittle.

The following steps should be followed to determine the cement's initial and final setting times:


Prepare a cement paste by mixing 400g of cement and water in a 0.85 water-cement ratio.

Use the Vicat apparatus to perform the test. The Vicat apparatus consists of a movable rod, a plunger (Needle ) and a platform.

Fill the Vicat mould with the cement paste and level the surface.

Lower the plunger gently to touch the surface of the cement paste and note the time taken for the plunger to penetrate 5-7mm from the top of the paste This is the initial setting time.

Wait for the cement paste to harden and repeat step .

This is the final setting time.

Apparatus Required:

Vicat apparatus
Stopwatch
Measuring cylinder
Trowel
Cement

The initial and final setting times of cement are affected by a number of factors.

Composition of cement: The chemical composition of cement affects its setting time. A higher percentage of C3A in cement leads to faster setting time.

Water-cement ratio: A higher water-cement ratio increases the setting time of cement.

Temperature: A higher temperature accelerates the setting time of cement, while a lower temperature slows it down.

Humidity: A higher humidity level slows down the setting time of cement.

Fineness of cement: A finer cement has a faster setting time.

in Marathi language :

या लेखात आपण सिमेंटच्या Initial and final Setting time, तसेच त्याची procedure, महत्त्व आणि Vicat उपकरणाच्या मदतीने परिणाम याविषयी जाणून घेऊ.

जेव्हा सिमेंट आणि पाणी एकत्र केले जाते, सिमेंट आणि पाणी यांच्यामध्ये होणाऱ्या रासायनिक अभिक्रियाला सिमेंटचे hydration म्हणतात. hydration होऊन सिमेंट पेस्टमध्ये बदलू लागतो. ताज्या तयार-मिश्रित सिमेंटमध्ये plasticity गुणवत्ता असते आणि यामुळे, पेस्ट कोणत्याही इच्छित आकारात तयार केली जाऊ शकते.

यावेळी, सिमेंट पाण्यावर प्रतिक्रिया देत राहते, हळूहळू त्याची plasticity and harden होऊ लागते. ही  पूर्ण प्रकिया Setting time of cement म्हणून ओळखले जाते.

 

1. ट्रेमध्ये 400 ग्रॅम सिमेंट ठेवावे. आता थोडे पाणी घाला. आणि  टाइमर सुरु  करा consistency 0.85P पेस्ट तयार करण्यासाठी पाणी  घालत  राहा, P is the Standard consistency of cement.

 

2. Cement पेस्ट मिश्रणाने Vicat mould भरा.

 

3. Vicat mould मधून उर्वरित अतिरिक्त पेस्ट काढण्यासाठी trowel चा वापर केला जातो. त्यानंतर, VICAT मोल्डला छिद्र नसलेल्या प्लेटवर ठेवा जसे की काचेच्या प्लेट.

 

4. 1 SQMM square needle Vicat उपकरणाच्या फिरत्या रॉडला जोडा आणि Plunger VICAT MOULD च्या पृष्ठभागाला हळूवारपणे स्पर्श करत असल्याची खात्री करा.

 

5. Plunger Release करा test mould मध्ये penetrate होऊ  द्या

6. Scale वर दर्शविल्याप्रमाणे mould च्या तळाशी Plunger प्रवेशाची नोंद घ्या.

7. जेव्हा Plunger mould च्या तळापासून 5 ते 7 mm आत प्रवेश करणे थांबवते तेव्हा चाचणी पूर्ण होते.

 

8. असे होईपर्यंत mould वरील विविध ठिकाणी प्रयोगाची पुनरावृत्ती करा.

 

 

Cement ची initial setting time म्हणजे सिमेंटला पाणी टाकल्यापासून ते mould च्या तळापासून मोजलेल्या 5 ते 7 mm खोलीवर needle fails to penetrate.

Initial setting time म्हणजे strength न गमावता cement ला कोणत्याही स्वरूपात moulded होईपर्यंत लागणारा वेळ.

 

OPC (Ordinary Portland Cement) चा initial Setting time 30 minute असते आणि final setting time is 10 hrs (600minute) असते.

Factor affection setting time of cement

1. Cement composition of Cement

2. water-cement ratio

3. Material ratio

4. Climatic conduction like temperature & humidity

5. admixtures

Are the main factor impacting cement setting time.