Behaviour of fire damaged cement and geopolymer concrete slabs under static and impact loading

Ulagambika, Patchirajan; Murugan, Madasamy

doi:10.1590/1517-7076-rmat-2024-0033

Patchirajan Ulagambika

Anna University Chennai, Government College of Engineering, Department of Civil Engineering, 627007, Tirunelveli, Tamilnadu, India.

https://orcid.org/0009-0002-2841-4443

Madasamy Murugan

Anna University Chennai, Government College of Engineering, Department of Civil Engineering, 627007, Tirunelveli, Tamilnadu, India.

*

Corresponding Author: Ulagambika Patchirajan, e-mail: ambika5545@gmail.com, murugan@gcetly.ac.in

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Figure 1
Gradation curve of fine aggregate.

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Figure 2
Gradation curve of coarse aggregate.

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Figure 3
Placing of reinforcement.

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Figure 4
Casting of specimens.

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Figure 5
Water curing of cement concrete slabs.

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Figure 6
Ambient curing of geopolymer concrete slabs.

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Figure 7
Set up for firing.

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Figure 8
Thermocouple.

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Figure 9
Exposure of fire on concrete slab.

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Figure 10
Fire damaged slabs.

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Figure 11
Load set up for static load test on slabs.

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Figure 12
Failure mode of fire damaged slab.

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Figure 13
Mass loss of cement concrete slabs subjected to different temperature and duration.

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Figure 14
Mass loss of geopolymer concrete slabs subjected to different temperature and duration.

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Figure 15
Overall comparison of Ultimate load carrying capacity of Cement and Geopolymer slabs at various temperatures and various durations.

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Figure 16
a) Impact load test set up. b) Punching failure of slabs by impact load test.

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Table 1
Properties of cement.

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Table 2
Properties of geopolymer binder (FA80: GGBS20).

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Table 3
Properties of fine and coarse aggregate.

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Table 4
Mix proportion for conventional concrete.

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Table 5
Mix proportion for geopolymer concrete.

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Table 6
Mass loss of cement concrete and geopolymer slabs subjected to different temperature and duration.

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Table 7
Ultimate load carrying capacity of cement and geopolymer concrete slabs subjected to different temperature and duration under static loading.

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Table 8
Load carrying capacity of steel reinforced cement concrete and geopolymer concrete slabs under impact loading condition.

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Table 9
Visual observation.

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Table 10
Physical and chemical response to fire.

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S.NO	TESTS PERFORMED	EXPERIMENTED VALUES	REQUIREMENTS AS PER IS 12269-2013
1	Standard consistency	31%	28–32
2	Initial setting time	55 minutes	Not less than 30
3	Final setting time	285 minutes	Not more than 600
4	Specific gravity	3.11	3.15
5	Fineness (<90 microns)	2.5%	<10%
6	3^rd day compressive strength of cement	30.0 N/mm²	Greater than 27.0 N/mm²
7	7^th day compressive strength of cement	42.0 N/mm²	Greater than 37.0 N/mm²
8	28^th day compressive strength of cement	56.5 N/mm²	Greater than 53.0 N/mm²

S.NO	TESTS PERFORMED	EXPERIMENTED VALUES
1	Consistency test	30%
2	Initial setting time	76 minutes
3	Final setting time	285 minutes

S.NO	PROPERTY	FINE AGGREGATE	COARSE AGGREGATE
S.NO	PROPERTY	FINE AGGREGATE	20 mm	12.5 mm
1	Specific gravity	2.61	2.89	2.81
2	Fineness modulus	2.75	6.8	6
3	Density	1685 kg/m³	1760 kg/m³	1710 kg/m³
4	Water absorption	0.54%	0.211%	0.203%

CEMENT (kg/m³)	M – SAND (kg/m³)	COARSE AGGREGATE (kg/m³)		WATER-CEMENT RATIO
CEMENT (kg/m³)	M – SAND (kg/m³)	20 mm	12.5 mm	WATER-CEMENT RATIO
350.0	705.60	747.56	505.09	0.48

FLYASH (kg/m³)	GGBS (kg/m³)	M – SAND (kg/m³)	COARSE AGGREGATE (kg/m³)		ALKALINE-BINDER RATIO
FLYASH (kg/m³)	GGBS (kg/m³)	M – SAND (kg/m³)	20 mm	12.5 mm	ALKALINE-BINDER RATIO
280	70	732.09	775.63	524.07	0.48

EXPOSURE CONDITION		MASS OF CEMENT CONCRETE SLAB (KG)			MASS OF GEOPOLYMER CONCRETE SLAB (KG)
TEMPERATURE (ºC)	DURATION (HOUR)	BEFORE	AFTER	% OF MASS LOSS	BEFORE	AFTER	% OF MASS LOSS
Room temperature	–	34.58	–	–	34.56	–	–
200	1	34.55	33.86	2	34. 62	34.10	1.5
	2	34.55	33.58	2.8	34.58	33.65	2.7
	3	34.56	33.28	3.7	34.60	33.25	3.9
400	1	34.54	33.02	4.4	34.54	33.05	4.3
	2	34.54	32.85	4.9	34.62	32.65	5.7
	3	34.58	32.51	6	34.55	32.06	7.2
600	1	34.60	31.90	7.8	34.60	31.69	8.4
	2	34.55	31.37	9.2	34.62	31.26	9.7
	3	34.62	30.81	11	34.55	30.75	11
800	1	34.55	30.37	12.1	34.62	30.43	12.1
	2	34.62	29.53	14.7	34.58	29.25	15.4
	3	34.58	28.63	17.2	34.56	28.06	18.8

EXPOSURE CONDITION		LOAD CARRYING CAPACITY OF CC SLAB (KN)	LOAD CARRYING CAPACITY OF GPC SLAB (KN)	% OF INCREASE IN LOAD CARRYING (COMPARING TO CC)
TEMPERATURE (ºC)	DURATION (HOUR)	LOAD CARRYING CAPACITY OF CC SLAB (KN)	LOAD CARRYING CAPACITY OF GPC SLAB (KN)	% OF INCREASE IN LOAD CARRYING (COMPARING TO CC)
Room temperature	–	34	40	17.65
200	1	37.4	47.2	26.20
	2	33.32	43.2	29.65
	3	32.3	38.8	20.12
400	1	31.62	39.2	23.97
	2	29.24	36.8	25.85
	3	27.2	34.4	26.47
600	1	28.9	36	24.57
	2	25.5	33.2	30.20
	3	22.1	30	35.75
800	1	22.78	28.8	26.43
	2	17.68	24.0	35.75
	3	13.6	20.4	50.00

FIRE EXPOSURE CONDITION		IMPACT STRENGTH
TEMPERATURE (ºC)	DURATION (HOUR)	CONVENTIONAL CONCRETE		GEOPOLYMER CONCRETE
TEMPERATURE (ºC)	DURATION (HOUR)	NO. OF BLOWS	IMPACT STRENGTH IN JOULES	NO. OF BLOWS	IMPACT STRENGTH IN JOULES
Room temperature	–	16	9182.16	12	6886.62
200	1	17	9756.05	13	7460.51
200	2	14	8034.39	11	6312.74
200	3	13	7460.51	10	5738.85
400	1	15	8608.28	12	6886.62
400	2	14	8034.39	11	6312.74
400	3	12	6886.62	9	5164.97
600	1	13	7460.51	10	5738.85
600	2	12	6886.62	9	5164.97
600	3	8	4591.08	5	2869.43
800	1	9	5164.97	6	3443.31
800	2	7	4017.12	4	2295.54
800	3	5	2869.43	3	1721.66

TEMPERATURE (°C)	WHAT HAPPENS
200	The color transitions to light gray.
400	The color further changes to gray, and up to 400ºC, there are no visible thermal cracks on the surface of the exposed concrete.
600	As the temperature increases, the color shifts to light pink, and at this stage, minor cracks and surface crazing become visible.
800	The color transforms to Gainsboro gray, and at this point, higher surface cracking and crazing become observable.

TEMPERATURE (° C)	DURATION (Hour)	WHAT HAPPENS
TEMPERATURE (° C)	DURATION (Hour)	IN CEMENT CONCRETE SLABS	IN GEOPOLYMER CONCRETE SLABS
For 200	1	No cracks are observed	Geopolymer concrete exhibits no formation of cracks.
For 200	2	Very minor cracks formation was observed	No crack formation
For 200	3	Minor crack formation was identified.	There is no formation of cracks.
For 400	1	Some Minor cracks have formed.	Very minor cracks formation was noted.
For 400	2	Moderate cracks formation was observed	Minor cracks formation was observed.
For 400	3	Extensive cracks formation was noted.	Moderate Crack formation was noticed.
For 600	1	Cracks of medium size were observed.	Observations revealed the formation of minor cracks.
For 600	2	Extensive cracks were observed.	Moderate cracks formation without any spalling of the concrete.
For 600	3	Cracks of medium size appeared within the first hour, followed by substantial spalling starting 1at 2:30 hr. Beyond this temperature threshold, Concrete loses its full structural capacity	Large cracks have formed, and there is no occurrence of concrete spalling.
For 800 – 1 Hr	1	The surface of the concrete exhibited the formation of extensive cracks.	Moderate Crack formation was noticed.
For 800 – 2 Hrs	2	65% of very extensive cracks and spalling occur, accompanied by a distinct and heavy sound.	Substantial cracks, accompanied by slight spalling of the concrete, occur.
For 800 – 3Hrs	3	Nearly 90% of the concrete undergoes complete damage, characterized by extensive cracks and spalling, accompanied by a pronounced and heavy sound.	Extensive formation of large cracks is accompanied by concrete spalling.

[1] Corresponding Author: Ulagambika Patchirajan, e-mail: ambika5545@gmail.com, murugan@gcetly.ac.in

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Behaviour of fire damaged cement and geopolymer concrete slabs under static and impact loading

ABSTRACT