Embed Size (px)
Citation preview
EVALUATION OF HEAT OF HYDRATION FOR HIGH PERFORMANCE CONCRETE INCORPORATING NORMAL AND ULTRA FINE GROUND GRANULATED BLAST FURNACE SLAG
B. Sabet Divsholi, Nanyang Technological University, Singapore Darren T.Y. Lim, Nanyang Technological University, Singapore Susanto Teng, Nanyang Technological University, Singapore
37th Conference on OUR WORLD IN CONCRETE & STRUCTURES: 29 - 31 August 2012, Singapore
Article Online Id: 100037019
The online version of this article can be found at:
http://cipremier.com/100037019
This article is brought to you with the support of
Singapore Concrete Institute
www.scinst.org.sg
All Rights reserved for CI‐Premier PTE LTD
You are not Allowed to re‐distribute or re‐sale the article in any format without written approval of
CI‐Premier PTE LTD
Visit Our Website for more information
www.cipremier.com
37th Conference on Our World in Concrete & Structures
29-31 August 2012, Singapore
EVALUATION OF HEAT OF HYDRATION FOR HIGH PERFORMANCE CONCRETE INCORPORATING NORMAL AND ULTRA FINE GROUND GRANULATED BLAST FURNACE SLAG
B. Sabet Divsholi1, Darren T.Y. Lim2 and Susanto Teng3
1Research Fellow; 2PhD Student, 3Associate Professor
School of Civil and Environmental Engineering, Div. of Structures and Mechanics Nanyang Technological University, Singapore
Blk N1, Level 1, 50 Nanyang Avenue, Singapore 639798 e-mail: <[email protected]> webpage: www.cee.ntu.edu.sg
Keywords: Heat of hydration, high performance, concrete, GGBS, UFGGBS
Abstract. Modern concrete buildings and infrastructures often require the use of high strength concrete. It is very likely that in the near future, the use of high strength concrete will become even more common. The Eurocode EN 206-1:2000 covers a concrete strength class of C100/115 (cylinder strength of 100 MPa/ cube strength of 115 MPa). Currently, with the advancement in concrete technology, achieving this strength is possible through conventional methods. Thanks to modern superplasticizer, achieving a concrete grade C100/115 with a flow diameter of over 500 mm is possible even for water-cementitious materials ratio (w/c) of 0.25. However, the cement consumption is increased with a reduction in w/c ratio. The heat of hydration is directly proportional to cement content. In Singapore exposure condition, the ambient temperature constantly fluctuates in the range of 25 to 33°C, leaving little room for heat evolution during hydration process, and the high hydration temperature may cause early age cracking. In this work, seven concrete mixes with w/c ratio of 0.25 with various percentages of Ground Granulated Blast-furnace Slag (GGBS) and Ultra Fine GGBS (UFGGBS) were cast. The compressive strength and heat of hydration was measured and compared with a grade 35 MPa concrete. The GGBS and UFGGBS replacement significantly reduced the peak temperature rise. The reduction in heat of hydration was more significant for GGBS compared to UFGGBS replacements.
1 INTRODUCTION
Concrete is the most widely used material in the construction industry for various purposes due to its ability to withstand high loads, ability to be cast in any shape and good resistance against wear and tear. Reducing the water-cementitious materials ratio (w/c) which in turn increases the cement content will produce a High Strength Concrete (HSC) [1]. Also finer cement particles results in faster and more complete hydration. However, an increase in cement fineness and cement content in concrete results in raising the concrete’s adiabatic temperature. The issue of high heat of hydration was assumed not affecting the general construction cases and was unique to mass concrete construction [2]. However, more and more new constructions are required to evaluate the heat of hydration. The Texas Department of Transportation (TxDOT) Specification 420 [3] limits mass concrete placement temperature to 24 °C, the maximum in-place temperature to 71 °C, and the maximum temperature difference in the concrete to 20 °C. The Contractors are required to submit a
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
temperature control plan for mass concrete (a concrete section with minimum dimension of 1.5 metre) before construction work begins [2].
Partial replacement of Portland Cement (PC) with Supplementary Cementitious Materials (SCM) such as Ground Granulated Blast-furnace Slag (GGBS) and Silica Fume (SF) not only improves both mechanical and durability properties of concrete [4] but also reduces the adiabatic heat development [5, 6, 7].In contrast to GGBS which is a slow reactant providing later development of microstructure [8], Ultra Fine GGBS (UFGGBS) contributes to both early and ultimate strength development of the concrete. As the fineness of the UFGGBS is increased, the total surface area for reaction is increased, resulting in increased rate of hydration and pozzolanic reactions. The rate of strength development of the concrete improves and the permeability of the concrete is reduced due to reduced total pore volume, pore connection and the better filling of the pores in the Interfacial Transitional Zone (ITZ) [1].
High Performance Concrete (HPC) mixes with w/c=0.25 and SCM replacement showed significant improvement in mechanical and durability properties of concrete. However, the development of heat of hydration is a real concern. The GGBS replacement in known to reduce the heat of hydration [5] however, the percentage of reduction needs to be carefully studied. In addition, study on the effect of UFGGBS on heat development is essential.
In this work, seven concrete mixes with w/c ratio of 0.25 with various percentages of GGBS and UFGGBS were cast. The compressive strength and heat of hydration was measured and compared with a grade 35 MPa concrete. The GGBS and UFGGBS replacement significantly reduced the peak temperature rise. The reduction in heat of hydration was more significant for GGBS compared to UFGGBS replacements.
2 EXPERIMENTAL INVESTIGATION
2.1 Materials Properties
The characteristic of OPC, GGBS and UFGGBS used in this work are presented in Table 1. The oxide composition and physical properties were examined by particle size analyser, BET test and X-Ray Diffraction (XRD) test. The BET surface areas of OPC, GGBS and UFGGBS were 1466, 2100 and 4968m
2/kg, respectively. Figure 1 shows the particle size distribution of OPC, GGBS and
UFGGBS. No crystalline phase was detected in the XRD results showing the high degree of reactivity of GGBS and UFGGBS. The coarse and fine aggregate used in this research were normal locally available aggregates, with the fine/coarse aggregate ratio of 1. The grading curve of the aggregates based on this ratio and the calculated upper and lower limits from ASTM C33/C33M [9] is shown in Figure 2. A polycarboxylate-based high range water reducing agent was added to obtain a concrete with optimum slump and workability.
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
Table 1: Materials Properties of OPC, GGBS and UFGGBS
OPC GGBS UFGGBS
Physical properties
Blaine Surface Area (m2/kg) 360 410 870
BET Surface Area (m2/kg) 1466 2100 4968
Particle Mean Diameter (µm) 15.96 9.21 4.09
Density(kg/m3) 3150 2720 2720
Oxide compositions (%)
SiO2 21.5 36 31.2
Al2O3 5.5 9 9
Fe2O3 4.5 1 1
CaO 63 44 35.1
SO3 2.5 1 0.1
MgO 2 8 11.8
Figure 1: Particle size analysis of OPC, GGBS and UFGGBS
Figure 2: Grading curve according to ASTM
0
1
2
3
4
5
6
7
8
9
10
0.1 1 10 100 1000
particle size (µm)
Volume(%)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%Grading Curve
ASTM Upper Limit
ASTM Lower Limit
0.15 0.3 0.6 1.18 2.36 4.75
Seive size
Percentage passing (%)
OPC
UFGGBS GGBS
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
2.2 Concrete Mix Design
Total of eight mixes were studied. The w/c ratio of the mixes was kept at 0.25 to limit the amount of water content and total cementitious materials. The total amount of cementitious materials in the mixes was around 580- 590 kg/m
3. Mix A was the control mix with 100% OPC. The rest of the mixes
maintained similar proportions to Mix A, albeit with different composition of the cementitious materials. Mixes B and C contained GGBS replacement of 45% and 60% respectively, whereas Mixes D, E and F had 30%, 45% and 60% UFGGBS replacement respectively. Mix G had a combination of 30% UFGGBS and 15% GGBS replacement. Mix J was an additional mix with a w/c ratio of 0.65. This mix will act as a control mix to analyse the heat of hydration versus commercially available normal strength concrete. The detailed mix proportions of the eight mixes are listed in Table 2.
Table2: Concrete mix proportions
Mix A B C D E F G J
Water/cementitious ratio 0.25 0.65
Aggregate/cementitious ratio
2.85 5
UFGGBS replacement (%)
0 0 0 30 45 60 30 0
GGBS replacement (%) 0 45 60 0 0 0 15 0
USF replacement (%) 0 0 0 0 0 0 0 0
Total cementitious materials (kg/m
3)
590 583 579 585 590 579 582 344
Coarse/fine aggregate ratio
1
Aggregate by weight ratio 0.69 0.75
2.3 Heat of Hydration
The setup for heat of hydration is shown in Figure 3. The test was carried out in an air-conditioned
room, maintained at 24 throughout the whole experiment. Using two fully sealed setups shown in
Figure 3 (a), the test was conducted in semi adiabatic condition. Using one setup as the calibration set to measure the rate of heat loss in various temperatures, the other setup was filled with fresh concrete with three samples to get the average reading for analysis. Each sample had a volume of 1 litre. The thermocouple type K was used to record the temperature. The wire was fixed in centre of each cell in a small plastic tube with internal diameter of 40 mm. As shown in Figure 3 (b), the tube was filled with oil to record the average temperature rather than localized temperature. The setups were fully sealed and covered during the experiment. The procedure was carefully controlled for all the eight casting to reduce the uncertainties in the results.
Using the data from the calibration set, the rate of heat loss subjected to temperature gradient of the environment was calculated with the Equation proposed below.
�� � ���� � 2����� � 24� (1)
where ��� is the initial stable measurement recorded from the calibration setup and r is the rate of heat loss per minute. Readings were taken at an interval of two minutes. The temperature of the room where the test was conducted was taken into account in the equation. Using the experimental data, the rate of heat loss was calculated to be r = 0.0011. As shown in Figure 4, Equation 1 is able to match the experimental results with a good approximation.
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
(b)
(a) (C)
Figure 3: (a) Overall setup for monitoring heat of hydration, (b) Thermocouple wire in plastic tube filled by oil, (c) inside view of hydration cell
Figure 4: Simulation of heat loss compared with experimental results
The rate of heat loss was used to calculate the total adiabatic temperature rise. This condition may simulate the centre of a thick concrete slab where the heat dissipation may not occur during the initial hours. The total adiabatic temperature rise was made up of two components: the delta temperature rise and cumulative heat loss of the concrete as shown in Equation 2 and Figure 5. The delta temperature was the temperature recorded by thermocouple wires minus the room temperature.
���� � �� � 24� � ∑ 2 � 0.0011 � �� � 24���� (2)
In which ���� is the adiabatic temperature at ��� measurement, �� is the actual temperature measured using thermocouple wire and �� � �� � 24� is the delta temperature rise.
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
0 20 40 60 80
Experimental data
Simulation
Temperature (°C)
Time (hours)
Thermocouple
in plastic tube
PVC pipe
Plastic Styrofoam
box
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
Figure 5: Relationship between adiabatic temperature rise, heat loss and delta temperature
The heat of hydration tests were conducted for the HPC mixes listed in Table 2. Two batches of the same superplasticizer were used to cast these mixes. However, the retardation period was not the same. In addition, the initial temperature of concrete was varied based on the time of date and casting. Therefore, the data’s were analyzed from start of temperature rise and were normalized to eliminate the initial variation in the temperature.
3 RESULTS AND DISCUSSIONS
3.1 Compressive strength results
The cube compressive strength results are summarised in Table 3. As shown in Table 3, except Mix C with 60% GGBS replacement, the other mixes have achieved similar or higher compressive strength compared to control Mix A with 100% OPC as early as 7 days water curing. The mixes with UFGGBS replacement achieved comparatively higher early and ultimate compressive strength as expected. The OPC replacement with GGBS and UFGGBS up to 60% had no negative effect on concrete compressive strength result.
Table 3: Cube compressive strength (MPa)
Mix Composition Curing age (days)
7 28 56 90
A 100% OPC 98 108 113 115
B 45% GGBS 98 110 116 117
C 60% GGBS 95 108 113 117
D 30% UFGGBS 108 112 116 116
E 45% UFGGBS 107 118 124 127
F 60% UFGGBS 98 113 115 120
G 30% UFGGBS+15% GGBS 110 117 125 128
3.2 Effect of GGBS on Heat of Hydration
The effect of GGBS replacement on heat of hydration was studied through the comparison of Mixes A, B, C and J. The compositions of the Mixes A, B and C were the same except for the amount
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0.00 10.00 20.00 30.00 40.00 50.00
Delta
Heat loss
Adibatic T
em
pe
ratu
re (
°C
)
Time (hours)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
of GGBS replacement. Mix B had 45% GGBS replacement and Mix C had 60% GGBS replacement. The delta temperature rise of the four mixes (Mixes A, B, C and J) are shown in Figure 6. Figure 7 shows the adiabatic temperature rise for the four mixes.
Comparing Mixes B and C with 45% and 60% GGBS replacement against Mix A with 100% OPC, there was a noticeable drop in the maximum delta temperature (peak temperature) of the concrete with the inclusion of GGBS. The reduction in the delta temperature was greater when the GGBS replacement level was increased. The inclusion of 60% GGBS replacement in Mix C achieved a delta
temperature of 10.9 which was comparable to the delta temperature of 10.1 recorded for Mix J.
As shown in Figure 7, the total amount of adiabatic temperature rise in the setup reduced with the increase in GGBS replacement. However, when compared to Mix J, the adiabatic temperature rise in Mix C with the highest amount of GGBS was noticeably higher than Mix J.
Figure 6: Delta temperature rise for Mixes A, B, C and J
Figure 7: Adiabatic temperature rise for Mixes A, B, C and J
0.0
5.0
10.0
15.0
20.0
25.0
0 10 20 30 40
OPC-340 kg/m3 cement
OPC-590 kg/m3 cement
45% GGBS
60% GGBS
Te
mp
era
ture
(°
C)
Time (hours)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0 10 20 30 40
OPC-340 kg/m3 cement
OPC-590 kg/m3 cement
45% GGBS
60% GGBS
Te
mp
era
ture
(°
C)
Time (hours)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
3.4 Effect of UFGGBS on Heat of Hydration
The effect of UFGGBS replacement on heat of hydration was investigated through the comparison of Mixes A, D, E, F and J. Mix D had 30% UFGGBS replacement, Mix E had 45% UFGGBS replacement and Mix F had 60% UFGGBS replacement. The delta temperature rise and adiabatic temperature rise of the mixes are shown in Figures 8 and 9 respectively.
Figure 8: Delta temperature rise for Mixes A, D, E, F and J
Figure 9: Adiabatic temperature rise for Mixes A, D, E, F and J
As shown in Figure 8, with the inclusion of UFGGBS, the delta temperature of the mixes were lower than that of the OPC control mix. As the replacement percentage was increased, the maximum delta temperature recorded was reduced. However even with a 60% UFGGBS replacement where the delta temperature recorded was the lowest among the mixes, the maximum temperature recorded
was still higher at 15 compared to Mix J at 10 . The adiabatic temperature rise for the different
mixes showed similar trend that with the increase in UFGGBS replacement, there was a reduction in the temperature rise as shown in Figure 9. The UFGGBS resulted in higher early compressive strength as early as seven days compressive strength yet the delta temperature rise and adiabatic temperature rise is considerably lower than 100% OPC Mix.
0.0
5.0
10.0
15.0
20.0
25.0
0 5 10 15 20 25 30 35 40
OPC-340 kg/m3 cement
OPC-590 kg/m3 cement
30% UFGGBS
45% UFGGBS
60% UFGGBS
Te
mp
era
ture
(°
C)
Time (hours)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0 10 20 30 40
OPC-340 kg/m3 cementOPC-590 kg/m3 cement30% UFGGBS45% UFGGBS60% UFGGBS
Te
mp
era
ture
(°
C)
Time (hours)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
3.3 Effect of GGBS Fineness on Heat Development
The effect of increased fineness of GGBS was investigated in this section through the comparison of Mixes B, C, E, F and G. Mixes B, E and G had 45% GGBS replacement of different fineness whereas Mixes C and F had 60% GGBS and UFGGBS replacement. Figures 10 and 11 show the delta temperature rise of the five mixes. Comparing Figures 10 and 11, the peak delta temperature rise of the UFGGBS mix was always higher than that of the GGBS mix when the replacement level was the same. It can be seen that the delta temperature rise was influenced by the fineness of GGBS in the mix. Mix G had 30% UFGGBS with 15% GGBS. Therefore the delta temperature rise was higher than that of Mix B with 45% GGBS replacement but lower than Mix E with 45% UFGGBS replacement.
Figure 10: Delta temperature rise for Mixes B, E and G
Figure 11: Delta temperature rise for Mixes C and F
Figures 12 and 13 present the adiabatic temperature rise of the five mixes. The total adiabatic temperature rise for both UFGGBS and GGBS at similar replacement level was the same. At 45%
replacement, the adiabatic temperature rise for Mixes B, E and G were around 33℃, whereas at 60%
replacement, the adiabatic temperature rise for Mixes C and F were around 28℃. The effect of GGBS fineness was mainly on the rate of temperature rise observed in Figures 12 and 13. The rate of temperature rise of Mixes E, F and G with UFGGBS replacement was sharp than the rate of temperature rise of Mixes B and C.
0.0
5.0
10.0
15.0
20.0
25.0
0 10 20 30 40
45% GGBS
45% UFGGBS
30% UFGGBS + 15% GGBS
Te
mp
era
ture
(°
C)
Time (hours)
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
0 10 20 30 40
60% GGBS
60% UFGGBS
Te
mp
era
ture
(°
C)
Time (hours)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
Figure 12: Adiabatic temperature rise for Mixed B, E and G
Figure 13: Adiabatic heat temperature rise for Mixes C and F
4 PREDICTION OF TEMPERATURE RISE IN CONCRETE HYDRATION
The data collected from the various heat of hydration tests analysed to predict the temperature rise in the concrete. The adiabatic condition assumed in this test setup may be considered to be the same as the centre of a thick concrete section, where the heat loss of the concrete at the centre is prevented by the surrounding concrete. Using the data, two empirical equations were proposed to predict the delta temperature rise and adiabatic temperature rise of a given concrete. In this study, the delta temperature was influenced by the degree of fineness of the GGBS. The degree of fineness of GGBS however has little or no influence on the adiabatic temperature rise of the concrete. The adiabatic temperature rise is influenced by the amount of individual cementitious materials present in the mix proportion. A linear relation between the cementitious materials content and temperature rise was assumed. The empirical equation predicting the adiabatic temperature rise and delta temperature rise are as follows:
�� � ��� � ��� (3)
�� � ��� � �� � � �!"� (4)
where:
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0 5 10 15 20 25 30 35 40
45% GGBS
45% UFGGBS
30% UFGGBS + 15% GGBSTe
mp
era
ture
(°
C)
Time (hours)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0 5 10 15 20 25 30 35 40
60% GGBS
60% UFGGBS
Te
mp
era
ture
(°
C)
Time (hours)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
Ta = Adiabatic temperature rise (°C)
Td = Delta temperature rise (°C)
C = Total OPC content (kg/m3)
S = Total GGBS content inclusive of UFGGBS (kg/m3)
NS = GGBS content (kg/m3)
FS = UFGGBS content (kg/m3)
A1, A2, D1, D2 and D3 were the empirical constants derived by minimising the squared summation of error as presented in Equations 5 and 6.
∑#$%&'�$( �� � *�$(�+,$( ���� -�$.(&
/0 (5)
∑#$%&'�$( �� � *�$(�+,$( ���� -�$.(&
/0 (6)
Where the concept of the best fit was considered to obtain the values of A1, A2, D1, D2 and D3 such that the squared summation of error would be minimised. Using Equations 5 and 6, the values of A1, A2, D1, D2 and D3 were 0.066, 0.041, 0.039, 0.025 and 0.006 respectively. Using the predicted values from the proposed equations, a correlation between the predicted delta temperature rise or the adiabatic temperature rise and the actual measured values were calculated. A correlation of 0.97 and 0.89 were obtained for the adiabatic temperature rise and delta temperature rise respectively. Figure 14 shows the plot of measured adiabatic temperature rise against the predicted values. The lowest and highest points in Figure 14 are belonging to Mix J “Grade 35 OPC” and Mix A “100% OPC”. Figure 15 shows the measured delta temperature rise against the predicted values.
Figure 14: Correlation between measured and predicted adiabatic temperature
R² = 0.967
20.0
25.0
30.0
35.0
40.0
20 25 30 35 40
Measured Adiabatic Temperature (°C)
Pre
dic
ted
Ad
iab
ati
c
Te
mp
era
ture
(°C
)
B. Sabet Divsholi, Darren T.Y. Lim and Susanto Teng
Figure 15: Correlation between measured and predicted delta temperature
5 CONCLUSIONS
The delta temperature rise and adiabatic temperature rise has linear relation with OPC content.
Both values were 1.7 times higher for Mix A compared to Mix J, where the OPC content is almost 1.7 times more for Mix A. Both GGBS and UFGGBS replacement resulted in reduced delta temperature and adiabatic temperature rise. The GGBS was more effective in reducing the delta temperature compared to UFGGBS replacement, however, the adiabatic temperature rise for GGBS and UFGGBS was almost the same for same amount of replacement. With increase in GGBS and UFGGBS replacement, the delta temperature rise and adiabatic temperature rise reduced noticeably. Two empirical equations were proposed to predict the temperature rise in hydration cylinder and adiabatic condition. Both equations can fairly predict the temperature rise.
Acknowledgment
The authors would like to acknowledge the research funding provided by National Research Foundation of Singapore (NRF) under CRP funded Project “Underwater Infrastructure and Underwater City of the Future”. GGBS was provided by EnGro Corporation Limited and the superplasticizer was provided by BASF South East Asia Pte Ltd.
References
[1] Sabet, D. B., Lim, D. T. Y. and Teng, S., “Ultra Durable Concrete for Sustainable Construction”, Advanced Materials Research, Vols. 368-373, 2012, pp 553-556. [2] Riding, K. A., Poole, J. L., Schindler, A. K., Juenger C. G. M. and Folliard, K. J., “Evaluation of Temperature Prediction Methods for Mass Concrete Members”, ACI Materials Journal 103 (5), 2006. [3] Texas Department of Transportation, “Specification 420,” June-July, 2004, pp. 494-527. [4] Lim, D. T. Y., Sabet, D. B. and Teng S., “In-situ Inspection of Ultra Durable Concrete Using Electrical Resistivity Technique”, Advanced Materials Research, Vols. 368-373, 2012, pp 1989-1992. [5] Aldea, C.-M., Cornelius, B., Balinski, J., Shenton, B., and Sato, J., “High-Volume Slag-Blended Cement Concrete for High-Density Concrete at Mid-Range Temperatures”,Special Publication. Volume: 263, 2009, pp. 95-110. [6] Kadri, E-H., Duval, R., Aggoun, S., and Kenai, S., “Silica Fume Effect on Hydration Heat and Compressive Strength of High-Performance Concrete”, ACI Materials Journal 106 (13), 2009. [7] Gjørv, O.E., Ngo, M.H., Sakai, K. and Watnabe, H., “Resistance Against Chloride Penetration of Low-Heat-High-Strength Concrete”, Proceedings, V. 3, Second International Conference on Concrete Under Severe Conditions: Environment and Loading, 1998, pp. 1827-1833. [8] Sarkar, S.L., “Roles of Silica Fume, Slag, and Fly Ash in the Development of High-Performance Concrete Microstructure”, ACI, Vol. 149, No. 25, 1994. [9] ASTM C33/C33M–08, Standard Specification for Concrete Aggregates, 2008.
R² = 0.89
10.0
15.0
20.0
25.0
10 15 20 25
Measured Delta Temperature (°C)
Pre
dic
ted
De
lta
Te
mp
era
ture
(°C
)
