Specific features of the present invention is:
One, the proportioning of cement, preparation and performance
1. the proportioning of cement
The proportioning of low-heat portland cement of the present invention is: cement clinker 〉=90%, gypsum≤10%.Wherein said high belite grog is the described grog of CN 1193613A, its C
2S content is not less than 40%, and gypsum is dihydrate gypsum, anhydrite or chemical gypsum.
Usually be controlled at initial set 〉=45min the time of coagulation of low-heat portland cement, final set≤10h, the grinding specific surface area of cement is controlled at 250~500m
2Between/the kg.
2. the preparation of cement
The preparation technology's flow process and the general purpose portland cement of low-heat portland cement are basic identical, the key distinction of the two preparation aspect is three aspects, first aspect is the mineral composition and the technology of preparing difference of grog, this sets forth in patent CN 1193613A, second aspect is a cement grinding requirement difference, one of key of low-heat portland cement grinding technology is the relation between coordinated development of control strength of cement and the cement heat release, make cement have higher intensity and lower aquation calorific value, it is high-strength that the third aspect is that low-heat portland cement that this patent relates to has characteristic-low-heat that other silicate cement do not possess, promptly do not need the admixture blended material can realize the low hydration heat of cement equally, simultaneously can proof strength high approximately 1-2 the strength grade of more similar low heat cement (10MPa).In addition, because the grindability of cement clinker is relatively poor, if adopt the grinding process condition of common manufacture of cement, the mill output fall can be up to 20~30%, therefore need determine the grinding fineness of cement according to strength of cement grade and hydration heat level, need adjust the steel ball grating in the grinding machine for this reason, suitably reduce the big nodule number 10~30% in the existing cement grinding mill corase grind storehouse, increase the steel hop count 10~30% in the fine grinding storehouse, to improve the mill efficiency of grinding machine effectively to cement clinker.
3. the performance of cement
(1) needs water-based and flowability
Low-heat portland cement is compared with general purpose portland cement has lower standard consistency water requirement (seeing Table 1), and the former is generally between 21.5~24.0%, and the latter is many between 24.0~27.5%.Under identical water cement ratio, the mortar degree of mobilization of low-heat portland cement is also apparently higher than general purpose portland cement, and low-heat portland cement is generally at 130~140mm, and general purpose portland cement is many between 120~130mm.These are indicating that all low-heat portland cement has better workability.
The basic physicals of table 1 cement
Specimen coding | Specific surface area m
2/kg
| Fineness % | Mark thick water requirement % | Mortar degree of mobilization mm | Time of coagulation (min) | Ultimate compression strength, MPa |
Initial set | Final set | 3d | 7d | 28d | 3m | 6m | 1y |
HBC | 364 | 4.4 | 22.0 | 137 | 2:42 | 3:53 | 4.4/ 20.5 | 5.9/ 30.7 | 8.6/ 59.8 | 10.5/ 80.6 | 11.0/ 87.9 | 11.1/ 90.9 |
PC | 367 | 2.8 | 27.3 | 121 | 2:33 | 3:34 | 6.4/ 38.4 | 7.6/ 51.3 | 8.3/ 61.5 | 9.0/ 69.6 | 9.6/ 70.3 | 9.4/ 74.5 |
Annotate: HBC-low-heat portland cement, PC-silicate cement
(2) with the adaptability of admixture
Compare with general purpose portland cement, the high-performance low-heat portland cement has better adaptability (seeing Table 2) to concrete admixture, during the admixture ordinary water-reducing agent, the clean slurry degree of mobilization of low-heat portland cement improves 10% than general purpose portland cement, increase rate is bigger during the admixture high efficiency water reducing agent, can reach 40~60%.These represent that all low-heat portland cement has better workability.
The clean slurry of cement was mobile when table 2 was mixed different admixture
Admixture | CLS | UNF-5 | JFL-5 | FDN |
Volume, * C% | 0.2 | 0.7 | 0.7 | 0.7 |
Water cement ratio, W/C | 0.35 | 0.29 | 0.29 | 0.29 |
Clean slurry degree of mobilization mm | PC | 174 | 172 | 178 | 108 |
HBC | 192 | 270 | 250 | 181 |
Annotate: CLS is wooden calcium retardation water reducing agent, and all the other are naphthalene series high-efficiency water-reducing agent.
(3) strength property
The strength development rule of low-heat portland cement and general purpose portland cement as shown in Figure 1 under the foster condition of mark.Although (1~7d) is relatively low for the low-heat portland cement early anti pressured intension, but the later strength rate of increase is big, 28d intensity promptly reaches more than the 52.5Mpa, and the development of intensity after this keeps higher increasing degree, the ultimate compression strength of low-heat portland cement is more than the 80MPa during to 3 months length of time, than with the high about 10MPa of label general purpose portland cement.The difference of 6 months the two ultimate compression strength during to 1 age period is more than 15MPa.
Low-heat portland cement is better than general purpose portland cement on strength property another notable feature is that the former has higher folding strength or higher bending and compressive strength ratio.As shown in Table 1, two kinds of cement are under the suitable condition of 28d folding strength, more than the high 1.5MPa of general purpose portland cement of the folding strength in 3~12 months length of time of low-heat portland cement than the corresponding length of time.
This 28d intensity of low-heat portland cement is suitable with general purpose portland cement, and later strength has determined it more to help guaranteeing the stable and reliable of cement concrete later stage performance far above the strength development rule of general purpose portland cement.
The low-heat portland cement that with the low hydration heat is one of notable feature will be mainly used in mass concrete and high-strength concrete etc., so the strength property of low-heat portland cement directly has influence on its application prospect under the temperature condition.Table 3 is low-heat portland cement and the intensity results of general purpose portland cement under different curing and blending amount of mixture material.Wherein HBC and PC are respectively the not low-heat portland cement and the general purpose portland cement of any blended material of admixture, and HBC-15 and PC-20 are respectively the low-heat portland cement and the general purpose portland cement of admixture 15% slag and 20% flyash.
Strength of cement mortar (MPa) under the table 3 different curing condition
Specimen coding | HBC | HBC-15 | PC | PC-20 |
Hydration age | 1d | 3d | 7d | 28d | 1d | 3d | 7d | 28d | 1d | 3d | 7d | 28d | 1d | 3d | 7d | 28d |
20 ℃ of marks are supported | 6.0 | 19.6 | 29.4 | 57.5 | 5.9 | 18.8 | 30.4 | 54.6 | 13.4 | 35.3 | 46.0 | 57.8 | 10.1 | 28.1 | 42.3 | 60.8 |
38 ℃ of water are supported | 16.1 | 30.8 | 42.9 | 62.8 | 18.5 | 34.8 | 45.4 | 64.4 | 30.7 | 42.1 | 47.0 | 52.7 | 23.8 | 36.6 | 42.8 | 54.3 |
50 ℃ of water are supported | 20.1 | 38.3 | 54.3 | 68.7 | 23.8 | 43.6 | 58.5 | 70.1 | 31.5 | 42.0 | 46.5 | 48.6 | 26.0 | 38.2 | 45.0 | 48.9 |
60 ℃ of water are supported | 22.8 | 46.1 | 62.9 | 70.3 | 34.5 | 56.3 | 70.8 | 70.8 | 33.7 | 39.2 | 40.8 | 50.8 | 29.5 | 42.2 | 48.2 | 47.0 |
70 ℃ of water are supported | 29.6 | 54.2 | 71.7 | 73.9 | 39.5 | 63.0 | 74.1 | 75.0 | 37.0 | 42.9 | 49.3 | 45.5 | 31.5 | 44.4 | 44.5 | 45.9 |
Rising along with curing temperature, 1~3d intensity of four kinds of cement all presents rising tendency, wherein two class cement intensity are suitable substantially with the amplitude of temperature increase during 1d, and 3d during the length of time general purpose portland cement increase with temperature, the amplification of its intensity is very little, and the intensity of low-heat portland cement then continues to increase; During to the 7d hydration age, along with the increase of curing temperature, general purpose portland cement intensity no longer increases, and 28d then presents downtrending the length of time, and the intensity of low-heat portland cement continues to present the trend of rising the length of time with the increase of curing temperature at 7~28d.
When the admixture blended material carried out modification to cement, the strength property of general purpose portland cement (PC-20) was compared the change that essence does not take place with former cement (PC), and both intensity differences are apart from very little.Low-heat portland cement (HBC-15) more former cement (HBC) on the hot strength performance then has some improvement.
Therefore low-heat portland cement is compared with general purpose portland cement has superior hot strength characteristic, has broad application prospects under mass concrete, high-strength concrete, steam-curing concrete goods, summer high temperature construction and high temperature environment for use.
(4) hydration heat
Low hydration heat is the notable feature that low-heat portland cement is different from general purpose portland cement.Table 4 has been listed the hydration heat testing data of low-heat portland cement (HBC) with general purpose portland cement (PC), moderate-heat portland cement (MHC), as shown in Table 4, reach in 28d intensity under the condition of peer-level, the hydration heat of low-heat portland cement is but very low, 3, the 7d hydration heat is lower by 15~20% than moderate-heat portland cement, and is more morely lower than the aquation calorific value of general purpose portland cement.
Table 4 hydration heat test-results
Cement type | 1d | 2d | 3d | 4d | 5d | 6d | 7d |
HBC | 159 | 181 | 196 | 208 | 219 | 227 | 234 |
PC | / | / | 247 | / | / | / | 289 |
MHC | 201 | 233 | 248 | 257 | 265 | 272 | 278 |
(5) wear-resisting and shrinkage performance
The wear loss of low-heat portland cement and contract with dry rate have reached the road corresponding prescribed value of silicate cement national standard (28d wear loss≤3.60kg/m in the length of time
2Contract with dry rate≤0.10%), and compare with general purpose portland cement, the contract with dry rate of low-heat portland cement significantly reduces, be 50~60% of general purpose portland cement contract with dry rate only, thereby guaranteed that the low-heat portland cement concrete has good volume stability.(the results are shown in Table 5)
Wear-resisting and the shrinkage performance of table 5 low-heat portland cement
Specimen coding | 28 days wear loss kg/m
2 | Contract with dry rate, % |
7 days | 14 days | 28 days | March | June |
PC | - | 0.060 | 0.083 | 0.103 | 0.115 | 0.096 |
HBC | 1.96 | 0.030 | 0.042 | 0.057 | 0.058 | 0.057 |
(6) chemical resistance of concrete performance
Low-heat portland cement is compared with general purpose portland cement, has better chemical resistance of concrete ability, as at 3%Na
2SO
4Maintenance is in the time of 6 months in the solution, its anti-corrosion coefficient still remain on 1.00 in addition higher level on, and the under equal conditions anti-corrosion coefficient of general purpose portland cement is below 0.60, and this explanation low-heat portland cement has excellent sulphate-corrosion resistance can (seeing Table 6).
The corrosion-resistant property contrast of table 6 low-heat portland cement and general purpose portland cement
Specimen coding | Anti-erosion coefficient (rapid method, 1 * 1 * cm tries body) |
3 times of seawater 3%Na
2SO
4 5%MgCl
2 |
28 days | March | June | 28 days | March | June | 28 days | March | June |
PC | 0.898 | 0.735 | 0.796 | 0.979 | 0.561 | 0.594 | 0.785 | 0.794 | 0.845 |
HBC | 0.939 | 0.813 | 0.854 | 1.158 | 1.079 | 1.072 | 0.843 | 0.910 | 0.861 |
Two, concrete preparation and utilisation technology
The concrete that utilizes low-heat portland cement of the present invention to substitute the ordinary Portland cement preparation has that water requirement is low, good with admixture adaptability, concrete slump through the time advantage such as loss little, later strength rate of increase height, good endurance.Except that being used to prepare the normal concrete, also can be used for preparing high-strength concrete, steam-curing concrete, mass concrete, concrete for hydraulic structure etc., its performance is as follows:
1. prepare high performance concrete with low-heat portland cement
High performance concrete at first should have high workability, this mainly by check the concrete slump and through the time change and estimate, test-results sees Table 7.Can obviously find out the difference of two kinds of workability of concrete energy by test, when identical water cement ratio, the initial slump of the two quite or the low-heat portland cement concrete slightly high, difference is apparent that slump-loss the most, adopt the concrete slump-loss of low-heat portland cement preparation much smaller than the general purpose portland cement concrete, the ordinary Portland cement concrete need increase water cement ratio just can reach the initial slump same with the low-heat portland cement concrete, and concrete mix slump-loss is bigger after 2 hours, lose flowability, serviceability is relatively poor.
Table 7 is mixed the concrete workability of high efficiency water reducing agent
The cement type | Cement consumption, kg/m
3 | W/C | The high efficiency water reducing agent kind | Volume % | The initial slump, cm | The 90min slump, cm | The 120min slump, cm |
HBC | 480 | 0.36 | UNF-5 | 1.0 | 20.2 | 16.8 | |
PC | 480 | 0.36 | UNF-5 | 1.0 | 20.2 | 11.2 | |
HBC | 550 | 0.31 | UNF-5 | 1.2 | 22.7 | 20.8 | |
PC | 550 | 0.31 | UNF-5 | 1.2 | 20.4 | 14.8 | |
HBC | 480 | 0.35 | WDN-7 | 1.0 | 22.0 | | 19.0 |
PC | 480 | 0.43 | WDN-7 | 1.0 | 22.0 | | 2.0 |
HBC | 550 | 0.30 | WDN-7 | 1.2 | 22.0 | | 22.0 |
PC | 550 | 0.38 | WDN-7 | 1.2 | 22.0 | | 1.0 |
Annotate: fine aggregate is a medium sand, fineness modulus 2.70; Coarse aggregate is a rubble, particle diameter 5~20mm.
The concrete strength development rule of the high flowability of admixture high efficiency water reducing agent the results are shown in Table 8, concrete strength development rule and cement testing result are basic identical, be that concrete early strength is lower than the ordinary Portland cement concrete, both are suitable substantially for 28 days intensity, concrete strength then improved 5~10Mpa than Portland cement concrete (PCC) in 90 days, in addition, low-heat portland cement late strength of concrete (after 28 days) rising tendency is obvious, and the gain in strength later in 28 days of ordinary Portland cement concrete is slow.
The strength development of table 8 chutable concrete
Cement type | Proportioning | Cement consumption kg/m
3 | The high efficiency water reducing agent volume, % | The initial slump, cm | The 2h slump, cm | Ultimate compression strength, MPa |
3d | 7d | 28d | 90d |
HBC | 1∶2.03∶2.81∶0.45 | 380 | 0.8 | 21.0 | 19.5 | 32.4 | 44.6 | 72.8 | 88.9 |
OPC | 1∶2.03∶2.81∶0.48 | 380 | 0.8 | 24.0 | 5.5 | 50.3 | 63.0 | 72.1 | 76.8 |
HBC | 1∶1.41∶2.30∶0.35 | 480 | 1.0 | 22.0 | 19.0 | 34.6 | 46.6 | 77.9 | 89.6 |
OPC | 1∶1.41∶2.30∶0.36 | 480 | 1.0 | 23.0 | 2.0 | 54.0 | 63.8 | 78.8 | 82.8 |
HBC | 1∶1.15∶2.04∶0.30 | 550 | 1.1 | 22.0 | 22.0 | 43.0 | 53.5 | 77.1 | 88.5 |
OPC | 1∶1.15∶2.04∶0.31 | 550 | 1.1 | 25.0 | 1.0 | 57.3 | 67.5 | 72.3 | 78.4 |
2. with low-heat portland cement preparation large volume concrete for hydraulic structure
(1) mechanical property
The low-heat portland cement concrete test (SD105-82) carries out according to " concrete for hydraulic structure testing regulation ", and test-results sees Table 9,10.Compare with the moderate-heat portland cement concrete, low-heat portland cement concrete early anti pressured intension is lower, but intensity increases rapidly after 7 days, concrete strength all is higher than the moderate-heat portland cement concrete during the 28 day length of time, later long-age intensity had bigger growth higher by 10~30% than moderate-heat portland cement concrete in 28 days, and also had the trend that continues growth.
Table 9 concrete mix
Numbering | Water-cement ratio W/ (C+F) | Sand coarse aggregate ratio Sp (%) | Flyash (%) | Admixture and volume | Every cubic meter of concrete starting material consumption (Kg/m
3)
|
High efficiency water reducing agent (%) | Air entrapment agent (/ ten thousand) | C+F (gelling material) | W (water) | S (sand) | A (aggregate) |
HBC | 0.55 | 0.30 | 0 | - | - | 231.0+0 | 127.0 | 621.5 | 455.0+455.0+ 300.0+300.0 |
MHC |
HBC-20 | 0.35 | 0.33 | 20 | 0.60 | 0.60 | 290.5+72.5 | 127.0 | 612.5 | 712.5+582.5 |
MHC-20 |
HBC-30 | 0.45 | 0.26 | 30 | 0.60 | 0.65 | 133.8+57.2 | 86.0 | 655.0 | 497.5+497.5+ 330.0+330.0 |
MHC-30 |
HBC-40 | 0.55 | 0.28 | 40 | 0.60 | 0.60 | 98.2+61.7 | 85.0 | 607.5 | 490.0+490.0+ 325.0+325.0 |
MHC-40 |
Annotate: (1) HBC is a low-heat portland cement, and MHC is 525
#Moderate-heat portland cement.
The concrete compression and tensile strength of low-heat portland cement, Young's modulus and limit stretch value all will be higher than the moderate-heat portland cement concrete, illustrate that the low-heat portland cement concrete makes moderate progress on toughness than the moderate-heat portland cement concrete.
Table 9 mechanical performance of concrete
Cement type | The slump, cm | Tensile strength, MPa | Ultimate compression strength/split tensile strength MPa | Resistance to compression bullet mould, GPa | Limit stretch value, * 10
-4 |
28d | 90d | 7d | 28d | 90d | 180d | 28d | 90d | 28d | 90d |
HBC | 7.5 | 3.76 | 3.97 | 13.0/ 1.09 | 49.3/ 3.03 | 58.8/ 3.80 | 63.0/ 3.77 | 30.1 | 35.0 | 1.37 | 1.28 |
PC | 4.7 | 2.51 | 3.14 | 24.1/ 1.79 | 40.4/ 2.60 | 47.6/ 3.20 | 48.9/ 3.40 | 29.8 | 33.9 | 1.04 | 1.17 |
HBC-20 | 7.5 | 3.22 | 3.58 | 21.0/ 1.39 | 57.0/ 3.20 | 71.6/ 4.28 | 79.2/ 4.90 | 32.0 | 37.3 | 1.09 | 0.98 |
MHC-20 | 5.5 | 2.95 | 3.49 | 37.3/ 2.61 | 51.0/ 3.01 | 60.9/ 3.79 | 69.3/ 4.29 | 31.6 | 35.8 | 0.94 | 1.14 |
HBC-30 | 6.4 | 2.68 | 3.18 | 9.20/ 0.78 | 36.1/ 2.49 | 53.1/ 3.59 | 59.4/ 3.95 | 28.8 | 35.3 | 1.01 | 1.08 |
MHC-30 | 4.7 | 2.30 | 3.02 | 26.0/ 1.82 | 35.4/ 2.41 | 46.2/ 2.99 | 52.9/ 3.61 | 30.4 | 34.7 | 0.99 | 1.03 |
HBC-40 | 6.7 | 1.85 | 2.74 | 1.50/ 0.33 | 19.5/ 1.73 | 35.8/ 2.56 | 44.5/ 3.57 | 24.9 | 32.1 | 0.69 | 0.80 |
MHC-40 | 4.5 | 1.79 | 2.42 | 13.6/ 1.01 | 21.9/ 1.63 | 32.3/ 2.56 | 39.5/ 2.87 | 24.1 | 30.5 | 0.80 | 0.92 |
(2) frost resistance
Freezing and thawing performance adopts the quick-freeze method, the results are shown in Table 10.Standard code: when relative dynamic Young's modulus drop to 60% or rate of weight loss reach 5% or relatively the weather resistance index be less than or equal to 60% freezing-thawing cycles, be the freeze proof label of test specimen.As can be seen from the test results, the low-heat portland cement concrete behind 300 freeze-thaw cycle, its relative dynamic elastic modulus (P
n%), mass loss rate (W
n%), all significantly better than the moderate-heat portland cement concrete.
Table 10 concrete antifreezing melts performance test (quick-freeze method)
Number of freezing and thawing | HBC-30 | MHC-30 | HBC-40 | MHC-40 |
P
n%/W
n%
| P
n%/W
n%
| P
n%/W
n%
| P
n%/W
n%
|
50 | 95.13/0.04 | 93.04/0.07 | 93.20/0.52 | 82.99/0.36 |
100 | 93.46/0.18 | 91.61/0.28 | 91.11/1.25 | 46.82/0.96 |
150 | 92.85/0.28 | 89.33/0.39 | 86.97/2.01 | |
200 | 92.65/0.47 | 87.11/0.55 | 80.85/2.56 | |
250 | 90.63/0.65 | 83.14/0.77 | 69.04/3.26 | |
300 | 90.49/0.89 | 82.26/0.95 | | |
(3) impermeability
The permeability resistance test is undertaken by GB GBJ82-85, the results are shown in Table 11.Test-results shows: the concrete anti-permeability performance of low-heat portland cement is better than the moderate-heat portland cement concrete, and this raising for its anti-steel bar corrosion performance is very favorable.
Table 11 concrete impermeability test
The cement kind | W/C | Cement consumption kg/m
3 | Doping quantity of fly ash, % | Air content % | Slump cm | 28d ultimate compression strength, MPa | Depth of penetration, mm |
HBC | 0.55 | 231 | - | 1.1 | 7.5 | 49.3 | 34 |
PC | 0.55 | 231 | - | 1.1 | 4.7 | 40.4 | 62 |
HBC-20 | 0.35 | 363 | 20 | 4.6 | 7.5 | 57.0 | 24 |
PC-20 | 0.35 | 363 | 20 | 4.7 | 5.5 | -51.0 | 26.7 |
(4) anti-carbonization
The check of low-heat portland cement concrete anti-carbonation properties adopts GBJ82~85 methods to carry out, and the results are shown in Table 12.Suitable with silicate cement from the carbonization coefficient with the concrete anti-carbonation properties of carbonation depth numerical value low-heat portland cement, because the adding of high efficiency water reducing agent increases concrete density, intensity improves, so the concrete anti-carbonation properties of the low-heat portland cement of admixture high efficiency water reducing agent is more better.
Table 12 concrete anti-carbonation properties
The cement type | Proportioning cement: sand: stone | W/C | Slump cm | To specific tenacity MPa | Carbonation intension MPa | The carbonization coefficient | Carbonation depth mm |
3d | 7d | 14d | 28d |
HBC |
| 1∶1.74∶2.96 | 0.48 | 9.0 | 66.3 | 64.4 | 0.96 | 2.6 | 3.0 | 3.8 | 5.1 |
PC | 1∶1.74∶2.96 | 0.51 | 7.0 | 63.7 | 61.2 | 0.96 | 3.0 | 3.8 | 4.9 | 5.9 |
HBC | 1∶1.15∶2.04 | 0.31 | 20.0 | 87.9 | 86.1 | 0.97 | 1.6 | 2.0 | 2.5 | 3.1 |
PC | 1∶1.15∶2.04 | 0.30 | 22.0 | 86.0 | 82.6 | 0.96 | 1.9 | 2.3 | 3.0 | 3.6 |
(5) anti-steel bar corrosion
Low-heat portland cement Concrete Resist Reinforcing Steel Corrosion test method adopts " steel bar corrosion accelerated test procedures " among the GB8076-97 (new sand cutting slurry method), and test-results is seen Fig. 2.According to the current potential-time curve of low-heat portland cement, prolongation in time, the reinforcing bar anode potential of low-heat portland cement mortar does not have obvious reduction, belongs to Passivation Curve, shows that anode rebar surface passive film is intact.Comprehensive low-heat portland cement and concrete basicity, chloride diffusion coefficient and carbonization test evaluation result prove that low-heat portland cement has good the steel protection property.
(6) resistance to fouling
China does not also have the standard test method of concrete resistant to chemical etching at present, when low-heat portland cement concrete resistant to chemical etching performance test is designed, consider that concrete is in opposing sulphate attack under the constant load in the buildings actual motion environment, it is higher to corrode concentration simultaneously, taked low-heat portland cement Sulfate Resistance of Concrete energy test method under high density etching medium and the loading condition, infusion method and drying and watering cycle method are adopted in sulphate attack.Test-results sees Table 13.
Under the accelerated test condition of high density, alternation of wetting and drying circulation and these several complex factors of loading action, the low-heat portland cement concrete shows very excellent sulphate-corrosion resistance energy.
Cement anti-erosion test-results Kp under the table 13 high density loading condition
Cement type | The Kp that drying and watering cycle is 10 times | 80000mg/l soaks 2 months Kp |
Unstressed | 40% stress | Unstressed | 40% stress |
MHC | 17.5 | 18.5 | 42.5 | 46.1 |
HBC | 87.1 | 96.0 | 103.5 | 85.2 |
(7) thermal insulation warming
The concrete thermal insulation warming of low-heat portland cement is Model Calculation routinely, has obtained its thermal insulation warming curve, and contrasts with the moderate heat cement concrete, the results are shown in Figure 3.Show as calculated, under identical conditions of mixture ratios, the calculating thermal insulation warming of High Belite Cement Concrete is lower, it only is moderate heat cement concrete 70%, concrete thermal insulation warming is descended 5~6 ℃, and as seen, High Belite Cement Concrete helps reducing dam concrete temperature inside stress and reduces the possibility that thermal cracking produces, and might simplify the temperature control measures of water conservancy project mass concrete, improve speed of application.
From above test-results as can be seen, over-all properties with the large volume concrete for hydraulic structure of low-heat portland cement preparation is better than the moderate-heat portland cement concrete, its characteristics are: the later strength height, good fluidity, slump-loss is little, and performances such as freeze proof, impervious, anti-erosion, anti-steel bar corrosion all are better than the concrete for hydraulic structure with the moderate-heat portland cement preparation.