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1、A C 1 COMPX23 Xf = bb2949 0508135 8 T 1 CHEMICAL ADMIXTURES Compilation 23 American Concrete Institute Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:30:18 MSTNo reproduction or netwo
2、rking permitted without license from IHS -,-,- 3 8 13 20 25 30 34 A C 1 COMP*23 * 0662947 0508336 738 6 hem i cal Admixtures AC1 Compilation 23 Admixtures - Whats New on the Market, by John M. Scanlon 40 VAE Redispersible-Powder Hydraulic-Cement Ad- mixtures, by D. Gerry Walters 44 Organic-Based Cor
3、rosion-Inhibiting Admixture for Reinforced Concrete, by Charles K. Nmai, Stephen A. Farrington, and Gregory S. Bobrowski 48 Antifreeze Admixture Developed in Japan, by K. Sakai, H. Watanabe, H. Nomachi, and K. Hamabe 53 Control of Plastic Shrinkage Cracking in Cold Weather, by Ephraim Senbetta and M
4、ark A. Bury Antifreeze Admixtures for Cold Weather Con- creting, by Charles J. Korhonen and Edel R. Cortez 62 68 75 Cold Weather Admixture, by John W. Brook, David F. Factor, Frederick D. Kinney, and Asok K. Sarkar 79 A Non-Chloride Accelerating Admixture for Class CF Fy Ash, by John W. Brook, Reyno
5、ld A. Berkey, and Hamid Farzam Non-Chloride Accelerating Admixtures for Early Compressive Strength, by Ken Rear and David Chin Extended Mix Time Concrete, by Frank A. Kozeliski Sodium Thiocyanate and the Corrosion Potential of Steel in Concrete and Mortar, by Charles K. Nmai and Jack M. Corbo EtPI C
6、oncrete, by James M. Aldred Antiwashout Admixtures in Underwater Concrete, by Kenneth L. Saucier and Billy D. Neeley Cost-Effective Use of Superplasticizers, by Tom Guennewig AdmixtureXement Incompatibility: A Case History, by Colin D. Johnston Copyright American Concrete Institute Provided by IHS u
7、nder license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:30:18 MSTNo reproduction or networking permitted without license from IHS -,-,- A C 1 COMP* u) .- o - o 10 - - O 2 28-Day Compressive Strength I 20C -10“ c -5“ c 4 6 Mix Number 8 7-Day Compre
8、ssive Strength I 20C N -5“ c -10“ c 4 6 Mix Number 8 Fig. 1. - Compressive strength of 7 concrete mixes cured at 20, - 5, and - 10 C. weather can increase normal con- creting cost by 50 to 100 percent - concrete costing $160/m3 ($122/yd3) to place in forms in the summer would cost $240 to $320/m3 ($
9、183 to $245/yd3) in the winter. Based on material price, the cost of the chemicals for the dosages used in this study range from $16 to $30/m3 ($12 to $23/yd3), which represents a 16 to 30 percent increase to the price of ready-mixed concrete. Al- though the material costs do not fully represent end
10、-user cost, it should be evident that antifreeze admixtures can be cost-competitive with normal winter concreting prac- tices. Conclusions Antifreeze concrete can be cured at temperatures significantly below O C (32 F) without harming its perform- ance compared to that of normal concrete cured at ro
11、om tempera- ture. Of the antifreeze concrete mixes tested, those containing so- dium nitrite/calcium nitrite and so- 32 AC1 COMPILATION Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:
12、30:18 MSTNo reproduction or networking permitted without license from IHS -,-,- A C 1 COflP*23 * 0662949 0508Lb 248 = dium nitrite/potassium carbonate performed the best - they were es- sentially unaffected by the - 5 and - 10 C (23 and 14 F) temperatures used in this study. Even for those concretes
13、 whose strength lagged be- hind that of the control mix, the prognosis is that they will eventu- ally recover full strength when thawed. The effects of these admixtures on durability, corrosiveness, workabil- ity, and ice formation, and the eco- nomics of their use in portland ce- ment concrete, wil
14、l be investigated in the future. It is hoped that these tests will provide a basis from which to evaluate other antifreeze admix- tures as they become available. The evaluation must include the study of the interaction between antifreeze admixtures and other admixtures and other special cements gain
15、ing popularity today. Laboratory tests supported by field demonstrations are needed to develop this technol- ogy for the U.S. construction in- dustry. Further study References 1. Korhonen, C.J., “Antifreeze Admix- tures for Cold Regions Concreting: A Liter- ature Review,” Special Report No. SR 90-32
16、, U.S. Army Cold Regions Research and En- gineering Laboratory, Hanover, N.H., Sept., 1990 14 pp. 2. Mironov, S.A.; Lagoyda, A.V.; and Ukhov, Ye.N., “Curing Concrete with Chemical Additives in Freezing Weather,” 1976, Draft Translation No. 545, US. Army Cold Regions Research and Engineering Laborato
17、ry, Hanover, N.H., 9 pp. 3. Kukko, H., and Koskinen, I., “RILEM Recommendations for Concreting in Cold Weather,” Research Note No. 827, Techni- cal Research Centre of Finland (VTT), Con- crete and Silicate Laboratory, 1988, 178 pp. 4. Kivekas, L.; Houvinen, S.; and Leivo, M. “Concrete Under Arctic C
18、onditions,” Research Report No. 343, Technical Re- search Centre of Finland (VTT), Concrete and Silicate Laboratory, 1985, 62 pp. 5. Goncharova, L.S., and Ivanov, F.M., “The Properties of Concretes Containing Antifreeze Admixtures,” Proceedings, 2nd International Symposium on Winter Con- creting, Vo
19、l. l . , Stroiizdat, Moscow, 1975, pp. 69-71 (in Russian). 6. Grapp, A.A.; Grapp, V.B.; and Kap- lan, A.S., “The Structure and Cold Resis- tance of Concretes Containing Antifreeze Admixtures,” Proceedings, 2nd Interna- tional Symposium on Winter Concreting, Vol. l . , Stroiizdat, Moscow, 1975, pp. 6
20、0-68 (in Russian). 7. Kuzmin, Y.D., “Concretes with Anti- freeze Admixtures,” Budivelnik Publishing House, Kiev, 1976, 115 pp. 8. Korhonen, R., “Experimental Con- struction in Kilpisjarvi: Experience of Trans- portation of Frost Resistant Concrete,” Re- search Note No. 808, Technical Research Centre
21、 of Finland (VTT), Building Labora- tory, 1987,28 pp., (in Finnish). 9. Virmani, Y.P., “Time-to-Corrosion of Reinforcing Steel in Concrete Slabs,” Re- port No. FHWA/RD-88/165, Federal High- way Administration, Washington, D.C., 1988, 45 pp. 10. Mironov, S.A., and Demidov, V.D., “Cohesion of New Conc
22、rete with Old Con- crete under Winter Conditions,” Hydro- technical Construction (Gidroteknicheskoe Stroitelstvo), No. 1, 1978, pp. 16-18, (Translation from Plenum Publishing Cor- poration). Charles J. Korhonen is a Research Civil Engineer with the Civil and Geotec h n ical Engineer i ng Research Br
23、anch of the US. Army Corps of Engineers at the Cold Regions Research and Engineering Laboratory, Hanover, N.H. Edel R. Cortez is a Civil Engineer with the Civil and Geotechnical Engineering Research Branch of the U.S. Army Corps of Engineers at the Cold Regions Research and Engineering Laboratory, H
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25、nt param- eters controlling serviceability in elevated slabs. Elevated Slabs contains impor- tantinformation foundin articles on topics including tolerance conflicts two-way slabs, and shore and reshore scheduiing using a mimmputer. If you are involved with the design and/or construction of elevated
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28、t P.O. Box 19150ekrnit, MI 482194150 Tel. (313) 532-26000Fax 313-5334747 33 CHEMICAL ADMIXTURES Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:30:18 MSTNo reproduction or networking p
29、ermitted without license from IHS -,-,- A C 1 COMP*( w o Q) I c -.-. * L . . : - ._ m E k a 0 0 E 2000 I O00 O Doce. fl oz/cwt cement Fig. 2-Dose response with Class CF fly ash at 70 F: comDressive strenath. beams, which were tested using third point loading in accordance with ASTM C 78. Specimens f
30、or length change were cast as specified by ASTM C 157. These specimens were moist-cured for 14 days, including the period in the molds. Results and discussion The accelerator shortened the set time of air-entrained concrete made at 70 F (21 C) by 80 to 180 minutes as the dose was increased from 25 t
31、o 150 oz/lOO lb (1625 t,o 9750 mV100 kg) of cement plus fly ash (Fig. 1). Compressive strengths of the concrete mixes containing all three doses of the admixture were higher than the strengths of the plain concrete at 3, 7, and 28 days Y 150 F I Oz - -I- -O.04OL O 10 20 30 40 50 0 Time. days Fig. 4-
32、Dose response with Class CF fly ash at 70 F: length change. (Fig. 2); however, there was little or no increase in compressive strength as the admixture dose was in- creased. Flexural strength also increased with the addition of the admixture (Fig. 3). At 3 days, flexural strengths increased as the a
33、dmix- ture dose increased; at 7 and 28 days, however, the flexural strengths were equal for the two lower dose rates. The results of length-change measurements displayed in Fig. 4 indicate that the admixture had no deleterious effect on shrinkage through 56 days. The air-void structure of air-en- tr
34、ained concrete containing Class CF fly ash and the accelerating ad- mixture met the specifications put forth in ASTM C 457 (Table 2). Al- though the value for the specific surface of the air bubbles decreased somewhat at a dose rate of 100 oz/lOO Ib (6500 m1/100 kg) of ce- ment plus fly ash, the val
35、ues ob- tained for the specific surface and spacing factor were within the range specified for freeze-thaw durability. The effect of the admixture on the setting time and compressive strength of non-air-entrained con- crete containing Class CF fly ash made at 50 F (10 C) was also deter- mined; the r
36、esults are shown in Fig. 5 and 6. As shown in Fig. 5, accel- eration of both initial and final set increased with an increasing dose rate. The maximum acceleration, 4 hours in initial set and 5 VI hours in final set, was obtained with 125 oz/lOO Ib (8125 m1/100 kg) of ce- ment plus fly ash. As shown
37、 in Fig. 41 CHEMICAL ADMIXTURES Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:30:18 MSTNo reproduction or networking permitted without license from IHS -,-,- A C 1 COMPXZ3 X t R O662
38、949 Admixture, fl odcwt cement - 50 100 NVR, fl odcwt cement 1.62 2.23 2.50 Air, percent, by pressure meter 5.4 5.0 6.2 Air, percent, point count 3.0 2.8 6.0 Specific surface, in. (- i) lo00 870 657 Spacing factor, i n . 0.0059 0.0069 0.0061 LU I n i t i a l Set Final Set 150 2.19 5.6 3.1 0.0059 976
39、 Dose. fl oz/cwt cement Fig. 5-Dose response with Class CF fly ash at 50 F: set time. R 3 Day 7 Doy -I Ooo I 28 L9 56 Day 3 m o o 4 9000 Dose. f l oz/cwt cement Fig. 6-Dose response with Class CF fly ash at 50 F: compressive strength. 6, the greatest increase in 1-day compressive strength, 170 perce
40、nt of that of plain, was also obtained with 125 oz/lOO lb (8125 m1/100 kg) of cement plus fly ash. At 3 days, the compressive strengths obtained for all four dose rates were essentially equal, 1000 to 1200 psi (6.9 to 8.3 MPa) greater than the compressive strength of the plain concrete. At 7 days, t
41、he com- pressive strengths of all of the mixes were equal, and at later ages - 28 and 56 day - the compressive strength of the mix without admix- ture was somewhat higher. Additional evaluations showed that the admixture would also ac- celerate setting time and increase early strength of concrete mi
42、xes containing Class F or Class C fly ash at 50 F (10 C). With Class F fly 20 18 16 14 I D F 12 E IO ._ t- 48 m 6 4 2 O l n 0508377 250 rn I n i t i a l Set Final Set Dose. f I oz/cwt cement Fig. 7-Dose response with Class F fly ash at 50 F set time. ._ 11000 I I Day 3 Day 7 Doy 4 9000 Oml 28 Day 19
43、 56 Days E8000 7000 6000 g 5000 ? 4WO 5 3000 2000 1 O00 O cn ._ a u Dose. fI oz/cwt cement Fig. 8-Dose response with Class F fly ash at 50 F: comoressive strenath. ash, initial set was accelerated by 4 1/4 hours and final set by 5 3/4 hours at a dose rate of 150 oz/lOO Ib (9750 m1/100 kg) of cement
44、plus fly ash (Fig. 7). The 1-day compressive strengths were 200 and 300 percent of that of plain at 50 and 150 oz/lOO lb (3250 to 9750 m1/100 kg) of cement plus fly ash, respectively (Fig. 8). Similar results were obtained with Class C fly ash. Initial set was ac- celerated by 6 hours and final set
45、by 8% hours at 150 oz/lOO Ib (9750 mV100 kg) (Fig. 9), and 1-day com- pressive strengths were 310 and 430 percent of that of plain at 50 and 150 oz/lOO lb (3250 and 9750 m1/100 kg) of cement plus fly ash (Fig. 10). As with the concrete con- taining Class CF fly ash, the effect of the admixture on st
46、rength devel- opment continued to 7 days, and later-age strengths were somewhat 42 AC1 COMPILATION Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:30:18 MSTNo reproduction or networkin
47、g permitted without license from IHS -,-,- A C 1 COMPx23 t X m Obb29Y9 0508178 197 m ” I I n i t i a l Set 3 Final Cet :t 16 L 14 . i2 I- 10 I % L E ._ 4 6 4 2 O Plain 50 150 Dose. l oz/cut cement Fig. 9-Dose response with Class C fly ash at 50 F: set time. lower in concrete containing the ad- mixtu
48、re. A reduction in compressive strength at later ages is often ob- served for concrete mixes to which an accelerating admixture has been added. As a result, concrete that contains an .accelerating admixture meeting the specifications for ASTM C 494, Type C, needs to have only 90 percent of the com-
49、pressive strength of the reference mix after 28 days.3 Therefore, in situations where it is desired to have concrete with higher later-age strengths, one can add more cement or fly ash or reduce the water-ce- mentitious ratio by using admix- tures meeting ASTM C 494 Type A (water-reducing) or Type F (high- range water-r