Improving Early Crack Resistance of Concrete by Shrinkage-Reducing Polycarboxylate Superplasticizer

Abstract

Abstract: Shrinkage-reducing polycarboxylate superplasticizer (SRPC) is a new type of concrete admixture with both shrinkage-reducing and water-reducing effects.Its early crack resistance to concrete will affect its application in engineering. In this paper, the effect of SRPC on the early crack resistance of concrete was investigated and compared with polycarboxylate superplasticizer (PCE) and shrinkage reducing agent of low molecular weight (SRA) by using a flat crack resistance tester. Moreover, surface tension of solution, shrinkage of concrete, pore structure of cement slurry, and cement hydration heat were analyzed to discuss the anti-cracking mechanism of SRPC. Experimental results show that SRPC improved the early crack resistance of concrete. When 0.15% (mass fraction) SRPC and 1.5% (mass fraction) SRA are added to the concrete, although the former’s shrinkage effect is not as good as SRA, SRPC still show better early crack resistance. Compared with PCE, the cracked areas of SRPC and SRA are reduced by 39.33% and 21.34%, respectively. Mechanism analysis show that SRPC reduce the shrinkage of concrete by reducing the surface tension of the pore solution and changing the pore structure, which is similar to SRA. Furthermore, compared with SRA, SRPC also delay the rate of cement hydration, reduce the heat of early hydration, inhibit the evaporation of water inside the concrete, thereby improving the early crack resistance of concrete.

Key words: concrete, polycarboxylate superplasticizer, early crack resistance, shrinkage reduction, cement hydration, mechanism of action

CLC Number:

TQ172.1

ZHANG Jian, MAO Qianjin, WANG Ziming, HUANG Lina, CUI Suping. Improving Early Crack Resistance of Concrete by Shrinkage-Reducing Polycarboxylate Superplasticizer[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(10): 3359-3365.

References

[1] 王子明,李慧群.聚羧酸系减水剂研究与应用新进展[J].混凝土世界,2012(8):50-56.
WANG Z M, LI H Q. New progress in the research and application of polycarboxylate water-reducing agents[J]. China Concrete, 2012(8): 50-56 (in Chinese).
[2] ZHANG Y R, KONG X M, GAO L, et al. Rheological behaviors of fresh cement pastes with polycarboxylate superplasticizer[J]. Journal of Wuhan University of Technology-Mater Sci Ed, 2016, 31(2): 286-299.
[3] HUANG H L, QIAN C X, ZHAO F, et al. Improvement on microstructure of concrete by polycarboxylate superplasticizer (PCE) and its influence on durability of concrete[J]. Construction and Building Materials, 2016, 110: 293-299.
[4] ZHANG Y R, KONG X M. Correlations of the dispersing capability of NSF and PCE types of superplasticizer and their impacts on cement hydration with the adsorption in fresh cement pastes[J]. Cement and Concrete Research, 2015, 69: 1-9.
[5] 钱晓倩,詹树林,方明晖,等.减水剂对混凝土收缩和裂缝的负影响[J].铁道科学与工程学报,2004,1(2):19-25.
QIAN X Q, ZHAN S L, FANG M H, et al. Negative influence of superplasticisers on shrinkage and cracking of concrete[J]. Journal of Railway Science and Engineering, 2004, 1(2): 19-25 (in Chinese).
[6] 谢韬,钱晓倩,胡超凡,等.减水剂掺量对混凝土早期收缩的影响及调控机制研究[J].混凝土,2020(8):15-18.
XIE T, QIAN X Q, HU C F, et al. Influence of superplasticiser on early shrinkage of concrete and its regulation mechanism[J]. Concrete, 2020(8): 15-18 (in Chinese).
[7] 周乐,张欣,关乾坤.聚羧酸减水剂在绿色混凝土中的力学性能[J].沈阳大学学报(自然科学版),2020,32(6):516-522.
ZHOU L, ZHANG X, GUAN Q K. Mechanical properties of polycarboxylate superplasticizer in green concrete[J]. Journal of Shenyang University (Natural Science), 2020, 32(6): 516-522 (in Chinese).
[8] 王子明,路芳.减缩型聚羧酸系高性能减水剂的现状与发展前景[N].中国建材报,2014-09-22(005).
WANG Z M, LU F. Current status and development prospects of shrinkage-reduced polycarboxylic acid-based high-performance water-reducing agents[N]. China Building Materials News, 2014-09-22(005) (in Chinese).
[9] 方绪顺,徐小平,陈国新,等.减缩型聚羧酸系减水剂的合成及性能研究[J].长江科学院院报,2015,32(12):134-138.
FANG X S, XU X P, CHEN G X, et al. Synthesis and performance of shrinkage-reducing polycarboxylate superplasticizer[J]. Journal of Yangtze River Scientific Research Institute, 2015, 32(12): 134-138 (in Chinese).
[10] 路芳,熊卫锋.减缩型聚羧酸减水剂对水泥基材料收缩性能的影响[J].混凝土,2014(5):91-92+96.
LU F, XIONG W F. Effect of shrinkage-reducing polycarboxylate superplasticizer on cement-based materials shrinkage performance[J]. Concrete, 2014(5): 91-92+96 (in Chinese).
[11] MARUYAMA I, TANIMURA M, MITANI Y, et al. Control of cracking in full-scaled columns made of ultra-high-strength concrete[J]. Materials and Structures, 2015, 48(6): 1627-1643.
[12] PARK S H, RYU G S, KOH K T, et al. Effect of shrinkage reducing agent on pullout resistance of high-strength steel fibers embedded in ultra-high-performance concrete[J]. Cement and Concrete Composites, 2014, 49: 59-69.
[13] LU Z C, KONG X M, LIU H, et al. Interaction of silylated superplasticizers with cementitious materials[J]. Journal of Applied Polymer Science, 2016, 133(43): 44161.
[14] WU L M, FARZADNIA N, SHI C J, et al. Autogenous shrinkage of high performance concrete: a review[J]. Construction and Building Materials, 2017, 149: 62-75.
[15] 顾越,冉千平,舒鑫,等.硅烷改性聚羧酸减水剂对水泥-硅灰浆体分散性能影响及机理[J].功能材料,2015,46(12):12087-12091.
GU Y, RAN Q P, SHU X, et al. Influence of silanized polycarboxylate superplastizers on fluidity of cement-silica fume pastes and its mechanism[J]. Journal of Functional Materials, 2015, 46(12): 12087-12091 (in Chinese).
[16] 沙胜男,史才军,向顺成,等.聚羧酸减水剂的合成技术研究进展[J].材料导报,2019,33(3):558-568.
SHA S N, SHI C J, XIANG S C, et al. The state-of-the-art synthesis techniques of polycarboxylate superplasticizer[J]. Materials Reports, 2019, 33(3): 558-568 (in Chinese).
[17] 李银斌,阮欣.机制砂混凝土抗裂性能试验研究[J].中外公路,2013,33(5):248-251.
LI Y B, RUAN X. Experimental study on the anti-cracking performance of machine-made sand concrete[J]. Journal of China & Foreign Highway, 2013, 33(5): 248-251 (in Chinese).
[18] 曹立学,郭君华,张磊,等.混凝土早期抗裂性能测试方法综述[J].硅酸盐通报,2020,39(10):3078-3089.
CAO L X, GUO J H, ZHANG L, et al. Review of test methods for early crack resistance of concrete[J]. Bulletin of the Chinese Ceramic Society, 2020, 39(10): 3078-3089 (in Chinese).
[19] 胡红梅,刘冬冬,余彬彬.外加剂对混凝土抗裂性能影响的试验研究[J].福建建材,2011(9):1-3+13.
HU H M, LIU D D, YU B B. Experimental study on the influence of admixtures on the anti-cracking performance of concrete[J]. Fujian Building Materials, 2011(9): 1-3+13 (in Chinese).
[20] 李悦,阮大威.不同外加剂对混凝土抗裂性能的影响[J].混凝土,2014(5):52-56.
LI Y, RUAN D W. Influence of different admixture on crack resistance of the concrete[J]. Concrete, 2014(5): 52-56 (in Chinese).
[21] MAO Q J, MA J F, WANG Z M, et al. Shrinkage reduction of cement-based materials containing polycarboxylate superplasticiser[J]. Magazine of Concrete Research, 2021, 73(5): 217-227.