锂渣高性能混凝土强度预测及圆环法早期抗裂性试验研究
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摘要
高性能混凝土早期收缩开裂是目前国内外的一个研究热点。为了充分利用新疆当地锂矿渣资源,我们用锂渣作为混凝土掺合料,来研究其在低水胶比下的力学特性。首先,在相同水胶比(0.3)和相同掺量(30%)条件下,以锂矿渣作为掺合料配制混凝土试件,通过试验优选出对强度贡献大的比表面积(950m2/kg)的锂渣。然后,在此基础上对水胶比为0.40、0.35、0.30、0.27以及锂渣掺量为0%、15%、20%、25%、30%、35%、和45%的混凝土强度特性进行了分析,并寻求出了最经济的锂渣掺量。采用上述试验数据,用人工神经网络对锂渣混凝土抗压强度做出了较为精确的预测,这为优化试验室配合比提供了技术保障。用圆环法测试比表面积为950m2/kg和水胶比为0.27条件下的各锂渣掺量对混凝土早期抗裂性影响。通过应变监测和裂缝观察的结果分析,得出影响混凝土早期抗裂性能的最佳锂渣掺量。最后,通过中试试验验证了锂渣混凝土具有较好的工程应用特性。通过研究发现：
(1)相同水胶比和相同掺量条件下,混凝土强度随锂渣比表面积的增大而增大,在比表面积为950m2/kg以后,不同龄期混凝土的抗压强度的增长率呈放缓趋势。
(2)影响混凝土强度的主要因素是水胶比、锂渣掺量、龄期。随水胶比的降低,同龄期混凝土的抗压强度逐渐增大,当水胶比降到0.27时,抗压强度增大较明显。
(3)相同条件下,锂渣掺量30%的混凝土的28d、90d抗压强度均大于等于掺量25%的混凝土的抗压强度；相比之下,掺量为35%、45%的混凝土的28d特征抗压强度降低不少。可见,30%锂渣掺量对混凝土强度来说是比较经济的掺量。
(4)采用低水胶比和合适的高效减水剂以及控制锂渣掺量的办法,可配制出满足一般工程要求的不同强度等级的高性能混凝土。尽管其早期强度稍有偏低,但中后期强度增幅明显,这得益于锂渣发挥了微集料填充作用和能增强中后期水化作用的功能。
(5)随着锂渣掺量的增加,试件裂缝数量和宽度明显减少,其最大裂缝宽度明显减小。但当掺量达到30%以后,其最大裂缝宽度又随其掺量的增加而增大,因此得出了锂渣混凝土抗裂的最佳锂渣掺量为30%。
Early shrinkage cracking of high performance concrete is a current hotspot of research at home and abroad.In order to make full use of local lithium-slag resources in Xinjiang,We use lithium slag as admixture of concrete kto research its the mechanical properties under low water binder ratio.First,we made concrete with lithium-slag under the premise of the same water binder ratio and the same dosage of lithium-slag and optimize lithium slag of surface area 950m2/kg which are large Contribution to the strength by test. On this basis,we analyze the concrete strength characteristics in the case that the water binder ratio are 0.4,0.35,0.3,0.27and lithium slag are15%,20%,25%,30%,35% and 45% respectively,and seek out the most economical lithium slag content.we have a more accurate prediction of concrete compressive strength by artificial neural network with the above experimental data,which provides technical support for optimizing mix of laboratory.Ring method test the influence of the dosage of lithium slag on its early-age anti-crak capability of concrete under the conditions of the same surface area (950m2/kg) and water binder ratio(0.27).We have obtained the best dosages of lithium slag which can resist early-age craking of concrete by monitoring concrete strain and observating concrete cracks. Good engineering prooerties of Lithium slag concrete has been verified by the pilot test at last.The research shows:
(1)with the increase of surface area of lithium slag,the compressive strength of concrete increase under the conditions of the same water binder ratio and the dosage of lithium slag;After more than surface 950m2/kg,the growth rate trend of concrete compressive strength of different ages is slower.
(2)The main facters affecting concrete strength:water binder ratio,the dosages of lithium slag,ages of concrete. With the decrease of water binder ratio,the concrete compressive strength in the same ages increase. Especially,when the water-binder ratio reached at 0.27, the changes is obviously.
(3)Under the same conditions,the lithium slag dosages30% of concrete compressive strength of the ages of 28days and 90days are greater than the dosages30%. In contrast,the 28days compressive strength of the lithiumslag dosages of 35%、45% are lower. Therefore,the lithium slag dosages of 30% is more economical for concrete compressive strength.
(4)With low water-binder ratio and proper super water reducing agent and control of slag content of lithium,making different strength grading high performanceconcrete which meet the requires of engineering. Although strength was low in the early period, the intensity became stronger later. It indicated that filling of the micro collection materials about lithium slag was more significant,and the hydrating performed obviously for the compressive strength in the later period.
(5)With the increase of the dosages of lithium slag,the crack width and numbers of specimens significantly reduced, and the maximum width of crack significantly decrease.But,after the lithium slag dosages of 30%,the maximum width of crack of concrete increase.Therefore, the 30%dosages of lithium slag is the best for early-age anti-crack capability of concrete.
(1)相同水胶比和相同掺量条件下,混凝土强度随锂渣比表面积的增大而增大,在比表面积为950m2/kg以后,不同龄期混凝土的抗压强度的增长率呈放缓趋势。
(2)影响混凝土强度的主要因素是水胶比、锂渣掺量、龄期。随水胶比的降低,同龄期混凝土的抗压强度逐渐增大,当水胶比降到0.27时,抗压强度增大较明显。
(3)相同条件下,锂渣掺量30%的混凝土的28d、90d抗压强度均大于等于掺量25%的混凝土的抗压强度；相比之下,掺量为35%、45%的混凝土的28d特征抗压强度降低不少。可见,30%锂渣掺量对混凝土强度来说是比较经济的掺量。
(4)采用低水胶比和合适的高效减水剂以及控制锂渣掺量的办法,可配制出满足一般工程要求的不同强度等级的高性能混凝土。尽管其早期强度稍有偏低,但中后期强度增幅明显,这得益于锂渣发挥了微集料填充作用和能增强中后期水化作用的功能。
(5)随着锂渣掺量的增加,试件裂缝数量和宽度明显减少,其最大裂缝宽度明显减小。但当掺量达到30%以后,其最大裂缝宽度又随其掺量的增加而增大,因此得出了锂渣混凝土抗裂的最佳锂渣掺量为30%。
Early shrinkage cracking of high performance concrete is a current hotspot of research at home and abroad.In order to make full use of local lithium-slag resources in Xinjiang,We use lithium slag as admixture of concrete kto research its the mechanical properties under low water binder ratio.First,we made concrete with lithium-slag under the premise of the same water binder ratio and the same dosage of lithium-slag and optimize lithium slag of surface area 950m2/kg which are large Contribution to the strength by test. On this basis,we analyze the concrete strength characteristics in the case that the water binder ratio are 0.4,0.35,0.3,0.27and lithium slag are15%,20%,25%,30%,35% and 45% respectively,and seek out the most economical lithium slag content.we have a more accurate prediction of concrete compressive strength by artificial neural network with the above experimental data,which provides technical support for optimizing mix of laboratory.Ring method test the influence of the dosage of lithium slag on its early-age anti-crak capability of concrete under the conditions of the same surface area (950m2/kg) and water binder ratio(0.27).We have obtained the best dosages of lithium slag which can resist early-age craking of concrete by monitoring concrete strain and observating concrete cracks. Good engineering prooerties of Lithium slag concrete has been verified by the pilot test at last.The research shows:
(1)with the increase of surface area of lithium slag,the compressive strength of concrete increase under the conditions of the same water binder ratio and the dosage of lithium slag;After more than surface 950m2/kg,the growth rate trend of concrete compressive strength of different ages is slower.
(2)The main facters affecting concrete strength:water binder ratio,the dosages of lithium slag,ages of concrete. With the decrease of water binder ratio,the concrete compressive strength in the same ages increase. Especially,when the water-binder ratio reached at 0.27, the changes is obviously.
(3)Under the same conditions,the lithium slag dosages30% of concrete compressive strength of the ages of 28days and 90days are greater than the dosages30%. In contrast,the 28days compressive strength of the lithiumslag dosages of 35%、45% are lower. Therefore,the lithium slag dosages of 30% is more economical for concrete compressive strength.
(4)With low water-binder ratio and proper super water reducing agent and control of slag content of lithium,making different strength grading high performanceconcrete which meet the requires of engineering. Although strength was low in the early period, the intensity became stronger later. It indicated that filling of the micro collection materials about lithium slag was more significant,and the hydrating performed obviously for the compressive strength in the later period.
(5)With the increase of the dosages of lithium slag,the crack width and numbers of specimens significantly reduced, and the maximum width of crack significantly decrease.But,after the lithium slag dosages of 30%,the maximum width of crack of concrete increase.Therefore, the 30%dosages of lithium slag is the best for early-age anti-crack capability of concrete.
引文
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[2]姚武.绿色混凝土[M].北京：化学工业出版社,2006：54-62.
[3]GSomerville.The Design Life of Structures[M].Edi.Blackie and Son Ltd.,1992:87-95.
[4]王庆霖.已有建筑物的可靠性评价与改造-苏联在这一领域的研究成果与经验[C].中国建筑学会建筑结构委员会第二届年会,南京,1991：198-202.
[5]Funahashi M.Predicating Concrete-free Service Life of a Concrete Struncture in a Chlorine Environment[J] ACI.Material Journal,1990:581-587.
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[8]Morinaga S. Prediction of Service Life Reinforced Concrete Buildings Based on the Corrosion Rate of Reinforcing Steel[C].Durability of Building Material and Components Proceedings of the 5th International Concrete Helded in Brighton, UK,1990:452-456.
[9]惠云玲.混凝土结构钢筋锈蚀耐久性损伤评估及寿命预测[J].工业建筑,1997(6)：58-62.
[10]Andrade C, et al.Cover Cracking As a Function of Rebar Corrosion [J].Material and Structures, 1993,26(163):453-464.
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[13]Munich.Thermal Cracking in Concrete at Early-Age [M]. The Publishing Company of RILEM, 1994:125-134.
[14]Cussion D, Repette W L. Early-age Cracking in Reconstructed ConcreteBridge Barrier Walls[J]. ACI Materials Journal,2000,97(4):438-446.
[15]Emborg M, Berander S.Assessment of Risk of Thermal Cracking in Hardening Concrete[J].ASCE Journal of Structural Engineering,1994,120(10):283-291.
[16]Altoubat S A, Lange D A. Early-age Stresses and Creep-Shrinkage Interaction of Restraint Concrete[R] New York, Technical Report of Research DOT 95-C-001,2001.
[17]张子明,郭兴文,杜荣强等.水化热引起的大体积混凝土墙应力与开裂分析[J].河海大学报,2002,30(5)：12-16.
[18]张士海,覃维祖,张涛等.混凝土早期抗裂性能评价-单轴约束试验方法的进展[J].混凝土与水泥制品,2002,(2)：13-16.
[19]Altoubat S A, Lange D A. Creep Shrinkage and Cracking of Restrained Concrete at Early Age[J]. ACI Materials Journal,2001,98(4):323-330.
[20]Munich.Prevention of Thermal Cracking in Concrete at Early Age[M].The Publishing Company of RILEM,1998:123-142.
[21]NevilAdam, AiticinPierre.High Performance Concrete-An overview[J].Materials and Structures, 1998(5):111-117.
[22]S.Lepage, M.Balbaki, E.Dallaire, P.C.Aiitcin.Early Shrinkage Development in A High Performance Concrete [J].Cement Concrete and Aggreagtes,1999,21(2):38-43.
[23]A.Radocea.Autogenous Volume Change of Concrete at Very Early Age[J].Maganine of Concrete Research.1998,50(2):63-69.
[24]巴恒静,高小建,杨英姿.高性能混凝土早期自收缩测试方法研究[J].工业建筑,2003,33(8)：43-48.
[25]S.P.Shah, C.Ouyang, S.Marikunte, W.Yang and B.GEmilie.A Method to Predict Shrinkage Cracking of Concrete[J].ACI Materials Journal.1998,95(4):78-86.
[26]D.Ravina, R.Shalon.Plastic Shrinkage Cracking of Concrete[J].ACI Materials Journal.1968,65(4).
[27]R.Bloom, A.Benture.Free and Restrained Shrinkage of Normal and High performance Concretes[J].ACI, Materials Journal,1995,92 (2):75-80.
[28]S.P.Shah, M.E.Karaguler. Effects of shrinkage-reducing admixtureson restrained shrinkage cracking of Concrete [J].ACI MaterialsJournal.1992,89(3):289-295.
[29]Karl.Wiegrink, Shashidhara.Marikunte.Shrinkage Cracking of high strength concrete[J]ACI, Materials Journal,1996,93(5):409-415.
[30]Surendra P.Shah, Chengsheng Quuang A Mathod to Predict Shrinkage Cracking of Concrete [J].ACI Material Journal,199,95 (4):339-346.
[31]David A.Whiting, Rachel J.Detwile.Cracking Tendency and Drying Shrinkage of Silica Fume Concrete for Bridge Deck Applications[J].ACI Materials Journal,2000,97(1):71-77.
[32]李亚杰.建筑材料[M].北京：中国水利水电出版社,2001,3,94-95.
[33]董长虹. MATLAB神经网络与应用[M].北京：国防工业出版社,2005,1,34-78.
[34]张德丰.MATLAB神经网络应用设计[M].北京：机械工业出版社,2009,1,14-96.
[35]朱凯,王正林.精通MATLAB神经网络[M].北京：电子工业出版社,2010,1,7-205.
[36]陈平雁.SPSS13.0统计软件应用教程[M].北京：人民卫生出版社,2009,5,173-189.
[37]李丽.高性能混凝土收缩与开裂规律的研究及机理分析[D].东南大学硕士学位论文,2004：8.
[38]王成启,金建昌.混凝土塑性收缩的试验研究[J].工程质量,2008(2)：40-43.
[39]郭奇.自密实混凝土制备方法及其收缩性能研究[D].北京工业大学硕士学位论文,2008,7.
[40]梁萍.混凝土塑性收缩裂缝成因及防裂措施研究综述[J].商品混凝土,2007(5)：25-29.
[41]桂海清.混凝土早期收缩与抗裂性能试验研究[D].浙江大学硕士学位论文,2004,6.
[42]马丽媛.高强混凝土收缩开裂的研究[D].北京：中国建筑材料科学研究院硕士学位论文,2005,7.
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[47]P.ShahC.uoyangete.A Method to Predit Shrinkage Cracking Characteristics of Concrete[J].ACI, Material Journal,1998,95 (4):339-346.
[48]张兰芳,陈剑雄.锂渣高强混凝土的试验研究[J].建筑与胶凝材料,2005(3)：29-31.
[2]姚武.绿色混凝土[M].北京：化学工业出版社,2006：54-62.
[3]GSomerville.The Design Life of Structures[M].Edi.Blackie and Son Ltd.,1992:87-95.
[4]王庆霖.已有建筑物的可靠性评价与改造-苏联在这一领域的研究成果与经验[C].中国建筑学会建筑结构委员会第二届年会,南京,1991：198-202.
[5]Funahashi M.Predicating Concrete-free Service Life of a Concrete Struncture in a Chlorine Environment[J] ACI.Material Journal,1990:581-587.
[6]牛荻涛.混凝土结构耐久性与寿命预测[M].北京：科学出版社,2003：3-7.
[7]Tuutti. Corrosion of Steel in Soncrete[J].CBI Forskning Research,1982:59-64.
[8]Morinaga S. Prediction of Service Life Reinforced Concrete Buildings Based on the Corrosion Rate of Reinforcing Steel[C].Durability of Building Material and Components Proceedings of the 5th International Concrete Helded in Brighton, UK,1990:452-456.
[9]惠云玲.混凝土结构钢筋锈蚀耐久性损伤评估及寿命预测[J].工业建筑,1997(6)：58-62.
[10]Andrade C, et al.Cover Cracking As a Function of Rebar Corrosion [J].Material and Structures, 1993,26(163):453-464.
[11]李金玉,曹建国.水工混凝土耐久性研究和应用[M].北京：中国电力出版社,2004：52-150.
[12]Reinhardt PE.Properties of Set Concrete at Early-Age State-of-Art-Reaport [J]Materials and Structures,1981,14 (84):399-402.
[13]Munich.Thermal Cracking in Concrete at Early-Age [M]. The Publishing Company of RILEM, 1994:125-134.
[14]Cussion D, Repette W L. Early-age Cracking in Reconstructed ConcreteBridge Barrier Walls[J]. ACI Materials Journal,2000,97(4):438-446.
[15]Emborg M, Berander S.Assessment of Risk of Thermal Cracking in Hardening Concrete[J].ASCE Journal of Structural Engineering,1994,120(10):283-291.
[16]Altoubat S A, Lange D A. Early-age Stresses and Creep-Shrinkage Interaction of Restraint Concrete[R] New York, Technical Report of Research DOT 95-C-001,2001.
[17]张子明,郭兴文,杜荣强等.水化热引起的大体积混凝土墙应力与开裂分析[J].河海大学报,2002,30(5)：12-16.
[18]张士海,覃维祖,张涛等.混凝土早期抗裂性能评价-单轴约束试验方法的进展[J].混凝土与水泥制品,2002,(2)：13-16.
[19]Altoubat S A, Lange D A. Creep Shrinkage and Cracking of Restrained Concrete at Early Age[J]. ACI Materials Journal,2001,98(4):323-330.
[20]Munich.Prevention of Thermal Cracking in Concrete at Early Age[M].The Publishing Company of RILEM,1998:123-142.
[21]NevilAdam, AiticinPierre.High Performance Concrete-An overview[J].Materials and Structures, 1998(5):111-117.
[22]S.Lepage, M.Balbaki, E.Dallaire, P.C.Aiitcin.Early Shrinkage Development in A High Performance Concrete [J].Cement Concrete and Aggreagtes,1999,21(2):38-43.
[23]A.Radocea.Autogenous Volume Change of Concrete at Very Early Age[J].Maganine of Concrete Research.1998,50(2):63-69.
[24]巴恒静,高小建,杨英姿.高性能混凝土早期自收缩测试方法研究[J].工业建筑,2003,33(8)：43-48.
[25]S.P.Shah, C.Ouyang, S.Marikunte, W.Yang and B.GEmilie.A Method to Predict Shrinkage Cracking of Concrete[J].ACI Materials Journal.1998,95(4):78-86.
[26]D.Ravina, R.Shalon.Plastic Shrinkage Cracking of Concrete[J].ACI Materials Journal.1968,65(4).
[27]R.Bloom, A.Benture.Free and Restrained Shrinkage of Normal and High performance Concretes[J].ACI, Materials Journal,1995,92 (2):75-80.
[28]S.P.Shah, M.E.Karaguler. Effects of shrinkage-reducing admixtureson restrained shrinkage cracking of Concrete [J].ACI MaterialsJournal.1992,89(3):289-295.
[29]Karl.Wiegrink, Shashidhara.Marikunte.Shrinkage Cracking of high strength concrete[J]ACI, Materials Journal,1996,93(5):409-415.
[30]Surendra P.Shah, Chengsheng Quuang A Mathod to Predict Shrinkage Cracking of Concrete [J].ACI Material Journal,199,95 (4):339-346.
[31]David A.Whiting, Rachel J.Detwile.Cracking Tendency and Drying Shrinkage of Silica Fume Concrete for Bridge Deck Applications[J].ACI Materials Journal,2000,97(1):71-77.
[32]李亚杰.建筑材料[M].北京：中国水利水电出版社,2001,3,94-95.
[33]董长虹. MATLAB神经网络与应用[M].北京：国防工业出版社,2005,1,34-78.
[34]张德丰.MATLAB神经网络应用设计[M].北京：机械工业出版社,2009,1,14-96.
[35]朱凯,王正林.精通MATLAB神经网络[M].北京：电子工业出版社,2010,1,7-205.
[36]陈平雁.SPSS13.0统计软件应用教程[M].北京：人民卫生出版社,2009,5,173-189.
[37]李丽.高性能混凝土收缩与开裂规律的研究及机理分析[D].东南大学硕士学位论文,2004：8.
[38]王成启,金建昌.混凝土塑性收缩的试验研究[J].工程质量,2008(2)：40-43.
[39]郭奇.自密实混凝土制备方法及其收缩性能研究[D].北京工业大学硕士学位论文,2008,7.
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