天然砂资源匮乏，机制砂是比较适宜的替代材料。自密实轻骨料混凝土具有免振捣、轻质高强的特点。采用机制砂配置自密实轻骨料混凝土，其相关研究刚起步，工作性能及力学性能研究并不全面，微观形貌、微观孔隙、混凝土破坏形式和损伤演化规律尚未明确。因此，本文以机制砂自密实轻骨料混凝土为研究对象，进行自密实性能试验、力学试验和微观试验，建立细观力学模型，从三个尺度阐释机制砂自密实轻骨料混凝土自密实性、力学特性、微观形貌以及变形破坏机理损伤演化。为这种新型建筑材料应用到大跨结构、高层及超高层结构中提供试验依据和理论支持。主要研究内容及结论如下：

（1）本文将固定砂石体积法和改进的全计算法相结合进行配合比设计，通过正交试验法，选取机制砂用量系数、水胶比和轻骨料用量系数三个因素，进行三因素三水平的设计。通过设计的9组配合比探究原材料用量对机制砂自密实轻骨料混凝土的自密实性能和龄期立方体抗压强度的变化规律的影响，并对基准配合比进行优化。

（2）研究粗细骨料对机制砂自密实轻骨料混凝土工作性能的影响规律。分别采用河砂、不同级配的机制砂、碎石和不同级别的轻骨料进行工作性能试验，得出采用轻骨料替代碎石骨料，可提高混凝土拌合物的填充性，机制砂替代河砂可提高拌合物的间隙通过性，且轻骨料级别越高，混凝土拌合物的抗离析性越好，硬化后混凝土中的骨料分布越均匀。

（3）对设计的三种强度等级的机制砂自密实轻骨料混凝土进行基本力学性能试验，探究机制砂自密实轻骨料混凝土基本力学参数随养护时间的变化规律，探究立方体抗压强度与劈裂抗拉强度、轴心抗压强度和抗折强度间的内在联系，以及测试机制砂自密实轻骨料混凝土应力-应变曲线。研究表明，三种强度等级的机制砂自密实轻骨料混凝土力学强度均达标，并且能够减轻混凝土四分之一的自重，其破坏模式是典型的脆性破坏。

（4）对三种不同强度等级的机制砂自密实轻骨料混凝土进行电子显微镜扫描、核磁共振、XRD物象分析等微观试验，重点研究其微观形貌和微观孔隙结构，结果表明，轻骨料吸水返水特性形成的内养护作用使得混凝土具有良好的过渡界面。通过对孔结构分析，结果表明机制砂自密实轻骨料混凝土强度等级越高，总孔隙率越小。

（5）采用Python编写二维骨料随机分布的脚本，将其导入ABAQUS软件建立混凝土随机骨料模型模拟混凝土的压缩破坏试验，得到机制砂自密实轻骨料混凝土的应力-应变曲线，并与试验值进行比较，验证细观力学模型模拟的合理性，在此基础上探究粗骨料形状对其应力-应变曲线的影响，结果表明：骨料形状对混凝土弹性模量和峰值应力的影响很小，对下降段曲线的影响较大。通过混凝土细观模拟的损伤应力云图，观察到最终破坏模式和试验试块破坏模式一致，以及混凝土内部损伤演化的全过程，从细观层面揭示机制砂自密实轻骨料混凝土的破坏过程。

Machine-made sand is a suitable material to replace scarce natural sand resources. Free-vibration, light-weight and high-strength are the characteristics of self-compacting concrete. Fixed sand volume method and improved total calculation method were adopted in this research, and manufactured sand self-compacting lightweight aggregates concrete were prepared. Correlated researches on working and mechanical properties of new concrete are still relatively lacking. Therefore, self-compacting performance test, mechanical test and micro test are carried out in this paper. The self-compacting properties, mechanical properties, micro morphology, deformation and failure mechanism and damage evolution of manufactured sand self-compacting lightweight aggregate concrete (MSLC) with manufactured sand are analyzed in multiple scales. The main research contents and conclusions are as follows:

(1) In this paper, the fixed sand volume method and the improved full calculation method are combined to design the mix ratio. Through the orthogonal experiment method, three factors are selected: Factor three-level design. Through the designed 9 sets of mix ratios, the influence of the amount of raw materials on the self-compacting performance of machine-made sand self-compacting lightweight aggregate concrete and the change law of the age cube compressive strength was explored, and the benchmark mix ratio was optimized.

(2) Study the influence of coarse and fine aggregates on the performance of machine-made sand self-compacting lightweight aggregate concrete. Using river sand, machine-made sand of different grades, crushed stone and different grades of lightweight aggregates to carry out work performance tests, it is concluded that the use of lightweight aggregates instead of crushed stone aggregates can improve the filling performance of the concrete mixture. Substituting river sand can improve the interstitial passability of the concrete mixture, and the higher the level of lightweight aggregate, the better the segregation resistance of the concrete mixture, and the more uniform the aggregate distribution in the concrete after hardening.

(3) Carry out cube compression test, split tensile test, axial compression test and flexural test for the designed self-compacting lightweight aggregate concrete of machine-made sand with three strength levels to explore the self-compacting lightweight aggregate concrete of machine-made sand The basic mechanical parameters of concrete change with curing time, the internal relationship between cubic compressive strength and split tensile strength, axial compressive strength and flexural strength, and the stress-strain curve of self-compacting lightweight aggregate concrete with machine-made sand . Research shows that the mechanical strength of self-compacting lightweight aggregate concrete with machine-made sand of three strength grades all meet the standard, and can reduce a quarter of the weight of the concrete, and its failure mode is a typical brittle failure.

(4) The self-compacting lightweight aggregate concrete with machine-made sand of three different strength grades was subjected to microscopic tests such as electron microscope scanning, nuclear magnetic resonance, XRD image analysis, etc., focusing on the study of its microscopic morphology and microscopic pore structure. The results showed that the lightweight aggregate The internal curing effect formed by the characteristics of water absorption and return water makes the concrete have a good transition interface. Through the analysis of the pore structure, the results show that the higher the strength grade of self-compacting lightweight aggregate concrete with machine-made sand, the lower the total porosity.

(5) Use Python to write a script for the random distribution of two-dimensional aggregates, import it into the ABAQUS software to establish a concrete random aggregate model to simulate the compression failure test of concrete, and obtain the stress-strain curve of self-compacting lightweight aggregate concrete with machine-made sand, and compare it with The experimental values are compared to verify the rationality of the mesomechanical model simulation. On this basis, the influence of the shape of the coarse aggregate on its stress-strain curve is explored. The results show that the shape of the aggregate has a great influence on the elastic modulus and peak stress of concrete. If it is small, it will have a greater impact on the descending curve. Through the damage stress cloud diagram simulated by the concrete meso-level, it is observed that the final failure mode is consistent with the failure mode of the test block, and the whole process of the internal damage evolution of the concrete, revealing the failure process of the machine-made sand self-compacting lightweight aggregate concrete from the meso level.

[1]陈家珑. 机制砂行业现状与展望[J]. 砂石，2010(6): 9-12.

[2]朱俊利，朗学刚，贾希蛾. 机制砂生产现状与发展[J]. 矿治，2001(4)：38-42.

[3]中华人共和国国家质量监督检验检疫总局，中国国家标准化管理委员会. GB/T 14684-2011. 建筑用砂[S]. 北京：中国标准出版社, 2011.

[4]胡蝶. 机制砂混凝土的工作性能、力学性能及抗氯离子侵蚀性能研究[D]. 广州大学，2018.

[5]吴涛，岳志豪，王洁，等. 自密实高性能轻骨料混凝土的研究[J]. 硅酸盐通报，2016，35(07)：2224-2229.

[6]李秉正. 轻骨料对机制砂自密实混凝土性能影响研究[D]. 重庆交通大学，2018.

[7]王建军. 机制砂和石粉在山西晋中地区商品混凝土中的应用研究[D]. 兰州理工大学，2018.

[8]陈家珑，周文娟. 我国人工砂的发展与问题探讨[J]. 建筑技术，2007，38(11)：849-852.

[9]华冬梅，刘旬. 机制砂混凝土特性和应用前景分析[J]. 建材发展导向，2018，16(12)：77-79.

[10]罗欢，王新，庞怀. 人工砂与河沙混凝土相关性能比对实验研究[J]. 房地产导刊，2015，(5).

[11]葛卫. 机制砂在高性能混凝土中的应用[J]. 价值工程，2017，36(30)：147-148.

[12]黄碧青. 绿色建材机制砂在混凝土中应用研究[J]. 绿色环保建材，2019(08)：23.

[13]孙铁石. 美国的建筑骨料现状[J]. 建材工业信息，1989(9)：12.

[14]石新桥. 机制砂在高性能混凝土中的应用研究[D]. 天津：天津大学，2007.

[15]韦庆东，冷发光，周永样，等. 国内外机制砂和机制砂高强混凝土应用现状[R] “全国特种混凝土技术及工程应用”学术交流会登2008年混凝土质量专业委员会年会，2008.

[16]杨文烈，邸春福. 机制砂的生产及在混凝土中的应用[J]. 混凝土，2008(6)：113-1.

[17]孙水涛. 机制砂及其混凝土的应用研究[D]. 成都：西南交通大学，2010.

[18]Prakash. Nanthagopalan. Contribution of steel fibers to the strength characteristics of lightweight concrete slab column connections failing in punching shear[J]. ACI Structural Journal, 1993, 8(2): 342-355.

[19]B.Menadi. Strength and durability of concrete incorporating crushed limestosand[J]. Construction and Building Materials .2009, 02: 625-633.

[20]Skaropoulou, G.Kakali, S.Tsivilis. Thaumasite form of sulfate attack in limestone cement concrete: The effect of cement composition, sand type and exposure temperature[J]. Construction and Building Materials, 2012, 36.

[21]Thomas Schmidt, Barbara Lothenbach, Michael Romer, etal. Scrivener Physical and microstructural aspects of sulfate attack on ordinary and limestone blended Portland cements[J]. Cement and Concrete Research.2009(12)

[22]马显红. 机制砂高性能混凝土配合比设计及质量控制[J]. 贵州大学学报(自然科学版)，2012，29(2)：136-140.

[23]张胜，周以林. 基于正交试验的机制砂混凝土配合比设计与研究[J]. 地下空间与工程学报，2013，9(05)：1097-1102.

[24]Yeol Choi, Jae-Hyuk Choi. A Comparative Study of Concretes Containing Crushed Limestone Sand and Natural Sand[J]. Open Journal of Civil Engineering, 2013, 03(01).

[25]鲁浩，李固华，杨家伟，等. 机制砂混凝土研究现状与存在问题分析[J]. 四川建材，2014，40(01)：3-4+6.

[26]Jiliang Wang, Zhifeng Yang, Yihan Liu. Effects of the lithologic character of manufactured sand on properties of concrete[J]. Journal of Wuhan University of Technology-Mater. Sci. Ed. 2014, 29(6).

[27]丁海峰，程建铝. 花岗岩机制砂混凝土的性能研究及应用[J]. 铁道科学与工程学报，2016，13(04)：682-688.

[28]申爱琴，张敬，樊莉，等. 高寒山区C40机制砂混凝土耐久性能[J]. 江苏大学学报(自然科学版)，2018，39(01)：115-119.

[29]Bhaskar Sangoju, G. Ramesh, B. H. Bharatkumar, etal. Evaluation of Durability Parameters of Concrete with Manufacture Sand and River Sand[J]. Journal of The Institution of Engineers (India)，2017，(98): 267-275.

[30]杨海峰，蒋家盛，李德坤，等. 机制砂再生混凝土基本力学性能与微观结构分析[J]. 硅酸盐通报，2018，37(12)：3946-3950.

[31]P. O. Awoyera, S. Karthik, P. R. M. Rao, R. Gobinath. Experimental and numerical analysis of large-scale bamboo-reinforced concrete beams containing crushed sand[J]. Innovative Infrastructure Solutions, 2019, 4(1).

[32]梁凯，陈正，朱惠英，等. 基于正交试验的机制砂混凝土抗压强度线性预测模型[J]. 混凝土，2019(11)：98-101+110.

[33]宋少民，程成，杨楠. 机制砂岩性对胶砂和混凝土性能影响的研究[J]. 混凝土，2019(09)：67-70.

[34]Kiran M. Mane, D. K. Kulkarni, K. B. Prakash. Performance of various pozzolanic materials on the properties of concrete made by partially replacing natural sand by manufactured sand[J]. Journal of Building Pathology and Rehabilitation, 2019, 4(22): 61-69.

[35]冯滔滔，蒋金洋，刘志勇，等. 机制砂超高性能混凝土的冲击压缩力学性能[J]. 硅酸盐学报，2020，48(08)：1177-1187.

[36]刘家慧，刘立新. 机制砂高强混凝土强度和弹性模量试验研究[J]. 建筑结构，2020，50(15)：96-99+57.

[37]袁大伟，杨萃娜. 轻骨料混凝土的研究现状分析及定义探讨[J]. 混凝土，2011(06)：26-28.

[38]Yun Wang Choi,Yong Jic Kim,Hwa Cheol Shin,etal. An experimental research on the fluidity and mechanical properties of high-strength lightweight self-compacting concrete[J]. Cement and Concrete Research, 2004, 36(9).

[39]辛全仓，张殿明，王振军，等. 自密实轻骨料混凝土配合比设计研究[J]. 公路，2007(05)：158-160.

[40]张云国，吴智敏，张小云，等. 自密实轻骨料混凝土的工作性能[J]. 建筑材料学报，2009，12(01)：116-120.

[41]王玉梅，刘锡军. 自密实轻骨料混凝土配合比设计及基本力学性能试验[J]. 混凝土，2012(06)：111-113.

[42]吴熙，江佳斐，范兴朗，等. 自密实轻骨料混凝土的高温性能[J]. 材料科学与工程学报，2014，32(03)：313-317.

[43]Savaş Erdem. X-ray computed tomography and fractal analysis for the evaluation of segregation resistance, strength response and accelerated corrosion behaviour of self-compacting lightweight concrete[J]. Construction and Building Materials, 2014, 61.

[44]董健苗，聂浩，燕元晶，等. 剑麻纤维增强自密实轻骨料混凝土力学性能的研究[J]. 新型建筑材料，2016，43(08)：89-91.

[45]Michael I. Kaffetzakis, Catherine G. Papanicolaou. Bond behavior of Reinfor- cement in Lightweight Aggregate Self-Compacting Concrete[J]. Construction and Building Materials, 2016, 113.

[46]张虎. 自密实钢纤维轻骨料混凝土的早期性能与损伤分析[J]. 材料导报，2017，31(20)：124-128.

[47]张向冈，陈停伟，杨健辉，等. 不同自密实轻骨料混凝土的强度及耐久性能影响因素分析[J]. 硅酸盐通报，2019，38(04)：962-968.

[48]Hasan Salehi, Moosa Mazloom. Opposite effects of ground granulated blast-urnace slag and silica fume on the fracture behavior of self-compacting lightweight concrete[J]. Construction and Building Materials, 2019, 222.

[49]杨健辉，刘梦，蔺新艳，等. 不同种类轻骨料混凝土的耐久性能比较[J]. 工业建筑，2020，50(02)：113-118+149.

[50]吴涛，杨雪，刘喜. 钢-聚丙烯混杂纤维自密实轻骨料混凝土性能研究[J/OL]. 建筑材料学报：1-14[2021-04-12].

[51]李杰林，周科平，张亚民，等. 基于核磁共振技术的岩石孔隙结构冻融损伤试验研究[J]. 岩石力学与工程学报，2012，31(06)：1208-1214.

[52]王萧萧，申向东，王海龙，等. 盐蚀-冻融循环作用下天然浮石混凝土的抗冻性[J]. 硅酸盐学报，2014，42(11)：1414-1421.

[53]Wang XiaoXiao, Shen XiangDong, Wang HaiLong, etal. Nuclear magnetic resonance analysis of concrete-lined channel freeze-thaw damage[J]. Journal of the Ceramic Society of Japan, 2015, 123(1433).

[54]刘光廷，王宗敏. 用随机骨料模型数值模拟混凝土材料的断裂[J]. 清华大学学报(自然科学版)，1996(01)：84-89.

[55]Walraven. J. C, Reinhardt. H. W, Theory and experiments on the mechanieal behavior ofcracks in plain and reforced concrete subject to shear loading[J]. HERON, 1991,26(lA):26-35.

[56]宋玉普. 多种混凝土材料的本构关系和破坏准则[M]. 中国水利水电出版社. 2002，12.

[57]过镇海. 混凝土的强度和本构关系一原理与应用[M]. 中国建筑工业出版社. 2004，03.

[58]彭一江，应黎坪. 再生混凝土细观分析方法[M]. 科学出版社，2018,9.

[59]田梦云，张恩，曹瑞东，路国运. 基于细观尺度的混凝土单轴力学性能仿真计算分析[J]. 应用力学学报，2020,37(03)：975-981+1384.

[60]金浏，杨旺贤，余文轩，杜修力. 基于细观模拟的轻骨料混凝土动态压缩破坏及尺寸效应分析. 工程力学，2020，37(03)：56-65.