微细钢纤维磷酸镁水泥砂浆力学性能及罩面修复试验

发布时间：2018-03-05 07:05

本文选题：磷酸镁水泥　切入点：快硬早强　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：修复破损路(道)面时,通常的做法是在原有路面上作(钢纤维)混凝土罩面加铺层,对于一些特殊道面诸如机场跑道、重要桥面等,更需快速抢修尽快通车。磷酸镁水泥具有凝结硬化快、早期强度高、在低温下(零下20°)仍可水化、耐高温性好、与旧混凝土的黏结性能优异、施工方便等优点。微细钢纤维相较于普通钢纤维,单位体积掺量下纤维根数更多,在混凝土基体中的分布更均匀且不易结团,尺寸更小,更适合修复工程。本文基于微细钢纤维优良改性作用和磷酸镁水泥独特性能,配制微细钢纤维磷酸镁水泥砂浆(Micro-fine Steel Fibre Reinforced Magnesia-Phosphate-Cement Mortar,简称MSFRMM),研究其力学性能和罩面修复混凝土路面板性能。本文开展工作如下:(1)磷酸镁水泥(Magnesia-Phosphate-Cement,简称MPC)的配制,研究了硼砂和复合两种缓凝剂下水胶比(W/C)、氧化镁与磷酸盐的物质的量比(M/P)及缓凝剂掺量对凝结时间与抗压强度的影响。(2)MSFRMM的力学性能,探究缓凝剂种类及掺量、水胶比、胶砂比、龄期和纤维掺量对抗压、抗折等基本力学性能和弯曲韧性的影响。(3)罩面修复普通混凝土板的受弯试验,优选MSFRMM配比,模拟混凝土路面板罩面修补,通过受弯试验,分析加铺层厚度、加铺层材料及纤维掺量等对破坏特征、极限承载力和挠度等的影响。论文取得了以下成果:(1)MPC的最佳配比:水胶比0.12,M/P为4,硼砂掺量6%或复合缓凝CR=9%;缓凝剂最佳掺量下,复合缓凝剂时强度较硼砂下降8%,但凝结时间却增加一倍。(2)采用硼砂和复合缓凝剂时,抗压强度分别可达36.2MPa(6h)、47.4MPa(12h)、50.1MPa(1d)、58.4MPa(3d)、68.2MPa(7d)和37.3MPa(6h)、40.9MPa(12h)、46.7MPa(1d)、50.8MPa(3d)、56.2MPa(7d),抗折强度可达9.5MPa(6h)、11.4MPa(12h)、15.6MPa(1d)、16.0MPa(3d)、17.4MPa(7d)和12.3MPa(6h)、16.3MPa(12h)、15.3MPa(1d)、19.4MPa(3d)、22.4MPa(7d),早期强度高,适用于道面快速抢修,采用复合缓凝剂时的抗折强度更大,纤维增韧作用更明显,相同水胶比下,复合缓凝剂的浆体拌合性更好。(3)材料弯曲试验的荷载-挠度曲线有较明显的变形硬化特征;各龄期下试件均为韧性破坏;弯曲性能随龄期增加而提高,在3d龄期时基本保持稳定。(4)MSFRMM做加铺层时,试件表现为多点多裂缝的韧性破坏,初始裂缝出现后在一定挠度内依然能够带裂缝继续承载,荷载-挠度曲线表现出明显的应变硬化特征。(5)相同加铺层厚度时,MSFRMM较普通混凝土罩面修复的承载力有显著提高,破坏时的挠度显著增加,与普通混凝土罩面修复板极限承载力相等的MSFRMM修复板残余强度对应的挠度较普通混凝土罩面时急剧增加,变形适应能力很强,板的韧性显著提高。(6)加铺层增厚时,各种加铺材料修复板的极限承载力都明显增加;加铺层纤维掺量增加极限承载力提高,但大于1.2%时提高不明显。
[Abstract]:When repairing damaged road (road) surface, the usual method is to make concrete overlay (steel fiber) overlay on the original pavement, for some special pavement such as airport runway, important bridge deck, etc. The magnesium phosphate cement has the advantages of fast setting and hardening, high early strength, hydration at low temperature (minus 20 掳), good high temperature resistance and excellent bonding performance with old concrete. Compared with the ordinary steel fiber, the micro steel fiber has more fiber roots per unit volume, more uniform distribution in the concrete matrix, less agglomeration and smaller size. This paper is based on the excellent modification of fine steel fiber and the unique properties of magnesium phosphate cement. Micro-fine Steel Fibre Reinforced Magnesia-Phosphate-Cement Mortar (MPC), a micro-fine Steel Fibre Reinforced Magnesia-Phosphate-Cement mortar, is prepared to study its mechanical properties and the properties of overlay repairing concrete pavement. The main work of this paper is as follows: 1) Magnesia-Phosphate-Cement-Cement. The effects of borax and composite retarder on the setting time and compressive strength were studied, and the effects of the content of magnesium oxide and phosphate on the setting time and compressive strength were studied. The types and contents of retarder, the ratio of water to binder, the ratio of cement to sand, the ratio of water to binder and the ratio of cement to sand were studied. Effect of age and fiber content on the basic mechanical properties and flexural toughness. The flexural test of repairing ordinary concrete slabs with overlay is carried out. The MSFRMM ratio is selected to simulate the repair of concrete pavement overlay, and the bending test is carried out. The failure characteristics of overlay thickness, overlay material and fiber content are analyzed. The effects of ultimate bearing capacity and deflection. The following results are obtained: water / binder ratio 0.12m / P = 4, borax content 6% or composite retarder CR9, and the optimum dosage of retarder, When using borax and composite retarder, the compressive strength can be up to 36.2 MPA / 6h, respectively, and the compressive strength can reach 47.4MPa / 12h / h ~ 50.1 MPA / 1 / 58.2MPa / 3d ~ 68.2MPa / 7d) and 37.3MPA / 6h / 40.9MPa / 12hm / 46.7MPa1d / 56.2MPa / 7d / 7d, respectively. When the composite retarder is used, the flexural strength is larger and the fiber toughening effect is more obvious. Under the same water / binder ratio, the composite retarder has better mixing property of the slurry, and the load-deflection curve of the bending test of the composite retarder has obvious deformation hardening characteristics. The flexural properties increased with the increase of age, and the flexural properties increased with the increase of age. When the specimens were covered with MSFRMM, the flexural properties showed the toughness failure of multi-point and multi-fracture when they were covered with MSFRMM at the age of 3 days, and the flexural properties of the specimens increased with the increase of age. After the initial crack appears, the bearing capacity of the crack can be continued with the crack within a certain deflection. The load-deflection curve shows obvious strain-hardening characteristics. 5) when the overlay thickness is the same, the bearing capacity of MSFRMM is significantly higher than that of the ordinary concrete overlay repair. The deflection of the MSFRMM repair slab which is equal to the ultimate bearing capacity of the ordinary concrete overlay plate increases dramatically compared with that of the ordinary concrete cover slab, and the deformation adaptability is very strong. When the thickness of the overlay is thickened, the ultimate bearing capacity of the overlay is obviously increased, and the ultimate bearing capacity is increased when the fiber content of the overlay is increased, but the increase is not obvious when the thickness of the overlay is greater than 1.2.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ177.62

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