【摘要】 MgO膨胀剂（MEA）可用于补偿墙体混凝土的收缩，但由于墙体混凝土构件所受约束力的方向和大小均不同，MEA在有约束的实体结构中膨胀量小，无约束的地方膨胀量大，这使MEA在墙体混凝土构件中的膨胀行为存在梯度效应，膨胀性能难以有效发挥。为研究MEA在混凝土实体结构内的实际补偿收缩能力及抗裂效果，实时监测了某水厂C35混凝土实体配筋墙从浇筑混凝土开始到105 d期间的温度变化和体积变形情况，通过去除温度变形，获得墙体结构体真实应变。实测结果表明：前70 d，试验墙体各测点均呈现稳定膨胀，膨胀速率约为2～3.5με/d,70 d之后膨胀变缓且基本趋于稳定，最大应变为251.4×10^-6;MEA的膨胀效能的发挥与结构体周围约束的方向有关，80 d时，x方向垂直于左侧约束和y方向垂直于地面约束的最大应变分别为250×10^-6和215×10^-6,x方向平行于地面约束和y方向平行于左侧约束的最大应变分别为210×10^-6和180×10^-6，垂直于限制方向比平行于限制方向应变更大，更有利于MEA膨胀效能的发挥。结果表明：在实际工程中，可通过改变各方向的限制程度的相对关系来调整膨胀率，使得MEA发挥工程需要的最佳膨胀效能，以提高材料补偿收缩能力和自应力水平。更多还原

【Abstract】 MgO expansion agent（MEA）can be used to compensate for the shrinkage of wall concrete,but due to the different directions and sizes of the constraint forces on the wall concrete members,the expansion of MEA is small in the constrained solid structure and large in the unconstrained place,which makes the expansion behaviour of MEA in the wall concrete members have a gradient effect,and it is difficult to play the expansion performance effectively.In order to study the actual compensating shrinkage capacity and anti-cracking effect of MEA within the concrete solid structure,it monitors in real time the temperature change and volume deformation of C35 concrete solid reinforced wall of a water plant during the period from the beginning of concrete pouring to 105 d.By removing the temperature deformation,the real strain of the wall structure body is obtained.The results of the measured show that:in the first 70 d,the test wall showed stable expansion at each measurement point,with an expansion rate of about 2～3.5 με/d,and after 70 d,the expansion slowed down and basically stabilised,with a maximum strain of 251.4×10^-6;the play of the expansion efficacy of the MEA is related to the direction of the constraints around the structural body,and when 80 d,the x-direction is perpendicular to the left-hand side of the constraint and the y-direction is perpendicular to the ground constraint,and the maximum strain is 250 ×10 ^-6 respectively.At 80 d,the maximum strains of x-direction perpendicular to the left side restraint and y-direction perpendicular to the left side restraint are 250×10^-6and 215×10^-6respectively,and the maximum strains of x-direction parallel to the ground restraint and y-direction parallel to the left side restraint are 210×10^-6and 180×10^-6respectively,and the perpendicular to the restraining direction should be larger than that of the parallel to the restraining direction,which is more favourable to the play of the expansion effectiveness of MEA.The results show that in practical engineering,the expansion rate can be adjusted by changing the relative relationship of the degree of restriction in each direction,so that the MEA exerts the optimum expansion efficacy required by the engineering,in order to improve the material′s ability to compensate for the contraction and the level of self-stress.更多还原