Wojnowski Damian, Francke Barbara, Garbacz Andrzej
Building Research Institute, Filtrowa 1, 00-611 Warsaw, Poland.
Department of Building Materials Engineering, Faculty of Civil Engineering, Warsaw University of Technology, Armii Ludowej 16, 00-637 Warsaw, Poland.
Materials (Basel). 2020 Sep 24;13(19):4254. doi: 10.3390/ma13194254.
This paper presents research dealing with the evaluation of the efficiency of concrete repairs with polymer-cement mortars made at low temperatures with two types of cement and modified by copolymer acrylic-styrene. The low temperature used for the tests, of about 8 °C, is representative for Central Europe, and was established based on the analysis of mean temperatures in Poland during the last 45 years. A comparative analysis of the basic properties of the mortar tested, important from the point of view of repair efficiency, was performed, i.e., flexural and compressive strength, modulus of elasticity, adhesion to the substrate, and porosity for mortars applied and cured at 8 °C and 21°, respectively. The studies were conducted using standard methods and supported with an assessment of microscopic images (1000× magnification). It was shown that when the temperature of polymer-cement composite (PCC) mortar application is lowered to values slightly exceeding the minimum film-forming temperature (MFT) temperature of the polymer modifier, the type of cement determines the effectiveness of the repair. Only for PCC mortar with CEM I sulfate-resistant types of cement was it possible to achieve the same strength parameters as at 21 °C, during 28 days of mortar curing, and at a lowered temperature. Starting from day seven of setting at both above-mentioned temperatures, a relation between the values of the flexural and compressive strength expressed as a quotient of these values, amounting to ca. 0.14-0.19, was found.
本文介绍了一项研究，该研究涉及对低温下用两种水泥制成并经丙烯酸 - 苯乙烯共聚物改性的聚合物水泥浆体进行混凝土修复效率的评估。试验所用的约8°C的低温代表中欧地区，它是根据对波兰过去45年平均温度的分析确定的。从修复效率的角度出发，对所测试砂浆的基本性能进行了对比分析，即分别在8°C和21°C下涂抹和养护的砂浆的抗折强度、抗压强度、弹性模量、与基材的附着力和孔隙率。研究采用标准方法进行，并辅以微观图像（1000倍放大）评估。结果表明，当聚合物水泥复合材料（PCC）砂浆的涂抹温度降低到略高于聚合物改性剂的最低成膜温度（MFT）时，水泥类型决定修复效果。只有对于使用CEM I抗硫酸盐水泥类型的PCC砂浆，在砂浆养护28天且温度降低的情况下，才有可能达到与21°C时相同的强度参数。从上述两种温度下的凝结第七天开始，发现抗折强度和抗压强度值之间存在一种关系，以这些值的商表示，约为0.14 - 0.19。
