Influence of Lowered Temperature on Efficiency of Concrete Repair with Polymer-Cement Repair Mortars

Abstract

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.

Study on the Effect of Three Types of Calcium Sulfate on the Early Hydration and Workability of Self-Compacting Repair Mortar

“…When used to repair construction and building structures, self-compacting repair mortar (SCRM) is a cement mortar made up of cement, mineral admixtures, fine aggregates, additives, etc., in the proper proportions. SCRM requires stirring with a specific amount of water or other liquids [ 1 , 2 , 3 , 4 , 5 ]. SCRM should also possess qualities including a suitable setting time, increased fluidity, stronger early strength, good resistance to segregation, and stable volume change in order to match the building criteria [ 6 ].…”