An experimental study on RC columns repaired on all four sides with cementitious mortars

Abstract

Structural ageing, action by aggressive agents, accidents, etc., all make it increasingly necessary to apply conservation and maintenance programs to building structures. Columns are some of a building's most critical elements, since the failure of a single column can lead to the collapse of the entire structure or a large part of it. Although great strides have been made in recent years in the field of reinforced concrete (RC) column repair and strengthening, there is room for further improvement in certain areas. This paper describes a study carried out in the ICITECH laboratories (Universitat Politècnica de València) on RC columns repaired on all four sides with cementitious-based mortars. A total of 18 specimens were tested, representing a group of square 20x20 mm 2 columns subjected to compressive axial loads. Different repair scenarios were considered in order to study the influence of the type of mortar used and the presence or absence of bonding agents between the mortar and the column concrete. The results obtained showed that bonding agents have no appreciable effect on the behaviour of the repaired columns. Of the two types of mortar used in the study (Classes R3 and R4), the columns repaired with the lower grade mortar (R3) were seen to behave better. The main novelty of this work lies in the fact that this is the first time that two types of mortar are compared in the repair of four column sides, in addition to the possible use of bonding agents between the mortar and the column.

Cement-based mortar patch repair of RC columns. Comparison with all-four-sides and one-side repair

“…In previous research the authors studied the behaviour of square cross-section columns repaired on all four sides [28] and on one side only [29]. The results are given below for later comparison with the results of the present work.…”

“…Four types of repairs were thus involved: R3-mortar with BA, R3-mortar without BA, R4-mortar with BA and R4-mortar without BA. These results were then compared with the results of previous studies by the authors on repairs on all four column sides [28] and on one side only [29].…”

Towards the utilization of waste glass powder in sustainable cement based overlays

“…a maximum grain size of up to 8 mm and a bulk density of 2.64 g/cm 3 . To make the concrete of both layers, quartz sand with a maximum grain size of up to 2 mm and a volume density of 2.62 g/cm 3 was used. It should be clarified that the surface of both elements was divided into four parts, each of which had an overlay with a different composition, which is given in Table 2.…”

“…More attempts have recently been focused on the modification of the material of an overlay with different additives. These attempts can be made during the construction or repair of a concrete structure [2][3]. As estimated in [4], around 50% of Europe's annual construction budget is spent on refurbishment and repair.…”

Axially loaded RC columns repaired on one side with cement-based mortars

“…Most of the studies on damaged columns focus on their strengthening by the commonlyused techniques of jacketing with: concrete [4][5][6], steel [7][8][9][10][11][12], ferrocement [13], or fibrereinforced polymers (FRP) [14]. There are also studies focused on repairing all four sides of the columns with cement-based mortars in order to recover the column's original load-bearing capacity [15]. The latest studies in this field have researched new combinations of materials to improve the effectiveness of the repairs, focusing on structures that have been seriously damaged, mostly during seismic events [16,17].…”