## 1 Introduction
The trigger mechanism relies on the fact that with a pH variation, the SAPs can enhance their shape due to the water absorption resulting in the reduction of the attachment between the primer layer and both the top coating and substrate, enabling the detachment of the top coating from the corresponding substrate. Moreover, in cementitious pastes a large number of ions are present (Ca\({}^{2-}\), K\({}^{+}\), Na\({}^{+}\), SO\({}_{4}\)\({}^{2-}\), OH\({}^{-}\) etc.) and pH of the mix water ranges between 11 and 13.4 [10; 15; 22; 24; 34]. The incorporation of SAPs in cementitious materials initially results in water absorbance during the cement paste mixing procedure and act as water reservoirs that will make water available during cement curing and hardening. In this way, SAPs contribute to maintaining higher levels of relative humidity thus mitigating early age shrinkage and at the same time favoring extended hydrating reactions which lead to denser cement microstructure by reducing the capillary pores in the cementitious matrix which leads to improved structure strength [9; 10; 15; 16; 17; 20; 23; 24]. Furthermore, upon crack formation and in the presence of water, SAPs reabsorb water on a separate event, swell and allow an immediate crack self-healing effect while the promotion of additional hydrating reactions of remaining unhydrated cementitious phases provide a crack self-healing effect, thus acting as internal curing agents [9; 10; 11; 14; 15; 16; 17; 23]. On the other hand, when water is released from SAPs particles in the cement matrix, SAPs deswell forming voids around them in the scale of macropores. These macropores are likely to act as strain inducers and be accounted for any strength loss detected in the final structure, a competitive effect to the internal curing promotion that was previously described [9; 10; 15; 17; 21; 31; 35]. It must be clarified that the overall SAPs behavior in cementitious materials highly depends on the nature of SAPs used and their characteristics such as structure, absorption/desorption behavior, morphology (particles shape, size and size distribution) and dosage in the cementitious matrix, as well as water to cement (w/c) ratio and the incorporation procedure adopted [9; 15; 17; 31; 35]. In most cases SAPs absorption/desorption has been examined in extracted or synthetic solutions. Nevertheless, there have also been some studies on the in-situ evaluation of this behavior when SAPs are incorporated in a porous cementitious matrix. The results from these studies revealed that SAPs desorption when in contact with a porous, cementitious material, is effected by the bonding between SAPs particles and the cementitious matrix and is governed by diffusion between SAPs particles and capillary sorption in the matrix [36; 37; 38]. Consequently, it is imperative to investigate the correlation between SAPs used and the response of the cementitious system with respect to its mechanical properties and its microstructure. The vast majority of commercial SAPs are copolymeric networks based on acrylic acid or acrylamide that may or may not have been partially neutralized [10; 11; 14; 15; 17; 18; 20; 21; 23; 31]. Because of the diversity of the parameters that have to be satisfied in the construction applications to enhance their internal curing action, SAP particles should preferentially have a homogeneous spherical shape, size in the submicron area so that the voids left behind after their deswelling are smaller and don't affect the structure mechanical properties and chemical affinity to the cement matrix so that they are more easily dispersed homogeneously in the cement paste [23]. The aim of this work was to examine the impact of the incorporation of tailored SAPs with respect to their structure (hybrid structure consisting of organic core--inorganic shell) on mortars mechanical strength in terms of flexural and compressive strength, microstructure and self-healing behavior. The synthesis and characterization of the incorporated SAPs have been thoroughly discussed in previous authors' work.