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The viability of using a SiMn slag as raw material for the preparation of alkali activated binder has been analysed. The slag has been characterized from the physical, chemical, mineralogical and microstructural point of view. The solution used for the alkali activation process was waterglass, which was prepared by the mix of a sodium silicate solution with sodium hydroxide. The influence of the following design parameters in alkali activated pastes has been studied: %Na2O, SiO2/Na2O ratio and activating solution/slag ratio. All the prepared specimens have been cured under a 100% of relative humidity atmosphere and no additives have been included in the formulations. For the evaluation of the alkali activation process a response surface methodology has been adopted by modelling the obtained results for different control parameters. The proposed experimental methodology consisted of a composite cubic-type experimental design which follows 2nd degree polynomial model. The control parameters of the pastes used in this research have been: workability, compressive strength at 7, 28 and 90 days of curing time, setting times and shrinkage at 50% of relative humidity. The results show that it is possible to valorise the SiMn slag through its use as an alkali activated binder. In general, workability decreases as the %Na2O increases and SiO2/Na2O ratio decreases. Initial setting times ranges from 38 to 263 min depending on the activating solution composition, and workability time decreases for increasing %Na2O. A compressive strength higher than 45 MPa can be achieved by the following activating conditions: 4.0-4.5%Na2O, SiO2/Na2O = 1.00 and activating solution/slag = 0.35-0.375. Shrinkage values of pastes that were cured at 50% of relative humidity ranged from 1.5% to 3.0%. Source writing has been changed to 11 points Times New Roman (except in tables, in which a 10 point size has been used) and normal space between characters.3. The relevant information on the shrinkage of hardened pastes should be included in the summary and conclusion part.The following text has been added to the abstract:"Shrinkage values of pastes that were cured at 50% of relative humidity ranged from 1.5% to 3.0%."The following text has been included in the conclusions:"High shrinkage values have been registered for all pastes in the 50% RH ambient. In these conditions, shrinkage achieves a stable value after 30 days. Shrinkage levels have ranged from 1.5% to 3.0% approximately and its maximum value is observed for s/s ratio around 0.38 and 4.5% Na 2 O in pastes with Ms = 1.00." The English writing should be greatly improved. In the following examples, word errorsWe apologize for the high number of grammatical errors that have been included in the text. Many of them are just a consequence of a lack of attention in the manuscript elaboration. The new version of the manuscript has been carefully revised.Reviewer #2:1. This article should be discussed by studying different aspects with previous studies. The results and the discussion part ...

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h i g h l i g h t s SiMn slag has been implemented as substrate for alkali activated mortars. Two types of alkali activators have been used: waterglass and sodium hydroxide. Silica sand, limestone and recycled concrete finer fraction have been used as sand. Mortars prepared with silica sand offered the best performance in mechanical tests.

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