Six replicates per series were used to determine the compressive strengths. Testing was conducted using an Ibertest Autest 200/10-SW (Madrid, Spain) test frame, the average and standard deviation of the results were then calculated and reported. Prior to microstructural characterization (Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (BSEM/EDX), one of the specimens, left unbroken, is submitted to immersion in isopropanol for 2 days to stop further hydration reactions. Subsequently, they were dried in a desiccator for a minimum of 48 h to eliminate any residual isopropanol. To prepare the powder samples (for the mineralogical analysis), specimen fragments were ground to pass through a 63 μm sieve as per previous recommendations to stop the reaction processes. Subsequently, they were mixed with isopropanol for 3 min, filtered and placed in a vacuum desiccator until a constant weight was attained. Changes in the pore structure were evaluated by mercury intrusion porosimetry (MIP) on a Micromeritics Poresize 9320 IV.09 mercury intrusion porosimeter (Micromeritics Instrument Corporation, Norcross, GA, USA), assuming a sample–mercury contact angle of 140◦. The microstructure of the samples was studied by Backscattering Electron Microscopy (BSEM) on a JEOL JSM6400 scanning electron microscope (Tokyo, Japan). Additionally, a semi-quantitative analysis of the chemical composition of the reaction products was conducted via Energy Dispersive X-ray spectroscopy (EDX) on a Links ISIS EDX analyzer, collecting at least 40 points from the cementitious matrix per sample; the data were processed using the Bruker ESPRIT 1.9 software, whereas the mineralogical and chemical composition of samples were studied via X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric analysis (TG/DTG). XRD measurements were carried out on a Bruker D8 Advance diffractometer (Karlsruhe, Germany) in a 2θ range of 5–60◦ with a step size of 0.02◦ every 0.5 s using CuKα radiation at 40 kV and 30 mA. The existing phases were identified and quantified using the DiffracPlus EVA 4 2.1 and TOPAS 5.0 software, in conjunction with a chemical reconciliation. A Nicolet 6700 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA, 02451) was employed for FTIR analysis, covering a range of 400 cm−1 to 4000 cm−1 with a resolution of 4 cm−1, using powdered samples embedded in KBr pellets (0.001 g sample/ 0.099 g KBr). Thermogravimetric analysis (TGA) was conducted using a Perkin-Elmer TG analyzer (PerkinElmer, Shelton, USA). Powdered samples underwent heating from room temperature to 800 ◦C at a rate of 10 ◦C min−1 under a N2 flow of 200 cm3/min.

COMPRESSIVE STRENGHTS folder: C S M-P-(2-3) H2O; C S M-P-(2-3) SO4 ; C S M-P-(2-3) SW. MIP folder: porosimetry_readme; M-P 3 CC 28d (Ref 0); M-P 3 LAB 28d (Ref 0); M-P 3 CC 28d H2O; M-P 3 CC 28d SO4; M-P 3 CC 28d SW; M-P 3 CC 90d H2O; M-P 3 CC 90d SO4; M-P 3 CC 90d SW; M-P 3 CC 180d H2O; M-P 3 CC 180d SO4; M-P 3 CC 180d SW; M-P 3 CC 1y H2O; M-P 3 CC 1y SO4; M-P 3 CC 1y SW; ); M-P 3 LAB 28d H2O; M-P 3 LAB 28d SO4; M-P 3 LAB 28d SW; M-P 3 LAB 90d H2O; M-P 3 LAB 90d SO4; M-P 3 LAB 90d SW; M-P 3 LAB 180d H2O; M-P 3 LAB 180d SO4; M-P 3 LAB 180d SW; M-P 3 LAB 1y H2O; M-P 3 LAB 1y SO4; M-P 3 LAB 1y SW. TG-DTG folder: TG-DTG_readme; loss of water; TG-DTG M-P 3 CC 28d, 1 year. XRD folder: XRD_readme; M-P 3 CC 28d H2O; M-P 3 CC 28d SO4; M-P 3 CC 28d SW; M-P 3 CC 90d H2O; M-P 3 CC 90d SO4; M-P 3 CC 90d SW; M-P 3 CC 180d H2O; M-P 3 CC 180d SO4; M-P 3 CC 180d SW; M-P 3 CC 1year H2O; M-P 3 CC 1year SO4; M-P 3 CC 1year SW. FTIR folder: FTIR_readme; FTIR M-P 3 CC Ref, 28d, 1y. SEM-EDX folder: BSEM-EDX_readme; mapping M-P 3 CC-REF; mapping M-P 3 CC-H2O; mapping M-P 3 CC-SO4; mapping M-P 3 CC-SW; SEM M-P 3 CC H2O a; SEM M-P 3 CC H2O b; SEM M-P 3 CC SO4 a; SEM M-P 3 CC SO4 b; SEM M-P 3 CC SW a; SEM M-P 3 CC SW b; EDX M-P-3 28d; EDX M-P-3 1y. WATER COMPOSITION folder

[EN] This is the experimental dataset used in the paper Materials 17, 4252 (2024) (https://doi.org/10.3390/ma17174252) Durability of magnesium potassium phosphate cements (MKPCs) pastes during 1 year of inmersión under chemical attack, focusing on the effects of deionized water, sodium sulfate and seawater, have been determined with different analytical tecnhiques. Prismatic specimens (1 × 1 × 6 cm3) of MKPC were prepared with different MgO/H2PO4 ratio (2 and 3), at different ages, cured under two curing conditions (CC and LAB), where were maintained up to 28 days: - CC: In a climatic chamber at 21 ± 3 ◦C and 99 ± 5% relative humidity (RH). - LAB: In the laboratory at 21 ± 3 ◦C and 52 ± 5% of relative humidity (RH). After these 28 days, three set of samples, for each curing regime, were prepared. One additional set was used as a reference (only cured for 28 days). Changes in the mechanical strengths, mineralogy (XRD, FTIR, TG/DTG), and microstructure (BSEM, MIP) of all 4 sets were determined.

We acknowledge financial support from the JIN project (PID2020-116738RJ-I0 AEI/10.13039/501100011033) and the RYC excellence contract (RYC2021-032620-I), funded by the Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/50110001033) and the European Union “Next generation EU/PRTR”.

Peer reviewed