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• The self-designed conductometric titrator can test the conductivity of solution and can test the concentration of sulfate. • The conductivity of Na 2 SO 4 and BaCl 2 solution increases linearly in the temperature range of 25–70 °C. • When titrating sulfate in cement-based materials, 0.02 mol/L BaCl 2 , 0.828 mL/s titrating rate of, and 10 mL volume titrated are recommended. The concentration of sulfate ion in cement-based materials is the basic data for the design and evaluation of concrete structures exposed to sulfate lakes and saline soil areas. In this study, a conductivity titrator was developed and used to test the sulfate concentration in concrete corroded by sulfate attack based on the Internet of Things. The theories of conductivity measurement and conductivity titration were described; The main hardware composition and software design of conductometric titrator were introduced; Then, the effects of temperature, concentration, hydroxyl ion and hydrogen ion on the conductivity of solution of sodium sulfate and barium chloride were explored by the titrator; The titration parameters, the influence of hydroxyl and hydrogen ion on sodium sulfate titration were determined by test of sulfate ion titrated by barium chloride with known concentration; Finally, the titrator was used to test the sulfate concentration in cement-based materials after sulfate attack. The results show that the titrator can measure the conductivity of solution with 0.4% accuracy and the concentration of sulfate ion with 0.8% accuracy; During the titration of sulfate ion, the concentration of barium chloride should be twice that of sulfate ion, the titration rate should be less than 0.828 mL/s, and the titration volume should be at least 10 mL; It is found that the influence of hydroxyl ion can be effectively eliminated by adding nitric acid or hydrochloric acid, and the influence of hydrogen ion can be effectively eliminated by adding sodium carbonate. This conductivity meter can accurately test the sulfate concentration in the concrete after corrosion. [ABSTRACT FROM AUTHOR]

• An innovation apparatus is developed based on the analyzation of a theoretical model. • The GIP method has been developed based on the proposed apparatus. • The porosity of cementitious materials tested by gas is comparable with that by water (WIP). • Compared to GIP, mercury intrusion porosimetry (MIP) has underestimated the porosity. • Gas is a more proper medium for intrusion porosimetry compared to water and mercury. Pore-structure in cementitious materials determines their chemical and physical properties. However, the quantitative characterization of pore-parameters has yet been investigated in depth. In this work, gas intrusion porosimetry (GIP) is accomplished by a proposed apparatus based on the theoretical model. The porosities of cementitious materials measured by GIP are compared to those obtained by conventional methods including water intrusion porosimetry (WIP) and mercury intrusion porosimetry (MIP). The three methods are assessed by an established empirical-model for the porosity-strength relationship of cementitious materials. The results show that the porosities obtained by GIP are near to those obtained by WIP and the difference is below 2.88%. The porosities determined by the MIP technique were 7.15%~16.71% smaller than those determined by GIP. The results deduced from the empirical model agree well with the measured data obtained by GIP (R2 > 0.95). Both the WIP and MIP decreased the empirical-model effectiveness to predict a trend. [ABSTRACT FROM AUTHOR]