Cit.edu.cn (Y.L.) College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; [email protected] Correspondence: [email protected]:

Cit.edu.cn (Y.L.) College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China; [email protected] Correspondence: [email protected]: Zhong, D.; Wang, S.; Gao, Y.; Wang, L.; Li, Y.; Wang, J. Influence of Rubber Powder Modification Strategies on the Mechanical and Durability properties of Rubberized Magnesium Oxychloride Cement. Crystals 2021, 11, 1323. https:// doi.org/10.3390/cryst11111323 Academic Editor: Tomasz Sadowski Received: 8 September 2021 Accepted: 25 October 2021 Published: 29 OctoberAbstract: Inside the present study, three modification solutions, which includes water washing, sodium hydroxide (NaOH), and styrene crylic emulsion, had been utilized to modify waste rubber powders. The influence of rubber powders around the mechanical properties and frost resistance of magnesium oxychloride cement was examined, as well as the distinct modification mechanisms had been also analyzed. Determined by the analysis of hydrophilic properties right after modification, styrene crylic emulsion achieved the most beneficial modification impact, though water washing produced the least modification effect; regarding mechanical properties, magnesium oxychloride cement mixed with NaOH modified rubber powders achieved the best modification effect, in which the 28 d flexural strength and compressive strength improved by 41.two and 59.6 , respectively. Throughout the freeze-thaw cycles, the mass loss of specimens was lowered with a rise in the content of rubber powders. Also, after 300 cycles, the relative dynamic modulus of elasticity of the blank sample was about 28.12 , whilst that from the magnesium oxychloride cement mixed with NaOH modified rubber powders was around 42.38 . Normally, the properties of the modified rubber powder agnesium oxychloride cement composite material can meet the requirements for Salubrinal site engineering supplies, which offers a theoretical basis and technical help for the application of rubberized magnesium oxychloride cement. Keywords: rubber powder; magnesium oxychloride cement; surface modification; sodium hydroxide; styrene crylic emulsion1. Introduction Magnesium oxychloride cement is definitely an inorganic cementitious material [1,2], which can be widely used in many industries (e.g., agricultural appliances, wood production and property decoration, fire-fighting pipelines, and so forth.) resulting from its beneficial properties, for instance becoming quickly Tetrachlorocatechol Technical Information forming, offering superior mechanical properties early-stage, good adhesion and excellent fire resistance [3]. Nonetheless, on account of its shortcomings, as an example, low toughness, substantial capacity, and proneness to warping deformation, its applications are restricted [80]. At present, the principal method to improve the flexural toughness of magnesium oxychloride cement would be to mix it with polypropylene fibers, polyethylene fibers, steel fibers, or other components [11]. Rubber can be a kind of elastic polymer. Adding it as a lightweight aggregate into cement paste can overcome the shortcomings of cement concrete and is a way of employing waste rubber and so lowering the pollution triggered by releasing it into the atmosphere [12,13]. This discovery has attracted important focus from scientific researchers; consequently, rubber cement-based composite materials came into getting as a new kind of composite material. It might be noticed from a lot of studies [146] that, soon after adding waste rubber powders as a lightweight filler into cement-based materials, the physical and mechanicalPublisher’s Note: MDPI stays neutral with regard to jurisdictional claim.