Brittle nature of gypsum restrains its wide application in construction industry. For improvement, a novel type of composite material, gypsum-based engineered cementitious composites (GS-ECC), was developed using specially chosen polyethylene (PE) fibers. This study investigated the rheological and mechanical properties of GS-ECC, that is, workability, uniaxial tensile and compressive behavior, flexural strength, etc The investigation showed that GS-ECC possessed excellent tensile strain-hardening behavior and saturated cracking characteristics with the average tensile strain capacity more than 5%. To explore the underlying mechanism, the microstructure of interface transition zone (ITZ) between gypsum crystals and PE fibers were investigated through the use of SEM. Single fiber pull-out test, bending-fracture test, and single crack tension test were conducted to investigate the mesoscopic properties from fiber/matrix interface to matrix toughness and fiber bridging capacity. This study demonstrates the feasibility of achieving strain-hardening gypsum-based composites by adding the PE fibers. K E Y W O R D S fiber-matrix interface, gypsum, polyethylene fiber, strain hardening gypsum composite, ultra-high ductility How to cite this article: Wang Y, Jian X, Yu J, Ye J, Dong F. Development of gypsum-based composites with tensile strain-hardening characteristics.

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This research aims to investigate the feasibility of replacing natural sand (NS) with recycled sand (RS) to enhance the mechanical property of engineered cementitious composites (ECC). For a comparative study, ECCs incorporating natural sands (NS) and recycled sands with different sieve sizes were taken as experimental subjects. The results demonstrated that RS-ECC possessed better tensile properties featuring saturated cracks and superior strain-hardening behavior than that of NS-ECC. The highest tensile strain capacity of RS-ECC was up to 7%. Meanwhile, the compressive and flexural strengths of RS-ECC were over 50 and 20 MPa. The pseudo-strain-hardening (PSH) index of the RS-ECC-20 grid and RS-ECC-12 grid were 141 and 201, which increased by 46% and 70% than that of NS-ECC. Furthermore, the thicker weak ITZ and comparatively aggregate/ITZ ratio were found in the RE-ECC by a microstructure test, which revealed and explained the mechanism for the lower matrix fracture toughness of RS-ECC.

Maximizing a monotone submodular function is a fundamental task in machine learning, economics, and statistics. In this paper, we present two communication-efficient decentralized online algorithms for the monotone continuous DR-submodular maximization problem, both of which reduce the number of per-function gradient evaluations and per-round communication complexity from T 3/2 to 1. The first one, One-shot Decentralized Meta-Frank-Wolfe (Mono-DMFW), achieves a (1 − 1/e)-regret bound of O(T 4/5 ). As far as we know, this is the first one-shot and projection-free decentralized online algorithm for monotone continuous DR-submodular maximization. Next, inspired by the non-oblivious boosting function (Zhang et al., 2022), we propose the Decentralized Online Boosting Gradient Ascent (DOBGA) algorithm, which attains a (1 − 1/e)-regret of O( √ T ). To the best of our knowledge, this is the first result to obtain the optimal O( √ T ) against a (1 − 1/e)-approximation with only one gradient inquiry for each local objective function per step. Finally, various experimental results confirm the effectiveness of the proposed methods.