112 / 2022-04-25 22:57:06

Mechanical Properties and Crack Characteristics of Seawater Sea-Sand Engineered Cementitious Composites (SS-ECC)

ECC,SHCC,sea-sand,seawater,mechanical properties,crack characteristics,probabilistic modeling

Engineered Cementitious Composite (ECC) is an advanced fiber-reinforced concrete exhibiting multiple-cracking and strain-hardening under tension. This study aims to explore the feasibility of producing high-strength seawater sea-sand Engineered Cementitious Composites (SS-ECC) for marine and coastal applications facing the shortage of freshwater and river/manufactured sand. The effects of key composition parameters including the sea-sand size (1.18/2.36/4.75 mm), the polyethylene fiber length (6/12/18 mm), and the fiber volume dosage (1.0/1.5/2.0%) on the mechanical performance of SS-ECC were comprehensively investigated. SS-ECC with tensile strength over 8 MPa, ultimate tensile strain about 5%, and compressive strength over 130 MPa were achieved. Using seawater and sea-sand had almost no negative effects on the 28-day mechanical properties of high-strength ECC. For SS-ECC, increasing fiber length and dosage enhanced the tensile strain capacity, and sea-sand size had limited effects on the tensile performance; these phenomena were interpreted by the micromechanical analysis.



The crack characteristics of SS-ECC (Fig. 1) were assessed and modelled, which are critical for its applications with non-corrosive reinforcements. The influences of sea-sand size, fiber length and fiber dosage on the crack characteristics of SS-ECC were explored. According to the experimental observation, micromechanical modelling and SEM analysis, smaller sand size and higher fiber dosage of SS-ECC resulted in smaller crack widths under the same tensile strain. Fiber length had no obvious effect under the same tensile strain below 2%, but 18-mm fiber led to larger crack widths at a strain level above 2%, due to a large fraction of fiber rupture after a certain crack opening. A five-dimensional representation was proposed to assess the overall performance of SS-ECC, by comprehensively considering both the crack characteristics (i.e., crack width and its variation) and the mechanical properties (i.e., compressive and tensile properties). A probabilistic model (Fig. 2) was also proposed to describe the stochastic nature and evolution of crack width, and it can be used to estimate the critical tensile strain on SS-ECC for a given crack-width limit and cumulative probability. Our findings can facilitate the design of SS-ECC in marine and coastal structures.