Capillary Transport of Water in Cracked and Non-cracked UHPFRC Specimens

Abstract

The primary goal of the present paper is to investigate the influence of cracking on water transport by capillary suction of UHPFRC. Prismatic specimens were firstly loaded under four-point bending up to specific crack open displacement (COD). Target COD, under loading, was varied between 200 and 400 μm, in steps of 50 μm. After unloading, a COD recovery was observed with residual COD ranging between 116-334 µm and 75-248 μm for UHPFRC-1.5% and UHPFRC-3.0% specimens, respectively. The crack pattern created was characterised (number of cracks and crack width) before capillarity testing. Sorptivity results of cracked UHPFRC-1.5% and UHPFRC-3% specimens remained in the range of 0.024 to 0.044 mg/(mm 2 .min 0.5), which are about 2 to 4 times higher than the sorptivity results of noncracked UHPFRC specimens. However, the maximum sorptivity observed on cracked UHPFRC is relatively low as compared to typical sorptivity results found in good quality conventional concrete or engineered cementitious composites (ECC).

Chloride Ion Penetration into Cracked UHPFRC During Wetting-drying Cycles

“…4b, displaying a good linear relation between COD res and COD load . This trend is in agreement with studies of Ma et al [8] and also with previous studies carried out by the authors [6].…”

“…5b, black marks). These results agree with previous findings of the authors [6]. The maximum crack width (see Fig.…”

“…• Developing a new UHPC mixture for rehabilitation/strengthening applications employing local available raw materials (including waste materials) and on-site fabrication under regular casting and curing conditions [5] • To mitigate autogenous shrinkage of UHPC employing internal curing, in order to minimise the early ages cracking risk [5] • To investigate several critical durability aspects of the new UHPC mixture and compare its performance to other UHPCs reported in the literature • Studying the influence of cracking on key durability parameters, such as water transport by capillary suction [6] and chloride ion penetration.…”

Durability of an UHPFRC under mechanical and chloride loads

“…Besides, it corroborates the range of durability parameters found in the literature for other UHPFRC [42,43,58]. The experimental characterisation of the capillary transport properties on cracked and non-cracked UHPFRC, with different fibre dosages, was also presented in previous work [44], and it showed its excellent tightness to water.…”

Quantitative Effects of Mixture Parameters on Alkali-Activated Binder-Based Ultra-High Strength Concrete at Ambient and Elevated Temperatures

“…To achieve high strength, extremely low water-to-cement ratio down to about 0.15, high-dose superplasticizer (> 3% by cement weight) (Way and Wille 2016;Xie et al 2018;Yoo et al 2020;von Werder et al 2021), and high cement clinker content (> 800 kg/m 3 ), are usually practiced, all of which undoubtfully contribute to the high material and environmental costs of UHSC. Although some attempts have been made in recent years to reduce the clinker content and costs of UHSC by incorporating low-carbon materials (e.g., GGBS, FA, limestone filler) (Matos et al 2019;Tai et al 2020), the majority of UHSC mixtures nowadays are fabricated based on the OPC binder systems. Few studies have ever systematically investigated the clinker-free UHSC based on more environmental-friendly binder systems, e.g., alkali-activated binders.…”