Investigation on early-age hydration, mechanical properties and microstructure of seawater sea sand cement mortar

Li, Peiran; Li, Wengui; Yu, Tao; Qu, Fulin; Tam, Vivian W.Y.

doi:10.1016/j.conbuildmat.2020.118776

Cited by 180 publications

(68 citation statements)

References 51 publications

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“…As an example, the compressive strength of OSD samples at the W/C ratio of 0.38 and 0.28 was 50.5 MPa and 59.9 MPa at 28 days, decreasing by 5.8% and 11.9%, respectively, compared to the corresponding ODD samples. Previous works also reported the evolution of the compressive strength of cement, mortar or concrete, but had inconsistent results (Chandrakeerthy, 1994; Chen et al, 2008; Girish et al, 2015; Islam et al, 2012; Jau et al, 2006; Li et al, 2020; Narver, 1964; Wang et al, 2018; Wegian, 2010; Xiao et al, 2017). A recent work, for instance, exploring the compressive strength of the OPC pastes using seawater as the mixing water and cured in an environmental chamber (20°C and 95% RH), reported that the seawater cement paste showed a higher compressive strength compared with that using DI water as the mixing water, and was increased by up to 50% after curing for 28 days.…”

Section: Resultsmentioning

confidence: 99%

“…Previous works on FRP-SSC mainly focused on its structural behavior and the durability of FRP bars in SSC environment. The mechanical performances of plain pastes/concrete using seawater or sea-sand were also studied in a few studies, but the results were inconsistent (Chandrakeerthy, 1994; Chen et al, 2008; Girish et al, 2015; Islam et al, 2012; Jau et al, 2006; Li et al, 2020; Narver, 1964; Wang et al, 2018; Wegian, 2010; Xiao et al, 2017). Wang et al (2018), for instance, found that the compressive strength of OPC pastes mixed with seawater can reach to about 53 MPa at 28 days, an increase of 50% compared with DI water OPC pastes.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of strength evolution of seawater OPC pastes

Zhang

Sun

Zheng

et al. 2021

Advances in Structural Engineering

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This work investigated the strength degradation mechanisms of seawater ordinary Portland cement (OPC) pastes. Two types of specimens were prepared ((i) OSD sample (i.e. OPC was mixed with seawater, and then cured in deionized (DI) water) and (ii) ODD sample (i.e. OPC was mixed with DI water, and then cured in DI water, as the reference system)). The use of seawater in preparing OPC pastes effectively increased the hydration rate and early-age mechanical strength, but lowered the mechanical strength at the later age. The higher hydration degree and larger amounts of carbonates with a smaller crystal size enabled the seawater OPC pastes to exhibit a higher early-age mechanical strength, increasing by 13.0%–17.0% compared with the DI water OPC pastes. While the formation of Friedel’s salt and the formation of calcium-silicate-hydrate (C-S-H) gel with a lower polymerization degree and mean molecular chain length resulted in the deterioration of the pore structure and negatively affected the later-age strength development of the seawater OPC paste, decreasing by 5.8%–11.9% compared with the DI water OPC pastes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of strength evolution of seawater OPC pastes

Zhang

Sun

Zheng

et al. 2021

Advances in Structural Engineering

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“…The relatively high early-age compressive strength of concrete mixed with saltwater has been reported by many existing studies (e.g. Kaushik and Islam, 1995;Li et al, 2020;Teng et al, 2019;Younis et al, 2018). This is generally believed to be due to the existence of chloride ions, which promotes the formation of a chloro-AFm phase (i.e.…”

Section: Compressive Strengthmentioning

confidence: 91%

“…Seawater consists of a range of chemicals which can affect the fresh and hardened properties of concrete (Xiao et al, 2017). Extensive experimental studies (Dhondy et al, 2019; Ghorab et al, 1989, 1990; Huang et al, 2020; Kaushik and Islam, 1995; Li et al, 2018, 2020; Nishida et al, 2013; Taylor and Kuwairi, 1978; Teng et al, 2019; Younis et al, 2018) have been conducted on seawater concrete of various strengths, ranging from normal strength concrete (e.g. Kaushik and Islam, 1995; Li et al, 2020; Younis et al, 2018) to ultrahigh strength concrete with a compressive strength of over 180 MPa (Teng et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Effects of mixing water salinity on the properties of concrete

Dhondy

et al. 2020

Advances in Structural Engineering

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The use of seawater and sea-sand in producing concrete has attracted increasing research attention in recent years to address the shortage of river sand and in certain applications the shortage of freshwater. In particular, reinforced concrete structures made of seawater sea-sand concrete (SSC) and corrosion-resistant fiber-reinforced polymer (FRP) are particularly attractive for the development of coastal and marine infrastructure (e.g. on remote islands) as durable structures can be created using locally available materials. Existing studies on SSC or seawater concrete have been largely limited to the use of mixing water with a salinity level close to the world-average ocean salinity. Against this background, the present paper reports the first ever systematic study on the effect of salinity of mixing water on the properties of concrete. The present study covered a wide range of salinity levels from 16.5 g/L to 82.5 g/L, and examined a wide range of short-term concrete properties including the heat of hydration, shrinkage, compressive strength and modulus of elasticity. The test results show that the salinity of mixing water has a considerable effect on the rate of hydration heat and shrinkage at early ages, as well as the cumulative release of hydration heat. It is also shown that the water salinity has a slight negative effect on the compressive strength and modulus of elasticity of concrete at ages older than 14 days.

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“…In addition, sulfate ions could change the pore size distribution of concrete by forming ettringite, meaning that the various ions (i.e., CO 3 2− , SO 4 2− , Cl − , Ca 2+ , Mg 2+ , Na + , etc.) present in seawater could induce the change in hydration products or mineral phases in the concrete [7,9]. Crack-closure work, therefore, is fundamental to protect the concrete from deterioration factors and to improve the long-term durability.…”

Section: Introductionmentioning

confidence: 99%

Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

et al. 2020

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The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

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Investigation on early-age hydration, mechanical properties and microstructure of seawater sea sand cement mortar

Cited by 180 publications

References 51 publications

Mechanism of strength evolution of seawater OPC pastes

Mechanism of strength evolution of seawater OPC pastes

Effects of mixing water salinity on the properties of concrete

Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

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