Effect of Phaeodactylum Tricornutum in Seawater on the Hydration of Blended Cement Pastes
Effect of Phaeodactylum Tricornutum in Seawater on the Hydration of Blended Cement Pastes
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DOI：
10.3390/coatings12111639
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发表时间：
2022-10
期刊：
影响因子：
3.4
通讯作者：
Junjie Wang;Lei Xu;Jia Guo;Y. Jiang;Hang He;Yuli Wang;W. Fu;Yingliang Zhu;Zhe Ye;Pukang He;Y. Zhang
中科院分区：
文献类型：
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作者：
Junjie Wang;Lei Xu;Jia Guo;Y. Jiang;Hang He;Yuli Wang;W. Fu;Yingliang Zhu;Zhe Ye;Pukang He;Y. Zhang
在一些难以获得淡水的地区，海水可以作为无钢筋混凝土的搅拌水。硅藻（如褐指藻）是生活在海水中的最丰富的微生物之一，在收集海水时它们可能是不可避免的。事实上，硅藻可以提供bio-SiO2和bio-CaCO3来源，即无定形纳米sio2和结晶纳米caco3，这可能有利于水泥水化。为此，通过抗压强度、XRD、DTG-DTA、SEM等测试，研究了海水中不同褐指藻浓度（海水与硅藻悬浮液重量比为0%、2.5%和5%）对普通硅酸盐水泥（OPC） （100% OPC）和磨粒矿渣（GGBS） （70% OPC + 30% GGBS）水泥水化的影响。结果表明，硅藻通过为C-S-H结构提供核来加速水泥水化，并通过非晶态纳米sio2和纳米caco3促进火山灰反应。硅藻水泥浆体中Ca(OH)2的生成也证实了水泥水化的加速。然而，也有研究发现，硅藻通过在C-S-H结构之间留下更多的弱键，降低了水泥浆体的抗压强度，这被认为是由硅藻中有机部分和形成微米间隙造成的。添加5%硅藻的OPC膏体与空白OPC膏体相比，28 d抗压强度降低最大可达50.1%。在GGBS膏体中，C-S-H颗粒之间提供桥接作用的能力取决于额外钙矾石的发展。这导致含有5%硅藻的GGBS膏体在28天后抗压强度下降7.6%。
Seawater can be used as mixing water for concrete with no steel reinforcement in some areas with difficult access to fresh water. Diatoms such as Phaeodactylum tricornutum are among the most abundant micro-organisms living in seawater, and they could be unavoidable when collecting seawater. In fact, diatoms can provide bio-SiO2 and bio-CaCO3 sources, namely amorphous nano-SiO2 and crystallised nano-CaCO3, which could be beneficial to cement hydration. Thus, the effects of different Phaeodactylum tricornutum concentrations (0%, 2.5% and 5% by weight of suspension of seawater and diatoms) in seawater on cement hydration in ordinary Portland cement (OPC) mixes (100% OPC) and ground granulated blast-furnace slag (GGBS) mixes (70% OPC + 30% GGBS) were investigated through tests of compressive strength, XRD, DTG–DTA and SEM. The results show that diatoms accelerated cement hydration by providing the nucleus for C-S-H structure and contributed pozzolanic reactions by amorphous nano-SiO2 and nano-CaCO3. The accelerated cement hydration was also confirmed by the fact that more Ca(OH)2 was formed in cement pastes with diatoms. However, it has also been found that diatoms decreased the compressive strength of cement pastes by leaving more weak bonds between the C-S-H structure, which was considered to be caused by the organic parts and the micron gap formed in diatoms. When comparing an OPC paste mix with 5% diatoms to a blank OPC paste, the reduction in compressive strength at 28 days can reach a maximum of 50.1%. The ability to provide bridging effects between C-S-H particles in GGBS paste was discovered to depend on the development of additional ettringite. This resulted in a 7.6% loss in compressive strength after 28 days in a GGBS paste with 5% diatoms.