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如果混凝土可以自我修复裂缝会怎样?

What if cracks in concrete could fix themselves? - Congrui Jin

生动 富有多样性和激情的城市本身就包含自己再生的种子——简•雅各布斯
混凝土是世界上应用最广的建筑材料
Concrete is the most widely used construction material in the world.
用于城市道路带
It can be found in swathes of city pavements,
跨越大河的桥梁
bridges that span vast rivers,
最高的摩天大楼中
and the tallest skyscrapers on earth.
但这种坚实的物质也有弱点
But this sturdy substance does have a weakness:
它容易毁灭性地破裂
it’ s prone to catastrophic cracking that costs tens of
每年都需要花费几百亿美元来修复
billions of dollars to repair each year.
但如果我们能让混凝土自行修复
But what if we could avoid that problem,
来避免这个问题 会怎么样呢?
by creating concrete that heals itself?
这种想法并不像它听起来那么不靠谱
This idea isn’t as far-fetched as it may seem.
其来源于对混凝土成形方式的理解
It boils down to an understanding of how concrete forms,
以及如何开发这一过程 使对我们有利
and how to exploit that process to our benefit.
混凝土是由粗糙的石头和沙粒组成
Concrete is a combination of coarse stone
也就是聚合物
and sand particles, called aggregates,
再混入水泥 一种由粘土和石灰岩
that mix with cement, a powdered blend
粉末组成的物质
of clay and limestone.
当把水加入到这一堆物质里时
When water gets added to this mix,
水泥形成一种糊状物 覆盖在聚合物上
the cement forms a paste and coats the aggregates, quickly hardening
通过一个叫做水合作用的化学反应 混泥土很快就会硬化
through a chemical reaction called hydration. Eventually,
最终 得到的材料很牢固 足以支撑
the resulting material grows strong enough to prop up buildings
向天空高耸数百米的楼房
that climb hundreds of meters into the sky.
四千年来 人们用各种方法
While people have been using a variety of recipes
来生产水泥
to produce cement for over 4,000 years, concrete
混凝土自身寿命短得惊人
itself has a surprisingly short lifespan.
二十到三十年之后 类似混凝土收缩
After 20 to 30 years, natural processes like concrete shrinkage,
过度冰冻 冰雪融化 重负载等自然过程 都能引起破裂
excessive freezing and thawing, and heavy loads can trigger cracking.
虽然不是严重的大裂缝
And it’s not just big breaks that count:
小的裂痕也可以具有危险性
tiny cracks can be just as dangerous.
混凝土经常被用作钢加固物周围的二次支撑
Concrete is often used as a secondary support around steel reinforcements.
在这种混凝土里 即使小的裂缝
In this concrete, even small cracks
也能进入水 氧气 和二氧化碳
can channel water, oxygen,
引起钢铁的侵蚀
and carbon dioxide that corrode the steel
导致灾难性倒塌
and lead to disastrous collapse.
在类似桥梁 公路 这经常用建筑
On structures like bridges and highways that are constantly
在导致大灾难之前
in use, detecting these problems before they lead
检查出这些问题 难度大而且成本高
to catastrophe becomes a huge and costly challenge.
但不这样做 可能就会危机成千上万的生命
But not doing so would also endanger thousands of lives. Fortunately,
幸运的是 我们已着手研究
we’re already experimenting
这种材料可以自行修复的方法
with ways this material could start fixing itself.
有些解决方法受到了混凝土天然自我修复机制的启发
And some of these solutions are inspired by concrete’s natural self-healing mechanism.
当水进入这些小裂缝
When water enters these tiny cracks,
会使混凝土的生石灰变成水化合物
it hydrates the concrete’s calcium oxide.
生成的氢氧化钙 并与空气中的二氧化碳反应
The resulting calcium hydroxide reacts with carbon dioxide in the air,
开始自发修复的过程 微观碳酸钙晶体
starting a process called autogenous healing, where microscopic calcium carbonate crystals
生成 并逐渐填充缝隙
form and gradually fill the gap. Unfortunately,
不幸的是 这些晶体只能
these crystals can only do so much, healing cracks
修复的宽度小于0.3毫米的裂缝
that are less than 0.3mm wide.
材料科学家已经知道
Material scientists have figured out how
通过添加隐藏胶水至混凝土混合物
to heal cracks up to twice that size by
能够修复的裂缝是原来的两三倍
adding hidden glue into the concrete mix.
如果我们把填满粘合剂的纤维用管输送进混合物里
If we put adhesive-filled fibers and tubes into the mixture,
当一个裂缝产生时 它们就会突然啪地打开
they’ll snap open when a crack forms,
释放粘性物 修复缝隙
releasing their sticky contents and sealing the gap.
但不同的混泥土对于化学性粘合物有不同的反应
But adhesive chemicals often behave very differently from concrete, and over time,
随着时间的推移这些粘合剂能导致更严重的裂缝
these adhesives can lead to even worse cracks.
所以 也许修复大裂缝的最好方法
So perhaps the best way to
是给混凝土
heal large cracks is to give concrete
修复自己的能力
the tools to help itself.
科学家发现 一些细菌和真菌能生产矿物质
Scientists have discovered that some bacteria and fungi can produce minerals,
包括在自发修复中发现的碳酸钙
including the calcium carbonate found in autogenous healing.
实验中把这种细菌或真菌孢子
Experimental blends of concrete include these bacterial or fungal spores
加入到混泥土的营养物质旁
alongside nutrients in their concrete mix,
它们可以冬眠数百年
where they could lie dormant for hundreds of years.
当裂缝最终出现 水慢慢流进混凝土
When cracks finally appear and water trickles into the concrete,
孢子开始苏醒 生长
the spores germinate, grow, and consume
消耗其周围的营养“液”
the nutrient soup that surrounds them,
改变它们的原有环境为碳酸钙成长创造更好的条件
modifying their local environment to create the perfect conditions for calcium carbonate to grow.
这些晶体逐渐填充缝隙
These crystals gradually fill the gaps,
大概三周后
and after roughly three weeks,
努力工作的微生物能完全修复几乎一毫米宽的裂缝
the hard-working microbes can completely repair cracks up to almost 1mm wide.
当裂缝修复后 细菌和真菌将制造孢子
When the cracks seal, the bacteria or fungi will make spores
再次休眠
and go dormant once more— ready
准备自我修复的新周期
to start a new cycle of self-healing
直到裂缝再次产生
when cracks form again.
虽然已经在广泛地研究这种技术
Although this technique has been studied extensively, we
但在它适用于全球混泥土生产之前
still have a ways to go before incorporating it
我们仍然有其它办法
in the global production of concrete. But,
但是 这些孢子有巨大的潜力
these spores have huge potential
使混凝土更加有弹力 持久
to make concrete more resilient and long-lasting—
极大减少混凝土生产中的
which could drastically reduce the financial and environmental cost
经济环境成本
of concrete production. Eventually,
最终 这些微生物
these microorganisms
可能促使我们重新思考 我们对城市的理解
may force us to reconsider the way we think
给没有生机的混凝土丛林 带来生命的活力
about our cities, bringing our inanimate concrete jungles to life.

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视频概述

未来混凝土自我修复原理和展望

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视频来源

https://www.youtube.com/watch?v=znSeL66e8qE

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