بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ , الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ , الرَّحْمَنِ الرَّحِيمِ , مَالِكِ يَوْمِ الدِّينِ , إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ , اهْدِنَا الصِّرَاطَ المُسْتَقِيمَ , صِرَاطَ الَّذِينَ أَنْعَمْتَ عَلَيْهِمْ , غَيْرِ المَغْضُوبِ عَلَيْهِمْ وَلاَ الضَّالِّينَ.
. 006. Nota Buat Pengunjung Blog..
CONCRETE, used in everything from the Pantheon in Rome to slum dwellings, is the most widely used building material in the world. But it has drawbacks. One of these is that concrete is not as weatherproof as the stone it often replaces. Salt and ice can turn tiny fractures in its surface into cracks or holes. But a new invention is designed to change this, by enabling concrete to repair itself. How does it work?
Attempts to make concrete more resilient date back centuries. The Romans often mixed horse hair into their concrete to reduce the amount that it shrank during hardening. They also added blood, which has the effect of making the stuff more frost-resistant by creating extra pores. More recently, chemicals that trap tiny air bubbles have been added to make concrete more durable, and in the 1990s small amounts of electrically conductive steel or carbon fibres were added to the mix, enabling the concrete to conduct electricity so that it can heat up or act a as sensor. A form of self-healing concrete was developed in 2009, when a team at the Delft University of Technology devised a process that involves mixing a special bacterium into the concrete before it is poured. The bacteria release crack-sealing chemicals—but only while they are still alive. The effect wears off after a year or so.
Chan-Moon Chung of Yonsei University in South Korea has devised an alternative approach: a self-healing concrete that relies on a trick that is chemical rather than biological. Dr Chung found that when two substances (called methacryloxypropyl-terminated polydimethylsiloxane and benzoin isobutyl ether) are mixed in sunlight they turn into a protective waterproof polymer that sticks to concrete. So he seals these two chemicals inside tiny capsules of urea and formaldehyde, and then mixes them into a liquid polymer and sprays it onto concrete blocks. As cracks appear in the concrete, the capsules in the vicinity rupture. The chemicals mix and, on exposure to the sun, set into a waterproof layer.
Dr Chung tested his idea by taking small blocks of concrete, both treated and untreated, cracking them and placing them in water for a day. He found that his untreated concrete blocks accumulated 11.3 grams of water. Concrete coated with capsule-free polymer took in 3.9 grams. But the concrete covered with a polymer layer containing his capsules absorbed just 0.4 grams. His treatment meant that the concrete was able, in effect, to heal itself when its surface was damaged. The Romans, along with modern engineers, would surely be impressed.
Link: How can concrete repair itself?.
Zulfarizan Zakaria "FABI
AYYI AALA IRABBIKUMA TUKAZZHIBAN" = Nikmat Tuhan Manakah Yang Engkau
Hendak Dustakan?........muhasabah buat diri kite ni belake kerana Allah
S.W.T.....
Perhatian:
Pemaparan tajuk-tajuk, gambar-gambar dan segala bagai, adalah pandangan
dan pendapat peribadi yang lebih menjurus kepada sikap dan sifat untuk
menjadi lebih baik dengan mengamalkan gaya hidup menurut perentah dan
larangan Allah S.W.T., antaranya bersikap dengan tiada prasangka, tidak
bertujuan untuk kebencian, tidak berkeperluan untuk bersubahat dengan
perkara bohong dan tiada kaitan dan berkepentingan dengan mana-mana
individu. Jujur., aku hanyalah hamba Allah S.W.T., yang hina dina.
BERSANGKA BAIK KERANA ALLAH S.W.T..
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