ﺗﺎﺛﯿﺮ ﻧﺎﻧﻮرس ﺑﺮ دوام ﺗﯿﺮﻫﺎي ﺑﺘﻦ ﻣﺴﻠﺢ ﺗﺤﺖ ﺑﺎرﻫﺎي ﺑﻬﺮهﺑﺮداري و ﺗﻬﺎﺟﻢ ﮐﻠﺮاﯾﺪ

Effect of Nano Clay on the Durability of Reinforced Concrete Beams under Service Loads and Chloride Attack

دوام ﺑﺘﻦﻫﺎي ﻣﺴﻠﺢ در ﻣﺤﯿﻂﻫﺎي ﺧﻮرﻧﺪه در ﺳﺎلﻫﺎي اﺧﯿﺮ ﺑﺎ اﺳﺘﻔﺎده از اﻓﺰودﻧﯽﻫﺎي ﻣﺨﺘﻠﻒ اﻓﺰاﯾﺶ ﯾﺎﻓﺘﻪ اﺳﺖ. در اﯾﻦ ﺗﺤﻘﯿﻖ ﻧﯿﺰ ﻧﺎﻧﻮ ذرات رس ﺑﻪ ﻣﯿﺰان 1 ،0/5 و 1/5 درﺻﺪ وزﻧﯽ ﺳﯿﻤﺎن، ﺟﺎﯾﮕﺰﯾﻦ ﺳﯿﻤﺎن در ﻃﺮح اﺧﺘﻼط ﺷﺎﻫﺪ ﺷﺪهاﻧﺪ. ﺑﺮ ﻫﻤﯿﻦ اﺳﺎس 24 ﻋﺪد ﺗﯿﺮ ﺑﺘﻦ ﻣﺴﻠﺢ ﭘﺲ از 28 روز ﻋﻤﻞآوري در آب ﺑﻪ ﺳﻪ ﮔﺮوه ﺗﻘﺴﯿﻢﺑﻨﺪي ﺷﺪﻧﺪ ﮐﻪ در ﻫﺮ ﮔﺮوه ﻣﯿﺰان ﺟﺎﯾﮕﺰﯾﻨﯽ ﻧﺎﻧﻮ ذرات رس ﻣﺘﻐﯿﺮ ﻣﯽﺑﺎﺷﺪ. ﮔﺮوه اول ﺷﺎﻣﻞ 8 ﻋﺪد ﺗﯿﺮ ﮐﻪ ﭘﺲ از 28 روز ﻋﻤﻞآوري در آب ﺗﺤﺖ آزﻣﺎﯾﺶ ﺧﻤﺸﯽ ﻗﺮار ﮔﺮﻓﺘﻨﺪ. ﮔﺮوه دوم و ﺳﻮم ﻧﯿﺰ ﻫﺮ ﮐﺪام ﺷﺎﻣﻞ 8 ﻋﺪد ﺗﯿﺮ ﺑﻮدﻧﺪ ﮐﻪ ﭘﺲ از 28 روز ﻋﻤﻞآوري در آب ﺑﻪ ﻣﺪت 6 ﻣﺎه در ﻣﺤﻠﻮل ﮐﻠﺮاﯾﺪ و ﭼﺮﺧﻪ ﺗﺮ و ﺧﺸﮏ ﻗﺮارﮔﺮﻓﺘﻪ و ﺳﭙﺲ ﺗﺤﺖ آزﻣﺎﯾﺶ ﺧﻤﺸﯽ ﻗﺮار ﮔﺮﻓﺘﻨﺪ، ﺑﺎ اﯾﻦ ﺗﻔﺎوت ﮐﻪ ﺗﯿﺮﻫﺎي ﮔﺮوه ﺳﻮم در ﻣﺪت 6 ﻣﺎه ﻗﺮارﮔﯿﺮي در ﻣﺤﻠﻮل ﺧﻮرﻧﺪه ﺗﺤﺖ ﺑﺎرﮔﺬاري ﻧﯿﺰ ﻗﺮار داﺷﺘﻨﺪ. ﻫﻤﭽﻨﯿﻦ ﻣﻘﺎوﻣﺖ ﻓﺸﺎري و ﺟﺬب آب ﮐﻠﯿﻪ ﻃﺮح اﺧﺘﻼطﻫﺎ در ﺳﻨﯿﻦ ﻣﺨﺘﻠﻒ اﻧﺪازهﮔﯿﺮي ﮔﺮدﯾﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ اﻓﺰودن ﻧﺎﻧﻮرس ﺑﻪ ﺑﺘﻦ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻗﺎﺑﻞ ﺗﻮﺟﻪ ﻣﻘﺎوﻣﺖ ﻓﺸﺎري ﺷﺪه و ﻫﻤﯿﻦ اﻣﺮ ﺑﺎﻋﺚ ﻣﯽﮔﺮدد ﮐﻪ ﻇﺮﻓﯿﺖ ﺧﻤﺸﯽ ﺗﯿﺮﻫﺎ ﻧﯿﺰ ﮐﺎﻫﺶ ﯾﺎﺑﺪ. ﻋﻼوه ﺑﺮ اﯾﻦ اﻓﺰودن ﻧﺎﻧﻮرس ﺑﻪ ﺑﺘﻦ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺟﺬب آب ﻧﯿﻢ ﺳﺎﻋﺘﻪ و اﻓﺰاﯾﺶ ﺟﺬب آب 24 ﺳﺎﻋﺘﻪ ﻣﯽﺷﻮد. ﺿﻤﻨﺎً ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻗﺮارﮔﯿﺮي ﺗﯿﺮﻫﺎ در ﻣﺤﻠﻮل ﮐﻠﺮاﯾﺪ و ﺳﯿﮑﻞﻫﺎي ﺗﺮ و ﺧﺸﮏ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻇﺮﻓﯿﺖ ﺧﻤﺸﯽ ﺗﯿﺮﻫﺎ ﻣﯽﮔﺮدد، اﻣﺎ ﺑﺎرﮔﺬاري ﺗﯿﺮﻫﺎ ﺗﺎﺛﯿﺮ ﻣﺨﺮب ﻣﺤﻠﻮل ﮐﻠﺮاﯾﺪ را ﮐﺎﻫﺶ ﻣﯽدﻫﺪ. ﻫﻤﭽﻨﯿﻦ ﺗﯿﺮﻫﺎي ﺣﺎوي ﻧﺎﻧﻮرس در ﺑﺮاﺑﺮ ﺗﻬﺎﺟﻢ ﮐﻠﺮاﯾﺪﻫﺎ ﺑﻪ ﻣﺮاﺗﺐ ﻋﻤﻠﮑﺮد ﺑﻬﺘﺮي داﺷﺘﻨﺪ.

Durability of reinforced concrete (RC) structures has been increased using different additives under corrosive environments in the recent years. In the present study, 0, 0.5, 1 and 1.5 percentage of nano clay particles were substituted as cement. Therefore, 24 RC beams divided in three groups after 28 days of curing. The first group consists of 8 beams which were tested after 28 days of moist curing. The second and the third groups consist of 8 beams in each group, which were tested after 6 months exposure in chloride solution and wetting and drying cycles, where the third group beams were additionally under service loads. Also, compressive strength and water absorption of the mixtures were evaluated at different ages. Results showed that the addition of nano-clay particles considerably reduces the compressive strength of concretes which consequently decreases the flexural capacity of the beams. In addition, nano-clay particles reduce the half-hour water absorption and increase 24-hour water absorption. Also, results showed that the wetting and drying cycles of chloride solution for 6 months reduces the flexural capacity of the beams, but service loads reduces the negative effect of the exposure. Also, the beams containing nano-clay particles showed better performance under chloride attack