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（清華大學(xué)土木工程系， 北京 100084）

［摘要］通過(guò)混凝土經(jīng)歷常溫（10℃）至-40℃及-80℃兩種溫度區(qū)間的凍融循環(huán)作用試驗(yàn)，考察混凝土低溫凍融循環(huán)作用下受壓強(qiáng)度變化規(guī)律和不同低溫凍融循環(huán)作用溫度區(qū)間的影響。結(jié)果表明，下降溫度下混凝土的破壞聲響短暫而清脆，呈現(xiàn)明顯的脆性破壞特征；而10℃時(shí)破壞聲響則稍長(zhǎng)且沉悶。隨低溫凍融循環(huán)作用次數(shù)的增加，試件破壞偏心現(xiàn)象逐漸顯現(xiàn)。經(jīng)歷兩種不同溫度區(qū)間凍融循環(huán)作用，隨凍融循環(huán)作用次數(shù)的增加，上限溫度時(shí)混凝土受壓強(qiáng)度的變化規(guī)律相似，均呈平穩(wěn)波動(dòng)狀；下限溫度時(shí)則對(duì)凍融更為敏感且不同溫度區(qū)間的變化規(guī)律有較大差別。混凝土受壓強(qiáng)度在下限溫度為-80℃時(shí)有明顯的下降趨勢(shì)，而在下限溫度為-40℃時(shí)則基本上呈平穩(wěn)波動(dòng)，但隨凍融循環(huán)作用次數(shù)增加兩者的差異逐漸減小。

［關(guān)鍵詞］混凝土； 超低溫； 凍融循環(huán)作用； 受壓強(qiáng)度； 溫度區(qū)間

中圖分類(lèi)號(hào)：TU318文獻(xiàn)標(biāo)識(shí)碼：A文章編號(hào)：1002-848X(2019)12-0083-06

Experimental study on compressive strength of concrete undergoing freeze-thaw cycle action from room temperature to -40℃ and -80℃

Shi Xudong， Qian Lei， Li Yaqiang， Wang Wenqiang

(Department of Civil Engineering, Tsinghua University, Beijing 100084, China)

Abstract:Through experiments on concrete undergoing freeze-thaw cycle action from room temperature（10℃）to -40℃and -80℃, the regularities of concrete compressive strength and the impacts of different temperature ranges on them during freeze-thaw cycles under ultralow temperature are investigated. The results show that the sound from the failure of concrete at the lower limit temperature is short and sharp, which shows apparent characteristics of brittle failure. But the failure sound at 10℃ is muffled and lasts longer. The eccentric failure of specimens appears gradually with the increase of freeze-thaw cycles. For concretes undergoing freeze-thaw cycles of two different temperature ranges, the compressive strength at the upper limit temperature shows similar regularities and fluctuates stably. But the compressive strength at the lower limit temperature is more sensitive to freeze-thaw cycle action and the regularities from the two temperature ranges are quite different. The compressive strength shows apparent downtrend when the lower limit temperature is -80℃, but fluctuates stably when the lower limit temperature is  -40℃ and the compressive strength difference between them decreases gradually with the increase of freeze-thaw cycles.

Keywords:concrete; ultralow temperature; freeze-thaw cycle action; compressive strength; temperature range

*國(guó)家自然科學(xué)基金項(xiàng)目(51478242)。

作者簡(jiǎn)介：時(shí)旭東，博士，教授，博士生導(dǎo)師，Email：shixd@mail.tsinghua.edu.cn。