水泥漿體膨脹性能隨納米氧化鎂和礦渣摻量的變化規(guī)律
發(fā)布時(shí)間：2018-07-14 20:30
【摘要】：受困于能源短缺,環(huán)境惡化等問題,我國確立了水電優(yōu)先的發(fā)展戰(zhàn)略。在水電開發(fā)中,水泥基材料仍將發(fā)揮重要作用,但是如何解決大體積混凝土易開裂的問題仍舊是難點(diǎn)。針對這一問題,我國開發(fā)的輕燒MgO膨脹劑具有水化需水量少、水化產(chǎn)物穩(wěn)定的優(yōu)點(diǎn),適用于補(bǔ)償大體積混凝土的溫降收縮,可以達(dá)到簡化溫控措施,加快施工進(jìn)度,提高工程效益的目的。但是其不足之處是:現(xiàn)行嚴(yán)苛的安定性檢驗(yàn)條件限制了輕燒MgO摻量的提高。也即在這個(gè)安定性摻量以內(nèi),混凝土的消溫降收縮往往還難以被完全抵消。根據(jù)目前的研究成果,混凝土的膨脹特性和輕燒MgO的安定性摻量均與其中的方鎂石的顆粒尺寸、制備溫度和養(yǎng)護(hù)條件等有關(guān)。故本論文研究了單摻納米MgO、輕燒MgO以及復(fù)摻納米MgO與輕燒MgO對水泥漿體膨脹性能和抗壓強(qiáng)度的影響。研究結(jié)果表明:(1)在硅酸鹽水泥中,納米MgO、輕燒MgO的最大體積安定性摻量分別約為10%、4%;在摻50%礦渣的硅酸鹽水泥中,納米MgO、輕燒MgO的最大體積安定性摻量約為8%、2%;在復(fù)摻2%(3%)輕燒MgO和50%礦渣的硅酸鹽水泥中,納米MgO的最大體積安定性摻量約為6%(0%);在復(fù)摻4%(5%)輕燒MgO和50%礦渣的硅酸鹽水泥中,其硬化漿體體積安定性不合格。(2)在40℃水中養(yǎng)護(hù)條件下,硅酸鹽水泥漿體的膨脹均隨MgO(輕燒MgO、納米MgO)摻量和養(yǎng)護(hù)時(shí)間的增加而增加,且摻有納米MgO的漿體的水化膨脹較易穩(wěn)定。例如,摻8%納米MgO的漿體膨脹在365 d齡期已穩(wěn)定,而摻6%輕燒MgO的漿體膨脹在365 d齡期尚未穩(wěn)定。(3)礦渣對摻納米MgO的硅酸鹽水泥漿體的膨脹和水化速率具有抑制作用。(4)在40℃水中養(yǎng)護(hù)條件下,在摻50%礦渣的硅酸鹽水泥中單摻納米MgO時(shí),膨脹較易穩(wěn)定;單摻輕燒MgO時(shí),膨脹較難穩(wěn)定;復(fù)摻輕燒MgO和納米MgO時(shí),膨脹趨于穩(wěn)定的時(shí)間居于兩者之間。(5)在40℃水中養(yǎng)護(hù)545 d條件下,摻納米MgO(0%~10%)和50%礦渣的硅酸鹽水泥凈漿試件的孔隙率隨納米MgO摻量的增加而降低,大毛細(xì)孔總孔隙率呈現(xiàn)先下降后上升的趨勢。(6)在40℃水中養(yǎng)護(hù)條件下,在復(fù)摻納米MgO和輕燒MgO以及50%礦渣的硅酸鹽水泥中,保持MgO總摻量不變,逐步增加輕燒MgO摻量可以獲得更大膨脹。(7)在40℃水中養(yǎng)護(hù)條件下,在摻有50%礦渣的硅酸鹽水泥中單摻納米MgO時(shí),摻納米MgO(0%~10%)的水泥漿體的抗壓強(qiáng)度不下降;單摻輕燒MgO時(shí),摻輕燒MgO的水泥漿體的抗壓強(qiáng)度隨摻量增加呈先上升后下降的趨勢;復(fù)摻輕燒MgO和納米MgO時(shí),MgO總摻量小于10%且其中輕燒MgO摻量小于5%的情況下,試件的抗壓強(qiáng)度不下降。綜上所述,納米MgO可以用作水泥或混凝土中的新型膨脹材料。復(fù)摻輕燒MgO和納米MgO可以獲得比單摻MgO更大更安全的膨脹量,也更具經(jīng)濟(jì)效益。
[Abstract]:Trapped by energy shortage and environmental deterioration, China has established the development strategy of hydropower priority. Cement based materials will still play an important role in hydropower development, but how to solve the problem of mass concrete cracking is still difficult. In order to solve this problem, the lightly burned MgO expander developed in China has the advantages of less hydration water requirement and stable hydration products, which is suitable for compensating the temperature drop and shrinkage of mass concrete, and can simplify the temperature control measures and accelerate the construction progress. The purpose of improving the efficiency of the project. But its shortcoming is: the present strict stability test conditions limit the increase of MgO content. In other words, it is difficult to completely counteract the temperature drop and shrinkage of concrete within this stable content. According to the present research results, the expansion characteristics of concrete and the stable content of MgO are related to the particle size, preparation temperature and curing conditions of periclase. Therefore, the effects of nano-MgO, lightly burned MgO and co-doped MgO and light-burned MgO on the expansive properties and compressive strength of cement paste were studied in this paper. The results show that: (1) the maximum volume stability of nano-MgO and lightly burned MgO in Portland cement is about 10 ~ 4, respectively, and in Portland cement with 50% slag, In Portland cement with 2% (3%) light burning MgO and 50% slag, the maximum volume stability of nano-MgO is about 6% (0%); in Portland cement with 4% (5%) light burning MgO and 50% slag, the maximum volume stability of MgO is about 6% (0%), and that of Portland cement with 4% (5%) of light burned MgO and 50% slag is about 6% (0%) in the Portland cement with 2% (3%) light burning MgO and 50% slag. The volume stability of hardened slurry is not up to standard. (2) under the condition of water curing at 40 鈩，
本文編號：2122863
[Abstract]:Trapped by energy shortage and environmental deterioration, China has established the development strategy of hydropower priority. Cement based materials will still play an important role in hydropower development, but how to solve the problem of mass concrete cracking is still difficult. In order to solve this problem, the lightly burned MgO expander developed in China has the advantages of less hydration water requirement and stable hydration products, which is suitable for compensating the temperature drop and shrinkage of mass concrete, and can simplify the temperature control measures and accelerate the construction progress. The purpose of improving the efficiency of the project. But its shortcoming is: the present strict stability test conditions limit the increase of MgO content. In other words, it is difficult to completely counteract the temperature drop and shrinkage of concrete within this stable content. According to the present research results, the expansion characteristics of concrete and the stable content of MgO are related to the particle size, preparation temperature and curing conditions of periclase. Therefore, the effects of nano-MgO, lightly burned MgO and co-doped MgO and light-burned MgO on the expansive properties and compressive strength of cement paste were studied in this paper. The results show that: (1) the maximum volume stability of nano-MgO and lightly burned MgO in Portland cement is about 10 ~ 4, respectively, and in Portland cement with 50% slag, In Portland cement with 2% (3%) light burning MgO and 50% slag, the maximum volume stability of nano-MgO is about 6% (0%); in Portland cement with 4% (5%) light burning MgO and 50% slag, the maximum volume stability of MgO is about 6% (0%), and that of Portland cement with 4% (5%) of light burned MgO and 50% slag is about 6% (0%) in the Portland cement with 2% (3%) light burning MgO and 50% slag. The volume stability of hardened slurry is not up to standard. (2) under the condition of water curing at 40 鈩，
本文編號：2122863
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