水泥浆体膨胀性能随纳米氧化镁和矿渣掺量的变化规律
发布时间：2018-07-14 20:30
【摘要】：受困于能源短缺,环境恶化等问题,我国确立了水电优先的发展战略。在水电开发中,水泥基材料仍将发挥重要作用,但是如何解决大体积混凝土易开裂的问题仍旧是难点。针对这一问题,我国开发的轻烧MgO膨胀剂具有水化需水量少、水化产物稳定的优点,适用于补偿大体积混凝土的温降收缩,可以达到简化温控措施,加快施工进度,提高工程效益的目的。但是其不足之处是:现行严苛的安定性检验条件限制了轻烧MgO掺量的提高。也即在这个安定性掺量以内,混凝土的消温降收缩往往还难以被完全抵消。根据目前的研究成果,混凝土的膨胀特性和轻烧MgO的安定性掺量均与其中的方镁石的颗粒尺寸、制备温度和养护条件等有关。故本论文研究了单掺纳米MgO、轻烧MgO以及复掺纳米MgO与轻烧MgO对水泥浆体膨胀性能和抗压强度的影响。研究结果表明:(1)在硅酸盐水泥中,纳米MgO、轻烧MgO的最大体积安定性掺量分别约为10%、4%;在掺50%矿渣的硅酸盐水泥中,纳米MgO、轻烧MgO的最大体积安定性掺量约为8%、2%;在复掺2%(3%)轻烧MgO和50%矿渣的硅酸盐水泥中,纳米MgO的最大体积安定性掺量约为6%(0%);在复掺4%(5%)轻烧MgO和50%矿渣的硅酸盐水泥中,其硬化浆体体积安定性不合格。(2)在40℃水中养护条件下,硅酸盐水泥浆体的膨胀均随MgO(轻烧MgO、纳米MgO)掺量和养护时间的增加而增加,且掺有纳米MgO的浆体的水化膨胀较易稳定。例如,掺8%纳米MgO的浆体膨胀在365 d龄期已稳定,而掺6%轻烧MgO的浆体膨胀在365 d龄期尚未稳定。(3)矿渣对掺纳米MgO的硅酸盐水泥浆体的膨胀和水化速率具有抑制作用。(4)在40℃水中养护条件下,在掺50%矿渣的硅酸盐水泥中单掺纳米MgO时,膨胀较易稳定;单掺轻烧MgO时,膨胀较难稳定;复掺轻烧MgO和纳米MgO时,膨胀趋于稳定的时间居于两者之间。(5)在40℃水中养护545 d条件下,掺纳米MgO(0%~10%)和50%矿渣的硅酸盐水泥净浆试件的孔隙率随纳米MgO掺量的增加而降低,大毛细孔总孔隙率呈现先下降后上升的趋势。(6)在40℃水中养护条件下,在复掺纳米MgO和轻烧MgO以及50%矿渣的硅酸盐水泥中,保持MgO总掺量不变,逐步增加轻烧MgO掺量可以获得更大膨胀。(7)在40℃水中养护条件下,在掺有50%矿渣的硅酸盐水泥中单掺纳米MgO时,掺纳米MgO(0%~10%)的水泥浆体的抗压强度不下降;单掺轻烧MgO时,掺轻烧MgO的水泥浆体的抗压强度随掺量增加呈先上升后下降的趋势;复掺轻烧MgO和纳米MgO时,MgO总掺量小于10%且其中轻烧MgO掺量小于5%的情况下,试件的抗压强度不下降。综上所述,纳米MgO可以用作水泥或混凝土中的新型膨胀材料。复掺轻烧MgO和纳米MgO可以获得比单掺MgO更大更安全的膨胀量,也更具经济效益。
[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，
本文编号：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，
本文编号：2122863
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