MgO對水泥熟料膨脹性能的影響
發(fā)布時間：2018-11-26 12:37
【摘要】：水泥熟料中方鎂石水化膨脹是引起混凝土體積不穩(wěn)定的重要因素之一,國家標準對水泥中MgO的含量有明確限制。但是,方鎂石不僅具有膨脹破壞性,還具有補償收縮性。MgO水化產(chǎn)生的體積膨脹可以有效補償大體積混凝土因溫度應(yīng)力產(chǎn)生的收縮,大幅度減少了裂縫的產(chǎn)生。與此同時,使用高鎂石灰石生產(chǎn)熟料還具有緩解高品質(zhì)石灰石資源日益匱乏的作用。針對水泥產(chǎn)業(yè)面臨的資源和環(huán)境問題,結(jié)合外摻MgO水泥研究成果,本課題研究了MgO對水泥熟料膨脹性能的影響,以期為高鎂石灰石高效利用提供理論依據(jù)。使用不同MgO含量的熟料制備了多種水泥凈漿和砂漿試件,然后將這些試樣在不同水浴溫度環(huán)境(20℃,50℃和80℃),不同空氣溫度環(huán)境(20℃,50℃和80℃)和不同地域自然環(huán)境(深圳,西安,烏魯木齊)養(yǎng)護。借助X射線衍射(XRD),掃描電鏡(SEM),熱重分析(TGA)等檢測方法來表征不同MgO含量熟料制備的水泥在不同養(yǎng)護條件下的水化產(chǎn)物和水化過程。測定了水泥砂漿試件在不同環(huán)境中的收縮特性,分析了MgO對水泥熟料中方鎂石和主要礦物相的含量的影響,SO_3的摻雜對高鎂水泥熟料中方鎂石的含量的影響以及SO_3及H3BO3單獨和共同摻雜對高鎂熟料中B礦晶型影響。研究表明:(1)在給定溫度空氣中養(yǎng)護的砂漿試件,水泥熟料氧化鎂含量高的試塊其收縮相對比較小,養(yǎng)護溫度的升高促進試件收縮的增加;養(yǎng)護在給定溫度水浴的水泥試塊,水泥熟料氧化鎂含量高的水泥試塊其膨相對比較大,溫度的升高對水泥試塊的膨脹具有促進作用。(2)熟料中的氧化鎂含量越高,方鎂石含量越高,熟料其易磨性越差。(3)氫氧化鎂的脫水反應(yīng)發(fā)生在340℃~410℃之間,出現(xiàn)脫水峰最大峰值的溫度為360℃。溫度越高,氧化鎂的水化速率越快,水化產(chǎn)物氫氧化鎂越多。(4)水泥凈漿在80℃水浴養(yǎng)護至7 d,距離未水化的方鎂石5μm左右的區(qū)域存在著含鎂的鋁硅酸鹽物質(zhì)。養(yǎng)護至130 d,高鎂熟料中方鎂石已幾乎完全水化,生成Mg(OH)2,周圍有C(M)-S-H的存在。(5)SO_3摻雜有效減小了高鎂熟料中方鎂石的含量。H3BO3摻雜能夠穩(wěn)定β型硅酸二鈣,形成了白硅鈣石Ca7MgSi4O16等晶體礦物,摻入SO_3后會導致Ca7MgSi4O16的MgO分解出來,形成方鎂石。(6)當SO_3和H3BO3同時對含鎂β-C2S進行穩(wěn)固的時候,SO_3和H3BO3有一個最佳配比:SO_3摻量4%,H3BO3摻量0.5%。在這個比例下,物料的水化反應(yīng)會達到最佳。
[Abstract]:The hydration expansion of periclase in cement clinker is one of the important factors that cause the volume instability of concrete. The content of MgO in cement is restricted by the national standard. However, periclase not only has expansion and destructiveness, but also compensates shrinkage. The volume expansion caused by MgO hydration can effectively compensate the shrinkage of mass concrete due to thermal stress, which greatly reduces the occurrence of cracks. At the same time, the use of high magnesium limestone to produce clinker can alleviate the shortage of high quality limestone resources. In view of the resource and environment problems faced by cement industry and combined with the research results of MgO cement, this paper studies the effect of MgO on the expansion performance of cement clinker, in order to provide theoretical basis for the efficient utilization of high magnesium limestone. A variety of cement mortar and mortar specimens were prepared by using clinker with different MgO content. The samples were then treated at different water bath temperatures (20 鈩，
本文編號：2358579
[Abstract]:The hydration expansion of periclase in cement clinker is one of the important factors that cause the volume instability of concrete. The content of MgO in cement is restricted by the national standard. However, periclase not only has expansion and destructiveness, but also compensates shrinkage. The volume expansion caused by MgO hydration can effectively compensate the shrinkage of mass concrete due to thermal stress, which greatly reduces the occurrence of cracks. At the same time, the use of high magnesium limestone to produce clinker can alleviate the shortage of high quality limestone resources. In view of the resource and environment problems faced by cement industry and combined with the research results of MgO cement, this paper studies the effect of MgO on the expansion performance of cement clinker, in order to provide theoretical basis for the efficient utilization of high magnesium limestone. A variety of cement mortar and mortar specimens were prepared by using clinker with different MgO content. The samples were then treated at different water bath temperatures (20 鈩，
本文編號：2358579
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