鎂渣制備可控膨脹性膠凝材料的研究
發(fā)布時(shí)間：2018-08-30 20:53
【摘要】：鎂渣是鎂廠冶煉金屬鎂時(shí)產(chǎn)生的固體廢棄物,但因出爐鎂渣采取自然冷卻的方式,導(dǎo)致鎂渣料的活性低,并且存在滯后膨脹的現(xiàn)象,這一直是制約鎂渣料應(yīng)用的關(guān)鍵所在,如何提高鎂渣料的活性,消除滯后膨脹危害對(duì)充分有效的利用鎂渣有著重要的意義。本文通過(guò)對(duì)鎂渣產(chǎn)生的條件及鎂渣的機(jī)理分析后,制定先采用自制小型冷卻設(shè)備對(duì)出爐鎂渣進(jìn)行冷卻,并通過(guò)控制風(fēng)量制備出不同冷卻速率鎂渣,分別為急冷鎂渣、半急冷鎂渣和自然冷鎂渣,對(duì)比分析三種冷卻速率鎂渣物化性能后,得出改變出爐鎂渣的冷卻速率對(duì)鎂渣物化性能的影響,并為制備可控膨脹性鎂渣膠凝材料提供適合的冷卻速率鎂渣。然后采用適合的冷卻速率鎂渣與水泥在不同比例下分別制備了鎂渣水泥膠凝料標(biāo)準(zhǔn)試塊及膨脹試塊,并通過(guò)物理性能檢測(cè),膨脹量測(cè)量,化學(xué)分析,XRD,SEM,壓汞等方法對(duì)比研究不同配比下鎂渣水泥膠凝料的物化性能及膨脹性,得到了以下結(jié)論:(1)改變冷卻速率會(huì)影響鎂渣中MgO的晶粒尺寸,自然冷鎂渣中MgO晶粒尺寸為98.32nm;半急冷鎂渣中MgO晶粒尺寸為10.534nm;急冷鎂渣中MgO晶粒尺寸為3.04nm。因此,隨著冷卻速率加快,MgO晶粒尺寸迅速減小,活性增大,有益于MgO早期水化。在急冷鎂渣與水泥制備的膠凝材料中,養(yǎng)護(hù)3d的衍射圖中有MgO衍射峰的出現(xiàn),但養(yǎng)護(hù)至28 d后,衍射圖中已幾乎不存在MgO衍射峰強(qiáng)。(2)隨著冷卻速率加快,鎂渣的物化性能均有所改變,自然冷鎂渣養(yǎng)護(hù)3d后基本未發(fā)生水化,抗壓強(qiáng)度值僅為3.75MPa,養(yǎng)護(hù)至28d后水化程度依然不明顯,抗壓強(qiáng)度值為13MPa;而急冷鎂渣養(yǎng)護(hù)3d后,抗壓強(qiáng)度值為11.33 MPa,并且在SEM圖像上可以觀察到大部分顆粒表面均覆蓋了一層薄薄的互連網(wǎng)狀的C-S-H凝膠,養(yǎng)護(hù)28d后抗壓強(qiáng)度值為21.7 MPa,其SEM圖像上可以觀察到C-S-H凝膠互相膠結(jié)的現(xiàn)象。(3)養(yǎng)護(hù)3d至28d過(guò)程中,自然冷鎂渣的內(nèi)部孔隙率由48.92%增加到67.72%,小孔占有的體積由55.95%下降到23.57%,最可幾孔徑尺寸幾乎沒(méi)有變化,約為91μm;半急冷鎂渣的內(nèi)部孔隙率由52.62%減小到42.63%,小孔所占體積由44.55%增加到67.53%,最可幾孔徑尺寸由91.25μm降至60.70μm;急冷鎂渣的內(nèi)部孔隙率由39.13%下降到31.32%,小孔所占體積由69.51%增加到97.27%,最可幾孔徑尺寸由60.75μm下降到0.83μm。(4)隨著鎂渣摻量的增加,急冷鎂渣水泥膠凝材料的水化程度減弱,膨脹性能增強(qiáng),當(dāng)鎂渣摻量為30%時(shí),膠凝材料一直表現(xiàn)出負(fù)膨脹現(xiàn)象,并且養(yǎng)護(hù)200d內(nèi)的負(fù)膨脹率最后穩(wěn)定在1.08%,這說(shuō)明膠凝材料依然存在很大的收縮行為;鎂渣摻量為40%時(shí),膠凝材料在養(yǎng)護(hù)200d內(nèi)先負(fù)膨脹,后正膨脹,并且最后穩(wěn)定在正膨脹0.12%,這表明膠凝材料的收縮行為被完全抵消了,且最終膠凝材料處于一種微膨脹狀態(tài);若將鎂渣摻量繼續(xù)增加到50%時(shí),膠凝材料的壓蒸安定性不合格。(5)隨著鎂渣摻量的增加,急冷鎂渣水泥膠凝材料的抗壓、抗折性能和密實(shí)度均降低,并且膠凝材料的孔隙率隨著養(yǎng)護(hù)時(shí)間的增加也逐漸下降,養(yǎng)護(hù)3d至28d過(guò)程中,膠凝材料的內(nèi)部孔徑尺寸變化范圍均在0~120μm內(nèi),其中,摻50%鎂渣膠凝材料的孔隙率由32.39%減小到26.76%,最可幾孔徑尺寸由60.67μm減小到1.3μm,小孔所占體積由66.51%增加至94.82%;摻40%鎂渣膠凝材料的孔隙率由28.48%減小至16.08%,最可幾孔徑尺寸由45.37μm減小到0.18μm,小孔所占體積63.67%增加至94.34%;摻30%鎂渣的膠凝材料養(yǎng)護(hù)3d后孔隙率是最小的,為26.98%,最可幾孔徑尺寸為45.45μm,小孔所占體積在為70.58%,養(yǎng)護(hù)至28d后,孔隙率下降至16.64%,最可幾孔徑減小至0.18μm,小孔所占體積增加到93.85%。
[Abstract]:Magnesium slag is a solid waste produced in magnesium smelting. However, the activity of magnesium slag is low and the phenomenon of delayed expansion exists because of the natural cooling of magnesium slag. This has always been the key to restrict the application of magnesium slag. The slag is of great significance.After analyzing the conditions of producing magnesium slag and the mechanism of magnesium slag,this paper establishes a self-made small-scale cooling equipment to cool the magnesium slag from the furnace,and prepares magnesium slag with different cooling rates by controlling the air flow rate,which are quenched magnesium slag,semi-quenched magnesium slag and naturally cooled magnesium slag.The three cooling rates are compared and analyzed. After the physicochemical properties of magnesium slag were studied, the influence of cooling rate of magnesia slag on the physicochemical properties of magnesia slag was obtained, and the suitable cooling rate of magnesia slag was provided for the preparation of magnesia slag cementitious material with controllable expansibility. The physical and chemical properties and expansibility of magnesia slag cement cementitious materials with different ratios were studied by physical properties testing, expansion measurement, chemical analysis, XRD, SEM and mercury intrusion test. The following conclusions were obtained: (1) Changing the cooling rate will affect the grain size of MgO in magnesia slag, the grain size of MgO in natural cooled magnesia slag is 98.32 nm; The grain size of medium MgO is 10.534 nm and that of quenched MgO is 3.04 nm. Therefore, with the increase of cooling rate, the grain size of MgO decreases rapidly and the activity of MgO increases, which is beneficial to the early hydration of MgO. There is almost no MgO diffraction peak strength. (2) With the acceleration of cooling rate, the physical and chemical properties of magnesium slag have changed. The natural cold magnesium slag has not been hydrated after 3 days of curing, the compressive strength value is only 3.75 MPa, and the hydration degree is still not obvious after 28 days of curing, the compressive strength value is 13 MPa; but the compressive strength value is 11.33 MPa after 3 days of quenching magnesium slag curing. The surface of most particles was covered with a thin layer of interconnected C-S-H gel, and the compressive strength was 21.7 MPa after 28 days of curing. The phenomenon of C-S-H gel cementation could be observed on the SEM images. (3) The internal porosity of natural cold magnesium slag increased from 48.92% to 67.72% during 3 to 28 days of curing. The volume of the pores decreased from 55.95% to 23.57%, and the most probable pore size almost remained unchanged, about 91 micron; the internal porosity of the semi-quenched magnesium slag decreased from 52.62% to 42.63%, the volume of the pores increased from 44.55% to 67.53%, the most probable pore size decreased from 91.25 micron to 60.70 micron; and the internal porosity of the quenched magnesium slag decreased from 39.13% to 31.32 micron. (4) With the increase of magnesia slag content, the hydration degree of the quenched magnesia slag cement cementitious material decreases, and the expansion performance increases. When the magnesia slag content is 30%, the cementitious material always shows negative expansion phenomenon, and the negative expansion rate of the cured 200 days. At last, it stabilized at 1.08%, which indicated that the cementitious material still had a large shrinkage behavior; when the content of magnesium slag was 40%, the cementitious material expanded negatively, then positively, and finally stabilized at 0.12% of the positive expansion within 200 days of curing, which indicated that the shrinkage behavior of the cementitious material was completely offset, and the final cementitious material was in a micro-expansion state; (5) With the increase of magnesium slag content, the compressive strength, flexural strength and compactness of the quenched magnesium slag cement cementitious materials decrease, and the porosity of the cementitious materials decreases gradually with the increase of curing time. During the curing period from 3 to 28 days, the internal properties of the cementitious materials decrease. The pore size ranges from 0.39% to 26.76%, the most probable pore size decreases from 60.67 to 1.3 micron, the volume of small pore increases from 66.51% to 94.82%, the porosity of 40% magnesium slag cementitious material decreases from 28.48% to 16.08%, and the most probable pore size decreases from 45.37 micron. The porosity of the cementitious material with 30% magnesium slag is the smallest, 26.98%, the most probable pore size is 45.45 micron, the volume of the pore is 70.58%. After 28 days, the porosity decreases to 16.64%, the most probable pore diameter decreases to 0.18 micron, and the volume of the pore increases to 93.85%.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ177
本文編號(hào)：2214261
[Abstract]:Magnesium slag is a solid waste produced in magnesium smelting. However, the activity of magnesium slag is low and the phenomenon of delayed expansion exists because of the natural cooling of magnesium slag. This has always been the key to restrict the application of magnesium slag. The slag is of great significance.After analyzing the conditions of producing magnesium slag and the mechanism of magnesium slag,this paper establishes a self-made small-scale cooling equipment to cool the magnesium slag from the furnace,and prepares magnesium slag with different cooling rates by controlling the air flow rate,which are quenched magnesium slag,semi-quenched magnesium slag and naturally cooled magnesium slag.The three cooling rates are compared and analyzed. After the physicochemical properties of magnesium slag were studied, the influence of cooling rate of magnesia slag on the physicochemical properties of magnesia slag was obtained, and the suitable cooling rate of magnesia slag was provided for the preparation of magnesia slag cementitious material with controllable expansibility. The physical and chemical properties and expansibility of magnesia slag cement cementitious materials with different ratios were studied by physical properties testing, expansion measurement, chemical analysis, XRD, SEM and mercury intrusion test. The following conclusions were obtained: (1) Changing the cooling rate will affect the grain size of MgO in magnesia slag, the grain size of MgO in natural cooled magnesia slag is 98.32 nm; The grain size of medium MgO is 10.534 nm and that of quenched MgO is 3.04 nm. Therefore, with the increase of cooling rate, the grain size of MgO decreases rapidly and the activity of MgO increases, which is beneficial to the early hydration of MgO. There is almost no MgO diffraction peak strength. (2) With the acceleration of cooling rate, the physical and chemical properties of magnesium slag have changed. The natural cold magnesium slag has not been hydrated after 3 days of curing, the compressive strength value is only 3.75 MPa, and the hydration degree is still not obvious after 28 days of curing, the compressive strength value is 13 MPa; but the compressive strength value is 11.33 MPa after 3 days of quenching magnesium slag curing. The surface of most particles was covered with a thin layer of interconnected C-S-H gel, and the compressive strength was 21.7 MPa after 28 days of curing. The phenomenon of C-S-H gel cementation could be observed on the SEM images. (3) The internal porosity of natural cold magnesium slag increased from 48.92% to 67.72% during 3 to 28 days of curing. The volume of the pores decreased from 55.95% to 23.57%, and the most probable pore size almost remained unchanged, about 91 micron; the internal porosity of the semi-quenched magnesium slag decreased from 52.62% to 42.63%, the volume of the pores increased from 44.55% to 67.53%, the most probable pore size decreased from 91.25 micron to 60.70 micron; and the internal porosity of the quenched magnesium slag decreased from 39.13% to 31.32 micron. (4) With the increase of magnesia slag content, the hydration degree of the quenched magnesia slag cement cementitious material decreases, and the expansion performance increases. When the magnesia slag content is 30%, the cementitious material always shows negative expansion phenomenon, and the negative expansion rate of the cured 200 days. At last, it stabilized at 1.08%, which indicated that the cementitious material still had a large shrinkage behavior; when the content of magnesium slag was 40%, the cementitious material expanded negatively, then positively, and finally stabilized at 0.12% of the positive expansion within 200 days of curing, which indicated that the shrinkage behavior of the cementitious material was completely offset, and the final cementitious material was in a micro-expansion state; (5) With the increase of magnesium slag content, the compressive strength, flexural strength and compactness of the quenched magnesium slag cement cementitious materials decrease, and the porosity of the cementitious materials decreases gradually with the increase of curing time. During the curing period from 3 to 28 days, the internal properties of the cementitious materials decrease. The pore size ranges from 0.39% to 26.76%, the most probable pore size decreases from 60.67 to 1.3 micron, the volume of small pore increases from 66.51% to 94.82%, the porosity of 40% magnesium slag cementitious material decreases from 28.48% to 16.08%, and the most probable pore size decreases from 45.37 micron. The porosity of the cementitious material with 30% magnesium slag is the smallest, 26.98%, the most probable pore size is 45.45 micron, the volume of the pore is 70.58%. After 28 days, the porosity decreases to 16.64%, the most probable pore diameter decreases to 0.18 micron, and the volume of the pore increases to 93.85%.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ177
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