本文選題：菱鎂礦 + 活性MgO　； 參考：《華中科技大學(xué)》2013年博士論文

【摘要】：減少普通硅酸鹽水泥(Ordinary Portland Cement,簡稱OPC)生產(chǎn)過程的碳排放,開發(fā)替代OPC的低碳水泥材料成為研究的熱點(diǎn)。OPC高溫煅燒下形成的過燒MgO(Dead-burned magnisa,簡稱過燒或死燒MgO)會(huì)產(chǎn)生后期膨脹,是OPC生產(chǎn)過程中需要控制的有害成分。近年來,低溫制備的高活性MgO (Reactive magnisa,簡稱活性MgO)在低碳鎂基水泥、水泥膨脹劑以及碳吸附材料中的應(yīng)用受到了廣泛關(guān)注。本文針對(duì)我國儲(chǔ)量較大的菱鎂礦資源,探討低溫煅燒菱鎂礦制備活性MgO及其活性評(píng)價(jià)方法,以及制備的活性MgO單摻到OPC中對(duì)水泥水化過程、膨脹特性、碳化特性等的影響規(guī)律。主要包括以下內(nèi)容： (1)菱鎂礦低溫煅燒制備活性MgO及其活性評(píng)價(jià)方法 在檸檬酸顯色時(shí)間、MgO水化轉(zhuǎn)化率的現(xiàn)有MgO活性評(píng)價(jià)方法基礎(chǔ)上,針對(duì)菱鎂礦600-750℃低溫煅燒存在分解不完全的情況,首次提出低溫制備活性MgO產(chǎn)物的修正水化轉(zhuǎn)化率評(píng)價(jià)方法,并通過XRD、SEM、TEM等手段對(duì)活性MgO的水化產(chǎn)物進(jìn)行表征。結(jié)果表明：焙燒溫度越低,保溫時(shí)間越短,單位質(zhì)量MgO活性越高,但菱鎂礦分解率越低。綜合考慮菱鎂礦分解率及MgO活性,采用自制回轉(zhuǎn)焙燒爐,在焙燒溫度700℃,保溫時(shí)間180min制備活性MgO產(chǎn)物用于后續(xù)水泥材料的研究。 (2)活性MgO水泥體系漿體的體積膨脹規(guī)律及機(jī)理探討 標(biāo)準(zhǔn)養(yǎng)護(hù)條件下,通過單摻MgO、復(fù)摻MgO與粉煤灰的摻料方式,研究不同活性MgO對(duì)水泥凈漿體積變化的影響規(guī)律。通過模擬漿體的40-50℃的溫度條件,設(shè)定水浸泡溫度為40℃,通過XRD、SEM、DTA/TG、比表面積及孔徑分析等分析手段,分析養(yǎng)護(hù)溫度對(duì)漿體膨脹率以及水化產(chǎn)物基本性能的影響。水浸泡升溫加速了水泥漿體的水化速度,單摻過燒MgO水泥凈漿的膨脹率顯著比同摻量活性MgO水泥凈漿的膨脹率大。XRD結(jié)果表明,活性MgO水泥漿體,MgO在43.126°(2θ)衍射峰值較低,Mg(OH)2在37.995°(2θ)處衍射峰面積較大；過燒MgO水泥漿體呈現(xiàn)相反的規(guī)律。過燒MgO水泥漿體在32.546°(2θ)處出現(xiàn)高峰值的衍射峰。MgO的活性影響水泥水化產(chǎn)物的組成和結(jié)構(gòu),從而導(dǎo)致水泥漿體水化前后體積的變化。單摻活性MgO水泥體系最優(yōu)摻量是8wt%；復(fù)摻活性MgO和粉煤灰的水泥體系,最優(yōu)摻量是10wt%MgO和20wt%PFA。選擇蒸壓養(yǎng)護(hù)(80-180℃)的方式,加速M(fèi)gO在體系中的水化過程。蒸養(yǎng)過程中漿體收縮與C-S-H凝膠失水,活性MgO的水化以及水泥水化產(chǎn)物的結(jié)晶有關(guān)。 (3)活性MgO水泥體系碳化規(guī)律及機(jī)理研究 以活性MgO與普通硅酸鹽水泥熟料、粉煤灰為原料設(shè)定MgO和粉煤灰的摻量范圍,進(jìn)行凈漿和砂漿的實(shí)驗(yàn)。碳化養(yǎng)護(hù)條件20±3℃、濕度70±2%,CO2濃度體積分?jǐn)?shù)為5.0±0.2%,10.0±0.2%,20.0±0.2%和80.0±0.2%。通過XRD、SEM、FTIR、孔徑分析等測(cè)試手段,分析凈漿pH變化規(guī)律、C02吸收量、碳化深度以及砂漿強(qiáng)度。水泥漿體PM2-2(MgO摻量20wt%和20wt%粉煤灰)在5%C02養(yǎng)護(hù)90d,C02吸收量的最大值為27.30%。酚酞試劑測(cè)定碳化深度,無色區(qū)是漿體的完全碳化區(qū),pH9.6。未碳化區(qū)pH為12.9,碳化反應(yīng)區(qū)均有較高的pH,范圍在9.6-12.9。砂漿碳化強(qiáng)度最大的樣品PM3-1(MgO摻量10wt%,粉煤灰摻量30wt%),10%C02碳化養(yǎng)護(hù)14d、28d和90d的抗壓強(qiáng)度分別為60.75MPa、53.69MPa和67.56MPa。 (4)活性MgO堿激發(fā)礦渣水泥體系體積變形 堿激發(fā)礦渣水泥(Alkali-activated slag,簡稱AAS)水化產(chǎn)物C-S-H凝膠的鈣硅比、孔徑結(jié)構(gòu)特征造成AAS比OPC漿體更容易開裂。復(fù)摻活性MgO及粉煤灰可以減少堿激發(fā)礦渣水泥的干燥收縮和化學(xué)收縮。在堿激發(fā)劑的模數(shù)和摻量、粉煤灰摻量、MgO摻量的單因素實(shí)驗(yàn)基礎(chǔ)上,采用表面響應(yīng)法(RSM,Response Surface Methodology)實(shí)驗(yàn)設(shè)計(jì)四因素三水平的實(shí)驗(yàn),得出體系最優(yōu)配比為粉煤灰：礦渣的質(zhì)量比FSR為0.4,堿激發(fā)劑的摻量10%,水玻璃模數(shù)1.6,MgO的摻量0.19。優(yōu)化配方MgO:slag:fly ash為20：56.3：23.7時(shí),砂漿試塊28d抗折強(qiáng)度為7.29MPa,抗壓強(qiáng)度44.58MPa。
[Abstract]:In recent years , high - activity MgO ( reactive magnisa , abbreviated as active MgO ) has been widely used in low - carbon magnesia - based cement , cement swelling agent and carbon adsorption material . In recent years , high activity MgO ( reactive magnum ) prepared at low temperature has been used in low - carbon magnesia - based cement , cement swelling agent and carbon adsorption material .

( 1 ) Low - temperature calcination of magnesite ore to prepare active MgO and its activity evaluation method

On the basis of the existing MgO activity evaluation method of the reaction time of citric acid and the hydration conversion rate of MgO , the method for evaluating the modified hydration conversion rate of active MgO product was proposed for the first time . The results showed that the lower the calcination temperature , the shorter the heat preservation time , the higher the MgO activity of the unit mass , the lower the decomposition rate of magnesite .

( 2 ) The volumetric expansion law and mechanism of active MgO cement system slurry

The effects of different active MgO on the volume change of cement paste were studied by means of single - doped MgO , MgO and fly ash . The effects of curing temperature on the swelling rate and the basic properties of hydration products were analyzed by means of XRD , SEM , DTA / TG , specific surface area and pore size analysis .
The MgO cement paste has a high peak value at 32.546 擄 ( 2 胃 ) . The activity of MgO affects the composition and structure of cement hydration products , which results in the change of volume before and after the hydration of cement slurry . The optimum mixing amount of single active MgO cement system is 8wt % .
The hydration process of MgO in the system was accelerated by selecting autoclaved curing ( 80 - 180 鈩，

本文編號(hào)：1983100