【正文】 d to accelerate alite hydration, and from 2 to 4%, belite hydration . A high gypsum content contributes to the formation of large amounts of ettringite, however, which retards paste setting and hardening and prompts substantial changes in volume as a result of micro structural expansion and cracking。因?yàn)檫@個(gè)原因 ,硅灰添加到水泥是用于制造高性能的散裝水泥 ,生產(chǎn)中必須采取的直接和間接的方法減少其對(duì)水化熱的影響 ,減少不良后果的造成開(kāi)裂的風(fēng)險(xiǎn)等。 PC1C3A 的含量高時(shí)，早期會(huì)產(chǎn)生大量的水化熱。同理，第三個(gè)階段中 PC2沒(méi)有鋁酸鹽生成的階段。 雖然在 PC2中加 10%和加 20%的硅灰相對(duì)于純 PC1來(lái)說(shuō)熱量的本質(zhì)是一樣的，但是還是發(fā)現(xiàn)有些差異的。對(duì)于純 PC1第三個(gè)峰則會(huì)完全消失。隨后，兩種不同的混合物中 SO3/Al2O3比例的下降促進(jìn)了鋁酸鹽的形成。最后，水化反應(yīng)開(kāi)始變慢，保持在一個(gè)較低的速率。第一階段為誘導(dǎo)期，圖三顯示了熱量釋放速率高是因?yàn)?C3A的初始水化反應(yīng)。在 25186。 水的多少對(duì)形態(tài)有很大的影響。PC2中的組成是 C3S（ 79%） ,C2S(2%),C3A(0%)、 C4AF(10%)。 在另一方面，每克摻雜了硅灰的硅酸鹽水泥釋放的熱量比沒(méi)摻雜硅灰的硅酸鹽水泥要多。 石膏含量高有助于形成大量的鈣礬石，然而這會(huì)阻止凝結(jié)時(shí)間和硬化，這些明顯的變化是因?yàn)槲⒂^結(jié)構(gòu)的膨脹和開(kāi)裂。這些效果的發(fā)展取決于熟料的礦物組成。 普通硅酸鹽水泥中摻入硅灰和石膏對(duì)水化反應(yīng)的影響 在混凝土設(shè)計(jì)中摻加活性礦物替代是一個(gè)很重要的環(huán)節(jié)。二氧化硅會(huì)直接和間接的影響水化反應(yīng)：后者是因?yàn)?在早期 火山灰質(zhì)活性的增加，前者是因?yàn)樗男螒B(tài)（微小的球體）和比表 面積 大。石膏含量低，反過(guò)來(lái)，會(huì)形成更多的硫酸鹽，降低了水化反應(yīng)的強(qiáng)度，從而阻礙了 C3A 的的分解。 實(shí)驗(yàn) 目的 鑒于要考慮石膏和硅灰這些物質(zhì)，現(xiàn)在研究的目標(biāo)是分析兩種不同成分的硅酸鹽水泥水化反 應(yīng)的整體效應(yīng)，以限制他們?cè)诟咝阅芑炷林械氖褂谩? 不同的化學(xué)和礦物成分的兩種硅酸鹽水泥主要差別表現(xiàn)在密度不同。硅酸鹽水泥顆?？梢栽黾铀嗨牡姆磻?yīng)面積。C 進(jìn)行了測(cè)量，記錄在第一個(gè) 48小時(shí)內(nèi)的水化熱和總的熱釋放量的數(shù)據(jù)，是通過(guò)計(jì)算面積不同下熱量釋放率的曲線。兩小時(shí)后第一個(gè)峰出現(xiàn)時(shí)，速率下降到 。 48小時(shí)候?qū)嶒?yàn)完成，把熱量釋放曲線的第三個(gè)峰值作為參考。結(jié)果在 11： 34— 14：24之間第三個(gè)峰值出現(xiàn)， 10%和 20%摻量的混合物還是要高于純 PC1。 圖二為 PC2的第一階段或者稱為誘導(dǎo)期，由于水化反應(yīng)的初始階段，有很高的的熱量釋放速率。在第一個(gè)階段，例如速率在 ，硅灰粒子的效果是稀釋硅酸鹽水泥。 總之，混合物中無(wú)論是第一個(gè)波峰和第二個(gè)波峰被推遲還是被率值降低，但是觀察到 PC1混合物的水化強(qiáng)度明顯要高。在實(shí)驗(yàn)研究的 48h 內(nèi)，摻雜了硅灰或摻雜了大量 硅灰的硅酸鹽水泥相比普通的硅酸鹽水泥產(chǎn)生的水化人要多。 在所有情況下，添加石膏會(huì)減弱水化反應(yīng)的強(qiáng)度。 a low gypsum content, in turn, favours the formation of monosulphoaluminate solid solutions before the end of the latent period of C3S hydration, thereby retarding the acceleration period of this pound . The study of mineral pozzolanic additions has also developed from the analysis of discrete systems . In the case of silica fume, which is a highly pozzolanic addition, it has been found that: ? After three days, at addition rates of 5 and 10%, C3A hydration is retarded . ? Additions of 5–10% accelerate alite hydration up to the age of 28 days ? Lastly, including the addition also heightens the hydration rate of _C2S during the first 28 days . The oute of all the foregoing is to produce greater heat of hydration at early ages , an effect that grows more intense as the percentage of the addition is raised from 5 to 10% . The high BET specific surface of silica fume has been identified as the cause of its overstimulation of Portland cement hydration reactions [11]. In addition, however, an indirect stimulatory effect on such reactions has been attributed to the substance, due to the fixation of calcium hydroxide in the pozzolanic reaction from the earliest ages [12]. On the one hand, the pozzolanic reaction has been confirmed to take place even in the first few days, chiefly on the grounds of the consumption of Ca2+ ions in the liquid phase, but also of the uptake – in descending order – of OH– and K+ ions [13–17]. And on the other, the amount of heat released per gram of Portland cement in pastes with silica fume has been found to amply exceed the amount of heat released by the respective plain pastes [18]. Experimental Objective In light of these considerations on substances such as gypsum and silica fume。 when gypsum was included in the SF – PC1/SF mixes –, in turn, all the curves were slightly retarded and the first trough and second peak were slightly attenuated. As in the case of plain PC1, the third peak disappeared altogether. The first stage or induction period for plain PC2, visible in Fig. 4, is also characterized by a high rate of heat release due to initial hydrolysis。C. Data were recorded during the first 48 h of hydration and the total heat released was puted by integrating the area under the rate of releaseage curve. This methodology is widely used to monitor hydration in pure Portland cement [1] as well as for cements containing mineral additions [24]. To obtain equally workable pastes, the water:cementitious material ratios used were for pure Portland cements, for mixes with 10% SF and for mixes with 20% silica fume. Results and discussion Figure 2 shows [OH–] and [CaO] determined at 48 h. Note that the pastes with SF showed pozzolanic activity at 48 h (., 6 days before its first specified age, 8 days [25]), in the case of PC1 at (additioncement) replacement rates of 10%, and in PC2 at rates of 15% or higher. Some of these mixes failed to show pozzolanicity at that age because the rate of the hydration reaction was so high that it could not be countered or pensated for by the fixation of the calcium hydroxide resulting from the pozzolanic reaction. Fig. 2 Pozzolanicity (Frattini test) at 48 h: results When gypsum was added to the samples, the [CaO] increased due to its partial dissolution in water, whereas [OH–] declined, partially because of the effect dilution of the Portland cement, although no pozzolanic activity was detected in any of the samples within the first 48 h. Figures 3 and 4 show the first