【摘要】：早強(qiáng)劑是一種常用于水泥混凝土制品生產(chǎn),快速施工的混凝土工程,低溫及負(fù)溫施工的混凝土工程的混凝土外加劑。傳統(tǒng)的早強(qiáng)劑在使用中存在混凝土工作性降低、強(qiáng)度倒縮、彈性模量后滯、堿-骨料反應(yīng)、泛霜等問題。如何開發(fā)和應(yīng)用早強(qiáng)效果顯著、對(duì)混凝土性能無不良影響的新型早強(qiáng)劑,是目前混凝土早強(qiáng)劑研究與應(yīng)用的重要課題。本文圍繞新型晶核型早強(qiáng)劑Vivid300(CN)的性能與早強(qiáng)機(jī)理,通過砂漿的流動(dòng)性試驗(yàn)、凝結(jié)時(shí)間試驗(yàn)、干燥收縮試驗(yàn),研究了Vivid300(CN)對(duì)砂漿流動(dòng)性、凝結(jié)時(shí)間及體積穩(wěn)定性的影響。通過砂漿及混凝土的力學(xué)試驗(yàn)研究了Vivid300(CN)對(duì)砂漿及混凝土強(qiáng)度發(fā)展的影響。分析密閉條件下水泥的水化溫度變化,研究了Vivid300(CN)對(duì)水泥水化溫度發(fā)展的影響;采用化學(xué)結(jié)合水法研究了Vivid300(CN)對(duì)水泥水化程度的影響;基于Krstulovic-Dabic模型,探討了Vivid300(CN)對(duì)水泥水化動(dòng)力學(xué)過程的影響;利用X射線衍射儀及掃描電子顯微鏡,分析了Vivid300(CN)對(duì)水泥水化產(chǎn)物成分及形貌的影響�；谝陨涎芯繉�(duì)新型晶核型早強(qiáng)劑的早強(qiáng)機(jī)理進(jìn)行了分析。試驗(yàn)結(jié)果表明:新型晶核型早強(qiáng)劑Vivid300(CN)不會(huì)造成砂漿流動(dòng)度的明顯降低;Vivid300(CN)與高減水型聚羧酸減水劑復(fù)合使用,砂漿的凝結(jié)時(shí)間隨摻量的增加而縮短;Vivid300(CN)與早強(qiáng)型聚羧酸減水劑復(fù)合使用,摻量小于2.0%時(shí)不會(huì)明顯縮短砂漿的凝結(jié)時(shí)間,摻量為5.0%時(shí)使砂漿的初凝及終凝結(jié)時(shí)間均有明顯縮短。新型晶核型早強(qiáng)劑能夠使水泥水化溫峰提前,峰值增加,加快水泥水化進(jìn)程;新型晶核型早強(qiáng)劑能夠加快水泥早期水化產(chǎn)物的生成,提高水泥的水化程度;新型晶核型早強(qiáng)劑不會(huì)使水泥水化產(chǎn)生新相,且能夠促進(jìn)早期水化產(chǎn)物中C-S-H凝膠的生成。新型晶核型早強(qiáng)劑能夠明顯提高砂漿及混凝土1d以內(nèi)的超早期強(qiáng)度;新型晶核型早強(qiáng)劑不會(huì)引起砂漿后期強(qiáng)度的倒縮;在蒸養(yǎng)養(yǎng)護(hù)條件下,新型晶核型早強(qiáng)劑能夠有效提高混凝土的蒸養(yǎng)脫模強(qiáng)度,摻5.0%新型晶核型早強(qiáng)劑的混凝土,50℃蒸養(yǎng)3h后的脫模強(qiáng)度相比空白組強(qiáng)度提升160%。新型晶核型早強(qiáng)劑Vivid300(CN)的早強(qiáng)機(jī)理分析表明:新型晶核型早強(qiáng)劑的主要組分A為水泥水化早期C-S-H凝膠的生成提供細(xì)小晶核,降低其結(jié)晶成核與晶體生長(zhǎng)的阻力,加快C-S-H凝膠的早期生成,大量生成的C-S-H凝膠將鈣礬石、氫氧化鈣等及其他水化產(chǎn)物膠結(jié)在一起,加快水泥漿體結(jié)構(gòu)的形成,提高水泥石的密實(shí)度,進(jìn)而起到早強(qiáng)作用。本文對(duì)新型晶核型早強(qiáng)劑Vivid300(CN)的研究將會(huì)為晶核型混凝土早強(qiáng)劑的應(yīng)用和發(fā)展提供支持。
[Abstract]:Early strength agent is a kind of concrete admixture which is often used in the production of cement concrete products and the rapid construction of concrete engineering and the construction of low temperature and negative temperature concrete engineering. There are some problems in the use of traditional early strength agents, such as low workability of concrete, shrinkage of strength, lag of elastic modulus, alkali-aggregate reaction, frost flooding and so on. How to develop and apply a new type of early strength agent, which has remarkable effect on early strength and has no adverse effect on the performance of concrete, is an important subject in the research and application of early strength agent of concrete at present. In this paper, the effects of Vivid300 (CN) on the fluidity, setting time and volume stability of mortar were studied by means of flow test, setting time test and drying shrinkage test. The influence of Vivid300 (CN) on strength development of mortar and concrete was studied through mechanical tests of mortar and concrete. The influence of Vivid300 (CN) on the hydration temperature of cement is studied by analyzing the change of hydration temperature of cement under the closed condition, and the influence of Vivid300 (CN) on the hydration degree of cement is studied by chemical combined water method. Based on the Krstulovic-Dabic model, the effect of Vivid300 (CN) on the hydration degree of cement is studied. The effect of Vivid300 (CN) on the hydration kinetics of cement was discussed, and the effect of Vivid300 (CN) on the composition and morphology of cement hydration product was analyzed by X-ray diffraction and scanning electron microscope. Based on the above studies, the mechanism of early strength of the new type of nucleated early strength agent is analyzed. The experimental results show that the new type of early strength crystal core agent Vivid300 (CN) will not significantly reduce the flow degree of mortar. Vivid 300 (CN) and high water reducing polycarboxylic acid water reducer are used in combination. The setting time of mortar shortens the combination of Vivid300 (CN) and early-strength polycarboxylic acid superplasticizer with the increase of content. When the content is less than 2.0, the setting time of mortar will not be significantly shortened, and the initial setting time and final setting time of mortar can be obviously shortened when the content is 5.0. The new crystal core early strength agent can advance the hydration temperature peak and increase the peak value of cement and accelerate the hydration process of cement, and the new crystal core early strength agent can accelerate the formation of cement hydration products and improve the hydration degree of cement. The new nucleated early strength agent does not make the hydration of cement produce new phase, and it can promote the formation of C-S-H gel in the early hydration product. The new type of crystal core early strength agent can obviously improve the super early strength of mortar and concrete within 1 day, the new type of early strength agent of crystal core type can not cause the shrinkage of the later strength of mortar, and under the condition of steaming and curing, The new type of nucleated early strength agent can effectively improve the strength of steaming and demoulding of concrete. The strength of concrete mixed with 5.0% of the new type of early strength agent at 50 鈩，

本文編號(hào)：2185317