葡萄糖酸鈉對(duì)混凝土起到什么作用？
來源：http://www.nttdr.com 日期：2020-04-29 發(fā)布人：admin
2.1 葡萄糖酸鈉對(duì)混凝土拌和物流動(dòng)性的影響可見，保持水灰比不變，調(diào)整葡萄糖酸鈉的摻量，混凝土初始坍落度隨著摻量的增加而增加。葡萄糖酸鈉中的羥基基團(tuán)，具有較強(qiáng)的固液表面活性，從而能吸附在水泥礦物顆粒表面形成溶劑化吸附層，阻礙了凝膠顆粒的接觸和凝聚，從而破壞了水泥的絮凝結(jié)構(gòu)，對(duì)水泥的初期水化有較強(qiáng)的抑制作用，使游離水增多，提高了水泥漿體的流動(dòng)性。
2.1 the effect of sodium gluconate on the concrete mixing dynamic can be seen that keeping the water cement ratio unchanged, adjusting the content of sodium gluconate, the initial slump of concrete increases with the increase of the content. The hydroxyl group of sodium gluconate has strong solid-liquid surface activity, which can adsorb on the surface of cement mineral particles to form solvation adsorption layer, which hinders the contact and aggregation of gel particles, thereby damaging the flocculation structure of cement, and strongly inhibiting the initial hydration of cement, increasing free water and improving the fluidity of cement paste.
2.2 葡萄糖酸鈉對(duì)混凝土含氣量的影響
2.2 effect of sodium gluconate on air content of concrete
葡萄糖酸鈉作為一種羥基羧酸類緩凝劑，具有一定的表面活化作用，羧基通過抑制水泥水化，在拌合料塑性階段釋放出了更多的自由水，相對(duì)提高了未水化水泥部分的水灰比；并且分子量因葡萄糖酸鈉的引入而增加，疏水能力也隨之提升，降低了拌和物的粘稠度，則氣泡易于合并長大，并上浮逸出，隨著葡萄糖酸鈉摻量的增大，混凝土含氣量不斷降低。
Sodium gluconate, as a kind of hydroxy carboxylic acid retarder, has a certain surface activation effect. By inhibiting cement hydration, carboxyl group releases more free water in the plastic phase of the mixture, which improves the water cement ratio of the non hydrated cement; moreover, the molecular weight is increased due to the introduction of sodium gluconate, and the hydrophobicity is also increased, which reduces the viscosity of the mixture, With the increase of the content of sodium gluconate, the air content of concrete decreases.
2.3 葡萄糖酸鈉對(duì)混凝土凝結(jié)時(shí)間的影響
2.3 effect of sodium gluconate on setting time of concrete
導(dǎo)入葡萄糖酸酸鈉明顯延緩了初凝和終凝時(shí)間，隨著葡萄糖酸鈉摻量的增加，初凝和終凝時(shí)間也在不斷延長，并且增長了初凝和終凝的間隔差。 葡萄糖酸酸鈉的羧基在水泥水化產(chǎn)物的堿性介質(zhì)中與游離Ca2+反應(yīng)生成不穩(wěn)定的絡(luò)合物，在水化初期抑制了液相中Ca2+的濃度，隨著水化進(jìn)程的繼續(xù)，這種不穩(wěn)定的絡(luò)合物將自行分解，水化將繼續(xù)正常進(jìn)行。其次OH-易與水分子通過氫鍵締合，再加上水分子之間的氫鍵締合，使水泥顆粒表面形成了一層穩(wěn)定的溶劑化水膜，阻止了水泥顆粒間的直接接觸，阻礙了水化的進(jìn)行，延緩了水泥的凝結(jié)時(shí)間。
The introduction of sodium gluconate obviously delayed the initial and final setting time. With the increase of the content of sodium gluconate, the initial and final setting time was also continuously extended, and the interval between initial and final setting increased. The carboxyl group of sodium gluconate reacts with free Ca2 + in the alkaline medium of cement hydration products to form an unstable complex, which inhibits the concentration of Ca2 + in the liquid phase at the initial stage of hydration. As the hydration process continues, the unstable complex will decompose itself, and the hydration will continue normally. Secondly, oh - is easy to associate with water molecules by hydrogen bond, coupled with the hydrogen bond association between water molecules, which forms a stable solvated water film on the surface of cement particles, prevents the direct contact between cement particles, hinders the hydration process, and delays the setting time of cement.
2.4 葡萄糖酸鈉對(duì)坍落度損失的影響
2.4 effect of sodium gluconate on slump loss
對(duì)于普通混凝土來說，流動(dòng)度經(jīng)時(shí)損失是一種正常現(xiàn)象，其根本原因是混凝土中的拌和用水量隨著水泥水化而逐漸消耗，部分水還會(huì)揮發(fā)到空氣中，時(shí)間越長混凝土拌和物的流動(dòng)度越小，更終混凝土失去塑性。葡萄糖酸鈉具有明顯的保塑作用和輔助塑化效應(yīng)，隨著摻量的增加，混凝土拌合料和易性逐步改善，初始坍落度也在不斷增加，由于水泥水化速度的降低，混凝土可以保持較長時(shí)間的塑性，葡萄糖酸鈉的摻量越大，保持塑性的時(shí)間越長。
For ordinary concrete, the loss of fluidity by time is a normal phenomenon. The basic reason is that the mixing water consumption in concrete is gradually consumed with the hydration of cement, and some water will volatilize into the air. The longer the time is, the less the fluidity of concrete mixture is, and finally the plasticity of concrete is lost. Sodium gluconate has obvious plasticizing effect and auxiliary plasticizing effect. With the increase of admixture, the workability of concrete is gradually improved, and the initial slump is also increasing. Due to the decrease of cement hydration speed, the concrete can maintain the plasticity for a long time. The larger the dosage of sodium gluconate is, the longer the plasticity is.
可以發(fā)現(xiàn)混凝土坍落度損失明顯增加。這是因?yàn)閾饺霚p水劑可以明顯降低水泥漿體的屈服應(yīng)力和粘度，但是減水劑效應(yīng)有明顯的時(shí)間特性，常常隨著時(shí)間而有較大的變化，減水劑的有效含量隨著時(shí)間增長而不斷減小，加劇了混凝土拌合料坍落度的經(jīng)時(shí)損失。
It can be found that the slump loss of concrete increases obviously. This is because the addition of superplasticizer can significantly reduce the yield stress and viscosity of cement paste, but the effect of superplasticizer has obvious time characteristics, which often changes with time. The effective content of superplasticizer decreases with time, which aggravates the time-dependent loss of concrete slump.
2.5 葡萄糖酸鈉對(duì)混凝土抗壓強(qiáng)度的影響
2.5 effect of sodium gluconate on compressive strength of concrete
摻入葡萄糖酸鈉后，水泥水化熱各時(shí)刻均有下降，延緩了放熱峰，降低了發(fā)熱峰值，并且水化熱的放熱速率特隨著降低，水化溫升出現(xiàn)推遲，對(duì)混凝土的絕熱溫升有延峰、消峰作用，從而降低了混凝土因早期內(nèi)外溫差過大，而產(chǎn)生溫度裂紋的概率，從而提高了混凝土的抗壓強(qiáng)度。
After adding sodium gluconate, the hydration heat of cement decreases at all times, delaying the exothermic peak and reducing the heating peak. With the decrease of the exothermic rate of hydration heat, the hydration temperature rise is delayed, which has the effect of prolonging and eliminating the peak on the adiabatic temperature rise of concrete, thus reducing the probability of temperature cracks caused by the excessive temperature difference between the inside and outside of concrete in the early stage, thus improving the concrete setting Compressive strength of soil.
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