葡萄糖酸钠对混凝土起到什么作用？
来源：http://www.jnjdbc.com 日期：2020-04-29 发布人：admin
2.1 葡萄糖酸钠对混凝土拌和物流动性的影响可见，保持水灰比不变，调整葡萄糖酸钠的掺量，混凝土初始坍落度随着掺量的增加而增加。葡萄糖酸钠中的羟基基团，具有较强的固液表面活性，从而能吸附在水泥矿物颗粒表面形成溶剂化吸附层，阻碍了凝胶颗粒的接触和凝聚，从而破坏了水泥的絮凝结构，对水泥的初期水化有较强的抑制作用，使游离水增多，提高了水泥浆体的流动性。
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 葡萄糖酸钠对混凝土含气量的影响
2.2 effect of sodium gluconate on air content of concrete
葡萄糖酸钠作为一种羟基羧酸类缓凝剂，具有一定的表面活化作用，羧基通过抑制水泥水化，在拌合料塑性阶段释放出了更多的自由水，相对提高了未水化水泥部分的水灰比；并且分子量因葡萄糖酸钠的引入而增加，疏水能力也随之提升，降低了拌和物的粘稠度，则气泡易于合并长大，并上浮逸出，随着葡萄糖酸钠掺量的增大，混凝土含气量不断降低。
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 葡萄糖酸钠对混凝土凝结时间的影响
2.3 effect of sodium gluconate on setting time of concrete
导入葡萄糖酸酸钠明显延缓了初凝和终凝时间，随着葡萄糖酸钠掺量的增加，初凝和终凝时间也在不断延长，并且增长了初凝和终凝的间隔差。 葡萄糖酸酸钠的羧基在水泥水化产物的碱性介质中与游离Ca2+反应生成不稳定的络合物，在水化初期抑制了液相中Ca2+的浓度，随着水化进程的继续，这种不稳定的络合物将自行分解，水化将继续正常进行。其次OH-易与水分子通过氢键缔合，再加上水分子之间的氢键缔合，使水泥颗粒表面形成了一层稳定的溶剂化水膜，阻止了水泥颗粒间的直接接触，阻碍了水化的进行，延缓了水泥的凝结时间。
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 葡萄糖酸钠对坍落度损失的影响
2.4 effect of sodium gluconate on slump loss
对于普通混凝土来说，流动度经时损失是一种正常现象，其根本原因是混凝土中的拌和用水量随着水泥水化而逐渐消耗，部分水还会挥发到空气中，时间越长混凝土拌和物的流动度越小，更终混凝土失去塑性。葡萄糖酸钠具有明显的保塑作用和辅助塑化效应，随着掺量的增加，混凝土拌合料和易性逐步改善，初始坍落度也在不断增加，由于水泥水化速度的降低，混凝土可以保持较长时间的塑性，葡萄糖酸钠的掺量越大，保持塑性的时间越长。
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.
可以发现混凝土坍落度损失明显增加。这是因为掺入减水剂可以明显降低水泥浆体的屈服应力和粘度，但是减水剂效应有明显的时间特性，常常随着时间而有较大的变化，减水剂的有效含量随着时间增长而不断减小，加剧了混凝土拌合料坍落度的经时损失。
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 葡萄糖酸钠对混凝土抗压强度的影响
2.5 effect of sodium gluconate on compressive strength of concrete
掺入葡萄糖酸钠后，水泥水化热各时刻均有下降，延缓了放热峰，降低了发热峰值，并且水化热的放热速率特随着降低，水化温升出现推迟，对混凝土的绝热温升有延峰、消峰作用，从而降低了混凝土因早期内外温差过大，而产生温度裂纹的概率，从而提高了混凝土的抗压强度。
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.