The main factors contributing to the incompatibility between admixtures and cement are as follows:
2.1 Factors of the admixture itself
The reasons within the admixture itself mainly consist of the following aspects: (1) diverse varieties; (2) disparities in structural functional groups; (3) Different degrees of polymerization; (4) Varied composition. These effects, via different means, can impact the adaptability with cement.
The admixtures produced by different manufacturers will also exhibit numerous differences. The main causes are: (1) the production process; (2) The technical level of the manufacturer’s production process; (3) The quality management level. Therefore, the products generated by different manufacturers are inevitably dissimilar.
2.2 The influence of the mineral composition of cement on admixtures
The mineral composition of cement exerts a significant influence on the admixture. The mineral composition of cement mainly encompasses tricalcium aluminate (C3A), tetralcium ferroaluminate (C4AF), tricalcium silicate (C3S), dicalcium silicate (C2S), etc. The different mineral composition is primarily determined by the raw materials and production process of cement production. Among the mineral composition of cement, the influencing factors on admixtures are C3A > C4AF > C3S > C2S. The hydration reaction of C3A is rapid, the early strength increases rapidly, the water requirement is substantial, when the C3A content is overly high (mass fraction is greater than 8%), the adsorption of C3A is significant, and the loss of the admixture action is considerable [2]. The name and scope of the cement mineral composition are presented in Table 1, and the characteristics of the mineral interaction with water are shown in Table 2.

2.3 The influence of adding regulated gypsum varieties to cement clinker
In the final process of cement production, gypsum needs to be added to adjust the setting time. The influence factors of the setting gypsum utilized by cement manufacturers on admixtures are anhydrite (industrial anhydrous gypsum) > semi-hydrous gypsum > dihydrous gypsum. Cement manufacturers frequently employ industrial anhydrous gypsum to save costs, which does not affect the cement from meeting the quality index requirements. For ordinary concrete without admixture, there is no adverse reaction. However, for modern concrete with admixture, the cement using anhydrite requires a large amount of water, the adsorption dose is significant, and the loss of the admixture is substantial. The effect of anhydrite on wood calcium is more pronounced, and there may even be a rapid coagulation (false coagulation) phenomenon.
2.4 The influence of cement fineness and particle gradation
Cement manufacturers often, in order to meet the requirements of the new cement standards, enhance market competitiveness, intensify grinding, improve the fineness of cement and enhance strength. Cement that is overly fine has a large water demand, a larger adsorption of external doses, and a significant loss of admixtures. Simultaneously, the excessively fine cement has a higher temperature during grinding, which will also decompose more hydrated gypsum into anhydrous gypsum, increasing the content of anhydrous gypsum and deteriorating the adaptability of the admixture. The poor adaptability of cement with admixtures is due to the poor particle gradation and the high net bleeding rate of cement pulp.
2.5 The alkali content of cement
Cement with an excessively high alkali content (alkali content > 0.8%) or an overly low alkali content (alkali content < 0.5%) is also prone to generating incompatibility with admixtures. The alkali in cement mainly originates from the raw materials used, especially lime and clay. Cement with an excessively high or low alkali content, when certain types of admixtures are added, will cause changes in the solubility of gypsum in the cement, thereby accelerating the hydration rate of the cement mineral component C3A, increasing the water requirement, and accelerating the work loss. Adding soluble Na2SO4 at this time can enhance its adaptability with admixtures. The addition of fly ash and mineral powder can have a secondary reaction with Ca(OH)2, the hydration product of cement, reducing the basicity of concrete and improving the adaptability of the admixture and cement.
2.6 The adaptability of fly ash and admixtures
If the fly ash is overly fine, more admixtures will be required to disperse the fly ash particles. The greater the burning loss of fly ash (that is, the greater the carbon content), the greater the water demand, the more significant the impact on the admixture. The carbon particles are large and porous, prone to absorbing water, and have a strong ability to adsorb admixtures, thereby increasing the admixture content, especially having a significant impact on the air entrainment agent.
2.7 The impact of aggregates
The mud content and lump content of aggregates are high, and a large number of fine clay particles will absorb more water and consume more admixtures, which will deteriorate the workability of freshly mixed concrete, facilitate separation, cause slump loss, and affect the strength of concrete. Improper concrete mix ratio and unreasonable sand rate will also increase the loss of slump. A small sand rate makes the concrete prone to segregation and bottom climbing, resulting in a large concrete slump loss. A too large sand rate requires more water for wetting, reducing the slump of concrete and influencing the strength of concrete. The poor grading of aggregates, especially the deficiency of the intermediate grain grade of aggregates, is also prone to causing concrete segregation, bottom climbing, concrete slump loss, and affecting the quality of concrete.

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