At present, water reducing agents have gradually become popular and are widely used in actual production in all walks of life. However, most technical personnel of commercial concrete companies do not fully understand the performance of water-reducing admixtures, and special attention should be paid to the precautions for use with cement. The common problems, causes and solutions when using water-reducing agents are described below.
High-performance water reducing agent can be used to improve the performance of concrete. However, when the water-reducing agent is used in ordinary cement, it will have poor compatibility and cannot meet the production needs of ordinary concrete. In many engineering constructions, problems of incompatibility with cement will occur. The main symptoms are low performance of the water-reducing agent or poor fluidity-increasing effect, too fast condensation speed, retarded condensation, and excessive slump loss over time. It can even reduce the strength of concrete. This phenomenon of poor compatibility is related to the variety and mechanism of superplasticizer, the selection and synthesis process of raw materials, and the composition and fineness of the cementitious material. Other factors such as ambient temperature and admixture dosage will also have a certain impact on compatibility. Huawei Yinkai believes that: cement mineral properties, MgO in cement, mineral admixtures, soluble sulfates, and cement specific surface area will all have an impact on cement compatibility.
Precautions when using water reducing agent
1. Sensitivity to water. Since the water reduction rate is relatively higher than that of Ne series and aliphatics, and it has high dispersion, the water reduction rate above 30% becomes more obvious as the dosage increases. Therefore, attention should be paid to the comprehensive adjustment of dosage and dosage to avoid segregation and plate secretion after over-doping. Water, too much air content. The raw materials used include changes in dry and wet moisture content of floor materials, cement adaptability and consistency, and changes in admixture fineness, specific surface area, and water demand. In rainy and snowy weather, the moisture content of the floor material changes drastically. Measurement requirements must be precise.
2. Sensitivity to temperature. The temperature difference between day and night, the temperature change point between morning and evening. The water temperature, floor material temperature, and glue material temperature specifications require no more than 60°C. Especially in the hot summer, the long-distance transportation of the mixture is related to time, the state of the mixture, the temperature of the tanker, whether to take measures to cool down by watering, or to add an appropriate amount of water and a few additives to keep the freshness of the mixture. Consider quality, strength and durability. In winter, considering that when the temperature is low, the delayed increase in slump and the lower temperature of the mixture are not conducive to the initial reaction, it can avoid serious mold explosion and concrete gravel sinking, affecting the homogeneity of the structure.
The promotion and application of water-reducing agents in concrete projects has promoted the rapid development of modern concrete technology, improved the quality of concrete production (improved durability), thereby achieving the effects of energy saving, material saving, and land saving. . Saving resources is the fundamental strategy to protect the ecological environment, thereby reducing energy consumption intensity and improving utilization efficiency and effectiveness. With its series of superior properties, the use of water-reducing admixtures in engineering construction is increasingly occupying a large share. Water-reducing admixtures have entered the system era, so the research and application of water-reducing admixtures has become increasingly critical. However, in the practical application of water-reducing admixtures, many undesirable phenomena will occur and the actual requirements of the project cannot be met. The reason for this is often the compatibility problem between the water-reducing admixture and cement. Due to the complex mineral composition of cement, the quality of cement production fluctuates greatly, which poses a great challenge to the compatibility of water reducing agents and cement. By studying and analyzing the compatibility issues between superplasticizers and cement from the perspective of cement, we can objectively and accurately guide various issues that should be paid attention to in actual cement production, and provide information for the production of high-quality, good-compatibility cement. theoretical support. </p
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