A kind of preparation method of starch-based cement hydration heat control material

Abstract

The invention provides a preparation method for a hydration heat control material of starch-based cement. The method comprises the following steps: uniformly mixing dextrin, starch and mixed dicarboxylic anhydride in a high-speed stirring mixer; performing melt extrusion on a mixture via a double-screw extruder, and crushing and sieving the mixture to obtain a product namely the hydration heat control material of the starch-based cement. The method has a simple and efficient process, the reaction time is greatly shortened, the usage of a solvent is avoided in a preparation process, and the harm to the environment caused by wastes is reduced. According to the hydration heat control material prepared through the method, the heat release rates of a hydration acceleration period and a hydration deceleration period can be greatly reduced, and the peak values of the hydration heat release rates can be effectively decreased by over 80 percent including 80 percent, thereby being different from a conventional retarder which greatly delays a hydration induction period.

Description

technical field

[0001] The invention belongs to the field of concrete admixtures for building materials, and in particular relates to a preparation method of a starch-based cement hydration heat regulating material. Background technique

[0002] The hydration reaction of cement is an exothermic reaction. The concrete made by mixing cement with water and other aggregates will generate a large amount of hydration heat during the setting and hardening process after pouring. Since concrete is a poor conductor of heat and has a large volume, the heat of hydration gathers inside the concrete and is difficult to dissipate, causing the internal temperature to rise sharply. At the same time, due to the rapid heat dissipation on the concrete surface, a large internal and external temperature difference is generated, resulting in different degrees of thermal expansion and contraction between the internal and external surfaces, which in turn generates tensile stress on the concrete surf...

Examples

Embodiment 1

[0027] Mix 700g of commercially available dextrin with a DE value of 4 and a solubility in cold water of 65%, 70g of wheat starch, 200g of succinic anhydride and 150g of phthalic anhydride in a high-speed mixer, and add it to a twin-screw extruder to melt and extrude . The processing temperature of the twin-screw extruder is 90°C, 110°C, 120°C, 125°C from the feed port to the discharge port, the screw speed is 120r / min, and the residence time of the material in the barrel is 10min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

Embodiment 2

[0029] 800g DE value is 6, cold water solubility is 72% commercially available dextrin, 160g cornstarch, 180g glutaric anhydride and 60g succinic anhydride are mixed uniformly in the high-speed stirring mixer, add twin-screw extruder and melt and extrude. The processing temperature of the twin-screw extruder is 70°C, 85°C, 90°C, 100°C from the feed port to the discharge port, the screw speed is 150r / min, and the residence time of the material in the barrel is 8min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

Embodiment 3

[0031] Mix 600g of commercially available dextrin with a DE value of 9 and a solubility in cold water of 78%, 90g of waxy cornstarch, 220g of succinic anhydride and 320g of phthalic anhydride in a high-speed stirring mixer, and add to a twin-screw extruder to melt extrude. The processing temperature of the twin-screw extruder is 90°C, 120°C, 130°C, 140°C from the feed port to the discharge port, the screw speed is 80r / min, and the residence time of the material in the barrel is 15min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

technical field

[0001] The invention belongs to the field of concrete admixtures for building materials, and in particular relates to a preparation method of a starch-based cement hydration heat regulating material. Background technique

[0002] The hydration reaction of cement is an exothermic reaction. The concrete made by mixing cement with water and other aggregates will generate a large amount of hydration heat during the setting and hardening process after pouring. Since concrete is a poor conductor of heat and has a large volume, the heat of hydration gathers inside the concrete and is difficult to dissipate, causing the internal temperature to rise sharply. At the same time, due to the rapid heat dissipation on the concrete surface, a large internal and external temperature difference is generated, resulting in different degrees of thermal expansion and contraction between the internal and external surfaces, which in turn generates tensile stress on the concrete surf...

Examples

Embodiment 1

[0027] Mix 700g of commercially available dextrin with a DE value of 4 and a solubility in cold water of 65%, 70g of wheat starch, 200g of succinic anhydride and 150g of phthalic anhydride in a high-speed mixer, and add it to a twin-screw extruder to melt and extrude . The processing temperature of the twin-screw extruder is 90°C, 110°C, 120°C, 125°C from the feed port to the discharge port, the screw speed is 120r / min, and the residence time of the material in the barrel is 10min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

Embodiment 2

[0029] 800g DE value is 6, cold water solubility is 72% commercially available dextrin, 160g cornstarch, 180g glutaric anhydride and 60g succinic anhydride are mixed uniformly in the high-speed stirring mixer, add twin-screw extruder and melt and extrude. The processing temperature of the twin-screw extruder is 70°C, 85°C, 90°C, 100°C from the feed port to the discharge port, the screw speed is 150r / min, and the residence time of the material in the barrel is 8min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

Embodiment 3

[0031] Mix 600g of commercially available dextrin with a DE value of 9 and a solubility in cold water of 78%, 90g of waxy cornstarch, 220g of succinic anhydride and 320g of phthalic anhydride in a high-speed stirring mixer, and add to a twin-screw extruder to melt extrude. The processing temperature of the twin-screw extruder is 90°C, 120°C, 130°C, 140°C from the feed port to the discharge port, the screw speed is 80r / min, and the residence time of the material in the barrel is 15min. The extruded product is pulverized and passed through a 100-mesh sieve to obtain the starch-based cement hydration heat regulating material of the present invention.

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