CN-114920473-B - Multi-element low-carbon and low-clinker composite cement and preparation method thereof

Abstract

The invention discloses a multi-element low-carbon and low-clinker composite cement and a preparation method thereof. The composite cement comprises, by weight, 25% -50% of silicate cement clinker, 15% -30% of activated kaolin material, 0-50% of slag, 2-15% of limestone and 0-5% of gypsum. The activated kaolin material is natural clay or industrial solid waste coal gangue (the kaolin content is more than or equal to 30%), and is subjected to crushing, grinding and low-temperature calcination at 600-800 ℃ to activate, and then the compound cement is prepared through batching, homogenization and grinding. Based on the synergistic hydration of kaolin, limestone and slag, the dosage of the multi-element low-carbon low-clinker composite cement clinker provided by the invention can be as low as 25%, and the multi-element low-carbon low-clinker composite cement clinker has the advantages of rapid strength development, good later-stage performance and compact microstructure, can solve the technical defects of high carbon emission and poor performance of low-clinker cement of the conventional ordinary Portland cement, can effectively consume solid waste, reduce cement cost, and is favorable for low-carbon sustainable development of the cement industry.

Inventors

• LIN ZHONGCAI
• LIU YUXUAN

Assignees

• 湖南大学
• 湖南大学

Dates

Publication Date

20260421

Application Date

20220630

Priority Date

20220630

Claims (4)

1. 1. The composite cement is characterized by comprising, by weight, 25% -35% of silicate cement clinker, 15% -30% of activated kaolin material, 41.2-50% of slag, 2-3.8% of limestone, 5% of gypsum and 0.25% of active ingredient metakaolin in the limestone and the activated kaolin material.
2. 2. The multi-element low-carbon and low-clinker composite cement according to claim 1, wherein the activated kaolin material is one of natural clay or industrial solid waste coal gangue, and the active ingredient metakaolin content is more than or equal to 30%.
3. 3. The multi-element low-carbon and low-clinker composite cement according to claim 1, wherein the slag is granulated blast furnace slag, the specific surface area is not less than 300m 2 /kg, and the 28-day activity index is not less than 95%.
4. 4. A method for preparing a multi-element low-carbon low-clinker composite cement according to any one of claims 1 to 3, comprising the steps of: Step 1), crushing an activated kaolin material to a particle size of 10-20mm, ball-milling for 5-40min at a rotational speed of 450r/min to form powder, then raising the temperature to 600-800 ℃ at a speed of 5-20 ℃/min by using a muffle furnace, and preserving the temperature for 1-2h to excite the activity of the activated kaolin material to obtain an activated kaolin material containing metakaolin; Step 2) mixing, homogenizing and grinding 25% -35% of silicate cement clinker, 15% -30% of activated kaolin material, 41.2% -50% of slag, 2% -3.8% of limestone and 5% of gypsum to obtain the multi-element low-carbon and low-clinker composite cement.

Description

Multi-element low-carbon and low-clinker composite cement and preparation method thereof Technical Field The invention belongs to the technical field of building materials, and particularly relates to a multi-element low-carbon and low-clinker composite cement and a preparation method thereof. Background The fuel consumption and limestone decomposition during cement production produce a significant amount of greenhouse gas carbon dioxide. The admixture is used for replacing cement clinker, so that the cement cost can be reduced, the energy consumption and the carbon dioxide emission are reduced, and the low-carbon green sustainable development trend of the current cement industry is realized. According to statistics, the average substitution rate of cement clinker in China is about 32.2 percent at present. Based on cement hydration and multicomponent synergistic reaction mechanism and physical and chemical theory such as setting and hardening, the low-clinker and multicomponent low-carbon composite cement is developed, so that the composite cement performance can be effectively improved, and the microcosmic compactness and mechanical property of the cement concrete are improved. Under the same performance requirement, the cement clinker substitution rate can be obviously improved, and the method has obvious advantages in energy conservation and emission reduction. In recent years, researchers at home and abroad generally consider a calcined clay limestone composite cement system (namely LC 3 cement) which has wide sources of raw materials and abundant reserves and has great potential. EP2253600A1, portland Limestone CALCINED CLAY CEMENT discloses a ternary composite cement system formed by combining burned clay, limestone and cement, which has the advantages of later mechanical property and durability comparable with ordinary Portland cement, and the clinker substitution rate is 50% at most, but has the defects of slow strength development, low early strength and the like, and influences the application of the ternary composite cement system in engineering to a certain extent. Meanwhile, when the cement content in the ternary composite cement system is further reduced, a large amount of unreacted burned clay and limestone exist in the system, so that the mechanical properties of the ternary composite cement system are obviously reduced, and the engineering requirements cannot be met. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide the low-carbon and low-clinker composite cement and the preparation method thereof. In order to achieve the aim, the invention forms a low-carbon and low-clinker composite cement technical scheme based on the synergistic hydration promotion effect of metakaolin, slag and limestone: the composite cement consists of Portland cement clinker 25-50 wt%, activated kaolin 15-30 wt%, slag 0-50 wt%, limestone 2-15 wt% and gypsum 0-5 wt%. In the multi-element low-carbon and low-clinker composite cement, the activated kaolin material is one of activated natural clay or industrial solid waste coal gangue, and preferably the active ingredient metakaolin content is more than or equal to 30%. In the multi-element low-carbon and low-clinker composite cement, the proportion of the limestone to the active ingredient metakaolin in the activated kaolin material is 0.25-1.00. In the multi-element low-carbon and low-clinker composite cement, the slag is granulated blast furnace slag, preferably the specific surface area is more than or equal to 300m 2/kg, and the 28-day activity index is more than or equal to 95%. The multi-element low-carbon and low-clinker composite cement is prepared by the following steps: Step 1) crushing the activated kaolin material until the particle size is smaller than 10-20mm, ball milling for 5-40min at the rotating speed of 450r/min to obtain powder, sieving with a 80 μm square-hole sieve to obtain less than 10% of sieve residue, heating to 600-800 ℃ at the speed of 5-20 ℃ by using a muffle furnace, and preserving the temperature for 1-2h to excite the activity of the activated kaolin material to obtain the activated kaolin material containing metakaolin. Step 2) mixing, homogenizing and grinding 25% -50% of silicate cement clinker, 15% -30% of activated kaolin material, 0-50% of slag, 2-15% of limestone and 0-5% of gypsum to obtain the multi-element low-carbon and low-clinker composite cement. The steps of batching, homogenizing and grinding the multi-element low-carbon and low-clinker composite cement in the step 2) can be carried out according to one of the following methods: the method 1) comprises the steps of grinding and mixing firstly, taking and uniformly mixing the ground silicate cement clinker, activated kaolin material, slag, limestone and gypsum according to the weight proportion to obtain the multi-element low-carbon and low-clinker composite cement, wherein the fineness of the multi-element low-carbon and low-cl