Auxiliary cementitious material for low carbon high performance concrete

Abstract

The invention discloses a low-carbon high-performance concrete supplementary cementitious material which is prepared from 20-70 parts of slag, 20-70 parts of coal ash, 5-10 parts of silica fume, 3-10 parts of desulfurized gypsum and 1-3 parts of water reducing agent by weight to form an admixture, wherein the slag, the coal ash, the silica fume and the desulfurized gypsum are micro aggregates of 100 nanometers to 100 microns; and the materials are sequentially placed in a mixer and stirred for 60-120 minutes at a speed of 60-120 rpm at normal temperature under normal pressure to obtain the supplementary cementitious material. The low-carbon high-performance concrete supplementary cementitious material disclosed by the invention can replace 70% of cement in concrete when applied to concrete; and even if the 70% of cement is replaced, the strength of the prepared concrete also can reach C15-C60. The low-carbon high-performance concrete supplementary cementitious material is suitable to be used as a building material and also has special purposes of back-fill grouting, toxic waste solidification and the like.

Description

technical field [0001] The invention relates to the international patent classification C04B construction concrete material technology, especially low-carbon high-performance concrete auxiliary cementitious material. Background technique [0002] In the prior art, concrete is composed of aggregate, cement stone structure and aggregate and cement stone interface transition zone. The latter two phases belong to microstructure. According to the relationship between microstructure and performance, cement stone, cement stone and aggregate interface The improvement of the two microstructures in the transition zone is the key to determine the performance of concrete. [0003] The cement stone formed after Portland cement hydration is mainly composed of hydration products calcium silicate hydrate [CSH], calcium hydroxide, unhydrated cement particle core, calcium aluminate hydrate, calcium ferrite hydrate, calcium Composition of alumite, etc. Most of the hydration products are clus...

AI Technical Summary

Problems solved by technology

[0012] However, whether it is cement, fly ash, or kaolin, although its specific surface area is relatively small, its particle gradation is relatively simple, which makes the micro-aggregate filling effect of concrete unable to be fully exerted. It will restrict its volcanic ash effect; in addition, the micro-aggregate filling effect of concrete needs the cooperation of water-cement ratio to fully exert, and the adaptability of water-reducing agent and cementitious material also greatly affects the various technical indicators of concrete. At a high water-binder ratio, even if the admixture is finer than the cement particles, it is difficult to play a filling role; at the same time, based on the limited understanding of the aforementioned theory in the prior art, no water reducer is added to the disclosed cementitious materials, which makes its When mixing into concrete mixture, it is further reduced for controlling the compactness of concrete and the performance after hardening

[0013] As far as the existing technology is concerned, the so-called improved high-durability concrete technology has not been widely used. The reason is that there is no means for controlling the water-binder ratio, which makes it difficult for many "high-durability concrete" to truly reflect the purpose of the invention. The performance pursued makes the strength and durability of concrete unguaranteed

This involves technologies such as the adaptability of admixtures, the micro-aggregate gradation of cementitious materials, and the state of sand and gravel aggregates as the control standard. Insufficient performance, especially when the addition amount is large, the early strength of cement and its products will drop sharply, resulting in prolonged setting time, and at the same time, the compressive and flexural properties will be reduced