Special compound additive for pebble-type permeable concrete

Abstract

The invention discloses a special compound additive for pebble-type permeable concrete, which comprises the following materials in parts by mass: 80-90 parts of ultrafine microbead, 10-15 parts of silicon ash, 20-30 parts of lithium slag powder and 0.0005-0.001 part of polyoxyethylene. The raw materials are measured according to the formula, and added into a mixer to be evenly mixed, thereby obtaining the product disclosed by the invention. The compound additive can obviously enhance the viscosity and water retention property of the cement mortar, and improve the coating property of the cement mortar on the pebble surface and the binding property with the pebble surface, so that the pebble-type permeable concrete mixture has favorable cohesiveness, water retention property and uniformity, solves the problem of poor surface mortar coating property of the pebble-type pervious concrete coarse aggregate, ensures the permeability and mechanical properties of the concrete as well as the engineering construction quality, and has favorable comprehensive benefits.

Description

Technical field [0001] The invention relates to the field of building materials, and specifically refers to a composite additive special for pebble-type permeable concrete. Background technique [0002] Concrete is a building material prepared by cementing materials (including cement, mineral admixtures, etc.), coarse and fine aggregates (such as sand, stone), water, and additives when necessary in a certain proportion; permeable concrete It does not contain fine aggregates. It is a porous concrete covered with a thin layer of cementitious paste on the surface of coarse aggregates to form a honeycomb structure with uniformly distributed pores, so it has the characteristics of air permeability and water permeability. [0003] Coarse aggregates in concrete refer to rock particles with a particle size> 4.75mm, which are divided into two categories: gravel and pebbles. Pebble-type permeable concrete refers to permeable concrete that uses pebbles as coarse aggregates. Because the su...

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Problems solved by technology

Pebble-type permeable concrete refers to permeable concrete that uses pebbles as coarse aggregate. Due to the smooth surface of pebbles, the permeable concrete mixed is often poor in wrapping. After vibration, the slurry is easy to sink, resulting in blocking the lower pores and affecting water permeability. property, and the upper part of the slurry is less, which also affects the bonding between coarse aggregates, resulting in unqualified strength of permeable concrete

[0004] In order to increase the cohesion of the pebble-type permeable concrete mixture, the commonly used method is to add silica fume (the amount is 3-5% of the total amount of cementitious materials, about 9-25kg / m 3 ), latex powder (the dosage is 3-4% of the total amount of cementitious materials, about 9-20kg / m 3 ), cellulose ether (the dosage is 0.8-1‰ of the total amount of gelling material, about 0.3-1kg / m 3 , depends on the viscosity of cellulose ether and the performance of various raw materials) and other thickening materials, but the cost of such materials is high, and the amount used in permeable concrete is also small, and the measurement accuracy is high, with an error of 0.1-5kg It will have a great adverse effect on the performance of concrete, and it is not convenient for the concrete quality control of on-site mixing construction.

At the same time, although such materials can increase the viscosity of cement paste, they cannot improve the adhesion between cement paste and the surface of pebbles. The surface of pebbles is still not uniform, and the homogeneity of pervious concrete is not good. its water permeability

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