RU2536520C1 - Cast-in-situ concreting method of sea platform - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to erection of cast-in-situ structures in difficult-to-access areas, and namely to cast concrete mixtures for cast-in-situ concreting of building structures. A cast-in-situ concreting method of a stationary sea ice-resistant platform involves preparation of concrete mix by mixing of dry components: a binding agent - Portland-slag cement, quartz sand, granite crushed stone with fraction of 5-20 mm, fine crushed mineral filler - MP-1 powder, with water and additives - a plasticising agent based on polycarboxylates - Muraplast FK-63 and hardening retarder - Centrament Retard 390, till concrete mix of cast consistency with cone spread of 50-70 cm is obtained, and with delamination of not more than 0.4% and with preservation capacity of at least 3 hours, supply of concrete mix to a framework with a concrete pump at flow rate of 2500-3000 l/h, and hardening is performed under normal conditions during 28-60 days, at the following component ratio, wt %: Portland-slag cement 13.3-16.9, quartz sand 42.4-42.6, the above said crushed stone 25.3-27.9, mineral powder MP-1 6.6-6.8, the above said plasticising agent 0.1-0.2, the above hardening retarder 0.07-0.08, and water is the rest.

EFFECT: providing viscosity and preservation capacity of concrete mix at its supply, and improving concrete crack resistance.

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Description

The invention relates to the construction of monolithic structures in remote areas, namely, cast concrete mixtures for monolithic concreting of building structures.

A known method of monolithic concreting by filling the formwork with a cast concrete mixture containing Portland cement, mineral aggregate, silica fume, superplasticizer and water, as well as hydrophobizing silicone fluid / 1 /.

A disadvantage of the known concrete mixture is the high consumption of binder, which leads to the appearance of temperature deformations during the hardening process when concreting large massifs, and also leads to an increase in the cost of concrete.

A known method of monolithic concreting by feeding a cast concrete mixture of the following composition: Portland cement, crushed stone, sand, bentonite, fly ash, plasticizer on a polycarboxylate ether base, water. The resulting concrete mixture has high mobility and does not require additional compaction / 2 /.

The disadvantages of the known methods of concreting from cast concrete mixtures are high cement consumption, low crack resistance when concreting large-sized structures of large volumes with limited access to the concreting areas due to thermal deformations during solidification of the massif. In addition, the known composition of the concrete mixture can not ensure the achievement of the parameters of the viscosity of the mixture and its retention, necessary for supplying the concrete pump to hard-to-reach places of construction.

The technical problem is to increase the crack resistance of monolithic concrete during concreting of large-sized structures and to ensure the viscosity and preservation of the mixture for supplying the mixture to inaccessible places of the structure.

The problem is achieved in that in the method of monolithic concreting of an offshore platform, including the preparation of a concrete mixture by mixing dry components - cement, quartz sand, crushed stone of a granite fraction 5-20 mm, finely ground mineral filler, with water and additives - a plasticizer based on polycarboxylates to obtain cast concrete mixture, the concrete mixture is fed into the formwork and cured before solidification, according to the invention, the concrete mixture is prepared by mixing the components to obtain a cast concrete mixture consistency with a cone spread of 50-70 cm, a delamination of not more than 0.4% and a shelf life of at least 3 hours, concrete is pumped into the formwork by a concrete pump with a flow rate of 2500-3000 l / h, and curing is carried out under normal conditions for 28-60 days, while slag Portland cement is used as a binder, MP-1 powder not activated from sedimentary rocks is used as a finely ground mineral filler, and Muraplast FK-63 plasticizer based on polycarboxylates and an additional TV retarder are used as additives glow of - Centrament Retard 390, with the following component ratio, wt. %:

Portland cement slag 13.3-16.9 quartz sand 42.4-42.6 crushed stone 25.3-27.9 mineral powder MP-1 6.6-6.8 specified plasticizer 0.1-0.2 specified retarder 0.07-0.08 water rest

The proposed method differs from the known one in that the concrete mixture is prepared by mixing slag Portland cement, sand, gravel and finely ground mineral powder MP-1 with mixing water and additives — a plasticizer and hardener to obtain a concrete mixture of molten consistency with a cone spread of 50-70 cm, delamination no more than 0.4% and a shelf life of at least 3 hours, the concrete mixture is fed into the formwork with a concrete pump with a flow rate of 2500-3000 l / h, and hardening is carried out under normal conditions for 28-60 days.

The proposed concrete mixture is characterized in that it contains slag Portland cement as a binder, MP-1 mineral powder not activated from sedimentary rocks, plasticizer based on Muraplast FK-63 polycarboxylates, Centrament Retard 390 hardening inhibitor, and the ratio of components as a finely ground mineral filler.

Introduction to the concrete mixture as a cement slag Portland cement helps to reduce heat during monolithic concreting and ensure the strength of concrete.

The mineral powder MP-1 ensures the stability of the properties of the concrete mixture and prevents sedimentation and delamination of the concrete mixture at a water-cement ratio of 0.6.

The hardening retarder ensures uniformity of concrete hardening over the entire monolith section and a hardening mode for 60 days.

The plasticizer provides the necessary mobility of the concrete mixture.

The predetermined feed rate of the concrete mixture into the formwork makes it possible to obtain a uniform distribution of the mixture over the cross section of the product and prevent stratification of the mixture.

The proposed ratio of components: crushed stone - sand - mineral powder, in combination with the specified plasticizer, makes it possible to obtain a self-compacting concrete mixture of cast consistency with low heat release of the specified viscosity and mobility retention parameters for concreting large-sized structures.

SUMMARY OF THE INVENTION

For concreting the ballast layer of the offshore platform, a self-compacting concrete mixture was prepared by mixing the dry components of slag Portland cement, quartz sand, crushed stone of granite fraction 5-20 mm, mineral powder MP-1, followed by mixing the mixture with water and additives - a hardening inhibitor Centrament Retard and a plasticizer based on polycarboxylates Muraplast FK-63. Concrete mixture of class B20 was prepared in accordance with GOST 7473-94. The components of the concrete mixture are loaded into the concrete mixer in the following sequence: crushed stone - sand - mineral powder MP-1 - cement - water with a solution of additives. The mixing time is at least 1.5-2 minutes. A cast concrete mixture was obtained, characterized by the following properties: cone spread of 50-70 cm, delamination not more than 0.4%, shelf life - more than 3 hours.

The concrete mixture was fed into the formwork with a flow rate of 2500-3000 l / h. Hardening was carried out in vivo for 60 days.

The characteristics of the materials used are given in table No. 1.

Examples of concrete mixes and data of physical and mechanical tests are summarized in tables No. 2, 3 and 4.

The proposed concrete mixture has the properties of a cast self-compacting mixture with high shelf life after its preparation, which makes it possible to continuously pump the concrete mixture into the formwork at a high speed during monolithic concreting of large-sized structures, for example, a ballasting layer of a marine stationary ice-resistant platform. Moreover, the proposed composition of the concrete mixture provides the optimum mode of hardening of the concrete mass of the ballasting layer of the offshore platform without cracking and, thus, makes it possible to ensure uniform hardening for 60 days upon receipt of the specified density and strength of concrete.

The proposed method allows to reduce the density of concrete, and consequently, the weight of the structure, increase crack resistance due to the curing mode of monolithic concrete, increase manufacturability due to the preservation of the mixture for more than 4 hours with a decrease in delamination and the possibility of supplying the concrete mixture with a pump to the concrete site of the object.

Information sources

1. RF patent No. 2057098, cl. C04B 28/04, publ. 03/27/1996

2. RF patent No. 2307810, class. C04B 28/04, publ. 10/10/2007 (prototype).

Claims (1)

A method of monolithic concreting of a marine stationary ice-resistant platform, including the preparation of a concrete mixture by mixing dry components - cement, quartz sand, crushed stone of a granite fraction 5-20 mm, finely ground mineral filler, with water and additives - a plasticizer based on polycarboxylates and a hardening retardant to obtain a cast concrete mixtures, the supply of concrete mixture to the formwork and curing until solidification, characterized in that the concrete mixture is prepared by mixing the components to obtain a concrete mixture and cast consistency with a cone spread of 50-70 cm, a delamination of not more than 0.4% and a shelf life of at least 3 hours, the concrete mixture is fed into the formwork with a concrete pump with a flow rate of 2500-3000 l / h, and hardening is carried out under normal conditions for 28-60 days, moreover, slag Portland cement is used as a binder, MP-1 powder is used as a finely ground mineral filler, Centrament Retard 390 is used as a hardening inhibitor, and Muraplast FK-63 is used as a plasticizer based on polycarboxylates, in the following ratio com ponents, wt.%:
Portland cement slag 13.3-16.9 quartz sand 42.4-42.6 crushed stone 25.3-27.9 mineral powder MP-1 6.6-6.8 specified plasticizer 0.1-0.2 specified retarder 0.07-0.08 water rest