Alkali free aluminate sulfate based shotcrete accelerator as stable suspension or redispersible solid

A technology of accelerator and concrete, applied in aluminum sulfate, aluminum sulfur compound and other directions, can solve the problems of complex and unstable system, and achieve the effect of long shelf life, prolong shelf life and reduce transportation cost.

Active Publication Date: 2018-02-16
SIKA TECH AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current solution has the additional disadvantage of increasing the number of componen...

Method used

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  • Alkali free aluminate sulfate based shotcrete accelerator as stable suspension or redispersible solid
  • Alkali free aluminate sulfate based shotcrete accelerator as stable suspension or redispersible solid
  • Alkali free aluminate sulfate based shotcrete accelerator as stable suspension or redispersible solid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] Example 1 (precipitated by concentration)

[0080] In a closed reactor, at 80°C, aluminum sulfate hydrate (Al 2 (SO 4 ) 3 14H 2 O) and aluminum hydroxide powder were mixed with 4 parts by weight of water in a weight ratio of 8:1. After a few minutes, the solution turned pale yellow, indicating that all starting material had dissolved and the reaction had started. The reactor was then opened to allow the water to evaporate. When 3 to 3.5 parts by weight of water evaporated, the reactor was closed and the temperature was set to 60°C. After some time (about 1 to 3 hours), the mixture thickened due to the growth of crystals in solution. The mixture was then rapidly cooled to room temperature and became solid within 5-10 minutes. Figure 5 are photographs of the obtained solid being broken into lumps and finally ground into powder, respectively.

[0081] The main phase of the solid formed is

[0082] 1.Al(SO 4 )OH·5H 2 O (oblique aluminum alum)

[0083] 2.Al 2...

Embodiment 2

[0086] Example 2 (direct precipitation by stoichiometric method)

[0087] Aluminum sulfate hydrate (Al 2 (SO 4 ) 3 14H 2 O) and aluminum hydroxide are mixed with water (weight ratio 8:1:0.8). The solid melted after a few minutes. The mixture was maintained at 120°C while mixing for about 1 hour. When it started to thicken, the mixture was then drained from the reactor and cooled to room temperature. It became solid within minutes.

[0088] The main phase of the solid formed is

[0089] 1. (H 3 O)Al 3 (SO 4 ) 2 (OH) 6 (hydroalumite), more than 50%

[0090] 2.Al 2 (SO 4 ) 3 ·xH 2 O, where 14

[0091] 3.Al(SO 4 )OH·5H 2 O (clinolum), only traces

[0092] The solid can remain in solid form, or can be redispersed as a suspension in water.

[0093] Analysis by X-ray Diffraction (XRD)

[0094] The solids prepared in Examples were analyzed by XRD, and the above-mentioned main phase was determined from XRD.

[0095] ima...

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PUM

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Abstract

Described is a shotcrete accelerator which is a solid comprising at least one of jurbanite and hydronium alunite or an aqueous suspension or slurry of the solid, and a method of producing the shotcrete accelerator as a solid. The solid shotcrete accelerator is redispersible in water yielding stable aqueous dispersions or slurries. Extended shelf life of the solids and aqueous dispersions and reduced transport costs are the main advantages compared to existing technologies.

Description

technical field [0001] The present invention relates to aluminum sulphate-based shotcrete accelerators, in particular to aluminum-sulphate-based shotcrete accelerators (AFAs) which are alkali-free. Background technique [0002] Accelerators for accelerating the setting and hardening of compositions comprising hydraulic binders such as concrete, mortar or shotcrete are well known to those skilled in the art. Conventional accelerators often include alkali metals, but these accelerators are often associated with undesirable disadvantages. Alkali-free accelerators are a well-known and growing technology for shotcrete applications. The chemistry of these accelerators is based on aluminum sulfate, especially on a combination of aluminum salts such as aluminum sulfate, aluminum hydroxide and aluminum hydroxysulfate, which can be used in the form of suspensions. [0003] Suspensions based on aluminum sulphate are often unstable due to uncontrolled phase combination of the aluminum...

Claims

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Application Information

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IPC IPC(8): C04B22/14C04B40/00C01F7/74
CPCC04B22/148C01F7/74C04B40/0042C04B2103/12C04B2111/00172C04B2111/1025C01P2002/72C01P2004/01
Inventor E·加卢奇P·于尔蓝得D·舍嫩贝格尔B·林德拉尔C·施滕格
Owner SIKA TECH AG
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