Blast Key method

Seismic retrofit

The blast key method is an advanced roughening that is environmentally safe method.

In the conventional case, roughening work occurs large vibration, noise and dust during seismic reinforcement progress. Also, resulting complaints came from neighbors and surround residents. In addition this method sets a bit special modification at the tip of the core drill, and cut the existing frame with wet the core drill to reduce dust during construction without damaging the housing surface. It is an eco-friendly roughening method that suitable for reinforcement work while the building is being used by people.

Features of the blast key method


  1. 1.Low vibration, low noise

    Compared to the conventional chipping method, this method is environmentally friendly, with low vibration and low noise (30 dB reduction).

  2. 2.Suppression of waste materials

    It becomes possible to control the occurrence of concrete rattles.

  3. 3.Quality Assurance

    Unlike the chipping method, it is possible to quantitatively evaluate the amount of roughness, so high quality can be ensured.

  4. 4.Proof of performance

    We have acquired “Assessment of Technology for Building Construction” from the General Building Research Corporation of Japan.

  5. 5.Cost reduction

    Compared to the conventional method, construction costs can be reduced by reducing damage to existing buildings and reducing the number of industrial waste concrete shells and post installation anchors.

Comparison between normal chipping method and blast key method

Schematic cross section

※Blast Key method was developed in a joint effort by Tobishima corporation and Toa corporation