SIMCON: Continuous fiber-mat High-Performance Fiber Reinforced Cementitious Composites

SIMCON, uses a manufactured continuous mat of interlocking discontinuous steel fibers, placed in a form, and then infiltrated with a flow able cement-based slurry. The use of continuous mats, typically made with stainless steel to control corrosion in very thin members, permits development of high flexural strengths and very high ductility with a reduced volume of fibers.

The experimental results demonstrate that SIMCON exhibits improved properties in tension, compression, flexure and shear even when comparatively low fiber volume fraction fiber-mats are used. Furthermore, since fiber-mats are pre-packed in the plant, distribution and orientation of fibers can be more accurately controlled, than is the case with short discontinuous fiber HPFRCs. These characteristics allow for the manufacturing of a unique cement-based fiber composite that can have different yet easily controllable properties in the longitudinal and transversal directions. These material characteristics are desirable in repair/retrofit of structural elements such as columns, which require a high increase in strength and toughness in the transverse direction while increasing only ductility but not strength in the longitudinal direction (i.e., "moment-carrying" direction).

The investigations also demonstrate that SIMCON has considerable potential for both  seismic repair/retrofit, as well as the development of novel, high-performance composite structural systems. 

In a retrofit situation continuous SIMCON fiber-mats, delivered in large rolls, can be easily installed by wrapping around members to be rehabilitated. In new construction of high-performance composite frames SIMCON is well suited for manufacturing high strength, high ductility, and thin stay-in-place formwork elements that eliminate the need for secondary and most of the primary reinforcement. 

First Step: Re-bars wrapped in SIMCON are put along the column to provide moment continuity through the joint region, as well as replacement of concrete with SIMCON in the anchorage region of the discontinuous bottom beam reinforcement.

Second Step: Additional layers of SIMCON mat are added to increase moment capacity at the column and beam zones facing the joint.

Third Step: the entire column (and portion of adjacent beams) is jacketed with SIMCON. Formwork is put next and mat is injected with a high-strength slurry (say 14,000 psi).

A two-dimensional layout of SIMCON and its unique manufacturing properties related to its fiber-mat configuration, open up novel possibilities for a cost-effective and improved structural performance that were not previously possible using other HPFRCCs, FRCs or any other conventional construction materials. Construction with SIMCON was also found to be simpler than if other HPFRCs, reinforced concrete, steel plates or different non-cement based composites were used. It is thus anticipated that when used in repair, retrofit, or new construction, the proposed approach will be less labor and equipment-intensive and more economical than conventional methods. 

Manufacturing of SIMCON is based on the use of widely available construction equipment and building expertise, and can thus be relatively easily introduced into the field without major re-training and changes in existing construction practices. Hence, this novel type of HPFRCC provides some unique new ways of developing durable and cost-effective high-performance infrastructural systems, essential for the economic well-being of the nation in the next century.