Low-strength concrete

A summary of the pmpeitie.s and categories of hand held pneumatic breakers is given by Vorster et at. (1992). For concrete repair work, breakers usually range from about 10 to 45 kg, or a maximum of about 20 kg for vertical or overhead work. Small self-contained electric units can be used for small areas in low strength concrete but pneumatic units with a separate compre.ssoi are required for most w ork. 

Finite Element Modeling of Seismic Performance of Low Strength Concrete Exterior Beam-Column Joints... 

Bedirhanoglu I, Ilki A, Pujol S, Kumbasar N (2010) Behavior of deficient joints with plainbars and low strength concrete. ACl Struct J 107(3) 300-310 De Witte FC, Kikstra WP (2010) DIANA finite element analysis. User s manual. Analysis procedures. TNO DIANA bv, Delft... 

It is important to stress that neither sodium silicate nor silico fluoride will improve the performance of a poor, low-strength, dusty concrete floor and if the surface is too porous, there is no way that all the material applied can react with the relatively small quantity of free lime in the concrete surface. All that will happen is that the pores will be filled with non-reacted powder, producing a most unpleasant alkaline dust, which can be very irritating to the skin and eyes when the floor is put into service. 

Adaska, W.S. and Krell, W.C., Bibliography on controlled low-strength materials (CLSM), Concrete International, 14 (10), 42-43, December 1992. 

ACI Committee 229, Controlled Low Strength Materials, ACI 229R, American Concrete Institute, Farmington Hills, MI, 1999. 

L.4.3 Approximately 10 to 25 mm (0.5 to 1 in.) of the top of the cementitious foundation material should be scarified with a chipping hammer before the grout is applied. This procedure is recommended to remove low-strength, high-porosity concrete in this area. The concrete foundation should be allowed to cure for at at least 7 days prior to this surface preparation. 

Lime/fly ash pozzolanic processes combine the properties of lime and fly ash to produce low-strength cementation. Kiln dust processes involve the addition of kiln dust to eliminate free liquids and usually form a low-strength solid. Lime-based processes for solidification use reactions of lime with water and pozzolanic (siliceous) materials, such as fly ash or dust from cement kilns, to form concrete, called a pozzolanic concrete. Wastes of desulfurization of gases and other inorganic wastes can be immobilized by this method. 

It has been shown that acid-resistant silicate polymer concretes based on liquid glass have high porosity (up to 18% to 20%), low strength and pot life, large shrinkage deformation, and insufficient water resistance. Therefore, they cannot be used as materials for load-bearing structural elements. 

Hydraulic limes are used for making mortar, plaster and concrete, particularly in Italy, France and Germany (see section 16.10 for their production). In the UK, their use is largely restricted to conservation and restoration work, where their slow set times and relatively low strengths are considered to be of particular benefit when used on weathered stonework [26.41]. 

---