LIGHTWEIGHT HIGH-PERFORMANCE CONCRETE MASONRY-BLOCK MIX DESIGN

Concrete for masonry block is different from poured concrete in many w ays. A zero slump mix is needed in concrete block mixes, while poured concrete usually requires some specific slump. Vibropress technology i s generally used for compaction of the blocks, and the blocks are imme diately demolded, unlike poured concrete constructions. The texture of the block is one of the controlling factors in block mix design, and curing of concrete blocks takes place in special moisture and temperat ure-controlled chambers, unlike most poured concrete constructions. Th e design of lighweight high-performance concrete block mixes is summar ized here. Factors involved in the mix design are discussed in detail. Laboratory test specimens, as well as plant-produced blocks, have bee n studied for strength, density, texture, and cost. It is demonstrated that units having 50 percent of the weight, 200 percent of the streng th, and 125 percent of the material cost of normal weight standard uni ts can be produced. When the potentially increased mason productivity due to laying lightweight units is included in the overall cost analys is, a cost savings is shown to be possible.