To compete in today's construction market, a wall system has to provide not only structural capacity, but other properties as well: energy conservation, fire resistance, durability, sound resistance, weather protection, and economy. These expectations are driven by three needs. The properties of lightweight concrete block make it suitable to meet each of them: increased thermal resistance, limiting fire spread, and improved jobsite productivity. STRENGTH-TO-WEIGHT RATIOS Decreasing weight while maintaining or increasing strength is the greatest challenge facing lightweight concrete block manufacturers. Two key areas where strength-to-weight ratios of lightweight concrete block can be improved are: aggregate properties, and mix compaction.