An essential aspect of job safety is fire prevention. In aiding this endeavor, superintendents and project managers often have the advice of insurance companies who perform inspection of the jobs, free of charge. Such inspections by insurance companies often result in reports with advice on fire-prevention procedures. Contractors will benefit from adoption of these recommendations. To deal most effectively with safety in the contractors organization, the contractor should assign responsibility for safety to one person, who should be familiar with all Federal and state regulations in the contractors area. This person should instruct superintendents and supervisors in safety requirements and, on visits to job sites, be constantly alert for violations of safety measures. The safety engineer or manager should ascertain that the construction superintendent holds weekly toolbox safety meetings with all supervisors and that the superintendent is writing accident reports and submitting them to the contractors insurance administrator. In addition, the safety supervisor should maintain a file containing all the necessary records relative to government regulations and keep handy a copy of Record- Keeping Requirements under the Occupational Safety and Health Act, Occupational Safety and Health Administration (U.S. Department of Labor, Washington, DC). Management should hold frequent conferences with this individual and with the insurance company to review the safety record of the firm and to obtain advice for improving this safety record. Community concerns with the results of new construction or disturbances from construction operations materially affect the construction industry. Some communities merely help shape projects that are being planned for construction in their environs. This aid consists of recommendations from community advisory boards and localization of planning. Other communities have assumed a more vigorous role in regulating construction, including the power of veto or costly delay over

Brick Properties Brick Technical Manual 6 1.3 Brick Strength Characteristic unconfined compressive strength (fuc) The fuc values are determined using the test method detailed in AS/NZS 4456.4 and is expressed in MPa (Mega Pascal). The test method involves subjecting the masonry unit to increasing load by compressing it between two metal platens in a compression testing machine. It is impractical to test every unit in a consignment, and usually a very small number of samples in relation to the large number of units it represents, are tested. For these reasons, the standard is based on the 95% characteristic value at a 75% confidence Figure 2 Compressive Strength of Masonry Units Brick Under Compression Load Cell Platen Effect of Platen Restraint Platen Hydraulic Ram level. This means that there is a 75% certainty that the strength of 95% of the units in the lot is higher than the characteristic strength determined from testing the samples. An aspect ratio (height-to-thickness ratio) factor is also incorporated to compensate for the frictional effects experienced between the unit and the platens which prevents the sideways spread of the unit as shown in figure 2. allows the results to be converted to an equivalent unconfined compressive strength value (fuc) independent of the dimensions of the unit. This strength value allows direct comparison of all masonry units, regardless of the size.

under the ACI 318 Building Code without special tests. When an aggregate for which no experience record is available is considered for use, the modulus of elasticity and shrinkage as well as the compressive strength should be determined from trial batches of concrete made with the aggregate. In some localities, aggregates acceptable under C33 or C330 may impart abnormally low ratios of modulus of elasticity of strength (E /
) or high shrinkage to concrete. Such aggregates should c c not be used. Principles for proportioning concrete to achieve a prescribed compressive strength after a given age under standard curing are simple. 1. The strength of a hardened concrete mix depends on the water-cementitious materials ratio (ratio of water to cementitious materials, by weight). The water and cementitious materials form a paste. If the paste is made with more water, it becomes weaker (Fig. 9.2). 2. The ideal minimum amount of paste is that which will coat all aggregate particles and fill all voids. 3. For practical purposes, fresh concrete must possess workability sufficient for the placement conditions. For a given strength and with given materials, the cost of the mix increases as the workability increases. Additional workability is provided by more fine aggregate and more water, but more cementitious materials must also be added to keep the same water-cementitious materials ratio. FIGURE 9.2 Curves show variation of 28-day compressive strength of normal-weight concrete with water-cementitious materials ratio. Solid lines indicate average results of tests. Dashed lines indicate relationship given in the ACI 318 Building Code for maximum permissible watercementitious materials ratio and specified 28-day