Masonry brickwork has a density of 149 Ib/ft³. Determine the maximum height(FT) of a brick wall if the allowable compressive stress is limited to 130 Ib/in?. and the brick is 4.0 in. thick and 5.5 in. wide. Answer in two decimal places.

1. What component of concrete that has affect its strength largely? Explain. 2. If you have to choose, an expensive high quality concrete or a less expensive with low quality concrete? Explain. 3. To reduce corrosion on steel reinforcement, what you have to consider in the design? 4. A 300mm X 500mm concrete beam with a 25mm diameter reinforcing bar spaced at 50mm o.c will be constructed using a non-air entrained concrete. The design compressive strength at 28 days is 30 MPa. Design a concrete mix for the beam. The properties of the aggregates and cement to be used are given in the table below. Use a trial batch of 0.15 m3. Specific Gravity Absorption Moisture content Coarse aggregate 2.75 (SSD) 1.2% Fine aggregate Cement 2.56 (SSD) 3.15 2.5% 2.5% 4.5% Unit weight (dry 1750 kg/m3 rodded) FM 2.45

0 ww C. 6.31 A concrete mix includes the following ingredients per cubic foot: a. Cement = 25 lb b. Water = 11 lb c. No admixture Table P6.31 shows possible changes that can be made to the mix ingredi- ents. Indicate in the appropriate boxes in the table what will happen in each case for the workability and the ultimate compressive strength as increase, decrease, or approximately the same. TABLE P6.31 to dignope Cement (lb) 25 28 25 25 25 25 25 amigur Water (lb) 15 11 11 8 11 11 11 Admixture None None Water reducer Water reducer Superplasticizer Air entrainer Accelerator What Will Happen? www.10345 Ultimate Compressive we Strength Workability

Chapter 13 Question: What is the elasticity of concrete for a normal weight mix (unit weight equal to 150 pcf) with a compressive strength of 5,000 psi? O 3.644 ksi O 4.074 ksi 4,287 ksi O 3.976 ksi O 3,834 ksi