Civil engineering board and affiliate programs

  WHAT IS CONCRETE : Concrete is a building material which made from mixture of cement , sand ,crush or gravel and water. and we poured this mixture in the form work which can give us the different shapes of element like stone which is too mush strong. WHY CONCRETE CRACKS : 1: Excess of water in concrete 2: Improper Compaction of concrete 3: Rapid drying of concrete 4: Temperature Variation 1: EXCESS OF WATER IN CONCRETE Concrete does not required much water to get maximum strength . we required limit water in concrete to achieve the maximum strength of concrete . when we increase the water in concrete so it can lose the strength , so therefore concrete can crack. water is just reducing in concrete to make workabality of concrete . so increasing of water can reduce the strength of concrete. 2: IMPROPER COMPACTION OF CONCRETE before placing concrete we have to proper compact the soil. and after that when we placed concrete so concrete should be compacted properly . when the con...

                    Table Contents 1 Soundneas 2 Wear Resistance 3 Alkali Aggregate Reaction 4 Other Alkali aggregate reactions 5 Alkali Silica Reactions 6 IMPURITIES PROPERTIES OF AGGREGATES The property of aggregates are mentioned below. 1. SOUNDNESS Rocks that undergo volume changes due to wetting and drying are . However, aggregate is susceptible to volume change during freezing and thawing cycles. Freezing can cause internal stresses to build up as water inside the aggregate freezes and expands. A critical size can be calculated below which freeze-thaw stress is not a problem; however, for most rock it is greater than normal sizes. 2. WEAR RESISTANCE A good aggregate will be hard, dense, strong, and free of porous material. The abrasion resistance of aggregate can be tested by the Los Angeles abrasion test; however, this test does not match well with concrete wear in the field. 3...

  ☞Depending upon the character of occupancy or the type of use, building can be classified into different categories as follows: 1. RESIDENTIAL BUILDINGS : These buildings include one or two private dwellings, apartment houses (flats), hotels, dormitories etc. 2. EDUCATIONAL BUILDINGS : These buildings include any building used for school, college or day care purposes involving assembly for instruction, education or recreation. 3 . INSTITUTIONAL BUILDINGS : These buildings include any building or part which is used for medical treatment etc. Such as Hospitals, nursing homes, orphanages, sanatoria, jails, prisons, mental hospitals etc. 4. ASSEMBLY BUILDINGS : These buildings may include any building or part of a building where a group of people gathers for recreation, amusement, social, religious or such types of purposes such as theaters, assembly halls, exhibition halls, restaurants, museum, club rooms, auditoria etc. 5. BUSINESS BUILDINGS : These shall includ...

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   10 POINTS SHOULD BE REMEMBER CIVIL ENGINEER ON SITE 1: Check size of bars for slab beam and column etc. 2: Length of bar for any steel which we use for construction works. 3: Position of bars. 4: Count No’s of steel bars 5: Check lap length of steel. 6: Check concrete cover for steel reinforcement. 7: Spacing of bar for beam column and slab etc. 8: Direction of bars 9: Check over all dimension of beam and slab. 10: Check beam and slab lever before starting concrete work

 Tendon Layout Tendons can have the following type of arrangement on plan Distributed - distributed (common in MIddle east and Australia) Tendons in the x and y directions are distributed over the length of the slab with a spacing not exceeding 1.5m. The issue with this arrangement is the tendon will be like a basket wieve and it’s difficult to know which one goes up and which one goes down. Banded - distributed (common in US) This will have the same distributed tendon as part 1 but one direction will be banded (usually grouped in a width 1-1.2m). No max spacing requirements for banded tendons Very easy to install as all the banded will be install first then the distributed Banded - banded Not very common Note: the horizontal spacing between tendons doesn’t affect the structures a lot, the most important thing is the tendon profiles (measured vertically) Economy of PT system PT slabs will commonly have up-to 30% less thickness, and complet...

 Myth associated with PT we cannot make an opening in PT slab, this is actually a false statement, a PT slab can be modified with proper calculations and expertise. We have made as big as 4m x5m opening in a PT slab which was required for sky light or escalators we need to do restressing periodically: this is also one of the things I hear about PT, but this is wrong. The strands are cut flush with the concrete surface and can not be restressed even if we wanted to. There is no requirements for restressing as we have low relaxation strands and a very good wedge anchor system PT slab can not crack: even though PT slabs are designed to be crack free at service load (at least based on ACI, some codes like EC allow for a certain degree of crack), cracks can be witnessed in PT slabs. This can attribute to one of the two 1. If the actual load exceeds the service load momentary 2. Surface cracks, which are very common No one can claim to have a crack free concrete by definition, we w...