Control, Construction and Isolation Joints

Control, Construction and Isolation Joints

Concrete shrinks irreversibly as it cures and dries out. After this initial shrinkage has occurred, concrete expands and contracts reversibly with changes in temperature and moisture content. This movement can cause concrete to crack uncontrollably unless it is reinforced with steel and built with special joints that are designed to control cracking locations.

 The amount of expansion and contraction that concrete will experience is influenced by several things, including the water content of the mix, and the weather conditions during the curing period. Mixes made with a high water content are more prone to cracking from initial shrinkage than drier, stiffer mixes. Reinforcing steel increases the strength of concrete and absorbs the stress of expansion and contraction, but it cannot prevent cracking altogether it can only distribute the stresses so that there will be many minute cracks instead of a few big ones. While reinforcement limits the amount of expansion and contraction to some extent, cracking and movement can also be regulated by subdividing the concrete into smaller sections with control joints and construction joints, and separating it from adjacent construction with isolation joints.

Preparing and Placing of Concrete

Preparing and Placing of Concrete

The following steps are involved in the concreting:

1.Batching

2.Mixing

3.Transporting and placing and

4.Compacting.

 1. Batching: The measurement of materials for making concrete is known as batching. The following two methods of batching is practiced:

(a) Volume batching

(b) Weight batching

(a) Volume Batching: In this method cement, sand and concrete are batched by volume. A gauge box is made with wooden plates, its volume being equal to that of one bag of cement. One bag of cement has volume of 35 litres. The required amount of sand and coarse aggregate is added by measuring on to the gauge box. The quantity of water required for making concrete is found after deciding water cement ratio. For example, if water cement ratio is 0.5, for one bag of cement (50 kg), water required is 0.5 × 50= 25 kg, which is equal to 25 litres. Suitable measure is used to select required quantity of water.

(b) Weight Batching: This is the recommended method of batching. A weighing platform is used in the field to pick up correct proportion of sand and coarse aggregates. Large weigh batching plants have automatic weighing equipments.

2.Mixing: To produce uniform and good concrete, it is necessary to mix cement, sand and coarse aggregate, first in dry condition and then in wet condition after adding water. The following methods are practiced:

(a) Hand Mixing

(b) Machine Mixing.

(a)  Hand Mixing: Required amount of coarse aggregate for a batch is weighed and is spread on an impervious platform. Then the sand required for the batch is spread over coarse aggregate. They are mixed in dry condition by overturning the mix with shovels. Then the cement required for the batch is spread over the dry mix and mixed by shovels. After uniform texture is observed water is added gradually and mixing is continued.

(b) Machine Mixing: In large and important works machine mixing is preferred. A typical concrete mixer. Required quantities if sand and coarse aggregates are placed in the drum of the mixer. 4 to 5 rotations are made for dry mixing and then required quantity of cement is added and dry mixing is made with another 4 to 5 rotations. Water is gradually added and drum is rotated for 2 to 3 minutes during which period it makes about 50 rotations. At this stage uniform and homogeneous mix is obtained.

3. Transporting and Placing of Concrete. After mixing concrete should be transported to the final position. In small works it is transported in iron pans from hand to hand of a set of workers. Wheel barrow and hand carts also may be employed. In large scale concreting chutes and belt conveyors or pipes with pumps are employed. In transporting care should be taken to see that seggregation of aggregate from matrix of cement do not take place.

Concrete is placed on form works. The form works should be cleaned and properly oiled. If concrete is to be placed for foundation, the soil bed should be compacted well and is made free fromloose soil.

Building Foundation

Building Foundation

The foundation is the most critical part of any structure and most of the failure is probably due to faulty foundations rather than any other cause. The purpose of foundation is to transmit the anticipated loads safety to the soil.

Basic requirements:

• To distribute the total load coming on the structure over a large bearing area so as to prevent it from any movement.
• To load the bearing surface or area at a uniform rate so as to prevent any unequal or relative settlement.
• To prevent the lateral movement of the structure.
• To secure a level or firm natural bed, upon which to lay the courses of masonry and also support the structure.
• To increase the suitability of the structure as a whole, so as to prevent it from overturning or sliding against such as wind, rain, frost etc.

Component parts of building

Component-parts-of-building

The building basically consists of three parts namely,

1) Foundation

2) Plinth and

3) Super structure

Foundation : It is the lowest artificially prepared part below the surface of the surrounding ground which is indirect contact with sub-strata and transmits all the loads to the ground (or sub-soil).

Plinth : It is the middle part of the structure, above the surface of the surrounding ground up to the surface of the floor immediately above the ground. Its function in the building is same as of sub-structure in the case of the bridge.

Super structure : It is that part of the structure which is constructed above the plinth level (i.e., ) ground level A building in general made of the following structural components.

1. Foundation

2. Plinth

3. Walls and piers in super structure

4. Ground, basement and upper floors

5. Doors and windows

6. Sills, Lintels and weather shades

7. Roofs8. Steps and stairs

9. Finishes for walls

10.Utility fixtures

Each of these components is an essential part of a building and requires due consideration in design and construction for their functional performance.

Testing the Consistence by Degree of Compatibility

Testing the Consistence by Degree of Compatibility

Principle:

The fresh concrete is placed carefully in the steel test container. Compaction must be avoided. When the container is full to overflowing, the concrete is smoothed flush with the edge without vibration. The concrete is then compacted, e.g. with a poker vibrator (max.bottle diameter 50 mm).  After compaction the distance between the concrete surface and the top of the container is measured at the centre of all 4 sides. The mean figure (s) measured is used to calculate the degree of compatibility.

Container dimensions                    Base plate        200 x 200 mm     (±2)

                           Height                      400 mm                   (±2)

Concrete in container                                  Concrete in container

before compaction                                       after compaction

Degree of compatibility: c=       h1

                                                   _________    (non dimensional)

                                                      h1 – S

Precast Concrete Applications

Precast Concrete Applications

Precast concrete has been used extensively in recent years. We have already discussed the advantages to this type of repair process. Here are some of the types of concrete structures where precast concrete can be used:

■ Navigation locks

■ Dams

■ Channels

■ Floodwalls

■ Levees

■ Coastal structures

■ Marine structures

■ Bridges

■ Culverts

■ Tunnels

■ Retaining walls

Expansive cement

expansive cement

A cement which when mixed with water forms a paste that tends to increase in volume, after setting, to a significantly greater degree than Portland cement paste does; used to compensate for volume decrease due to shrinkage or to induce tensile stress in reinforcement. Classified as Type K: Contains anhydrous aluminosulfate burned simultaneously with a Portland cement composition, or burned separately when it is to be inter-ground with Portland cement clinker or blended with Portland cement, calcium sulfate, and free lime. Type M: A mixture of Portland cement, calcium aluminates cement, and calcium sulfate. Type S: A Portland cement containing a large computed tri calcium aluminates content, modified by an excess of calcium sulfate above usual optimum content.

What are the core strengths we possess in this business ?

Mastour ReadyMix is a ready mix concrete and cement products company Kingdom of Saudi Arabia

ROBUST INFRASTRUCTURE. SPEED OF DELIVERY. CUSTOMISED SOLUTIONS. SUPERIOR QUALITY.
Mastour ReadyMix’s value proposition stems from a variety of synergistic factors, with the most important one being rich experience and comprehensive know-how of our team which help to customize mixes to suit the diverse requirements of clients.
With our commitment to develop robust infrastructure with high production capacities and focus on manufacturing superior quality in fully automated batching plants and ensuring speed in delivery using sophisticated equipment, methods and means, Mastour ReadyMix is all set to garner a significant share of this industry.
Additionally, testing of raw materials & fresh concrete and large fleet of transit mixers & mobile and stationary pumps help discharge concrete at high elevations and over long distances.
Setting up of a concrete testing laboratory:
At Mastour ReadyMix, we understand that our concrete and cement products, are the most unique and versatile building materials in the Saudi Arabia. It can assume virtually any shape and reach great strengths. Concrete is ideal for any building project such as residential homes, schools, high-rise buildings, bridges, dams, highways etc. Concrete is perishable in its plastic state and very “sensitive” from the time the raw materials are combined to the final product. Mixing, transportation, placing, and curing can influence its plastic and hardened properties. This is why Mastou ReadyMix places great emphasis on quality by expanding the parameters of its concrete quality management model from quality control to quality assurance. Mastou ReadyMix is leading the way to higher quality practices with the implementation of a Quality Management System based on the guidelines and principles
This laboratory would help us in:
• Becoming expert in mix designs of high strength concrete.
• Gathering knowledge of durable production of concrete.
• Concrete practices and repair/rehabilitation of deteriorated
structures
• Offering services to large institutional clients
• Finalizing of mix designs, development of special concretes,
mixes for hollow, solid and paving concrete blocks, optimization
of mixes.
• Conducting trials for the optimization of admixture doses etc.
Our experienced technical and marketing team enables us to define & specify quality standards and also design concrete mixes to meet clients’ specific requirements while our strong Reasearch & Development and market knowledge helps to avoid setting of Ready mix Concrete, which are critical aspects in the Ready mix Concrete business.
Our ability consistent and assured quality of concrete with the flexibility to easily insert admixtures, manufactured under stringent conditions to prevent overdosing of admixture, while also checking the slump, gives a fillip to our already superior quality standards.
Lastly, we are well poised to raise the quality bar by virtue of our ability to integrate backwards and carry out mining and crushing activities using the latest technology crushing equipment.

Concrete Block

Mastour ReadyMix is a Ready mix concrete and cement products company Jeddah Saudi Arabia.

Concrete block, cement block, and foundation block – is a large rectangular brick used in construction. Concrete blocks are made from cast concrete, i.e. Portland cement and aggregate, usually sand and fine gravel for high-density blocks. Lower density blocks may use industrial wastes as an aggregate. Clinker blocks use clinker as aggregate. In non-technical usage, the terms cinder block and breeze block are often generalized to cover all of these varieties. Lightweight blocks can also be produced using aerated concrete

Uses

Concrete block, when built in tandem with concrete columns and tie beams and reinforced with rebar, is a very common building material for the load-bearing walls of buildings, in what is termed “concrete block structure” construction. Large buildings typically use copious amounts of concrete block; for even larger buildings, concrete block supplements steel I-beams. Tilt-wall construction, however, is replacing Concrete Block Structure for some large structures.

Parking Stoppers

Mastour Ready Mix provides its customers with high-quality branded cement products for their construction needs

A parking space commonly contains a parking Stoppers, a barrier which is used to prevent cars from pulling too far into the space and obstructing a neighboring parking space, curb, or sidewalk.

This barrier, also called a Parking Stoppers, is usually made of concrete  and will normally be a horizontal bar to stop the tires from moving forward or a vertical bar that may cause damage to the vehicle if contact is made. In a parking garage, the barrier will often be a concrete wall.

All of our Parking Stoppers have a smooth form finish. The stops are vibrated as they are cast to provide good consolidation of the concrete which increases durability and improves their appearance. Holes are formed through the tops of the curbs at each end of the piece so that a ½” thick piece of rebar can be inserted for anchoring to asphalt or concrete surfaces. You can be sure that when you buy from us, you are buying a strong, durable product that you deserve. Don’t spend good money on cheap imitation parking stoppers, put your hard earned money in a quality product.

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