 Hi everyone, Myself Supriya Pasnur working as an assistant professor in civil department from Walton Institute of Technology, Solaapur. Today's class, we are going to discuss the concrete block machinery. These are the learning outcomes. At the end of this session, students will be able to impart the knowledge of the hollow block machinery and its use and will be able to select the type of the bond for the machinery work. Introduction. It is a large rectangular brick which is used in the construction. Generally they are made up of the cast concrete, that is the Portland cement and the aggregate. Usually the sand and the fine gravel for the high density blocks. Even the lower density blocks may use the industrial waste as an aggregate. So these blocks, they can be built of various shapes and sizes depending upon their use. So the Indian standard, that is the IS 2185-2005 Part 1, that is concrete machinery units specification. It covers the following machinery units which are used for both the constructions such as the load bearing construction and the partition walls. And it is used in the residential buildings and the public buildings such as the schools and the churches or any other buildings. So the concrete machinery units. The block density, actually the density of the block it is calculated by dividing the mass of the block by the overall volume which includes the holes of the cavities and the end recesses. So just I will try to explain you the sketch of this. So these are the cores over here. So the cores in the block they should be 2 in number and they should preferably of the oval shape. And the face shells. The face shells are the outer two plates of the machinery blocks which are connected together by the webs. And webs are the solid sections of the hollow concrete block. They are connected together by the face shells. So this is the length of the block and this is the height of the block and the width of the block. So the height of the block it will be around 200 to 100 mm whereas the length of the block is 400 mm, 500 mm or 600 mm. And the width of the block it is 50 mm, 75 mm and it goes on increasing keeping an interval of 50 mm till 300 mm. So these are the parts of a machinery unit. And the gross area actually the gross area of the block it can be calculated by the area on the on its bedding face that is the total area occupied by the block on its bedding face which includes the areas of the blocks. So this is the table which consists of the minimum face shell and the web thickness. So here you can see the minimum that is the nominal block width which is 100 mm or less than 100 mm. As we have seen that the width of the block it varies from 50 mm, 75 mm and goes on till 300 mm. So here when the block thickness block width it is of 100 or less than 100 the face shell thickness is 25 mm and the thickness of the web is 25 mm. And the total thickness of the web per course in any of the 200 mm length of the wall it is 25 mm. So likewise when you over when the block width it is over 200 mm over there you can see that the facial thickness is 35 mm and this is the thickness of the web that is 30 mm and it goes on increasing from 25 to 30 mm. So this is the table of the facial thickness. Actually the facial thickness it should be the thickness which is recommended by the Concrete Association of India. It should be less than 5 centimetre and even the net area or the total area which is occupied by the block it should be around 55 to 60% of the gross area. So next we have the classification. So before the classification I will just tell you about the mix whatever the during the manufacture of the block what are the mixed to be used that is the course aggregate and the fine aggregate are to be used during the manufacturing. So the course aggregate it should be around 40% whereas the fine aggregate it should be 60% and the concrete mix which is used for the manufacturing is 1 is to 6 and even the strength of the block it should be around 30 kg per centimetre square and next is the water absorption of the block actually which is used for the external walls it should be around 10% consumption of the water and that which will be used for the internal walls the water consumption should be around 15% and the blocks which are used for the construction of the walls over there the dried blocks should be used most probably. So next is the classification and the materials of the concrete block. So the concrete block it consists of three grades that is the hollow concrete block in that we have the grade A and grade B and the solid concrete block it is grade C and these are the materials which are used that is the cement, aggregate, fly ash, water and the admixtures. So this is the table which consists of the blocks that is the now you have the type that is the hollow concrete block the load bearing actually the grade A it is the it is used for as a load bearing unit and the block density which is used during the manufacturing it should be around 1500 kg per metre cube for the grade A block and you can see over here that they are manufactured for a minimum average compressive strength of 3.5, 4.5 till 15 15 Newton per mm square respectively at 28 days. So next is the grade B. So the grade B the block density of this it should be less than 1500 kg per metre cube and not less than 1100 kg per metre cube. So even here we can see that they are manufactured for an average compressive strength of 3.5 and 5 Newton per mm square and these are also used as a load bearing unit. Next is the solid load bearing unit. This is a grade C it is a solid load bearing unit and they are also used for the load bearing constructions and then next is the they have the block density which should not be less than 1800 kg per metre cube and they are manufactured for an average compressive strength of 5 Newton per mm square and 4 Newton per mm square at 28 days respectively. Here you can pause the video for 2 seconds and try to give the answer for this. What is the density of the hollow concrete block? Yeah, this is the answer for that the density of the hollow concrete block is 1000 to 1500 kg per metre cube. These are the types of the concrete hollow blocks. First you have the hollow load bearing concrete block. The hollow blocks actually they are used as the load bearing walls and they are intended to carry the extra load also other than the self-weight. So here they are used for the actually they are easier in handling and even the facility for conducting the steel reinforcement is provided through the hollows. Next is the solid load bearing block. Here you can see there is no provision of the hollows and the cores in the hollows. The solid load bearing concrete block. This is used as a load bearing block and the steel reinforcement. There is no provision of the steel reinforcement in this. So it is not intended to carry any other load other than its self-weight. So next is the hollow non-load bearing concrete block. So you can see that this is the this is the hollow non-load bearing block. This is used for the fences and the wall partition walls. This is used for the construction of the partition walls and they are used as the fences and there is no provision of the steel reinforcement and even they are not intended to carry any extra load other than its own load. Next is the concrete building tiles. So the concrete tiles which are made up of the sand, cement or the water and the pigments and are not fired with the clay tiles and actually they are cured at a temperature of 60 degrees. So the curing process actually it is carried out so that it can be transported easily and it can be even during the manufacturing it can be led easily and even they can made stronger over time. Next is the concrete brick. This is a solid concrete. This is a solid concrete. It is used for the partition walls and also it can be used as the they are used as the partition walls and over the wide openings of the windows. Next is the types of the concrete. There are some more types of the hollow concrete blocks. This is the concrete stretcher block. So these are the most commonly used type of the block the stretcher block. Actually these blocks they are placed along the land they are placed along it along the land parallel to the face of the work and they are actually used used at the corners of the machinery. Next is the corner concrete corner block. The name itself says that they are used for the corners of the machinery work where you have a small openings of the windows or the door openings. Next is the concrete pillar block. So these are used for the construction of the pillars where the actually the ends of the blocks are visible. Here you can see this is the ends of the block. So over there the these types of the blocks are in use. Next is the jam concrete block. So a wood search jam block. It is used whether whether stretcher block and the corner blocks are in widely used over the elaborate window openings. So whether this type of the block can be used. Next is the partition concrete block. So this type of the blocks they are used for the partition walls. Next is the lintel concrete block. They are used for the construction of the lintel that is over the openings of the doors and the windows. The frog brick block. So there is the frog type of group which is done on the top of the block. So over here the mortar is filled to increase the thickness of this block and they can be used for the any type of the construction wherever the partition walls and the window openings and all it can be used over there. Next is the bull nose concrete block. The bull nose concrete block it is the same purpose as we have seen for the corner blocks. Only the difference is that when you have a needed of a when you have a round sharp edge round edge to be needed at the corners over there the bull nose concrete block can be used. So here are the MCQs. While manufacturing the concrete masonry bricks the cement aggregate ratio should not be thinner than 1st option is 1 is to 6 1 is to 3 3 is to 4 1 is to 4 hope so you have got the answer. Yeah this is the right answer for that next is the in concrete masonry hollow concrete units are used for dash walls neither the load bearing nor or non load bearing only the load bearing third is the only non load bearing and for this either the load bearing nor the non load bearing this is the right answer for that these are the references thank you