By: Andy

Andy — Sat, 25 Jun 2022 02:21:16 +0000

There are a few issues here.
1) Specifications may be cut and paste from project to project by the civil engineers to keep costs down but needs to be uniquely assessed and job specific. For example:In a block of flats suspended floors might be specified at 32MPS, 20 agg, 80 ml slump or 32/20/80. Let’s say this concrete is being pumped 20 metres horizontally through steel pipes then goes through a 90 degree angle to be pumped vertically through steel pipes to reach the suspended floor. Then it goes through another 90 degree angle followed by steel pipes for 10 metres followed by a reducer into 20 metres of flexible rubber pipe which then discharges the concrete in to the slab. The question is, is 20/32/80 an appropriate design. The answer is no, but that is what the civil engineers requested at tender stage based on cut and paste specifications. The whole design is now flawed. This is why on unsupervised building sites there is the constant high revolution whirr of the concrete agi drum because water has been added to make it pump but this weakens the concrete leading to potential compressive strength failure. The specification should read for this scenario 32/20/150 or 32/20/180, as this is how the concrete is being placed.
2) The industry itself has no mandated minimum requirements for concrete technical management roles in Australia. In the UK the industry requires people to have 5 years minimum technical experience plus concrete technology qualifications. Here in Australia, you don’t need any role specific qualifications or time in a supervisory role. You could have a degree in ceramics or home economics or another totally irrelevant subject and still get the job title of technical manager responsible for mix design, and all other aspects of concrete quality.
3) Here in Australia builders can self certify their own quality of the build so don’t need to pay for any testing and can add water to an unsupervised site agi to help with placement. There needs to be an independent observer/certifier I.e. an old fashioned clerk of works to certify all aspects of the build such as construction drawings replicated by placement of steel, concrete, layout etc. this is not happening on all sites because it is not a mandated requirement in Australia.

By: Alejandro

Alejandro — Thu, 23 Jun 2022 19:40:00 +0000

Buenas tardes,
La verdad con mucho respeto debo decir que para esta prueba no se requiere de un “experto” simplemente se necesita tener claro el método y con esto ya la prueba debería salir sin ningún problema.

Este ensayo es la mejor forma de identificar esa calidad de entrega de hormigón, por tanto no creo razonable siquiera pensar en dejar de lado esta prueba tan importante y que definitivamente nos brinda una buena idea de lo que estamos a punto de recibir en la obra.

Ahora los profesionales que se encargan de pedir el producto, si deben tener claro que necesitan y entender que las plantas de hormigón están en plena capacidad de entregar un buen producto, somos nosotros en obra quienes debemos actualizarnos y tomar decisiones técnicas y apoyadas en el mismo desempeño del producto y buenos elementos. Una saludo

Comments on: What is the concrete slump test controversy?

By: Andy

By: Alejandro