EOQ, JIT and fixed costs in the Ready-mixed concrete industry

The successful implementation of just-in-time (JIT) purchasing policy in many industries has prompted many companies that still use the economic order quantity (EOQ) purchasing policy to ponder if they should switch to the JIT purchasing policy. Despite existing studies that directly compare the costs between the EOQ and JIT purchasing systems, this decision is, however, still difficult to be made, especially when price discount has to be considered. JIT purchasing may not always be successful even though plants that adopted JIT operations have experienced or can take advantage of physical space reduction. Hence, the objective of this study is to expand on a classical EOQ with a price discount model to derive the EOQ–JIT cost indifference point. The objective was tested and achieved through a survey and case study conducted in the ready-mixed concrete industry in Singapore.

A model for comparative analysis of inventory costs of JIT and EOQ purchasing in the ready mixed concrete industry

A model for comparing the inventory costs of purchasing under the economic order quantity (EOQ) system and the just-in-time (JIT) order purchasing system in existing literature concluded that JIT purchasing was virtually always the preferable inventory ordering system especially at high level of annual demand. By expanding the classical EOQ model, this paper shows that it is possible for the EOQ system to be more cost effective than the JIT system once the inventory demand approaches the EOQ-JIT cost indifference point. The case study conducted in the ready-mixed concrete industry in Singapore supported this proposition.

Potential reduction of concrete deterioration through controlled DEF in hydrated concrete

Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on cracked walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading through the concrete structure. In this study, finely dispersed crystallization nuclei achieved by adding air-entraining agent (AEA) and short vibration of specimens is presented as the main prerequisite for reducing DEF-induced deterioration of hydrated concrete. The study presents the method and mechanism for obtaining the required nucleation. Controlling long-term DEF by providing AEA-induced crystallisation nuclei, prevented excessive and rapid initial strength improvements, and resulted in a slight increase of compressive strength of fine grained concrete with only marginally lower density.

Concrete gown for immaterial flows

Concrete Gown for Immaterial Flows was a sculptural installation and performance commissioned by the Hayward Gallery as part of the Mirrorcity exhibition (14 October 2014 - 4 January 2015). In an age of increasingly abstract power, ideology is disavowed as a twentieth century relic. We are instead told we are governed by pragmatic decisions based on charts and figures. Responding to this notion, Concrete Gown for Immaterial Flows is comprised of a concrete materialisation of abstract financial charts. It forms a stage upon which a series of live music performances take place. Musicians were commissioned to produce new interpretations of Nathan Alterman's "Morning Song", an old Zionist love song to the state, promising to clothe it in concrete and cement. Thus, the immateriality of financial transactions is made physical and given the monumental language it lacks in a patriotic offering for our times.

Analysis of experimental interlocking blocks of concrete with addition of residues of process the tires retreading production

Analysis of experimental interlocking blocks of concrete with addition of residues of process the tires retreading production. With the population growth in recent years, industry in general has adjusted itself to resulting demand. the industry of tire retreading generates residues that have been discarded without any control. this adds to environmental pollution and promotes the proliferation of vectors harmful to health, aiming to find an application for this type of residues, this study presents experimental results to interlocking concrete block pavements, with addition of residues tires, interlocking blocks were built up and we determined, through laboratory tests, the need to set the mark that provide greater return regarding analyzed characteristics, there are four types of dosage of concrete with residues tires. We accomplished tests of compression strength, water absorption and resistance to impact. Through the preliminary results, we verified that are satisfactory, confirming the possibility of applying this type of interlocking block in environments with low demand, which would bring the economy of natural sources of aggregates, beyond ecological benefits through the reuse of residues from retreading of tires.

The concept of quasi-integrability: a concrete example

We use the deformed sine-Gordon models recently presented by Bazeia et al [1] to take the first steps towards defining the concept of quasi-integrability. We consider one such definition and use it to calculate an infinite number of quasi-conserved quantities through a modification of the usual techniques of integrable field theories. Performing an expansion around the sine-Gordon theory we are able to evaluate the charges and the anomalies of their conservation laws in a perturbative power series in a small parameter which describes the ""closeness"" to the integrable sine-Gordon model. We show that in the case of the two-soliton scattering the charges, up to first order of perturbation, are conserved asymptotically, i.e. their values are the same in the distant past and future, when the solitons are well separated. We indicate that this property may hold or not to higher orders depending on the behavior of the two-soliton solution under a special parity transformation. For closely bound systems, such as breather-like field configurations, the situation however is more complex and perhaps the anomalies have a different structure implying that the concept of quasi-integrability does not apply in the same way as in the scattering of solitons. We back up our results with the data of many numerical simulations which also demonstrate the existence of long lived breather-like and wobble-like states in these models.