Concrete

Making Concrete in Cold Conditions

Published

10 years ago

February 28, 2017

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Cold weather is defined as a period when the average daily temperature falls below 4?C for more than three successive days. These conditions warrant special precautions when placing, finishing, curing and protecting concrete.

Concrete production always faces a problem during cold weather. There are two main problems associated with cold weather. The general rule is that the concrete has to gain strength till about 500 psi (35 kg per cm2).

Concrete can freeze before it gains strength which breaks up the matrix;
Concrete sets more slowly when it is cold – very slow below 6? C; below 4? C, the hydration reaction basically stops and the concrete doesn’t gain strength.
But these are concrete temperatures, not air temperatures. So when it’s cold, the concrete has to be protected until it can handle the cold on its own. The general rule is that the concrete has to gain strength till about 500 psi (35 kg per cm2). Almost the same time that the concrete achieves 500 psi compressive strength, hydration of the cement consumes enough of the water in the original mix so that even if it does freeze, there’s not enough water left in the pores to damage the concrete. With most concrete, even at 6?C, this happens during the second day.

To help it reach that 500 psi strength, the mix can then be changed to get it to set more quickly or protect the concrete from the cold – or more likely do both.

Changes to Concrete Mix during Cold Weather
Many of the problems with cold weather can be overcome by the ready mix producer. Here are a few things to keep in mind:
Hot water: A ready mixed concrete producer will usually have, and use, hot water in the concrete when the weather turns cold. Most producers will try to have the concrete be at least 180C when it leaves the plant, which is generally good enough depending on air temperature and thickness of the concrete element. The slump has to be specified at less than 100 mm and air-entrained concrete should be used to reduce bleeding.

Accelerators: Since colder weather leads to colder concrete, the set time can be delayed. Accelerators added to the concrete can keep it on schedule. Addition of 2 per cent (by weight of cement) of calcium chloride is the traditional way to accelerate the hydration reaction – it is very effective and reasonably cheap. But – a big but -that much chloride can lead to corrosion of any steel embedded in the concrete (like rebar) and can lead to a mottled surface appearance with coloured concrete.

Non-chloride accelerators are also widely available and are very effective. They won’t discolour the concrete, but they are a bit expensive. Accelerators are not anti-freeze agents – they simply increase the rate of the hydration reaction.

Fly ash: Producers should typically stay away from using fly ash or slag cement in cold weather, since those materials set more slowly and generate less internal heat; slag can cause the same effect.

To make the reaction a bit hotter, the ready mix producer can add some extra cement (typically 60 kg per cubic metre) or can use Type III (high-early strength) cement, which hydrates more rapidly.

Producers have to be careful with water reducers in cold weather, since they can slow the set time. Besides, cooler concrete seldom needs water reduction since the cooler temperatures prevent slump loss. For admixtures added at the job site, they shouldn’t be used if they have frozen. The chemicals may have separated.

Precautions before Placing Concrete in the Cold
When cold weather comes on unexpectedly, the following tips will help:
Frozen ground: Concrete should be never placed on frozen ground or onto ice or snow. There are a couple of problems with this. First, frozen ground will settle when it thaws, cracking the concrete. Second, when the ground is cold, the concrete in contact with it will be cold and will set more slowly. Crusting might also occur, with the top part of the concrete set and the bottom still soft. If the ground is frozen, it can be thawed using hydronic heat pipes and blankets (such as those from ground heaters), or electric blankets.

Anything that will come in contact with the concrete should be warmed up, including forms and any embedment, to at least 00C. If it’s not too cold and everything is covered with tarps the day before the pour, it will stay dry and warm enough.

Concrete

Assam Cabinet Approves Rs. 110 bn JK Lakshmi Cement Investment

ADB-backed project to restore 102 community beels also approved

Published

6 hours ago

September 28, 2026

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The Assam Cabinet has approved an investment of Rs. 110 bn by JK Lakshmi Cement for a clinker manufacturing unit and four associated cement grinding units in the state. Chief Minister Himanta Biswa Sarma announced the decision on 24 September 2026, along with approvals covering wetland restoration and industrial support.

The proposed cement investment is expected to generate around 2,000 direct jobs. The project forms part of the state government’s latest measures to attract manufacturing activity and strengthen industrial infrastructure. The Cabinet also approved a State Capital Investment Subsidy for eligible manufacturing units covered by the substantive provisions of the Uttar Poorva Transformative Industrialization Scheme, or UNNATI, 2024.

The subsidy will apply to units that qualified under the scheme but were unable to secure registration by the extended deadline of 30 September 2026. The measure is intended to support eligible businesses that missed the registration process while continuing to meet the scheme’s substantive requirements.

The Cabinet also cleared an Asian Development Bank (ADB)-funded project for the restoration and rehabilitation of at least 102 derelict community beels across Assam. The ADB loan component is Rs. 6.38 bn, while the Assam government’s contribution will be Rs. 1.59 bn.

In another decision, the Cabinet approved a rent-based or pro bono arrangement for constructing a laboratory and ancillary infrastructure for the Spices Board under the Ministry of Commerce and Industry. The facility will be built at Ulubari in Guwahati, with the Agriculture Department coordinating with the Public Works Department (Buildings) to construct it according to designs and specifications provided by the board.

Concrete

JSW Cement Receives Rs. 2.3 bn GST Demand Notice

JSW Cement faces a GST demand over alleged incorrect classification.

Published

6 hours ago

September 28, 2026

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JSW Cement has received a show-cause notice proposing a Goods and Services Tax (GST) demand of Rs. 2.3 bn, along with applicable interest and a 10 per cent penalty, over an alleged incorrect classification of transactions. The notice was issued by the Additional Commissioner of Central Tax, Belagavi Audit Commissionerate, on September 24, 2026.

The proposed demand relates to the period from April 2022 to March 2024 and has been issued under Section 73 of the Central Goods and Services Tax (CGST) Act, 2017. The company disclosed the notice in a filing with the stock exchanges and said the matter involved an alleged short payment of GST.

The proposed amount comprises Integrated GST (IGST) of Rs. 1.22 bn, Central GST (CGST) of Rs. 540.5 mn and State GST (SGST) of Rs. 540.5 mn. The department has also cited alleged contraventions of Sections 9, 37 and 39 of the CGST Act, with interest proposed under Section 50 and the penalty under Section 73.

JSW Cement said the financial impact of the notice would be limited to the proposed tax demand, applicable interest and penalty. However, it assessed that the matter would not have a material impact on the company. The cement manufacturer is preparing its reply to the show-cause notice.

The notice was issued to JSW Cement, which is part of the Sajjan Jindal-promoted JSW Group. The company reiterated that the total proposed GST demand stood at Rs. 2.3 bn, excluding the applicable interest and 10 per cent penalty, and that the proceedings remained at the show-cause stage.

Shares of JSW Cement ended at Rs. 115.65 on the BSE on Thursday, down Rs. 2.60, or 2.20 per cent, from the previous close. The stock movement came as the company disclosed the proposed tax demand and its intention to respond to the department’s notice.

Concrete

Montra Electric, Wonder Cement Deploy 250-Vehicle EV Fleet

Fleet to haul cement on a 1,450-km corridor across four states

Published

6 hours ago

September 28, 2026

admin

Montra Electric and Wonder Cement have begun commercial operation of a 250-vehicle deployment of Rhino 5538 EV 4×2 tractor-trailers on an electric freight corridor linking Rajasthan with ports in Gujarat. The companies said the fleet is being used for regular cement logistics rather than a limited pilot, making it one of the largest heavy-duty electric truck deployments by an Indian industrial company.

An initial 30 trucks were introduced from Wonder Cement’s plant in Nimbahera, Rajasthan, in July 2026. They are hauling full payloads on daily routes between Nimbahera and Dahej Port and between Nimbahera and Tuna Port, covering approximately 1,450 km across Rajasthan, Madhya Pradesh, Maharashtra and Gujarat. The vehicles operate to schedules comparable with those of the company’s conventional diesel fleet.

The corridor is supported by 13 dedicated charging stations positioned to enable long-distance duty cycles within industrial turnaround times. The Rhino 5538 EV is available with a 55 t Gross Combination Weight option and is designed for cement, coal and clinker transport. Its specifications include a 282 kWh lithium iron phosphate battery, a Permanent Magnet Synchronous Motor producing 280 kW and 2,000 Nm of torque, 18 per cent continuous gradeability and a 6-speed Automated Manual Transmission.

The vehicle has a stated range of 198 km under specified test conditions, with one side loaded and the other empty. It can charge from 20 to 100 per cent State of Charge in 60 minutes and is supported by more than 95 per cent assured uptime. Montra Electric and Wonder Cement said the deployment would assess electrification through payload capacity, turnaround performance and daily availability in live freight operations.

Montra Electric said the same operating model could support steel, mining, infrastructure and port haulage, where fixed routes and predictable turnaround windows are common. The company has more than 750 heavy-duty electric vehicles on Indian roads and has covered over 30 mn km across its deployments. Montra Electric operates as the clean mobility arm of the Murugappa Group, with businesses spanning heavy commercial vehicles, smaller commercial vehicles, three-wheelers and electric tractors.