Comparative Study of Setting Time and Heat of Hydration Development of Portland Cement According to EN 196-3

Abstract

One of the most critical properties of cementitious materials is the initial (IST) and final (FST) setting time, which helps to plan the transportability, workability and demoulding of concrete over time. The standards used to determine the setting time are based on measurement of penetration resistance; these are measured of the depth of penetration with a well-defined body (usually a Vicat needle) into a cement paste as a function of time. Two European standards deal with setting time: EN-196-3 and EN 480-2. EN 196-3 is used to determine the setting time of cement paste of standard consistency. Semi-adiabatic calorimetry (SAC) can be a suitable method for determining the setting time of cementitious materials and concretes of non-standard consistency. This method examines the heat evolution of the hydration reaction of cement. The heat evolution is proportional to the change in viscosity during the setting process and to the Vicat needle penetration depth. This study aimed to find a simple, more accurate and cheaper alternative measurement method for determining the setting time of cementitious materials, which can also be applied to concretes.

1. Introduction

One of the most important parameters of the cementitious materials is the initial (IST) and final (FST) setting time. Knowing these data, it is possible to plan the maximum workability, casting (IST), and the initial hardening time can be estimated (FST) for formwork removal. The hydrate compounds formed during the hydration of clinker minerals (alite, belit, celite, felite) that evolve a solid matrix from the viscous slurry. The standards used currently measure this transformation process using various penetration resistance procedures (ASTM C191–19, ASTM C266–20, ASTM C403/C403M-16, ASTM C807–20, ASTM C953–17, AASHTO T131–20, AASHTO T154–18, ISO 9597:2008). These technics can be for example the Vicat needle test, Gillmore needles test, and the Hilti nail gun test [1].

The most common method for setting time measurement is the Vicat needle test. This method is applied by EN 196–3. A needle of well-defined weight and diameter is penetrated into cement paste of standard consistency during the process. The penetration of the needle is inversely proportional to the actual viscosity of the test sample, thus and the setting progress.

Despite the simplicity and prevalence of this method, several attempts have been made to induce the penetration method as this technique is applicable only for cement sludge and does not allow monitoring of the whole cement setting process. Such a method includes measuring ultrasonic impulse velocity [2, 3, 4, 5, 6] and the electrical resistance [7, 8, 9]. These methods are complex in structure and require high-level expertise that makes their use difficult.

Recently, the measurement based on semi-adiabatic calorimetry (SAC) has become popular for determining the setting time of cementitious materials [10, 11, 12, 13, 14, 15, 16, 17, 18]. During the procedure, the change in the hydration heat development of the cement is monitored as the clinker minerals chemically react with the water, which results in heat generation (exothermic reaction). The resulting temperature change usually follows the change in mechanical properties as well. The advantage of thermal analysis is the simple design of the measuring system which consists only of a thermally insulated vessel (calorimeter), a thermocouple and a data logger. In addition, ASTM C1679 and ASTM C1753 can help design and improve the successful execution of SAC tests.

During our measurement, we observed several disadvantages of the Vicat method prescribed by the EN 196–3 standard: discontinuous, inaccurate method, the drop number is limited, the examination of non-standard consistency (slightly plastic) mixtures is difficult. The standard measurement of the end of the setting time can be challenging with an automatic device, especially in the case of cementitious pastes with a long setting time [19, 20, 21], and automated devices are expensive equipment.

In this study, we compared the setting time of CEM I 42.5 N pure Portland cement according to EN 196–3 with the heat evaluation profile recorded during the calorimetric tests with three different water/cement (w/c) ratios. The measured cement paste was prepared using only deionised water and cement; no admixtures were added for the mixture preparation.

According to our hypothesis, the Vicat method can be substitute heat hydration measurement of the cement paste based on the results obtained from the synchronising of the two processes.

2. Short introduction of EN 196-3 standard

Currently, there are two European standards in force for determining the setting time of cementitious materials. The EN 196–3 cement testing method and the EN 480–2 deal with investigating concrete admixtures, but this standard also uses the Vicat method.

The same method is used for ASTM standards. These methods also measure the penetration resistance during the setting of cementitious materials using the Vicat and the Gillmore method. However, these standards already include mortar and concrete testing (ASTM C403/C403M-16, ASTM C807–20, ASTM C953–17).

The EN 196–3 standard principle is “cement paste of standard consistency has a specified resistance to penetration by a standard plunger.” The water content of the cement paste of standard consistency must be determined from several different mixtures. The setting time is defined by “observing the penetration of a needle into cement paste of standard consistency until it reaches a specified value.”

The standard specifies the following parameters:

• The laboratory in which specimens are prepared and tested shall be maintained at a temperature of (20 ± 2) °C and relative humidity of not less than 50%.

• The mixer must be conforming to EN 196–1.

• The procedure of the cement paste: quantity of cement (500 ± 1 g), the method of mixing:

  • the cement and water must be added within 10 s (zero time),

  • start mixing at slow speed (140 ± 5 rpm) for 90 s,

  • the mixing must be stopped for 30 s – during this time the cement paste must be scraped off the wall of the bowl and placed in the middle of it,

  • it follows another 90 s mixing, so the whole mixing time is 30 min.

• The temperature of the cement, the water and the apparatus used for the specimen preparation must be 20 ± 2°C,

• During the underwater tests, the water bath must be thermostatically controlled at (20.0 ± 1.0) °C.

• Vicat apparatus:

  • Plunger for determination of standard consistency: cylinder of at least 45 mm effective length and of (10.00 ± 0.05) mm diameter (Figure 1).

  • Vicat needle for initial set: steel and in the form of a right cylinder of effective length of at least 45 mm and diameter (1.13 ± 0.05) mm (Figure 1).

  • The total mass of moving parts shall be (300 ± 1) g.

  • Needle with attachment for final set: a needle with a ring attachment of diameter approximately 5 mm (Figure 1)

  • Vicat mould: it shall be made of hard rubber, plastics or brass. It shall be of cylindrical or truncated conical form (40.0 ± 0.2) mm deep and shall have an internal diameter of (75 ± 10) mm. A base plate must be placed which is larger than a ring and at least 2.5 mm thick, waterproof and resists to the effect of cement paste.

Figure 1.

Plunger for determination of standard consistency (left) Vicat needle for initial set time determination (middle), needle with attachment for final set time evaluation (right) (EN 196–3).

The cement paste must be prepared with a standard mixer according to the method as described in the EN 196–1. Then the lightly oiled Vicat mould is placed at a lightly oiled base plate (usually glass), then filled it with cement paste without compaction or vibration. The standard consistency of cement paste with smoothed upper surfaced is measured; then the plunger is changed for a needle at least 45 mm length and 1.13 ± 0.05 mm in diameter, and the initial setting time for this water content is determined.

For initial setting time (IST), the standard refers to the time that elapses between the mixing of the cement paste (zero time) and the time until the distance between the needle and the base plate is 6 ± 3 mm (penetration 34 ± 3 mm). To determine the final setting time (FST), the mould should be inverted, and the measurement must be continued with the needle with attachment. The time when the needle is already less than 0.5 mm penetrated in the cement paste is considered to be the final setting time, so only the needle and not the attachment leaves a mark on the surface of the specimen.

3. The problems during the standard measurement

The Vicat method, according to EN 196–3 is a penetration measurement, which can only be applied to standard consistency cement paste. It is possible to measure mortar with a modified Vicat test recommended by ASTM C807, but this method cannot be used for mortars with non-standard consistency. For the determination of setting time of concretes, an approximate result can be obtained by penetration resistance measurement using ASTM C403.

The method recommended by EN 196–3 can be challenging to determine for mixtures with non-standard consistency (viscosity). The Vicat mould can easily tip over, and the lower viscosity materials may leak at the bottom of the ring. Therefore, we designed a threaded Vicat mould (Figure 2) that also includes the base plate and fits precisely on the rotating plate of the Controls Vicamatic2 instrument used in our studies.

Figure 2.

Threaded Vicat mould.

After determining the IST, the threaded Vicat mould can be disassembled as needed and then inverted with the cement paste placed in it to measure FST. However, in the case of measurements with automatic Vicat instrument, it is impossible or very complicated to determine the end of the setting time according to the standard. Thus, the needle for the initial set is most often used for the whole test, and the sample is usually not reversed. In this case the shrinkage of the specimen must be considered by the effect of which FST seemingly appears at penetration rate more than 0.5 mm in the case of most measurements.

One of the main disadvantages of this method is from its discontinuous nature, due to which we cannot monitor the binding process precisely. The penetration resistance of cement paste which is proportional to changes in the viscosity of the material can be estimated by only individual “sampling”.

The automatic device we use can perform 44 standard drops, which means that when measuring mixtures with unknown setting times, this “sampling” has to be managed, especially in the case of cement pastes with a long setting time [19, 20, 21]. We can miss the IST if we start the measurement too early or set up a too-long delay time on the automatic Vicat device. In addition, care must be taken to set the proper drop sequence in order to achieve sufficient measurement accuracy.

4. Determination of setting time by thermal method

In order to avoid the problems mentioned above and to be able to monitor the setting process, semi-adiabatic calorimetry (SAC) is an increasingly widespread method for determining the setting time of cementitious mixtures [10, 11, 12, 13, 14, 15, 16, 17, 18].

The SAC method is suitable for determining the setting time of cement paste, mortar, and concrete, respectively. We can monitor the setting process; it is possible to measure more accurately. It is not disturbed by the shrinkage of the specimen. It can be done with a simpler and cheaper measuring instrument.

The ASTM C403 standard proposes two methods for the thermal determination of the setting time:

• The Derivatives method determines the initial setting time (IST), as the time which results from the maximum curvature of the second derivative of the hydration temperature–time function (Figure 3). It defines the final setting time (FST), as the time corresponding to the peak of the first derivative curve of the temperature–time function (Figure 4). This method may function well for clear data sets, but it is sensitive to the peaks not belonging to the ones occurring in data and to environmental changes [10, 11, 14, 15, 18].

• The Fractions method defines the initial and final setting times as a percentage of the temperature rise below the main hydration peak from baseline to the measured maximum (Figure 5). The initial and final setting times are determined as a percentage of the total semi-adiabatic temperature rise of the sample. 21% and 42% are the default initial and final setting time values at standard laboratory curing conditions [10, 11, 14, 18].

Figure 3.

Determination of IST from the derivatives method.

Figure 4.

Determination of FST by the derivatives method.

Figure 5.

Determination of the IST and FST as defined by fractions method.

This method is more stable than the Derivatives method, but it is more sensitive to the definition of baseline temperature [10].

5. The comparative measurement heat of hydration and the setting time according to EN 196-3

In our work, we investigated whether there is a simple correlation between the standard Vicat method and the heat evolution measurement results similar to the ASTM standard methods, which could lead to a method based on in many respects cumbersome and inaccurate penetration measurements. The tests were performed using CEM I 42.5 N cement and deionised water at 0.25, 0.28 and 0.31 water/cement ratios (w/c) at 26 ± 0.5°C. For the measurement we used Controls Vicamatic2 type automatic Vicat device, 300x400x300 mm polystyrene calorimeter and Comet M1200 data logger. We made three parallel measurements from each w/c; then the results were averaged.

In the first step, we synchronised the clock of the Vicat device and the data logger, and then we prepared the cement paste with the given w/c ratio according to the standard. For mixing, a standard Controls 65-L0502 mortar mixer was used to prepare a sufficient amount of sample for both Vicat and heat evolution testing.

For the standard setting time measurement, the threaded Vicat mould (Figure 2) was filled with cement paste and placed on the rotating plate of the automatic Vicat device. Air bubbles were removed from the sample by gentle tapping, and then the surface was smoothed.

For the semi-adiabatic (SAC) measurement, 1800 g (about 1 dm³) of the same cement paste was filled into a 1 l beaker pre-smeared with a form release agent. The sample was placed in the calorimeter. The Teflon-coated thermocouple was then immersed so that it extended to the centre of the sample (Figure 6).

Figure 6.

Polystyrene calorimeter with data logger.

During the measurement of heat of hydration the frequency of the temperature data collection was 5 min. By increasing the w/c, the Vicat measurement had to be started with a delay because the binding started later due to the higher water content.

6. Results and discussion

Data from the standard Vicat method and heat evolution measurements were synchronised and plotted on one graph (Figures 7–9). We represented the depth of each penetration of Vicat measurement on bar graphs in the setting time – heat development diagrams, while the blue curve shows the hydration heat development of the cement. The penetration at IST is marked with a blue bar; and the FST is marked with a red column according to EN 196–3 standard.

Figure 7.

Setting time—Heat evolution function (left), derivative method (right), w/c = 0.25.

Figure 8.

Setting time—Heat evolution function (left), derivative method (right), w/c = 0.28.

Figure 9.

Setting time—Heat evolution function (left), derivative method (right), w/c = 0.31.

According to the standard, when the penetration depth of the needle sinks only 34 ± 3 mm (6 ± 3 mm from the base plate) into the test specimen is considered to be IST. Thus, the time corresponding to the penetration depths of 37 and 31 mm can also be considered IST, which means that it is up to the person performing the measurement to consider which time he considers the initial setting time. This method can cause a problem, especially when measuring mixtures with long setting times, where this interval can mean a difference of several hours [19, 20, 21]. Determining the end of the setting time is even more of a problem, as penetration damages the surface of the specimen during the test and lowers it due to possible shrinkage, which makes it difficult to determine the FST accurately.

We considered the initial setting time to be the first penetration values smaller than 37.00 mm during our measurements. However, in determining the FST, we compared the previous test performed according to the standard (needle exchange, inversion of the specimen) with the result of the test performed with the needle used for the initial set, without inverting the specimen. Based on these, the time of penetration less than 2.00 mm below the level previously calibrated to 40 mm was considered to be the final setting time.

During the cement paste preparation previously, the temperature suddenly rises, then after a dormancy period, the temperature starts to rise again. In the case of the cement paste tested in the calorimeter, the maximum temperature exceeded 100°C in all cases. It was found that by increasing the w/c factor, the setting time is also extended in proportion to the initial temperature: w/c = 0.25 IST = 1:35–1:50, w/c = 0.28 IST = 2:05–2:15, w/c = 0.31 IST = 2:35–2:45 (see Table 1). Slower hydration is likely caused by an increased distance between particles [22]. Another factor may be that more water absorbs more heat, which is not used to accelerate the binding reaction.

		Vicat	Vicat-SAC		Vicat	Vicat-SAC		SAC
Sample name	w/c	IST [h:min]	TIST [°C]	ΔTIST [°C]	FST [h:min]	TFST [°C]	ΔTFST [°C]	Tmax [°C]	ΔtTmax. [h:min]
CW_05	0.25	1:35	34.1	8.3	2:20	38.1	14.9	106.4	5:05
CW_06	0.25	1:40	33.9	8.3	2:40	42.0	16.4	107.7	5:00
CW_07	0.25	1:50	34.7	8.7	2:30	39.1	13.1	107.2	5:15
CW_08	0.28	2:05	35.2	9.1	3:20	49.4	23.3	109.0	5:25
CW_09	0.28	2:05	34.8	8.8	2:55	41.4	15.4	108.2	5:35
CW_10	0.28	2:15	35.4	9.4	3:05	43.3	17.3	107.0	5:35
CW_11	0.31	2:35	36.7	10.5	3:20	43.7	17.5	104.2	6:10
CW_12	0.31	2:40	36.8	10.5	3:40	47.7	21.4	102.5	6:20
CW_13	0.31	2:45	35.9	9.9	4:05	51.7	25.7	103.4	6:30

Table 1.

Results of comparative measurements of Vicat and SAC method.

At 0.25 w/c ratio, the initial setting time occurred at a temperature rise of 8.3–8.7°C, while at 0.31 w/c ratio, an initial temperature (26 ± 0.5°C) of up to 10.5°C (Table 1). However, the temperature fluctuation of the mixtures prepared with the same w/c ratio measured at IST remained below 0.3°C, therefore the IST and FST values can be determined by measuring the temperature difference (ΔT_IST, ΔT_FST) similarly to the Fractions method at the same conditions. During our measurements, the initial setting time occurred at w/c = 0.25 is approx. 8.5°C, at w/c = 0.28 is approx. 9.0°C, and at w/c = 0.31 approx. 10°C temperature rise.

Notations: Vicat—setting time values obtained by the Vicat method, SAC—results of semi-adiabatic calorimetry, Vicat-SAC—temperature values for setting times measured with Vicat needle.

We examined the applicability of the Derivative method, but as shown in Figures 7–9, we observed significant differences in the measurement results. Using the Derivative method, IST was 1:40–2:00 delayed compared to the Vicat method, irrespective of w/c, while FST followed it with a 5–10 min lag. Thus, FST occurred with a delay of 0:35 and 1:20 compared to the standard method after the measurement.

Table 1 summarises the measurement results of the Vicat method and heat evolution. IST and FST denote the initial and final setting time, T_IST, T_FST mark the temperature value measured at this time, and ΔT_IST and ΔT _FST are the temperature difference measured from the initial temperature (26 ± 0.5°C). The T_max. and ΔT_max. are the maximum temperature or the corresponding temperature difference, while Δt_Tmax. shows the spent time until the maximum temperature value is reached.

We also found similar differences in the Derivatives method with the Fractions method. Table 2 shows the temperature values (T_{Fract IST}, T_{Fract FST}) for the given w/c ratio, calculated by the Fractional method, and the corresponding FSTs (Fract IST, Fract FST), and the difference between the results of the Fractions and the Vicat method (Δt_Fract-IST, Δt_Fract-FST) are indicated.

Sample name	w/c	TFract IST[°C]	Fract IST [h:min]	ΔtFract-IST [h:min]	TFract FST [°C]	Fract FST [h:min]	ΔtFract-FST [h:min]
CW_05	0.25	42.7	2:45	1:10	59.7	3:25	1:05
CW_06	0.25	42.8	2:45	1:05	60.1	3:25	0:45
CW_07	0.25	43.1	2:50	1:00	60.1	3:30	1:00
CW_08	0.28	43.5	3:00	0:55	60.9	3:45	0:25
CW_09	0.28	43.3	3:05	1:00	60.5	3:45	0:50
CW_10	0.28	42.0	3:05	0:50	60.0	3:50	0:45
CW_11	0.31	42.4	3:15	0:40	58.8	4:05	0:45
CW_12	0.31	42.1	3:15	0:35	58.1	4:10	0:30
CW_13	0.31	42.3	3:30	0:45	58.5	4:25	0:20

Table 2.

Results of comparative measurements of Vicat and fractions method.

It can be seen that the IST values calculated by the Fractions method give on average 40–65 min longer and the FST 31–56 min longer set values. The proportional factors (k_IST, k_FST) calculated by us in relation to the setting time measured by the Vicat method, as a function of the w/c ratio, are summarised in Table 3 (Eq. (1)). It was found that the constant proportionality factors of 21% and 42% given for the Fractions method increase with the w/c ratio.

w/c	kIST [%]	kFST [%]
0.25	10	18
0.28	11	23
0.31	13	28

Table 3.

The calculated proportional factors compared with the Vicat values.

$$k_{\mathit{ST}}\left[\%\right]=\frac{∆T_{\mathit{ST}}}{∆T_B}\bullet 100$$E1

where ΔT_ST is the temperature change belonging to IST or FST; ΔT_B is the difference between the maximum and the initial (room) temperature.

Based on these results the setting times can be calculated as follows (Eqs. (2) and (3)):

$${\mathrm{\Delta T}}_{\mathrm{IST}}\left(\mathrm{IST}\right)={\mathrm{k}}_{\mathrm{IST}}\left(\mathrm{w}/\mathrm{c}\right)\bullet {\mathrm{\Delta T}}_{\mathrm{B}},$$E2

$${\mathrm{\Delta T}}_{\mathrm{FST}}\left(\mathrm{FST}\right)={\mathrm{k}}_{\mathrm{FST}}\left(\mathrm{w}/\mathrm{c}\right)\bullet {\mathrm{\Delta T}}_{\mathrm{B}}$$E3

In our experiments, we assumed that for a given type of cement, with a defined w/c factor, for a given initial temperature and preparation method (see EN 196–3), the heat of reaction (heat of hydration) is the same under semi-adiabatic conditions. This also means that the reaction rate is constant, so the ratio of the time to maximum temperature (Δt_Tmax.) and the setting times (IST, FST) do not change. So, we calculated these differences (Eq. (4)):

$${\mathrm{\Delta t}}_{\text{Tmax}-\mathrm{IST}}={\mathrm{\Delta t}}_{\text{Tmax}.}–\mathrm{IST};{\mathrm{\Delta t}}_{\text{Tmax}-\mathrm{FST}}={\mathrm{\Delta t}}_{\text{Tmax}.}–\mathrm{FST}$$E4

, which proved to be nearly constant as expected. The fluctuations in the results were largely due to an error in the Vicat method (Table 4).

Sample name	w/c	ΔtTmax-IST [h:min]	ΔtTmax-FST [h:min]
CW_05	0.25	3:30	2:45
CW_06	0.25	3:20	2:20
CW_07	0.25	3:25	2:45
CW_08	0.28	3:20	2:05
CW_09	0.28	3:30	2:40
CW_10	0.28	3:20	2:30
CW_11	0.31	3:35	2:50
CW_12	0.31	3:40	2:40
CW_13	0.31	3:45	2:25

Table 4.

The differences between the time of maximum temperature and Vicat values.

7. Conclusions

The Vicat method prescribed by the EN-196-3 standard is a widespread measurement that is still in use today mainly due to its simple implementation. The measurement is used to determine the setting time of standard consistency cement paste; however, it is not suitable for non-standard flow cement paste or for testing mortars and concretes. It does not give a comprehensive picture of the setting process; it is inaccurate, which is a problem, especially in the case of cement pastes with a longer setting time. The measurement result depends to a large extent on the skill of the person performing the measurement, and in the case of the use of automatic Vicat devices, the end of the setting time cannot be determined according to the standard, or only with a great difficulty.

The semi-adiabatic calorimetric (SAC) method measures the amount of heat (reaction heat) released during the hydration reaction of a cementitious material, which is proportional to the reaction rate of the clinker minerals (and additives), i.e. the hardening process. The heat of hydration depends on the fineness of the grinding fineness of the cement, the w/c ratio, the method of preparation, the ambient temperature, the quality and quantity of additional materials. This means that for a given cement type and w/c ratio, at a constant environmental temperature, with the same mixing mode, the hydration heat development process takes place in the same way. Thus, for a given mixture, the time to the initial and final setting times and to the maximum of heat evolution is almost constant.

During our measurements, the setting properties of CEM I 42.5 N cement were investigated at 0.25, 0.28, and 0.31 w/c ratios with deionised water without admixtures and aggregates. We sought a parameter comparing the results of the heat evolution curve and the Vicat penetration test to estimate the initial (IST) and final (FST) setting time. As w/c increases, the setting time (ST) values extend and the associated temperature changes also increase, so these characteristics can only be used to determine the setting time for the mixtures of the same composition (Eqs. (5)–(7)).

$$\mathrm{w}/\mathrm{c}=0.25\mathrm{IST}\propto {\mathrm{T}}_0+8.5°\mathrm{C}$$E5

$$\mathrm{w}/\mathrm{c}=0.28\mathrm{IST}\propto {\mathrm{T}}_0+9.0°\mathrm{C}$$E6

$$\mathrm{w}/\mathrm{c}=0.31\mathrm{IST}\propto {\mathrm{T}}_0+10.0°\mathrm{C}$$E7

where T₀ is the initial temperature.

The IST, FST and the time to maximum temperature (Δt_Tmax.) occur proportionally later for mixtures with higher w/c ratios, however, the time between them (Δt_Tmax-IST, Δt_Tmax-FST) is almost constant (Table 3).

For the mixtures used in our studies, the IST and FST were measured 3.5 and 2.5 hours before Δt_Tmax. Minor fluctuations were observed only in the determination of FST values caused by the uncertainty resulting from the Vicat method. We can conclude that the setting time (ST) of the cement paste made of ordinary Portland cement without admixtures and aggregates can be determined without the use of Vicat apparatus. It can be determined accurately by SAC method with the knowledge of the time to maximum temperature (Δt_Tmax) corresponding to the maximum temperature value (T_max.) (Eqs. (8) and (9)):

$$\mathrm{IST}\propto {\mathrm{\Delta t}}_{\text{Tmax}}–3:30$$E8

$$\mathrm{FST}\propto {\mathrm{\Delta t}}_{\text{Tmax}}–2:30$$E9

Therefore, the SAC method is well applicable to simple Portland cement-water mixtures in the range of 0.25–0.31 w/c. Using too much mixing water (w/c > 0.44) will cause cement paste bleeding (water separation from the cement). Excess water does not participate in the chemical reaction of setting, but at the same time, it impedes the setting process and, due to its high heat capacity, draws heat out of the system.

The applicability of the SAC method to the investigation of the setting properties of CEM I 42.5 N Portland cement was confirmed at 0.25, 0.28, and 0.31 w/c ratios. Other cement pastes or mortars and concretes prepared without admixtures and supplementary materials may behave similarly, but it needs to be verified by further testing.

Acknowledgments

The authors of this article would like to thank Dr. László Csetényi for his helpful comments and supports, as well as Dr. Tamás Kói for his help in the mathematical problems occurred.

The authors acknowledge the support by the Hungarian Research Grant NVKP_16-1-0019 “Development of Concrete Products with Improved Resistance to Chemical Corrosion, Fire or Freeze-Thaw.”

List of referred standards

EN 196–3: 2017 Methods of testing cement. Part 3: Determination of setting time and soundness.

EN 480–2:2007 Admixtures for concrete, mortar and grout. Test methods. Part 2: Determination of setting time.

ASTM C191–19 Standard Test Methods for Time of Setting of Hydraulic Cement by Vicat Needle. ASTM International. West Conshohocken. PA. 2019. DOI: 10.1520/C0191-19

ASTM C266-20 Standard Test Method for Time of Setting of Hydraulic-Cement Paste by Gillmore Needles. ASTM International. West Conshohocken. PA. 2020. DOI: 10.1520/C0266-20

ASTM C403 / C403M-16. Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance. ASTM International. West Conshohocken. PA. 2016. DOI: 10.1520/C0403_C0403M-16

ASTM C807–20. Standard Test Method for Time of Setting of Hydraulic Cement Mortar by Modified Vicat Needle. ASTM International. West Conshohocken. PA. 2020. DOI: 10.1520/C0807-20

ASTM C953-17. Standard Test Method for Time of Setting of Grouts for Preplaced-Aggregate Concrete in the Laboratory. ASTM International. West Conshohocken. PA. 2017. DOI: 10.1520/C0953-17

ASTM C1679-17. Standard Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal Calorimetry. ASTM International. West Conshohocken. PA. 2017. DOI: 10.1520/C1679-17

ASTM C1753 / C1753M-15e1. Standard Practice for Evaluating Early Hydration of Hydraulic Cementitious Mixtures Using Thermal Measurements. ASTM International. West Conshohocken. PA. 2015. DOI: 10.1520/C1753_C1753M-15E01

AASHTO T131–20 Standard Method of Test for Time of Setting of Hydraulic Cement by Vicat Needle. American Association of State and Highway Transportation Officials. 2020.

AASHTO T154–18 Standard Method of Test for Time of Setting of Hydraulic Cement Paste by Gillmore. Needles. American Association of State and Highway Transportation Officials. 2018.

ISO 9597:2008 Cement-test Methods – Determination of Setting Time and Soundness. International Organization for Standardization